BIOL 1104 UNIT 3

Primary Succession

newly exposed or newly formed rock is colonized by living organisms.

Day 17

BIOL 1104 DAY 17: WE'RE ALL IN COMPETITION COMPETITION · Similar to growth rate, but now it is RELATIVE. · How do organisms that use the same resource (water, space, food, sunlight) end up limiting each other's distribution or abundance? How do we think about a CARRYING CAPACITY that is ACROSS SPECIES? · For a given set of abiotic and biotic conditions (the context is always key), the RELATIVE FITNESS OR COMPETITIVE STRENGTH is their RELATIVE ability to grow in that context. · LAST TIME, WE TALKED ABOUT POPULATIONS. NOW, WE SEE HOW THEY INTERACT IN COMMUNITIES. · Lab example of competition: 2 species of Paramecium have a certain logistic growth on their own; competitive exclusion when together. · Always pay attention to the axes on the graph, though! Textbook example shows that for given resources, these 2 species vary for r and K INDIVIDUALLY; but together, P. aurelia is still more efficient than the other species at using available resources. · Competition can be INDIRECT - both organisms need same food, light, etc, but don't physically encounter one another. · Or DIRECT where one physically prevents the other from thriving. · What are the many resources that types of organisms may compete over? · A puzzle: "paradox of the plankton" is that to humans, oceans seem evenly-mixed, but to microscopic plankton, nearly endless distinct habitats and resources. · COMPETITION FOR... SPACE? · Trees and sunlight; sagebrush and water; barnacles and bare rock (a stable place to live and feed) · Competition can affect overall distribution of one or both species, as shown with where LARVAE settle vs where they survive as adults, crowd each other out. · NICHE - area a species is found is set by the environment (fundamental niche) and interactions (REALIZED niche) · THINGS EAT THINGS: · It all starts with PRODUCTIVITY (photosynthetic organisms get eaten -herbivory-, and that group of consumers gets eaten -predation-) · Sunlight generates glucose, glucose metabolized into ATP, etc · Tremendous diversity of how organisms obtain energy. Autotrophs and heterotrophs. · Trait diversity among organisms includes defenses against being eaten, and traits to enable getting past these defenses. · DEFENSES: · MECHANICAL - shells, thorns, armor, spines · CHEMICAL - diverse enzyme pathways produce toxic compounds to discourage being eaten. · PHYSICAL - make detection difficult, or advertise/display chemical defenses (aposematism). · BEHAVIORAL - speed, aggregation (clustering), or schooling - balance between signaling and being quiet (ex. frogs). · NOT EVERY ORGANISM CAN EAT EVERY OTHER ORGANISM. · A whole spectrum of SPECIALIST consumers (including predation, herbivory) that have particular trait: allow them to crack shells, avoid spines, etc. · And GENERALIST consumers that use their feeding (trophic) traits to consume a broad range of organisms. · So, now the abundance of one species, again, influences the abundance of another! · The influence goes both ways - the energy in plants or prey are needed by consumers, so if resources disappear, so does the consumer! · Remember the up and down graph fluctuation of the Hare (prey) and Lynx (predator) populations. · CLASSES of interactions among species! · 1. Negative for one of the species: HERBIVORY, PREDATION, PARASITISM (positive for one organism, negative for the other) -Relative size of organisms important! A LION is a predator of a ZEBRA, but a TICK is a parasite on a lion! -Also can be sub-lethal predation! Many Joro spiders are missing 1-2 legs, to what effect on fitness? · 2. Negative for both species: COMPETITION over a limiting resource, so presence of competitor reduces growth ( r ) and/or (K) · 3. Maybe beneficial for at least one: MUTUALISM (+/+) both benefit (mutual symbiosis), or one benefits and the other is unaffected - COMMENSALISM (+/0) (Commensal Symbiosis) like a bird nesting in a tree. · 4. Positive interactions at community level - presence of one species benefits many other species through HABITAT FORMATION (foundation species) or environmental FACILITATION (ex. some species cannot survive without presence of one species). · CORALS have mutualism with DINOFLAGELLATES (ALGAE) but also generate 3D HABITAT - facilitates life for many other species on the reef! · SPECIAL CLASS: "KEYSTONE:" · Crab Mithrax living in branches of coral Oculina on Carolina coasts · This single species has a major effect when present in the coral colony. · Effects? · 1. Coral has fewer algae growing on it. · 2. Coral grows faster, less likely to die. · 3. More species live in a larger coral colony! · So, Mithrax presence leads to higher diversity, but the coral itself is the FOUNDATION for community. · MANY PREDATORS ARE KEYSTONE SPECIES (at the top of the arch, if they are removed, the ecosystem collapses) · Coral is FOUNDATION SPECIES (provides habitat), Mithras is KEYSTONE SPECIES (affects other species). · SPECIAL CLASS: "FOUNDATION" · Some species generate habitat that makes it possible for many other species to live in/on/around them, these are FOUNDATION species. · Good example: corals, Spartina cordgrass, mangroves, giant kelp. · We will separate these 2 important classes of ecological roles next! · COMMUNITY MEASUREMENTS: · HOW MANY SPECIES are there in a community (as with population - how you define may be spatial, or type of environment) · What is the RELATIVE ABUNDANCE OF SPECIES in that community? Are abundances "even" or quite variable? · Are some species more IMPORTANT to those metrics than others? Is there importance based on productivity, habitat, or trophic control? · Bob Paine counted the relative abundance of large/abundant benthic intertidal organisms. · Control plots - don't do anything but count · Treatment plots - experimentally manipulate by removing a predator · CONTROL PLOTS involve different random QUADRATS or areas than the TREATMENT PLOTS · RELATIVE ABUNDANCES ADD UP TO 1. · MASSIVE effect - but first note that the "control" plot still changes through time. Species arrive as larvae, survive, grow, and die - sometimes, influenced by different environments each year (storms, El Nino, ice, etc) · These changes are stochastic/not predictable · The "treatment" plot led to a huge shift that is DETERMINISTIC and predicted by the experiment and hypothesis of the effects of the keystone predator. When sea stars were removed, everything disappeared, except mussels. · "If I change the environment, how will the community change in a measureable way?" - Results of this show INTERACTIONS ARE IMPORTANT FOR DIVERSITY, ABUNDANCE. · EXPERIMENTAL ERA: · Much progress made in early 20th century with OBSERVATION and mathematical models. · Post-Paine: huge increase in experimental manipulation of ecosystems. (Human disruption). · ANY ORGANISM: how do you manipulate abundance? Exclosure/cage to keep them out? To keep them in? · WHY DOES THIS COMMUNITY CHANGE THE WAY IT DID? · All prey items and other members of FOOD WEB need either algae or plankton to eat, or eat other animals. · But many of them must have space/territory that they CANNOT MOVE FROM (barnicles, mussels; slow organisms like chitons, snails) which they COMPETE for as they grow. · Most of these marine organisms have biphasic life cycles, adults little/no movement but larvae swim and feed for weeks after birth, moving 10s-100s of kilometers from parents. · ADDENDUM: · The Pisaster (sea star: keystone predator) study as described notes that the abundance of many visible species went down. · But, living in the spaces between the mussels are many other species, so it is more accurate to say the KEYSTONE species fundamentally changes the system, and that effect may depend on scale of organism. · So, the mussels facilitate other diversity (positive). · WHAT ABOUT FACILITATION/POSITIVE INTERACTIONS? · They key is the effect PROPORTIONAL to abundance. · A FOUNDATION species is important but also dominant in abundance (a positive for other species). At first, a foundation species may be all you see at first in a Spartina marsh, or tall grass prairie. · COMPETITIVE EXCLUSION tends to be proportional: abundance of one species negatively influences abundance of the other. · KEYSTONE species - PRESENSE/ABSENSE IS DISPROPORTIONATE TO ABUNDANCE, HUGE EFFECT DESPITE NOT BEING IN HIGH ABUNDANCE. · Patch-size dependent habitat modification and facilitation on New England cobble beaches by Spartina alterniflora: · Part experimental manipulation, part the best ecology data collection trip ever! · Like ball-point pens, patch size is skewed distribution (most are small). · Larger Spartina beds stabilize cobble beach better, allow more plant diversity to grow. · Increased size of the patch results in increased stability and diversity. MANGROVES · Mangrove ecosystems in brackish (lower salinity) water - these trees are FOUNDATION species because they stabilize the sediment, provide 3D habitat for fish, epibionts (organisms living on other organisms), and more. · POSITIVE INTERACTION: as with Spartina marsh, the more habitat there is, the more species can be found (species-area relationship). · WHAT IF INSTEAD, YOU ADD SOMETHING TO AN ECOSYSTEM? CAN IT BE A "KEYSTONE?" · As Bob Paine noted: some species just have far greater consequence with their presence/absence than others! · If we think of that effect AND THEIR ABUNDANCE, you can think about foundation species, keystone species, and everything in between more clearly.

Chapter 21

CHAPTER 21: CONSERVATION AND BIODIVERSITY 21.1. Importance of Biodiversity. · Traditionally, ecologists have measured BIODIVERSITY by taking into account both the number of species and the number of individuals in each of those species. · However, biologists are using measures of biodiversity at several levels of biological organization (including genes, pops, and ecosystems) to help focus efforts to preserve biologically and technologically important elements of biodiversity · Some ecosystems are collapsing. Endangered species. Especially in tropical rainforests. · Ultimately, human species cannot exist without its surrounding ecosystems · Our ecosystems provide our food · A common meaning of biodiversity is simply the number of species in a location or on Earth · More sophisticated measures take into account the relative abundances of species · Ex. A forest with 10 equally common species of trees is more diverse than a forest that has 10 species of trees wherein just one of those species makes up 95% of the trees rather than them being equally distributed!!!!!!!! GENETIC AND CHEMICAL BIDIVERSITY · Genetic diversity is one alternate concept of diversity. GENETIC DIVERSITY/VARIANCE - raw material for adaptation in a species. A species' future potential for adaptation depends on genetic diversity held in genomes of individuals in pops that make up the species. (Through mutations, variation already exists). The same is true for higher taxonomic categories. A genus with very diff types of species will have more genetic diversity than a genus w/ species that look alike and have similar ecologies. · Genus w/ greatest potential for subsequent evolution is most genetically diverse one. · Most genes code for proteins, which in turn carry out the metabolic processes that keep organisms alive and reproducing. · Genetic diversity can also be conceived of as CHEMICAL DIVERSITY, in that species with different genetic makeups produce different assortments of chemicals in their cells (proteins as well as the products and byproducts of metabolism). · This chemical diversity is important for humans because of potential uses for these chemicals, such as medications. · Far cheaper to discover compounds made by an organism than to synthesize them in a lab · Chemical diversity is one way to measure diversity important to human health and welfare · Through selective breeding, humans have domesticated animals, plants, and fungi, but even this diversity is suffering losses because of market forces and globalism in human agriculture and migration · Ex. International seed companies produce only a few varieties of a given crop and abandone traditional diverse varieties · Human pop depends on crop diversity directly as a stable food source, and its decline is troubling ECOSYSTEMS DIVERSITY · ECOSYSTEMS DIVERSITY: number of different ecosystems on Earth or in a geographical area. · Whole ecosystems can disappear even if some of the species might survive by adapting to other ecosystems · Loss of ecosystem means loss of interactions between species, loss of unique features of coadaptation, and loss of biological productivity · Ex. Loss of prairie ecosystem in North America · Prairies are now replaced by crop fields, pasture lands, and suburban sprawl · Many species survive, but hugely productive ecosystem that was used for starting agriculture is now gone · Soils are now being depleted unless they are maintained artificially at greater expense · Decline in soil productivity occurs because interactions in original ecosystem have been lost · Despite effort, knowledge of the species that inhabit the planet is limited · Recent estimate suggests that (1.5 million) eukaryotic species for which science has names account for less than 20% of total number of eukaryote species on planet · Estimates of prokaryotic diversity largely guesses · Given that Earth is losing species at an accelerating pace, science knows little about what is being loss · Biodiversity is NOT evenly distributed on the planet · ENDEMIC SPECIES - found in only one location · Endemics with highly restricted distributions are particularly vulnerable to extinction · Biodiversity in almost every taxonomic group of organism increases as latitude declines (becomes closer to the equator) · It is not yet clear why biodiversity increases closer to equator, but hypotheses include the greater age of the ecosystems in the tropics vs temperate regions, which were largely devoid of life or drastically impoverished during last ice age · Greater age provides more time for speciation · Also, greater energy the tropics receive from the sun vs the lesser energy input in temperate and polar regions · Complexity of tropical ecosystems may promote speciation by increasing HABITAT HEREROGENEITY, or number of ecological niches, in the tropics, relative to higher latitudes. · Provides more opportunities for coevolution, specialization, and greater selection pressures leading to population differentiation · Tropics have been perceived as being more stable than temperate regions, which have a pronounced climate and day-length seasonality. · Tropics have their own forms of seasonality, like rainfall, but they are generally assumed to be more stable environments and this stability might promote speciation. · # of endemic species higher in tropics · Tropics also have more biodiversity hotspots · Our knowledge of the species in tropics is lowest · Because of human activity, in tropics, potential for biodiversity loss is greatest · As species disappear from an ecosystem, other species are threatened by the changes in available resources · Biodiversity is imp to the survival and welfare of human pops because it impacts our health and ability to feed ourselves through agriculture and harvesting pops of wild animals HUMAN HEALTH · Many medications are derived from natural chemicals made by a diverse group of organisms · Ex. Many plants produce SECONDARY PLANT COMPOUNDS, which are toxins used to protect the plant from insects and other animals that eat them · Some secondary plant compounds also work as human medicines · Other primates have also self-medicated with plants · Many medications were once derived from plant extracts but are now synthesized · Antibiotics are compounds largely derived from fungi and bacteria · In recent years, animal venoms and poisons have excited intense research for their medicinal potential · Humans benefit psychologically from living in biodiverse world. Evolutionary history has adapted us to living in a natural env and that built environments generate stresses that affect human health. AGRICULTURAL · There is great crop diversity. Ex. 7 species of potatoes, and thousands of varieties of it · Potato famine: the single potato variety grown in Ireland became susceptible to a potato blight, wiping out the crop. Showed risk of low crop diversity. · Seed companies must breed new varieties to keep up with evolving pest organisms. But these same companies have participated in decline of varieties available as they focus on selling fewer varieties in more areas of the world, replacing traditional local varieties. · Loss of wild species related to a crop will mean the loss of potential in crop improvement. · Maintaining the genetic diversity of wild species related to domesticated species ensures our continued supply of food · Biodiversity creates the conditions under which crops are able to grow through what are known as ecosystem services - valuable conditions or proesses that are carried out by an ecosystem · Crops are not grown, for most part, in built environments. They are grown in soil. · Although some agr soils are rendered sterile using controversial pesticide treatments, most contain huge diversity of organisms that maintain nutrient cycles - breaking down organic matter into nutrient compounds that crops need for growth. · These organisms also maintain soil texture that affects water and oxygen dynamics in the soil that are necessary for plant growth. · Replacing the work of these organisms in forming arable soil is not practically possible · Ecosystem services occur within ecosystems, such as soil ecosystems, as result of the diverse metabolic activities of the organisms living there, but they provide benefits to human food production, drinking water availability, and breathable air. · Other key ecosystem services related to food production are plant pollination and crop pest control · Honeybee populations in North America have been suffering large losses caused by a syndrome called colony collapse disorder, a new phenomenon with an unclear cause · Other pollinators include other insects and birds · Loss of these species would make growing crops requiring pollination impossible, increasing dependence on other crops · Humans compete with crop pests for food · Pesticides help, but they are costly and lose their effectiveness over time as pops adapt · Also kill non-pest species and beneficial insects, and risk health of farmers and consumers · Also can damage neighboring ecosystems · Bulk of work of removing pests is actually done by predators and parasites of those pests, but it is not well studied · The greater the landscape complexity (forests and fallow fields near to crop fields), the greater the effect of pest-suppressing organisms · Introducing multiple enemies of pea aphids (an alfalfa pest) increased yield of alfalfa significantly · Shows that diversity of pests is more effective at control than one single pest · Loss of diversity in pest enemies will inevitably make it more difficult and costly to grow food · The world's growing human pop faces significant challenges in the increasing costs and other difficulties of producing food WILD FOOD SOURCES · In addition to farming crops and raising animals, humans obtain food from wild pops, primarily wild fish pops · Few fisheries on Earth are managed sustainably · Since 1990, production from global fisheries has declined · Fishery extinctions rarely lead to complete extinction of the harvested species, but rather to a radical restructuring of the marine ecosystem in which a dominant species is so over-harvested that it becomes a minor player · Loss of an inexpesneive protein source to pops that cannot afford to replace it will increase the cost of living and limit societies in other ways · In general, the fish taken from fisheries have shifted to smaller species and the larger species are overfished · Ultimate outcome could clearly be the loss of aquatic systems as food sources 21.2. THREATS TO BIODIVERSITY. · Core threat to biodiversity on the planet is combination of human pop growth and the resources used by that pop · 3 greatest proximate threats to biodiversity are habitat loss, overharvesting, and introduction of exotic species. · The first 2 of these are a direct result of human pop growth and resource use. · Third results from increased mobility and trade. · 4th major cause of extinction, anthropogenic (human-caused) climate change, has not yet had a large impact, but is predicted to become significant during this century · Env issues like toxic pollution have specific effects on species, but are not generally seen as threats at the magnitude as others HABITAT LOSS · Remove the entire habitat within the range of a species and, unless they are one of the few species that do well in human built environments, species will become extinct · Human destruction of habitats accelerated in latter half of 20th century · About 91% of river lengths in US have been modified with damming or bank modifications · Species of amphibians that must carry out parts of their life cycles in both aquatic and terrestrial habitats are at greater risk of pop declines and extinction because of the increased likelihood that one of their habitats or access between them will be lost · Amphibians have been declining in numbers and going extinct more rapidly than many other groups OVERHARVESTING · Serious threat to many species, but particularly to aquatic species · Causes of fishery collapse are both economic and political · Most fisheries are managed as a common resource, available to anyone willing to fish, even when the fishing territory lies within a country's territorial waters · TRAGEDY OF THE COMMONS: fishers have little motivation to exercise restraint in harvesting a fishery when they do not own the fishery. · General outcome of harvests of resources held in common is their overexploitation · In a few fisheries, the biological growth of the resource is less than the potential growth of the profits made from fishing if that time and money were invested elsewhere. In these cases (ex. whales), economic forces will drive toward fishing the population to extinction. · For most part, fishery extinction not equivalent to biological extinction. The last fish of a species is rarely fished out of the ocean. · But, there are some instances in which true extinction is a possibility. · Whales have slow growing pops and are at risk of complete extinction through hunting. · Also, some species of sharks w/ restricted distributions that are at risk of extinction. · Groupers are another pop of slow-growing fish that, in Caribbean, include species at risk of overfishing extinction · Coral reefs very diverse marine ecosystems - face peril from several processes. Home to 1/3 of world's marine fish species.. Most home marine aquaria that are wild-caught organisms - not cultured organisms. Pops of some species have declined in response to harvesting, showing that the harvest is not sustainable. Also concerns of the effect of pet trade on some terrestrial species such as turtles, amphibians, birds, plants, and even orangutans. · BUSH MEAT - generic term for wild animals killed for food. · Hunting practices (particularly in equatorial Africa and parts of Asia) believed to threaten several species with extinction. · Recent commercialization of the practice now has bush meat available in grocery stores, which has increased harvest rates to the level of unsustainability · Human pop growth has increased need for protein foods that are not being met from agriculture · Species threatened by bush meat trade are mostly mammals like monkeys and great apes living in Congo basin EXOTIC SPECIES · Species that have been intentionally or unintentionally introduced by humans into an ecosystem in which they did not evolve · Human transportation of people and goods (especially trade) has increased this · Most exotic species introductions fail because of low number of individuals introduced or poor adaptation to ecosystem they enter · Some exotic species have characteristics that make them successful in new ecosystem, undergo pop increases in new habitat, and reset ecological conditions in new env, threatening species that exist there. · So, exotic species can become invasive species. Threatens other species through competition for resources, predation, or disease. · Lakes and islands particularly vulnerable to extinction threats from introduced species · In Lake Victoria, intentional introduction of Nile perch was largely responsible for extinction of many cichlids species · Islands do not make up a large area of land on the globe, but they do contain a disproportionate number of endemic species because of isolation from mainland ancestors · Many introductions of aquatic species have occurred when ships have dumped ballast water taken on at a port of origin into waters at a destination port. (Water contains living organisms like plant parts, microorganisms, eggs, larvae, or aquatic animals). · Invading exotic species can also be disease organisms · It now appears that the global decline in amphibian species recognized in 1990s, in some part, is caused by a fungus which causes the disease CHYTRIDIOMYCOSIS · Evidence that the fungus is native to Africa and may have spread through transport of a commonly used laboratory and pet species: African clawed frog · Early evidence suggests that another fungal pathogen introduced from Europe is responsible for WHITE-NOSE SYNDROME, infects cave-hibernating bats in eastern North America and has spread from a point of origin in western New York CLIMATE CHANGE · Climate change, specifically the anthropogenic warming trend presented underway, is recognized as a major extinction threat, particularly when combined with other threats such as habitat loss · Due to emission of greenhouse gases, primarily carbon dioxide and methane, caused by burning fossil fuels and deforestation. · Warming trend will shift colder climates toward the north and south poles, forcing species to move with their adapted climate norms, but also to face habitat gaps along the way · These shifting ranges will impose new competitive regimes on species as they find themselves in contact with other species not present in their historic range · Ex. Polar bears and grizzly bears now coming into contact with each other, mating. · Changing climates also throw off the delicate timing adaptations that species have to seasonal food resources and breeding times · Scientists have already documented many contemporary mismatches to shifts in resource availability and timing · Populations are not moving quickly enough with the warming trends · Climate gradients will also move up mountains, eventually crowding species higher in altitude and eliminating the habitat for those species adapted to the highest elevations · Some climates will eventually disappear · Rate of warming appears to be accelerates in the arctic, which is recognized as serious threat to polar bear pops that require sea ice to hunt seals during winter months · Seals are only source of protein for polar bears · Finally, global warming will raise ocean levels due to meltwater from glaciers and greater volume occupied by warmer water · Island sizes will be reduced, which will affect some species · Gradual melting and subsequent freezing of the poles, glaciers, and higher elevation mountains - a cycle that has provided freshwater to environments for centuries - will be altered · Could result in overabundance of salt water and shortage of freshwater 21.3. PRESERVING BIODIVERSITY. · Number of species on the planet (or in any geographical area) is result of an equilibrium of 2 evolutionary processes that are ongoing: SPECIATION AND EXTINCTION. · Both are natural "birth" and "death" processes of macroevolution. · When speciation rates begin to outstrip extinction rates, number of species will increase. Reverse is true when extinction rates overtake speciation rates. · Throughout history of life on earth, 2 processes have fluctuated to a greater or lesser extent · There have been 5 sudden, dramatic losses in biodiversity: mass extinctions · A sixth, or Holocene, mass extinction has mostly to do with the activities of Homo sapiens · Ex. Dodo bird was hunted by humans to extinction · Estimates of EXTINCTION RATES are hampered by the fact that most extinctions are probably happening without being observed · Extinction of a bird or mammal is often noticed by humans, especially if its been hunted or used. But, many organisms not noticeable to us · One "species year" is one species in existence for one year · Background extinction rate is about 1 per million species years. E/MSY. · One million species years could be one species persisting for one million years, or a million species persisting for one year. · If there are 10 million species in existence, we would expect 10 of those species to become extinct in a year. This is the background rate. · But, considering that more species have gone extinct than we can measure (ex. specie we don't know about), the estimated extinction rate is actually closer to 100 E/MSY · Predicted rate by end of century is 1500 E/MSY · A second approach to estimating present-time extinction rtaes: correlate species loss with habitat loss. Based on measuring forest-area loss and understanding SPECIES-AREA RELATIONSHIP: rate at which new species are seen when the area surveyed is increased. · Likewise, if habitat is reduced, the number of species seen will also decline · As one increases, so does the other, but not in a straight line · Estimate: with about 90% of habitat loss an expected 50% of species would become extinct · As you increase forest area, number of species will increase and then level out · Species-area estimates have led to estimates of present-day species extinction rates of about 1000 E/MSY and higher · One explanation why observations don't show this amount of loss: there is a delay in extinction. Takes some time for species to fully suffer the effects of habitat loss and they linger on for some time after their habitat is destroyed, but eventually become extinct. · Also, species-area relationship may lead to an overestimate of extinction rates. · Using an alternate method would bring estimates down to 500 E/MSY in coming century. This is still 500 times the background rate. CONSERVATION OF BIODIVERSITY CHANGING HUMAN BEHAVIOR · Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) treaty came into force 1975 · Endangered Species Act · When an at-risk species is listed by the Act, US Fish and Wildlife Service is required to develop a management plan to protect the species and bring it back to sustainable numbers · Global warming expected to be a major driver of biodiversity loss · Protected lands (in preserves) tend to contain less economically valuable resources, rather than being set aside specifically for the species or ecosystems at risk · Either the % of area protected must be increased, the % of high quality preserves must be increased, or preserves must be targeted with greater attention to biodiversity protection · Researchers argue more attention to the latter is required · BIDIVERSITY HOTSPOT: conservation concept developed by Norman Myers 1988. Geographical area that contain HIGH NUMBERS OF ENDEMIC SPECIES. Aimed to identify important locations on planet for conservation efforts, a kind of conservation triage. · Original criteria: 1500 or more species of endemic plants and 70% of the area disturbed by human activity. · In general, large preserves are best because they support more species, including species with large home ranges. More core area of optimal habitat, more niches to support more species, and attract more species because they can be found and reached more easily · PRESERVE - area of land set aside with varying degrees of protection for organisms that exist within the boundaries of the preserve · Preserves perofmr better when there are partially protected buffer zones around them of suboptimal habitat · Preserves in shape of a square or circle will be better than a preserve with many thin "arms" · Political and economic pressures typically make preserves smaller, never larger, so setting aside large areas is difficult · Enforcement of protections is also hard for countries without resources to prevent poaching · Climate change creates problems for preserves as species in them migrate to higher latitudes as the habitat of the preserve becomes less favorable · Conservation preserves reinforce the cultural perception that humans are separate from natre HABITAT RESTORATION · May reintroduce certain KEYSTONE SPECIES. Ex. Wolf, a keystone predator - instrumental in maintaining diversity within an ecosystem. · Removing a keystone species from an ecological community causes a collapse in diversity. · Restoring a keystone species effectively can restore biodiversity in the community · Other large-scale restoration experiments underway involve dam removal · In US, since mid 1980s, many aging dams are being considered for removal rather than replacement, because of shifting belief about the ecological value of free-flowing rivers. · So, restoration of naturally fluctuating water levels (often dams reduce variation in river flows), which leads to increased fish diversity and improved water quality · In pacific northwest, dam removal projects expected to increase pops of salmon, which is considered a keystone species because it transports nutrients to inland ecosystems during its annual spawning migrations · In Atlantic coast, dam removal allows return of other spawning and anadromous fish species (born in fresh water, live most of lives in salt water, and return to fresh water to spawn) ROLE OF ZOOS AND CAPTIVE BREEDING · Transofrmation of missions of zoos from collection and exhibition facilities to organizations dedicated to conservation is ongoing · Captive breeding programs often fail when species are reintroduced into the wild · Education is a positive impact of zoos on conservation efforts

Chapter 19

Chapter 19: Population and Community Ecology 19.1. Pop Demographics and Dynamics · Effects of invasive species are one aspect of what ecologists study to understand how populations interact within ecological communities, and what impact natural and human-induced disturbances have on characteristics of communities · Populations are dynamic entities. Size and compositions fluctuate in response to many factors · Statistical study of populations is DEMOGRAPHY: a set of mathematical tools designed to describe populations and investigate how they change. · LIFE TABLES: detail the life expectancy of individuals within a population. Initially developed by life insurance companies to set insurance rates. · All living pops can be studied w/ this approach · Pops characterized by POPULATION SIZE (total number of individuals) and POPULATION DENSITY (number of individuals per unit area). · Pop size can affect potential for adaptation because it affects amount of genetic variation present in the pop. · Density can affect interactions w/ a pop such as competitions for food and ability of individual to find a mate · Smaller organisms tend to be more densely distributed than larger organisms · Scientists usually study pops by sampling a representative portion of each habitat and use this sample to make inferences about pop as a whole · A QUADRAT is a wood, plastic, or metal square randomly located on the ground and used to count the number of individuals that lie within its boundaries. (Use it for immobile organisms like plants, or for every small or slow moving organisms). · Square must be placed at random locations within habitat enough times to produce an accurate estimate of size and density · For smaller mobile organisms, like mammals, a technique called MARK AND RECAPTURE is used. Mark a sample of captured animals in some way and release them back into env to mix w/ rest of pop. Then, new sample captured and determine how many of marked animals are in the new sample. Assumes in a larger pop, low % of marked organisms will be recaptured. · Pop Size N = (Number Marked First Catch x Total Number Second Catch) / Number Marked Second Catch · SPECIES DISTRIBUTION PATTERN is distribution of individuals within a habitat at a particular point in time - broad categories of patterns are used to describe them. · Individuals in a pop can be distributed at random, in groups, or equally spaced apart · Known as random, clumped, or uniform distribution patterns · Random ex. Wind-dispersed seeds germinate wherever they happen to fall in favorable environments. (Ex. Dandellion seeds). · Clumped ex. Oak trees drop theor seeds straight to ground. Also animals that live in social groups. · Uniform ex. Plants that secrete substances inhibiting the growth of nearby individuals. Also territorial animal species. · Demography: statistical study of pop changes over time: birth rates, death rates, and life expectancies · Life tables include infant mortality rate, and MORTALITY RATE: % of surviving individuals dying at a particular age interval, and life expectancy at each interval · Mortality Rate = (number of individuals dying at this age interval) / (number of individuals surviving) x 100 · SURVIVORSHIP CURVE: graph of number of individuals surviving at each age interval vs time. · Allow us to compare the life histories of different populations. · Type 1 curve: mortality is low in early and middle years and occurs mostly in older animals. Humans and most mammals. Typically produce few offspring and provide good care to offspring increasing likelihood of their survival. · Type II curve: mortality is relatively constant throughout entire life span, and equally likely to occur at any point. Ex. Many bird pops. · Type III: early ages experience higher mortality and much lower mortality for organisms that make it to advanced years. Typically produce large numbers of offspring, but provide little care for them. Trees and marine invertebrates. 19.2. POPULATION GROWTH AND REGULATION. · 2 simplest models for pop growth use deterministic equations (do not account for random events) to describe rate of change · FIRST MODEL: EXPONENTIAL GROWTH: THEORETICAL POPULATIONS THAT INCREASE IN NUMBERS WITHOUT ANY LIMITS TO THEIR GROWTH. · SECOND MODEL: LOGISTIC GROWTH: introduces limits to reproductive growth that become more intense as pop size increases. · Neither adequately describes natural pops, but provide comparison EXPONENTIAL GROWTH: · Darwin and Malthus said pops w/ unlimited natural resources grow very rapidly (exponential), and pop growth decreases as resources become depleted (indicating a logistic growth). · Best ex. of exponential growth: bacteria. Binary fission is quick w/ an abundant supply of nutrients that do not become depleted. Growth rate increases as organisms are added. · When pop size, N, is plotted over time, a J-SHAPED GROWTH CURVE IS PRODUCED. · When a species is introduced into new habitat that it finds suitable, may show exponential growth for a while · GROWTH RATE (r)- BIRTH RATE B - DEATH RATE D · POPULATION GROWTH RATE = rN · Value of r can be pos (pop is increasing) or neg (decreasing) or 0 (unchanging, a condition known as ZERO POPULATION GROWTH) · EXPONENTIAL GROWTH IS NOT THE CASE IN THE REAL WORLD. NATURAL RESOURCES ARE LIMITED. · To model reality, of limited resources, developed LOGISTIC GROWTH MODEL · CARRYING CAPACITY / K - population size, which is determined by the maximum population size that a particular environment can sustain · In real pops, a growing pop often overshoots its carrying capacity an death rate increases beyond birth rate, cuaisng pop size to decline back to carrying capacity or below it · Most pops fluctuate around carrying capacity, don't exist right at it · POP GROWTH = rN (K - N / K) · K-N is number of individuals that may be added to a pop at a given time, and K - N / K is the fraction of carrying capacity available for future growth. · When N is almost 0 and quantity in brackets is almost equal to 1 (or K/K), growth is close to exponential · When pop size is equal to carrying capacity, or N=K, quantity in brackets is equal to zero and growth is equal to 0. · Graph of this equation (logistic growth) yields the S-SHAPED CURVE. · More realistic than exponential growth · 3 diff sections to S Shape. Initially, growth is exponential because there are few individuals and ample resources. Then, resources begin to become limited, growth rate decreases. Finally, growth rate levels off at the carrying capacity of the environment, w/ little change in pop number over time. · Logistic model assumes every individual will have equal access to resources and thus an equal chance for survival · In real world, phenotypic variation among individuals within a pop means that some individuals will be better adapted to their environment than others · Resulting competition for resources among pop members of same species is termed INTRASPECIFIC COMPETITION. · Intraspecific competition may not affect pops that are well below carrying capacity, as resources are plentiful · As pop size increases, competition intensifies. Accumulation of waste products can reduce carrying capacity of the environment too. · Yeast shows S-shaped logistical curve. · In real world, there are variations to this idealized curve. · Ex. Sheep and harbor seals exceed carrying capacity for short periods of time and then fall below the carrying capacity afterward. · This fluctuation in pop size continues to occur as pop oscillates around its carrying capacity · Even w/ this oscillation, logistic model is confirmed · Model is a simplification. Implicit in logistic model is that environment does not change, which IS NOT THE CASE. · Carrying capacity varies annually · In many areas, carrying capacity during winter is much lower than it is in summer · Also, natural events can alter environment and hence its carrying capacity · Also, pops do not exist in isolation. Share env w/ other species, competing for same resources (INTERSPECIFIC COMPETITION). · Pop growth regulated in a variety of ways. These are grouped into DENSITY-DEPENDENT FACTORS, in which density of the pop affects growth rate and mortality, and DENSITY-INDEPENDENT FACTORS, which cause mortality in a pop regardless of pop density. · Understanding these helps prevent extinction or overpopulation · Most density-dependent factors are biological in nature and include predation, inter and intraspecific competition, and parasites. · Usually the denser a pop is, the greater the mortality rate · Ex. During intra and interspecific competition, reproductive rates of species will usually be lower, reducing their rate of growth. · In addition, low prey density increases the mortality of its predator (difficulty looking for food) · When pop is denser, diseases spread more rapidly · In a study comparing a high-density pop to a low-density pop, the low density pop grew and the high density pop stayed same. Difference in growth rates of 2 pops was caused by MORTALITY, NOT BY A DIFFERENCE IN BIRTH RATES. Numbers of offspring birthed by each mother was unaffected by density. But there was juvenile mortality caused by mother's malnutrition due to scarce high-quality food in dense pop. · Some DENSITY-INDEPENDENT FACTORS: weather, natural disasters, pollution. · In real life, density-dependent and density-independent factors can interact · Dense pop that suffers mortality from a density-independent cause will be able to recover differently than a sparce pop · Ex. A pop of deer affected by harsh winter will recover faster if there are more deer remaining to reproduce (higher density) · Suites of characteristics may evolve in species that lead to particular adaptations to env , which impacts the kind of pop growth their species experience · Life history characteristics like birth rates, age of first reproduction, numbers of offspring, and death rates EVOLVE · K-SELECTED SPECIES - adapted to stable, predictable environments. Pops tend to exist close to their carrying capacity. These species tend to have larger, but fewer, offspring and contribute large amounts of resources to each offspring. Ex. Elephants. · R-SELECTED SPECIES - adapted to unstable and unpredictable environments. Have large numbers of small offspring. Do not provide a lot of resources or parental care to offspring, and offspring are relatively self-sufficient at birth. Ex. Marine invertebrates like jellyfish. · These 2 extreme strategies are at 2 ends of continuum on which real species life histories will exist. · Life history strategies do not need to evolve as suites, but can evolve independently of each other, so each species may have some characteristics that trend toward one extreme or the other 19.3. THE HUMAN POPULATION. · Humans are NOT unique in their ability to alter their environment · Humans, however, have ability to alter environment to INCREASE ITS CARRYING CAPACITY, sometimes to detriment of other species · Human use of resources growing quick, to extent that some worry about ability of Earth's environment to sustain its human pop · Long-term exponential growth carries with it the potential risks of famine, disease, and large-scale death, as well as social consequences of crowding such as increased crime · Use of fossil fuels has altered ecosystems, now some are in danger of collapse · Depletion of ozone layer, desertification and topsoil loss, and global climate change caused by human activities · HUMAN POP IS GROWING EXPONENTIALLY (since 1000 AD) · Time it takes to add a particular number of humans to pop is becoming shorter · This acceleration in growth rate will likely begin to decrease in coming decades, but pop will continue to increase and threat of overpopulation remains, because damage caused to ecosystems and biodiversity is LOWERING HUMAN CARRYING CAPACITY OF PLANET · Humans' unique ability to alter env in myriad ways is responsible for human pop growth, resets the carrying capacity and overcomes density-dependent growth regulation · Ex. Agriculture, shelters, language, technology, migration, public health · Fundamental cause of acceleration of growth rate for humans in last 200 years has been reduced death rate due to development of technological advances of industrial age, urbanization, and exploitation of energy in fossil fuels (which are responsible for increasing resources available for pop growth through agriculture -mechanization, pesticides, and fertilizers- and harvesting wild pops) · AGE STRUCTURE is the proportion of a population in different age classes. · Countries w/ rapid growth have a pyramidal shape (many younger individuals, at reproductive age). Most often observed in underdeveloped countries where individuals do not live to old age, and there is high birth rates. HIGHEST GROWTH RATES HERE. · Slow growth: ex. USA: still pyramidal, but fewer young/reproductive age individuals and more old people · Other developed countries (ex. Italy): zero pop growth. Conical age structure, with an even greater % of middle-aged and older individuals. · Efforts to moderate population control led to the ONE-CHILD POLICY in China. · Family planning education programs in other countries have been helpful · But human pop continues to grow · Inequalities in access to food and other resources will continue to widen · Many underdeveloped countries trying to improve their economic condition are less likely to agree with provisions to reduce greenhouse gas emissions without compensation 19.4. COMMUNITY ECOLOGY. · Pops of one species never live in isolation from pops of other species · Interacting pops occupying a given habitat form an ecological community!!!!!!!! · Diversity of community: number of species occupying the same habitat and their relative abundance · Areas w/ low species diversity (ex. Antarctica) still contain a wide variety of living organisms, but diversity of tropical rainforests is much greater · Pop sizes of predators and prey in a community are not constant over time, and they may vary in cycles that appear to be related · Ex. In one study, predator pop lags one to two years behind prey pop. Explanation: as hare (pry) numbers increase, there is more food available to lynx (predator), allowing its' pop to increase · When predator pop grows to threshold level, however, they kill so many prey that prey numbers begin to decline, followed by decline in predator pop · When predator pop is low, prey pop begins to increase, starting the cycle anew · Any heritable character that allows an individual of a prey pop to better evade its predators will be represented in greater numbers in later generations · Traits that allow predator to catch prey better will lead to greater number of offspring w/ that trait · Leads to adaptations driven by reciprocal evolutionary responses in those pops · Defenses may be mechanical, chemical, physical, or behavioral · Mechanical defenses (ex. armor in animals or thorns in plants) discourage predation and herbivory (animals eating plants) by discouraging physical contact · Many plant species produce secondary plant compounds (chemical) that serve no function for plant except that they are toxic to animals and discourage consumption · Many species use body shape and coloration to avoid detection by predators · MIMICRY - a harmless species imitates the warning coloration of a harmful species. · In other mimicry cases, multiple species share the same warning coloration, but all of them actually have defenses. This improves the compliance of all the potential predators. · All species have an ecological niche · Niche is a unique set of resources used by a species, which includes its interactions with other species. · COMPETITIVE EXCLUSION PRINCIPLE states that 2 species cannot occupy the same niche in a habitat. So, diff species cannot coexist in a community if they are competing for the same resources. · This works because over time, when there is overlap in resource use, the traits that lessen reliance on the shared resource will be selected for leading to evolution that reduces the overlap. (Species 'back off' of the resource). · If either species is unable to evolve to reduce competition, then the species that most efficiently exploits the resources will drive the other species to extinction. · Symbiosis: close, long term interactions between individuals of different species. May be COMMENSAL (one species benefits while the other is neither harmed nor benefited), MUTUALISTIC (both species benefit), or PARASITIC (harms one species and benefits the other) · COMMENSALISM: often difficult to identify because it is hard to prove that one partner does not derive some benefit from the presence of the other. · MUTUALISM: ex. termites mutualistic symbiosis with protists that live in its gut. Termite benefits from protists' ability to digest cellulose. Protists are only able to because of the presence of symbiotic bacteria within their cells that produce the cellulase enzyme. Without the protozoa, the termite could not obtain energy from its food. Protozoa benefit from protective environment and constant supply of food from wood chewing. Prorists benefit from the enzymes provided by their bacterial endosymbionts, while bacteira benefit from a doubly protective env and constant source of nutrients from 2 hosts. · Lichens: 2 fungi, 1 algae · PARASITISM: organism that feeds off another without immediately killing the organism it is feeding on. HOST IS HARMED. Parasite may kill their hosts, but there is usually selection to slow down this process to allow parasite time to complete its reproductive cycle before it or its offspring are able to spread to another host. · Reproductive cycles of parasites are complex, sometimes requiring more than one host species CHARACTERISTICS OF COMMUNITIES · Can be characterized by structure (number and size of pops and their interactions) and dynamics (how members and their interactions change over time). · SPECIES RICHNESS: a term used to describe the number of species living in a habitat or other unit. · Species richness varies across the globe · Related to latitude: the greatest species richness occurs near equator, and owest near the poles · Other factors influence species richness as well. ISLAND BIOGEOGRAPHY attempts to explain great species richness found in isolated islands, and has found relationships between species richness, island size, and distance from mainland · RELATIVE SPECIES ABUNDANCE is number of individuals in a species relative to the total number of individuals in all species within a system. · FOUNDATION SPECIES - often have highest relative abundance of species - considered base/bedrock of community, having greatest influence on its overall structure. Often the primary producers, and they are typically abundant. Ex. Kelp (a species of brown algae). May physically modify the environment to produce and maintain habitats that benefit the other organisms that use them. Ex. Kelp described above or tree species found in a forest. · KEYSTONE SPECIES - one whose presence has inordinate (disproportionately large) influence in maintaining the prevalence of various species in an ecosystem, the ecological community's structure, and sometimes its biodiversity. · Community dynamics - changes in community structure and composition over time, often following ENVIRONMENTAL DISTURBANCES such as volcanoes, earthquakes, storms, fires, and climate change · Communities w/ relatively constant number of species are said to be at equilibrium. · Equilibrium is dynamic with species identities and relationships changing over time, but maintaining relatively constant numbers · Following a disturbance, community may ot may not return to equilibrium state · Succession describes sequential appearance and disappearance of species in a community over time after a severe disturbance · PRIMARY SUCCESSION - newly exposed or newly formed rock is colonized by living organisms. · SECONDARY SUCCESSION - a part of an ecosystem is disturbed and remnants of the previous community remain. · In both cases, there is a sequential change in species until a more or less permanent community develops · Primary succession occurs when new land is formed, following eruption of volcanoes, etc. As lava flows into ocean, new land is continually being formed. · Weathering and other natural forces break down rock enough for the establishment of hearty species such as lichens and some plants, known as PIONEER SPECIES. These species help to further break down the mineral-rich lava into soil where other, less hardy but more competitive species, such as grasses, shrubs, and trees, will grow and eventually replace the pioneer species. · Over time the area will remain an equilibrium state, with a set of organisms quiet different from the pioneer species · Secondary succession. Ex. Oak and hickory forests cleared by wildfire. Burn most vegetation, and unless the animals can flee the areas, they are killed. Their nutrients are returned to ground in form of ash. Thus, although the community has been drastically altered, there is a soil ecosystem present that provides a foundation for rapid recolonization. · Before the fire, vegetation was dominated by tall trees with access to the major plant energy resource: sunlight. · After the fire, trees no longer dominate · Thus, first plants to grow back are usually annual plants followed within a few years by quickly growing and spreading grasses and other pioneer species · Due, at least in part, to changes in env brought on by growth of grasses and forbs, over many years, shrubs emerge along with small pine, oak, and hickory trees · These organisms are called intermediate species · Eventually, over 150 years, forest will reach its equilibrium point and resemble the community before the fire. Equilibrium state is referred to as CLIMAX COMMUNITY, which will remain until the next disturbance. · Climax community typically characteristic of a given climate and geology. Although the community in equilibrium looks same once it is attained, the equilibrium is a dynamic one with constant changes in abundance and sometimes species identities. · The return of a natural ecosystem after agricultural activities is also a well-documented secondary succession process!!!

Chapter 20

Chapter 20: Ecosystems and the Biosphere 20.1. WATERFORD'S ENERGY FLOW THROUGH ECOSYSTEMS · Ecosystem ecology is an extension of organismal, population, and community ecology · Ecosystem comprises all the biotic components (living things) and abiotic components (non-living) in a particular geographic area · Some of abiotic components include air, water, soil, and climate · Ecosystem biologists study how nutrients and energy are stored and moved among organisms and surrounding atmosphere, soil, and water · ECOSYSTEM - a community of living organisms and their abiotic (non-living) environment · Can be small or large · 3 broad categories of ecosystems based on their general environment: freshwater, marine, terrestrial · Within these 3 are individual ecosystem types based on env habitat and organisms · Often competition for limited resources, occurs within and between species · Components of physical env (climate, elevation, geology) also influence community dynamics · Freshwater ecosystems: least common, quite diverse. · Marine ecosystems are most common. Conisst of 3 types: shallow ocean, deep ocean water, and deep ocean bottom · Shallow: biodiverse coral reef ecosystems · Deep ocean water: large numbers of plankton and krill that support it · These 2 environments are important to aerobic respirators worldwide, as photoplankton perform 40% of all photosynthesis on Earth · Not as diverse, but deep ocean bottom contain many organisms. · Terrestrial ecosystems, known for diversity, grouped into large categories called BIOMES - large scale community of organisms, defined on land by the dominant plant types that exist in geographic regions of the planet with similar climatic conditions. Ex. Tropical rainforests, savannas, deserts, grasslands, temperate forests, tundras. · There are many ecosystems within these biomes · Grouping these ecosystems into just a few biome categories obscures the great diversity of the individual ecosystems within them · Ecosystems are routinely exposed to various disturbances · Ex. Yearly variations in rainfall and temperature · Many disturbances are result of natural processes · Ex. Succession. After forest fire, grass, then bushes, then trees eventually grow back. · Impact of env disturbances caused by human activities is now as significant as the changes wrought by natural processes · EQUILIBIRUM is a DYNAMIC STATE of an ecosystem in which, despite changes in species numbers and occurrence, biodiversity remains somewhat constant. · In ecology, 2 parameters to measure changes in ecosystems: RESISTANCE AND RESILIENCE. · RESISTANCE: ability of an ecosystem to remain at equilibrium in spite of disturbances. · RESILIENCE: speed at which an ecosystem recovers equilibrium after being disturbed. · Ecosystem resistance and resilience especially important when considering human impact · Nature of an ecosystem may change to such a degree that it can lose its resilience entirely. · This process can lead to complete destruction or irreversible altering of the ecosystem · FOOD CHAIN: linear sequence of organisms through which nutrients and energy pass as one organism eats another. Levels are producers, primary consumers, higher level consumers, and finally decomposers. · There is a single path through a food chain · Each organism occupies a specific TROPHIC LEVEL (energy level), its position in food chain or food web · APEX CONSUMERS: organisms as the top of the food chain. · One major factor that limits the number of steps in a food chain is energy. · Energy is lost at each trophic level and between trophic levels as heat and in the transfer to decomposers. · Thus, after a limited number of trophic energy transfers, the amount of energy remaining in the food chain may not be great enough to support viable populations at yet a higher trophic level. · At each level (going up), there is less energy available, and usually (but not always) supports a smaller mass of organisms at the next level · One problem when using food chains to describe most ecosystems. Even when all organisms are grouped into appropriate trophic levels, some of these organisms can feed (or be fed) on more than one trophic level. · In addition, species feed on and are eaten by more than one species. · So, linear model of ecosystems (the food chain) is a hypothetical, overly simplistic representation of ecosystem structure · A holistic model (includes all the interactions between diff species and the environment) is more accurate: FOOD WEB: concept that accounts for the multiple trophic feeding interactions between each species. · 2 general types of food webs are often shown interacting within a single ecosystem. · GRAZING FOOD WEB has plants or other photosynthetic organisms at base, followed by herbivores and various carnivores. · DETRITAL FOOD WEB consists of base of organisms that feed on decaying organic matter, including decomposers (break down dead and decaying organisms) and detritivores (consume organic detritus). Ex. Bacteria, fungi, and invertebrate animals that recycle organic material back into biotic part of ecosystem as they themselves are consumed by other organisms. · As ecosystem require a method to recycle material from dead organisms, grazing food webs have an associated detrital food web. · Ex. In a meadow, plants support a grazing food web of diff organisms, while at same time supporting a detrital food web of bacteria and fungi feeding off dead plants and animals. Simultaneously, detrital food web contributes energy to a grazing food web (animals eat the fungi, etc). · Energy used by most complex metabolic pathways (usually in ATP form), especially those responsible for building large molecules from smaller compounds. · PHOTOSYNTHETIC AND CHEMOSYNTHETIC ORGANISMS ARE AUTOTROPHS · Photosynthetic autotrophs use sunlight, chemoautotrophs use inorganicmoleculees · They are the producer trophic level · Rate at which photosynthetic producers incorporate energy from the sun is called GROSS PRIMARY PRODUCTIVITY. · Not all energy incorporated by producers is available to other organisms because they also must use energy to grow and reproduce · NET PRIMARY PRODUCTIVITY is the energy that remains in the producers after accounting for these organisms' respiration and heat loss. · Chemoautotrophs are primarily bacteria and archaea found in rare ecosystems where sunlight is not available. Ex. In hydrothermal vents, use hydrogen sulfide as source of chemical energy. · BIOMAGNIFICATION: one of the most important consequences of ecosystem dynamics in terms of human impact. Increasing concentration of persistent, toxic substances in organisms at each successive trophic level. These substances are fat soluble, not water soluble, and are stored in fat reserves of each organisms. · DDT was commonly used pesticide before its dangers to apex consumers, such as bald eagle, became known. · In aquatic ecosystems, organisms from each trophic level consumed many organisms in lower level, which caused DDT to increase in birds (apex consumers) that ate fish. Thus, birds accumulated sufficient amounts of DDT to cause fragility in their eggshells. · DDT banned in US in 1970s · Other substances that biomagnify are polychlorinated biphenyls (PCB), used as coolant liquids in US until banned in 1979. Also heavy metals like mercury, lead, cadmium. · These substances best studied in aquatic ecosystems where predatory fish species accumulate high concentrations of toxic substances that are low cocentrations in env and in producers. · Ex. PCB concentrations INCREASE from the producers of the ecosystem through the different trophic levels of fish species. · SO, AS YOU GO UP TROPHIC LEVELS, LESS ENERGY, BUT MORE TOXIC SUBSTANCES (BIOMAGNIFICATION). · EPA recommends pregnant women and young kids not consume swordfish, shark, etc. because of high mercury content. · Fish low in mercury: salmon, shrimp, polluck, catfish. 20.2. BIOGEOCHEMICAL CYCLES. · Energy enters ecosystem through sunlight (or inorganic molecules) and leaves as heat during transfers between trophic level · Rather than flowing through ecosystem, matter that makes up living organisms is conserved and recycled · 6 most common elements associated with organic molecules: carbon, nitrogen, hydrogen, oxygen, phosphorus, and sulfur - take on variety of chemical forms and may exist for long periods · Geological processes play a role in cycling of elements on Earth · Recycling of inorganic matter between living organisms and their nonliving environment is BIOGEOCHEMICAL CYCLE. · Water: HYDROSPHERE is area of Earth where water movement and storage occurs (as liquid water on or beneath surface, or ice, or water vapor) · Carbon: found in organic macromolecules. Imp constituent of fossil fuels. · Nitrogen: major component of our nucleic acids and proteins and is critical to human agriculture. · Phosphorus: major component of nucleic acids, is one of main ingredients in artificial fertilizer in agriculture, has impacts on our surface water · Sulfur, critical to 3D folding of proteins (as in disulfide binding), is released into atmosphere by burning of fossil fuels · Cycling of these elements is interconnected · Ex. Movement of water critical for nitrogen and phosphorus leaching into rivers and oceans WATER CYCLE · 97.5% of water on Earth is salt water · Of remaining water, 99% is locked as underground water or ice · Thus, less than 1% of fresh water is present in lakes and rivers · Water cycle is driven by sun's energy as it warms the oceans and other surface waters · Leads to evaporation and sublimation (ice to water vapor), thus moving large amounts to atmosphere · In most natural terrestrial environments, rain encounters vegetation before it reaches the soil surface · A significant % of water evaporates immediately from the surfaces of plants. · What is left reaches the soil and begins to move down · Surface runoff occurs only if the soil becomes saturated with water in a heavy rainfall · Most water in soil will be taken up by plant roots · Plant will use some of this water for its own metabolism, some will find its way into animals that eat plants, most will be lost back to atmosphere through evapotranspiration. · Water enters vascular system through roots and evaporates/transpires through stomata of leaves. Water in soil not taken up by plant and that doesn't evaporate is able to percolate into subsoil and bedrock. Forms groundwater. · Groundwater is significant reservoir of fresh water. Exists in the pores between particles in sand and gravel, or in fissures of rocks. Shallow groundwater flows through pores and fissures, finds way to stream or lake to become surface water. · Streams do not flow because they are replenished from rainwater directly; they flow because there is a constant inflow from groundwater. · Most groundwater reservoirs / aquifers are the source of drinking or irrigation water drawn up through wells. · In many cases these aquifers are being depleted faster than they are being replenished by water percolating down from above. · Rain and surface runoff are major ways in which minerals, including carbon, N, P, and S are cycled from land to water. CARBON CYCLE · C is 4th most abundant element in living organisms · C compounds contain energy, and many of these compounds from plants and algae have remained stored as fossilized carbon, which humans use as fuel. · C cycle most easily studied as 2 interconnected subcycles: one dealing with rapid C exchange among living organisms and the other dealing with the long-term cycling of C through geologic processes BIOLOGICAL CARBON CYCLE · Living organisms are connected in many ways, even between ecosystems · Ex. Exchange of C between heterotrophs and autotrophs within and between ecosystems by way of atmospheric CO2 · CO2 is basic building block that autotrophs use to build mulit-C, high-energy compounds like glucose · Energy harnessed from sun is used to form covalent bonds to link C atoms together · These chem bonds store this energy for later use in respiration · Most terrestrial autotrophs obtain their CO2 directly from atmosphere, while marine autotrophs acquire it in dissolved form (carbonic acid) · Oxygen: a byproduct of fixing carbon inorganic compounds · Photosynthetic organisms responsible for maintaining 21% of oxygen content in atmosphere · Partners in biological carbon exchange are heterotrophs (especially herbivores - primary consumers). Acquire the high energy carbon compounds from the autotrophs by consuming them and breaking them down to obtain ATP. Most efficient type of respiration (aerobic) requires oxygen in atmosphere or water. So, constant exhcnage of oxygen and CO2. · Autotrophs also respire and consume organic molecules they form. · They release more oxygen gas as a waste product of photosynthesis than they use for their own respiration. BIOGEOCHEMICAL CARBON CYCLE · Carbon reservoirs (long term) include atmosphere, bodies of liquid water, ocean sediment, soil, rocks (including fossil fuels), and Earth's interior · Level of CO2 in atmosphere is greatly influenced by reservoir of carbon in oceans · Exchange of carbon between atmosphere and water reservoirs influences how much C is found in each · CO2 dissolves in water and (unlike oxygen and nitrogen gas) reacts with water molecules to form ionic compounds. · Some of these ions combine with calcium ions in seawater to form calcium carbonate, major component of shells of marine organisms · Organisms form sediments on ocean floor. Calcium carbonate forms limestone (largest carbon reservoir on Earth). · On land, C stored as organic carbon from decomp of living organisms or weathering of terrestrial rock and minerals. · Deep under ground, at land and at sea, are fossil fuels, the anaerobically decomposed remains of plants that take millions of years to form. · Non-renewable because their use far exceeds their rate of formation · NON-RENEWABLE RESOURCE is either regenerated very slowly or not at all. · C enters atmosphere from land too (including land beneath surface of the ocean) by eruption of volcanoes and other geothermal systems. · C sediments from ocean floor are taken deep within Earh by the process of SUBDUCTION: movement of one tectonic plate beneath another. C released as CO2 when a volcano erupts or from volcanic hydrothermal vents. · CO2 also added to atmosphere by animal husbandry practices of humans. · Large number of land animals results in increased CO2 levels in atmosphere caused by their respiration. NITROGEN CYCLE · Getting nitrogen into living world is difficult. · Plants and phytoplankton are not equipped to incorporate N from atmosphere (which exists as tightly bonded triple covalent N2), even though this molecule makes up 78% of atmosphere · N enters living world via free-living and symbiotic bacteria, which incorporate N into their macromolecules through NITROGEN FIXATION · Cyanobacteria live in most aquatic ecosystems w/ sunlight; play key role · Use inorganic sources of N to fix it · Rhizobium bacteria live symbiotically in root nodules of legumes (ex. peas, beans, peanuts) and provide them w/ organic N · Free-living bacteria like Azotobacter also N fixers · Many processes (like primary production and decomposition) are limited by available supply of N · The N that enters living systems by N fixation is eventually converted from organic N back inter N gas by bacteria. Occurs in 3 steps in terrestrial systems: AMMONIFICATION, NITRIFICATION, AND DENITRIFICATION. · Ammonification converts nitrogeneous waste from living animals/remains of dead animals into AMMONIUM NH4+ by certain bacteria and fungi · Nitrification: ammonium converted to nitrites (NO2-) by nitrifying bacteira, like Nitrosomonas · Denitrification: bacteria (like Pseudomonas and Clostridium) convert nitrates into nitrogen gas, allowing it to re-enter atmosphere · Human activity can release N into environment by 2 primary means: COMBUSTION OF FOSSIL FUELS (releases diff Nitrogen Oxides) AND USE OF ARTIFICIAL FERTILIZERS (contain nitrogen and P compounds) in agriculture, which are then washed into lakes, streams, and rvers by runoff · Atmospheric nitrogen (other than N2) is associated with several effects on Earth's ecosystems including production of acid rain (as nitric acid HNO3) and greenhouse gas effects (as nitrous oxide N2O), causing climate change · Major effect from fertilizer runoff is saltwater and freshwater EUTROPHICATION: nutrient runoff causes overgrowth of algae and problems · Similar process occurs in marine nitrogen cycle, where ammonification, nitrification, and denitrification are performed by marine bacteria and archaea · Some nitrogen falls to ocean floor, which can be moved to land in geologic time by uplift of Earth's surface, into terrestrial rock · Movement of nitrogen from rock directly into living systems is significant too PHOSPHORUS CYCLE · P is major component of nucleic acids and phospholipids, and as calcium phosphate, makes up supportive components of our bones · Phosphorus often limiting nutrient (necessary for growth) in aquatic (particularly FRESHWATER) ecosystems · P occurs in nature as phosphate ion PO4 3- · In addition to phosphate runoff from human activity, natural surface runoff occurs when it is leached from phosphate-containing rock by weathering, sending phosphates into rivers, lakes, ocean · This rock has its origins in the ocean · Phosphate-containing ocean sediments form primarily from bodies of ocean organisms and from their excretions. But, volcanic ash, aerosols, and mineral dust may also be significant phosphate sources. · This sediment then is moved to land over geologic time by uplifting of Earth surface. · Phosphorus also reciprocally exchanged between phosphate dissolved in ocean and marine organisms · Movement from phosphate from ocean to land through soil is very slow · Excess phosphorus and nitrogen that enter these ecosystems from fertilizer runoff and from sewage cause excessive growth of algae · The death and decay of these organisms (and the growth of bacteria that eat them) depletes dissolved oxygen, leads to death of aquatic organisms · Fish kills often in summer months · DEAD ZONE - area in lakes and oceans near mouths of rivers where large areas are periodically depleted of their normal flora and fauna; zones can be caused by eutrophication, oil spills, dumping toxic chemicals, etc. SULFUR CYCLE · As part of the amino acid cysteine, S is involved in the formation of proteins · S cycles between oceans, land, and atmosphere · Atmospheric S found in form of sulfur dioxide (SO2), enters atmosphere in 3 ways: decomposition of organic molecules, volcanic activity and geothermal vents, and burning of fossil fuels by humans · On land, S deposited in 4 major ways: precipitation, direct fallout from atmosphere, rock weathering, and geothermal vents · Atmospheric S (SO2) as rain falls through the atmosphere. S is dissolved in form of weak sulfurous acid H2SO3. · S can also fall directly from atmosphere in process of FALLOUT. · Also, as S-containing rocks weather, S is released into soil. These rocks originate from ocean sediments that are moved to land by geologic uplifting of ocean sediments. · Terrestrial ecosystems can then make use of these soil sulfates (SO2 4-), which enter the food web by being taken up by plant roots. · When these plants die, S released back into atmosphere as H sulfide (H2S) gas. · S enters ocean n runoff from land, atmospheric fallout, and from underwater geothermal vents. · Some ecosystems rely on chemoautotrophs using S as a biological energy source. · This S then supports marine ecosystems in the form of sulfates. · Human activities have played a role · Burning of fossil fuels (ESPECIALLY COAL) releases larger amounts of hydrogen sufide gas into atmosphere · As rain falls through this gas, it creates phenomenon of acid rain, which damages natural env by lowring pH of lakes, killing many plants and animals · ACID RAIN is corrosive rain caused by rainwater falling to ground through sulfur dioxide gas, turning it into weak sulfuric acid, which causes damage to aquatic ecosystems. · Also degrades buildings chemically 20.3. TERRESTRIAL BIOMES. · Earth's biomes can be either terrestrial or aquatic · 8 major terrestrial biomes on Earth are distinguished by characteristic temperatures and amount of precipitation · Since a biome is defined by climate, the same biome can occur in geographically distinct areas with similar climates · There are also large areas on Antarctica, Greenland, and mountain ranges covered by permanent glaciers that support little life · These are not considered biomes. They also have very low precipitation. (Deserts). TROPICAL RAINFORESTS · Referred to as tropical wet forests · Found in equatorial regions · Most diverse terrestrial biome · This biodiversity largely unknown to science and is under threat through logging and deforestation for agriculture · Also nature's pharmacy because of potential for new drugs hidden in chemicals produced by huge diversity of plants, animals, etc. · Vegetation: spreading roots and broad leaves that fall off throughout the year, unlike the trees of deciduous forests that lose their leaves in one season. · These forests are "evergreen" year round · Temp and sunlight profiles are stable compared to other terrestrial biomes. · Lack of temperature seasonality leads to year-round plant growth, rather than the seasonal growth seen in other biomes · More constant amount of sunlight allows more solar radiation, so longer days (longer period of time for plant growth) · Considerable seasonal variation in annual rainfall · Tropical rainforests have wet months in which there can be lots of precipitation, or dry months · However, driest months can still exceed the ANNUAL rainfall of some other biomes · High net primary productivity · But, high rainfall quickly leaches nutrients from the soils of these forests, which are typically low in nutrients · Vertical layering of vegetation and formation of distinct habitats for animals within each layer · On forest floor is a sparse layer of plants and decaying plant matter · Above that is an understory of short, shrubby foliage · A layer of trees rises above understory and is topped by a closed upper CANOPY - uppermost overhead layer of branches and leaves · Some additional trees emerge through this closed upper canopy · These layers provide diverse and complex habitats for the variety of plants, animals, and other organisms within the tropical wet forests · Many species of animals use the variety of plants and the complex structure of tropical forests for food and shelter · Rainforests are not the only forest biome in the tropics; there are also TROPICAL DRY FORESTS, characterized by dry season of varying lengths. These forests commonly experience leaf loss during dry season. Loss of leaves from taller trees during dry season open sup canopy and allows sunlight to the forest floor that allows the growth of thick ground-level brush, which is absent in tropical rainforests · Extensive tropical dry forests in Africa (including Madagascar), India, southern Mexico, South America SAVANNAHS · Grasslands with scattered trees, and they are found in Africa, South America, and Northern Australia · Hot, tropical areas and a lot of annual rainfall · Extensive dry season and consequent fires · As a result, scattered in grasses and forbs (herbaceous flowering plants) that dominate the savannah, there are relatively few trees · Since fire is an importance source of disturbance in this biome, plants have evolved root systems that allow them to quickly re-sprout after a fire DESERTS · SUBTROPICAL DESERTS exist in north and south latitude and are centered in tropic of cancer and tropic of Capricorn · Frequently located on downwind or lee side of mountain ranges, which createa rain shadow after prevailing winds drop their water content on the mountains · This is typical of North American deserts · Other regions (like Saraha or Namib) are dry because of the high pressure, dry air descending at those latitudes · Subtropical deserts are very dry; evaporation typically exceeds precipitation · Subtropical hot deserts can have daytime soil surface temperatures above 140 F · Temp drops far at night because there is little water vapor in air to prevent radiative cooling of land surface · Subtropical deserts characterized by low annual precipitation, lack of predictability in rainfall · Low species diversity of this biome closely related to its low and unpredictable precipitation · Despite relatively low diversity, desert species exhibit fascinating adaptations to the harshness of their environment · Very dry deserts lack perennial vegetation that lives from one year to next. Many plants are annuals that grow quick and reproduce when rainfall occurs, then die · Perennial plants in deserts have adaptations to conserve water: deep roots, reduced foliage, water-storing stems · Seed plants in desert produce seeds that can lie dormant for extended periods between rains · Most animal life in subtropical deserts has adapted to a nocturnal life, spending hot hours beneath ground · Namid desert is oldest on planet. Supports many endemic species (found only there) because of this great age. · In addition, there are cold deserts that experience freezing temp in witner and any precipitation is in the form of snowfall · Largest one: GOBI desert in north China and south Mongolia, Taklimakan desert in west China, Turkestan Desert, and Great basin desert of US CHAPARRAL · Also called scrub forest and is found in California, along Mediterranean Sea, and along south coast of Australia · Annual rainfall in this biome ranges from 65 cm to 75cm, and majority of rain is in winter · Summers: dry, many chaparral plants are dormant · The chaparral vegetation is dominated by shrubs and is adapted to periodic fires, with some plants producing seeds that germinate after a hot fire · The ashes left behind after fire are rich in nutrients like nitrogen that fertilize soil for plant regrowth · Fire is natural part of maintenance of this biome and frequently threatens human habitation in this biome TEMPERATE GRASSLANDS · Found throughout central north America, where they are also known as prairies. In Eurasia known as steppes. · Have pronounced annual fluctuations in temperature with hot summer and cold wintet · Annual temp variation produces specific growing seasons for the plants. · Plant growth is possible when temperatures are warm enough to systain plant growth, in spring, summer, fall · Temp grasslands have few trees except those found growing along rivers or streams · Dominant vegetation tends to consist of grasses · Treeless condition is maintained by low precipitation, frequent fires, grazing · Soils are fertile because the subsurface of the soil is pakced with the roots and rhizomes (underground stems) of these grasses · Roots and rhizomes act to anchor plants to ground and replenish the organic material (humus) in the soil when they die and decay · Fires, which are a natural disturbance in temperate grasslands, can be ignited by lightning strikes. Also appears that lighning-caused fire regime in north American grasslands was enhanced by intentional burning by humans · When fire is suppressed in temperate grasslands, vegetation eventually converts to scrub and dense forests · Often, restoration or management of temperate grasslands requires use of controlled burns to supporess growth of trees TEMPRATE FORESTS · Most common biome in eastern north America, western Europe, eastern asia, Chile, New Zealand · Found through mid-latitude regions · Temperate forests have defined growing seasons during spring, summer, early fall · Precipitation roughly constant through year · Deciduous trees are dominant plant in this biome with fewer evergreen conifers · Lose their leaves each fall and remain leafless in winter · Little photosynthesis during dormant winter period · Each spring, new leaves appear as temp increases · Because of the dormant period, the net primary productivity of temperate forests is less than that of tropical forests · In addition, temperate forests show far less diversity of tree species than tropical rainforest biomes · The trees of the temperate forests leaf out and shade much of ground · But, more sunlight reaches the groun din this biome than in tropical rainforests because trees in temperate forests do not grow as tall · The soils of the temperate forests are rich in organic and organic nutrients compared to tropical rainforests · This is because of thick layer of leaf litter on forest floors and reduced leaching of nutrients by rainfall · As this leaf litter decays, nutrients are returned to the soil · Leaf litter also protects soil from erosion, insulates the ground, and provides habitats for invertebrates and their predators BOREAL FORESTS · AKA Taiga or coniferous forest · Canada, Alaska, Russia, north Europe · Also found above a certain elevation (and below high elevations where trees cannot grow) in northern hemisphere mountains · Biome has cold, dry winters and short, cool, wet summers · Annual precipitation usually slow. Little evaporation because of cold temperatures. · Long and cold winters in boreal forest have led to predominance of cold-tolerant cone-bearing plants. · These are evergreen coniferous trees like pines, spruce, and fir, which retain their needle-shaped leaves year-round · Evergreen trees can photosynthesize earlier in spring than deciduous trees because less energy from sun is required to warm a needle-like leaf · Evergreen trees grow faster than deciduous trees in boreal forest · Also, soils tend to be acidic with little available nitrogen · Leaves are a nitrogen-rich structure and deciduous trees must produce a new set of these nitrogen-rich structures every year · So, coniferous trees that retain N-rich needles in a nitrogen-limiting ev may have a competitive advantage over broad-leaf deciduous trees · Net primary productivity is lower than that of temprate and tropical forests · Aboveground biomass of boreal forests is high because slow-growing tree species are long-lived and accumulate standing biomass over time · Species diversity is less than that in temperate and tropical · Lack layered forest structure · Structure of boreal forest is often only a tree layer and a ground layer · When confer needles are dropped, they decompose more slowly than broad leaves · So, fewer nutrients are returned to soil to fuel plant growth ARCTIC TUNDRA · North of subarctic boreal · Arctic regions · Also exists at elevations above tree line on mountains · Plants have short growing season of about 60 days · However, during this time, almost 24 hours of daylight and plant growth is rapid · Annual precipitation of Arctic tundra is low with little annual variation in precipitation · And, as in boreal, little evaporation · Plants generally low to grond and include low shrubs, grasses, lichens, small flowering plants · Little species diversity, low net primary productivity, and low aboveground biomass · Soils of Arctic may remain in a perennially frozen state referred to as PERMAFROST. · Permafrost makes it impossible for roots to penetrate far into soil and slows the decay of organic matter, which inhibits the release of nutrients from organic matter · Melting of the permafrost in brief summer provides water for a burst of productivity while temperatures and long days permit it · During growing season, ground can be completely covered with plants or lichens 20.4. AQUATIC AND MARINE BIOMES. · In case of aquatic biomes, abiotic factors include light, temperature, flow regime, and dissolved solids · The aquatic medium (water) has different physical and chemical properties than air · Even if water in pond or other body of water is perfectly clear (no suspended particles), water on its own absorbs light · While there are some abiotic and biotic factors in terrestrial ecosystem that shade light (like fog, dust, insect swarms), these are not usually permanent features of the v · As you descent deep enough into body of water, sunlight cannot reach · Importance of light controls productivity through photosynthesis · In addition to light, solar radiation warms bodies of water · Water temp affects rates of growth and amount of dissolved oxygen available · All natural water contains dissolved solids, or salts · Fresh water contains low levels of such dissolved substances because water is rapidly recycled through evaporation and precipitation · Oceans have relatively constant high salt content · Brackish water environments (at interface of marine and freshwater ecosystems) have complex and variable salt environments · Lakes in closed drainage basins concentrate salt in their waters and can have very high salt content that only a few specialized species can inhabit MARINE BIOMES · Ocean is a weak solution of mineral salts and decayed biological matter · Within ocean, coral reefs are a 2nd type of marine biome · Estuaries, coastal areas where salt water and fresh water mix, form a 3rd marine biome · All of ocean's open water is the PELAGIC REALM (OR ZONE) · BENTHIC REALM (OR ZONE) extends along ocean bottom from shoreline to deepest parts of ocean floor · From surface to bottom or the limit to which photosynthesis occurs is the PHOTIC ZONE · At depths greater than 200 m, light cannot penetrate, thus is referred to as APHOTIC ZONE · Majority of ocean is aphotic and lacks sufficient light for photosynthesis · Deepest part of ocean, Challenger Deep in western Pacific OCEAN · Physical diversity of the ocean (ex. light, oxygen availability) influence diversity of organisms that live within it · INTERTIDAL ZONE is oceanic region that is closest to land. With each tidal cycle, alternates between being inundated with water and left high and dry. · Extremely variable env because of tides · Organisms may be exposed to air at low tide and are underwater during high tide. · So living things that thrive in intertidal zone are often adapted to being dry for long periods of time · Shore of intertidal zone repeatedly struck by waves and the organisms found there are adapted to withstand damage from pounding action of waves · Exoskeletons of shoreline crustaceans protect them from desiccation (drying out) and wave damage · Few algae and plants establish themselves in constantly moving sand or mud · NERITIC ZONE extends from margin of intertidal zone to depths of about 200 m at the edge of the continental shelf. When water is relatively clear, photosynthesis can occur in neritic zone. Water contains silt and is well-oxygenated, low in pressure, and stable in temperature. These factors all contribute to the neritic zone having the highest productivity and biodiversity of the ocean. · Phytoplankton (including photosynthetic bacteria and larger species of algae) are responsible for the bulk of this primary productivity. Zooplankton, protists, small fishes, and shrimp feed on the producers and are the primary food source for most of the world's fisheries. Majority of these fisheries exist within neritic zone. · Beyond neritic zone is open ocean: OCEANIC ZONE/PELAGIC ZONE/OPEN OCEAN. · Within oceanic zone, thermal stratification. Abundant phytoplankton and zooplankton support pops of fish and whales. Nutrients are scarce and this is a relatively less productive part of marine biome. When photosynthetic organisms and organisms that feed on them die, their bodies fall to ocean. Open ocean lacks process for bringing the organic nutrients back up to the surface. · Beneath pelagic zone is BENTHIC REALM, the deepwater region beyond the continental shelf. · Bottom of benthic realm is comprised of sand, silt, and dead organisms. · Temp decreases as water depth increases · NUTRIENT-RICH portion of the ocean because of the dead organisms that fall from the upper layers of the ocean. Because of this high level of nutrients, a diversity of fungi, sponges, sea anemones, marine worms, sea stars, fishes, and bacteria exists · Deepest part of ocean is ABYSSAL ZONE. Very cold and very high pressure, HIGH OXYGEN CONTENT, and low nutrient content!!!!!!!! · Variety of invertebrates and fishes found in this zone, but the abyssal zone does not have photosynthetic organisms. Chemosynthetic bacteria use the hydrogen sulfide and other minerals emitted from deep hydrothermal vents. Use hydrogen sulfide as energy source and serve as the base of food chain found around the vents. · So, as you go out from land, Intertidal, then Neritic, then Oceanic. As you go downward, Oceanic, then Photic, then Aphotic, then Abyssal. Photic, Aphotic, and Abyssal are all part of the PELAGIC. Benthic stretches vertically along the continental shelf (all the way from intertidal out and down to the ocean floor of the abyssal). See figure 20.28. · CORAL REEFS are ocean ridges formed by marine invertebrates living in warm shallow waters within the photic zone. Ex. Great Barrier Reef off of Australia. Other coral reefs are fringing islands, directly adjacent to land, or atolls. · Coral-forming colonies of organisms (members of phylum Cnidaria) secrte a calcium carbonate skeleton. These skeletons slowly accumulate, thus forming underwater reef. Corals found in shallower waters have a mutualistic relationship with photosynthetic unicellular protists. · Waters in which these corals live are nutritionally poor, and without this mutualism, it would not be possible for large corals to grow because there are few planktonic organisms for them to feed on. · Some corals in deep cold waters don't have mutualistic relationship with protists; must obtain energy exclusively by feeding on plankton using stinging cells on their tentacles · Coral reefs: one of the most diverse biomes. · It is estimated that more than 4000 fish species inhabit coral reefs · These fishes can feed on coral, the CRYPTOFAUNA (invertebrates within calcium carbonate structures), or seaweed and algae · PLANKTIVORES here eat plankton · ESTUARIES: biome where the ocean meets fresh water. So, fresh and salt water found in same vicinity · Diluted, brackish salt water · Form protected areas where many of offspring of crustaceans, mollusks, and fish begin their lives · Salinity is imp factor that influences the organisms and the adaptations of the organisms found in estuaries · Salinity of estuaries varies and is based on the rate of flow of its freshwater sources · Once or twice a day, high tides bring salt water into the estuary · Low tides occurring at same frequency reverse the current of salt water · Daily mixing of fresh and salt water is a physiological challenge for the plants and animals that inhabit estuaries · Many estuarine plant species are halophytes, plants that can tolerate salty conditions · Halophytic plants are adapted to deal with salt water spray and salt water on their roots · In some halophytes, filters in roots remove salt from the water that the plants absorb · Animals like mussels and clams have developed behavioral adaptations that expend a lot of energy to function in this rapidly changing env · When these animals are exposed to low salinity, stop feeding, close their shells, and switch from aerobic respiration (using gills) to anaerobic respiration (does not require oxygen). When high tide returns to estuary, salinity and oxygen content of the water increases, and these animals open their shells, begin feeding, and return to aerobic respiration. FRESHWATER BIOMES · Include lakes, ponds, and wetlands (standing water) as well as rivers and streams (flowing) · Various roles and human benefits are referred to as ECOSYSTEM SERVICES · Lakes and ponds are found in terrestrial landscape and are connected w/ abiotic and biotic factors of terrestrial biomes LAKES AND PONDS · Temp is an important abiotic factor · In summer, thermal stratification of deep lakes occurs when upper layer of water is warmed by sun and does not mix with deep cool water · Process produces sharp transition between warm and cold water · 2 layers do not mix until cooling temps and winds break down the stratification and water in lake mixes from top to bottom · During period of stratification, most of productivity occurs in warm, well-illuminated upper layer, while dead organisms slowly rain down into the cold, dark layer below where decomposing bacteria and cold-adapted species such as lake trout exist · Like ocean, has a photic layer · Phytoplankton (ALGAE AND CYANOBACTERIA) are found here and provide base of the food web of lakes and ponds · Zooplankton (like small crustaceans) consume phytoplankton · At bottom, bacteria in aphotic zone break down dead organisms that sink to the bottom · N and particularly P are important limiting nutrients in lakes and ponds · So, they are determining factors in the amount of phytoplankton growth in lakes and ponds · When there is large input of N and P (from sewage runoff and fertilizer), growth of algae skyrockets, resulting in ALGAL BLOOM · Algal blooms can reduce light penetration in water · Lake or pond becomes aphotic and photosynthetic plants cannot survive · When algae die and decompose, severe oxygen depletion of water RIVERS AND STREAMS · Carry water from the source or headwater to the mouth at a lake or ocean · Abiotic features of rivers and streams vary along length · Streams begin at a point of origin: SOURCE WATER, which is usually cold, clear, low in nutrients. CHANNEL (width of river or stream) is narrower here than at any other place along the length of the river or stream. · Headwater streams are of necessity at a higher elevation than the mouth of the river and often originate in regions with steep grades leading to higher flow rates than lower elevation stretches. · Faster-moving water and short distance from its origin results in minimal silt levels in headwater streams; therefore, the water is clear · Photosynthesis here mostly attributed to algae that are growing on rocks; the swift current inhibits the growth of phytoplankton. · Photosynthesis may be further reduced by tree cover reaching over the narrow stream. · This shading also keeps temps lower · Additional input of energy can come from leaves or other organic material that falls into a river or stream from the trees and other plants that border the water · When the leaves decompose, organic material and nutrients in leaves are returned to the water · Leaves also support a food chain of invertebrates that eat them and are eaten by predatory invertebrates and fish · Plants and animals have adapted to fast-moving water · Ex. Leeches have elongated bodies and suckers on both ends · As river or stream flows away from source, width of channel gradually widens, current slows, and the temperature characteristically increases · Increasing width results from increased volume of water from more and more tributaries · Gradients are typically lower farther along the river, which accounts for the slowing flow · With increasing volume can come increased silt, and as the flow rate slows, silt may settle, thus increasing the deposition of sediment · Phytoplankton can also be suspended in slow water · So, water will not be as clear as it is near the source · Water is also warmer as a result of longer exposure to sunlight and the absence of tree cover over wider expanses between banks · Worms and insects can be found burrowing into the mud · Predatory vertebrates include waterfowl, frogs, and fishes · In heavily silt-laden rivers, these predators must find food in the murky waters, and, unlike trout in the clear waters at the source, these vertebrates cannot use vision as their primary sense to find food. · Instead, more likely to use taste or chemical cues to find prey. · When a river reaches the ocean or a large lake, the water typically slows dramatically and any silt in the river water will settle. · Rivers with high silt content discharging into oceans with minimal currents and wave action will build deltas, low-elevation areas of sand and mud, as the silt settles onto ocean bottom · Rivers with low silt content or in areas where ocean currents or wave action are high create areas where the fresh water and salt water mix. WETLANDS · Environments in which the soil is either permanently or periodically saturated with water · Different from lakes and ponds because they exhibit a new continuous cover of emergent vegetation · EMERGENT VEGETATION consists of wetland plants that are rooted in the soil, but have portions of leaves, stems, and flowers extending above the water's surface. · Several types of wetlands. Ex. Marshes, swamps, bogs, mudflats, salt marshes · Freshwater marshes and swamps characterized by slow and steady water flow · Bogs develop in depressions where water flow is low or nonexistent · Bogs usually occur in areas where there is a clay bottom with poor percolation · Percolation is the movement of water through the pores in the soil or rocks · Water found in a bog is stagnant and oxygen depleted because oxygen used during decomp of organic matter is not replaced. · As oxygen in water is depleted, decomposition slows. · This leads to organic acids and other acids building up and lowering the pH of the water. · At a lower pH, nitrogen becomes UNAVAILABLE to plants. Creates challenge for plants because nitrogen is a limiting resource. · Some types of bog plants (like sundews, pitcher plants, venus flytraps) capture insects and extract the nitrogen from their bodies. · Bogs have low net primary productivity because the water found in bogs has low levels of nitrogen and oxygen.

Day 16

DAY 16: POPULATIONS AND DIVERSITY · Any given area - or habitat - has a number of species (S) and ecologists ask why so many, or so few - what controls this? · RELATIVE ABUNDANCE - frequency of observed diversity, all frequencies sum to 1 · What gets counted depends on spatial scale of area being studied, size and type of organism · WHY did we count our pens? · 1. Natural diversity is not evenly distributed across the planet (biogeography, biomes, environmental gradients). · 2. Natural distributions of "types" or "species" diversity (including alleles) tend to be UNEVEN in abundance - a few common types (black, blue), many rare types (pink, teal, orange). · 3. Larger area/volume you study, the more diversity found - called the "species-area relationship." · 4. Large area tend to include more habitat types - places for diversity to live, get resources they need, minimize stress. COUNTING DIVERSITY · Idea here in part is that we decide what and how to count, and what "counts" · If you only count black, blue, red, green PHENOTYPES or SPECIES, you find there are some not fully enumerated · If you decide to talk about diversity in a field - how do you count? How big must the plant or insect be to count? What about worms? · Let's say there were around 15 pink pens. And now we represent the FREQUENCY in the population · Counting the SUM OF SQUARES of these frequencies leads to "SIMPSONS INDEX:" how many species dominate? In this case, roughly 3 "describe" the community. · With biogeography, we aren't saying the different zones are completely different; they are DOMINATED by different plants and animals. · With biomes, the huge habitat classification of the world - same thing: we see "oak/pine forest" or "Spartina/Juncus marsh" or similar generalizations based on the few species that dominate. · These mathematical transformations like (inverse) Simpsons index: help guide ecologists into useful simplifications of ecological systems as defined. · As habitat area increases, species diversity increases... Big implications. · Distributions within distinct samples: · A QUADRAT is a standardized way of assessing a defined area · We cannot count everything, everywhere. · Sampling diversity lets us ESTIMATE larger quantities or concepts - and variation in observations tell us something about interactions - do they compete for resources? Stay together for safety, mating? · Back to POPULATIONS: · "You cannot measure something until a boundary for it has been decided... You have to have a thing to measure... It is DECIDED; that way, we can take responsibility for our decisions." · Populations are "a collection of organisms that are required to be in some way equivalent" and USEFUL for hypothesis · Salmonids (salmon) great examples of population ecology and ecosystem return of nutrients · HYPOTHESIS TESTING: · We rejected our null hypothesis (everything is equally everywhere) because a more complicated MODEL (species are found where physiological, growth, and reproductive needs are best met) has better support · Still doesn't tell us how organisms interact with each other, only the environment · So, we start to ask if interactions among organisms are a better explanation for observed data and compare this hypothesis to simpler ones · How do ORGANISMS interact with abiotic and biotic factors in habitat - what do they need for energy, what eats them? · How does a POPULATION of organisms change in abundance, given diversity in that population and interactions with the environment? · The interactions among distinct populations or species describe COMMUNITY ECOLOGY, which influences patterns of diversity in that area. · ECOSYSTEM level less about specific organisms, and more how nutrients and energy (C, H, O, N, P, S) move/cycle through system · LANDSCAPE, BIOME, BIOSPHERE increasingly large scales · CHONPS: 6 most abundant elements - others very important, though. Many more are required, but these are most ABUNDANT. · Human Ecology: · Trade-offs in life history traits, including tolerances - cold-adapted species are stressed in tropics; plants that defend themselves from herbivory grow more slowly than those that don't need defenses. · We are only truly global organisms because of modifying the environment - this itself influences the ecology of almost everything else... · Is there hope? · Yes. But not much time. A small number of companies/industries cause the vast majority of carbon/environmental damage. Do what you can to influence those companies or not support that use of energy and resource. · We have capability to transform with renewable energy, and we can share the resources we have BETTER. Vote! · Bigger organisms, more spread out (lower density), broader distribution · How big is a population? · A POPULATION - for comparisons - has to be defined, a particular group of organisms in a particular region in a defined time. · We use samples or QUADRATS (standardized sampling spaces) for immobile/sessile organisms to randomly sample larger space and use that to make inference about larger area · But what if they move around? · Procedures for TAGGING organisms to identify how many in an area (does the MARK affect fitness/survival of the organism? Make sure the tag doesn't attack predators, etc. That would bias results). · Mark-recapture methods - what is the ratio of marked and unmarked individuals, how can we estimate the population size? · A large population would have a lower rate of recapturing marked individuals (may help us define boundaries of a population) · You catch and mark 15 birds. Next day catch 20, 5 of them are already marked. If ¼ of the individuals caught the second time are banded, that suggests that the N=15 that we banded the first time represent ¼ of all the individuals in this population. So, the population size is 15x4 = 60. · N = (# marked, time 1) x (# caught, time 2) / (# marked caught time 2) · Distribution of INDIVIDUALS across space indicates (maybe a hypothesis?) how organisms move and interact! · RANDOM: null model of dispersal and habitat requirements. · CLUMPED: social interactions? Mating, defense? · UNIFORM: competitive or antagonistic interactions? · DEMOGRAPHY: · From simple counts or density, can characterize: · How many eating a particular prey item? · How many died, how many born? · How many carry parasites? · Male-female ratios · All of these (and more) affect trajectory of population size. · FECUNDITY (reproductive output) of an organism interacts with survivorship. · More offspring, typically less care/resource provided to offspring, high offspring mortality (type 3) · Fewer offspring, more care/resource, lower early mortality (Type 1) · EGG SIZE AND PARENTAL CARE TELL A LOT ABOUT AN ORGANISM AND SURVIVORSHIP. · But biology - reality - is complicated. Few species fit idealized curves, those are themselves MODELS - simple representations. · Is it a high-fecundity species like a sea urchin, with only a few out of a million surviving? Or, od it a Rhinoceros with few offspring, cared for maternally? · CICADAS... ARE SALMON? · Semelparity - only reproduces once per lifetime, put lots of resources toward that event (vs. iteroparity: multiple events). · Salmon, cicadas - examples where outcome is massive shift in ECOSYSTEM resources from one environment to another (Salmon: from ocean to forests and back; cicadas from soil to aboveground and back) · ENERGY BUDGETS - caloric energy intake toward maintenance, growth, reproduction, INCLUDING OFFSPRING CARE. · POPULATION GROWTH: · Remember there are more individuals born than can possibly survive!!!!!! · If environment is better - more food, less stress, more survival... · Where (1 + (b-d)) > 1, there will be population growth. · Where (1 + (b-d)) < 1, population decline. · FORMS OF GROWTH: · EXPONENTIAL (1+ (b-d)) = growth rate r (rate of intrinsic growth), change is r x N · Very rapid population increases... But all organisms need a resource to maintain, grow, reproduce. · Carrying capacity K: how many individuals can survive given the food/resources available. · LOGISTIC growth: a MODEL for growth that adds just one parameter K that is far better. Change in population size becomes r x N x ((K-N) / K) · When N is close to K, growth slows to zero!!!!!!! · Exponential requires ONE parameter r, only predicts accurately when starting FAR from carrying capacity K. · Logistic requires 2 (r, K), but better predictions · Exponential: J shape. Per capita growth rate ( r ) doesn't change, even if population gets very large · Logistical: S shape: Per capita growth rate ( r ) gets SMALLER as population approaches its maximum size. (r gets smaller as N approaches K). · LIFE HISTORY AND TRADE-OFFS: · Life history refers to the tendency of a species to mate a certain way, have a certain number of offspring of a certain size that disperse in a certain way, given their environment!!! · The more STABLE an environment, the more an organism will maintain population close to carrying capacity K; typically type I or II survivorship, more parental care/provisioning, more within-species competition for resources!!!!!! · The more UNPREDICTABLE environment, more likely for populations to "bloom" (like dinoflagellates, bacteria, etc), typically type III survivorship, many small offspring, little care. · Organisms sometimes get called "r-selected" or "K-selected" to represent these extremes · R and K are context dependent. · K for humans is decreasing even as N goes up - it is NOT a fixed number, changes as energy needs per individual change (industrialization, agriculture) and as resources are depleted (forests, water, oil, marine fish, etc) · Intergovernmental Panel on Climate Change (IPCC) report 2 years ago - action in next 12 years will determine the likelihood of limiting sea level rise, changes in precipitation, weather, global heat. · R is the rate possible assuming resource need/availability, K is the population size possible assuming a certain need. · WE (HUMANS) ARE REDUCING OUR CARRYING CAPACITY. Book Excerpt Notes: · Best way to control populations is naturally. Balance of all populations (predators, prey) · Risk of Lyme disease goes up as roster of native animals, in given area, goes down · In area of high diversity, mouse and tick populations remain small, so the disease remains insignificant · Larger land area: more diversity

Day 18

DAY 18 · MAYFLIES: · TRAITS likely similar to first flying insects - long tails, wings do not fold flat on abdomen · Juvenile stage "naiad" or "nympth" in streams/rivers - presence indicates LOW POLLUTION · Brief lives (minutes to days) the ORDER EPHEMEROPTERA, massive hatches can be seen on radar! · Adults do not have functional mouths, do not eat - find a mate and die. · When mayflies emerge, they transfer nutrients FROM rivers TO terrestrial habitat as birds, etc. eat them - of course, a favorite for trout a well, so not always a TRANSFER. · Some studies suggest mayfly populations are PHOSPHORUS limited - so how does new phosphorus end up in the water? · A river is "nutrient soup" · Autochthonous remains: those of freshwater or riparian animals that lived and died within the stream ecosystem itself; their decomposition is a form of internal nutrient cycling, provided the animals obtained most of their food within the aquatic system. Remains can be continuous (death occurs at steady rate) or pulsed (animals due en masse). · Allochthonous remains: those resulting from animals that primarily lived outside of the stream ecosystem. Death and decomp represents a transfer of nutrients and carbon into the system. Like autochthonous inputs, we can divide these remains into pulsed and continuous. · Phosphorus: exists in 2 forms, white and red phosphorus. Highly reactive, never found as a free element on Earth. Concentration in Earth's crust. In minerals, generally occurs as phosphate. Produces glow when exposed to oxygen (oxidation of the white, but not red, phosphorus) - chemiluminescence. Together w/ N, arsenic, antimony, bismuth, phosphorus is classified as a PNICTOGEN. · P: essential for life. Phosphates are component of DNA, RNA, ATP, phospholipids. Elemental P first isolated from human urine, and bone ash important P source. P mines contain fossils because phosphate is present in animal remains. Low P levels are an important limit to growth in some aquatic systems. Vast majority of P compounds mined are consumed as fertilizers. P is needed to replace P that plants remove from the soil, and its annual demand is rising nearly twice as fast as growth of human pop. Other applications: organophorphous compounds in detergents, pesticides, nerve agents. · In Atamaca desert, lizards graze in kelps in intertidal, supplying elements through their waste products and bodies to the driest desert on Earth. Almost any other life depends on elements brought from the sea. · ATP: ATP and energy transfers involve phosphate groups. Organisms are competing for life over something this simple. · Why do ecosystems change through time - what is similar about a keystone predator and a fire? DISTURBANCE (makes space for more diversity in a way) · Where do RAW nutrients come from that sustain an ecosystem? How often do they move from one ecosystem to another? · What are ways that humans are accelerating some of this movement of elemental nutrients through the BIOSPHERE (all of it)? What are the consequences? · COMMUNITY CHANGE THROUGH TIME: · Competition, predation, parasitism tend to be DETERMINISTIC mechanisms - in certain context, we can predict the outcome. · As with "control" side of Paine's experiment, also STOCHASTIC (random) shifts in abundance that are results of unpredictable variation in reproductive success of populations - no direction through time ("drift") · ECOLOGY IS NOT STATIC: · Always changing - through random AND deterministic processes. · Disturbance (a sea star eating lots of mussels, a fire, etc) opens up opportunities for new organisms to arrive/grow. · Lack of DISTURBANCE - community may change less as it reaches climax state. · SUCCESSION (change in species structure of ecological community over time) IS JUST AN EXPECTATION OF CHANGE: · Pace and order of succession is the primary distinction between the 2 types of succession: · What is important to YOU to know is that life comes back, but not necessarily the same as it was. · Primary succession: "bare rock:" there is no soil left. So you must have erosion, wind, rain, and eventually you have soil, so that plants can grow back. · Secondary succession: "soil remains:" disturbance, but soils remain. Common after forest fires. Life is ready to come back. Pioneer organisms are some of the ones that come after there is a disturbance. · Climax: what happens AFTER SUCCESSION. After everything comes back and then levels out. · A disease wiped out the Caribbean urchin Diadema, allowing algae to overgrow many corals - ecosystems may stabilize in a new successional pathway. · ECOSYSTEMS AFFECT EACH OTHER: · How energy, chemicals, nutrients move between ecosystems is a key to understanding diversity and ecology overall. · C, H, O, N, P, S are key for life to thrive - as water and oxygen, CO2 or carbonic acid, nitrogen in amino acids, DNA; phosphorus in DNA, bones, and more; and SULFUR in amino acids, microbial nutrient loop · If any of these change in amount, it influences the biodiversity in that ecosystem · CHANGING LIFE AROUND THE PLANET HAS BIG EFFECTS · CHEMICAL CYCLING AND ENERGY FLOW IN ECOSYSTEMS. · Autotrophs (plants, algae, some bacteria) are COLLECTORS, concentrating carbon, energy, and minerals in organic matter (food). Heterotrophs (animals, fungi, most bacteria) are scatterers, digesting food and releasing its carbon, minerals and energy back to the environment. · This is happening at all physical scales! · MICROSCOPIC AND MACROSCOPIC SCALES OF CARBON CYCLING: · "Microbial loop" - decomposition into dissolved organic carbon (DOC) supports microbial growth; protists eat microbes, small metazoans eat protists, etc. · AUTOTROPH LOOP: sunlight and CO2 or HCO3 (in water) to make glucose, moves up and into the CONSUMER portion of food web to be incorporated. · DECOMPOSITION: excreted/dropped waste, fungi and microbes break down - many carbon inputs to a system of soil or water at the base. Autotrophs collect carbon, heterotrophs scatter it. · CARBON CYCLES, OVERSIMPLIFIED: · Air - photosynthesis - sugar/complex molecules - consumption - metabolism/decomposition - gas (biological carbon cycle) · Air - photosynthesis - sugar/complex molecules - storage - retention (permafrost, fossil fuels, CaCO3 shells, etc). BIOGEOCHEMICAL CARBON CYCLE. · SHOULD BE A SLOW EXCHANGE BETWEEN THESE 2 CYCLES - ON ORDER OF 100S TO MILLIONS OF YEARS. · Air - photosynthesis - sugar/complex molecules - storage (phossil fuels, carbonate minerals) - burning/chemical fragmentation - gas (ACCELERATION OF EXCHANGE BETWEEN CYCLES) · PERMAFROST: · Plant matter grown at a time when region was warmer; wholly or decomposed into soil. · Regional cooling (the biomes tundra, taiga) in Arctic - soil and organic matter frozen at certain depth (soil is largest reservoir of carbon in terrestrial ecosystems!!!) · Climate change/warming - permafrost is THAWING, release of CO2 (aerobic respiration) and CH4 (methane, anaerobic respiration) · Rate of microbial decomposition is temperature/moisture dependent. "Stored" soil carbon is becoming available to the biological carbon cycle, removed from the biogeochemical carbon cycle. · Mysterious craters in Siberia linked to melting permafrost. Formed by greenhouse gases violently erupting. · CEMENT (CONCRETE): · Calcium carbonate - biogenic (shells, coral skeletons, coccolithopores, etc) as well as geologic origins. · To make cement, limestone (CaCO3) is HEATED to make calcium oxide and CO2 (released) - so a double release of carbon dioxide · Concrete industry creates up to 5% of man-made emissions of CO2 - accelerates BIOGEOCHEMICAL CARBON CYCLE · ATMOSPHERIC CO2: · The increase can be attributed to fossil fuels because of distinct isotopic chemical signatures from fossil fuels versus respiration or "natural cycles." · CO2 is not the only "greenhouse gas," but it is directly associated with human consumption, particularly "developed" nations (but affecting all others) · ECOSYSTEM EFFECTS: · Dr. Paine's Pisaster experiment (community ecology) explained how change in BIOTIC (get rid of predator) affected a change in BIOTIC (change in diversity patterns) · Another way to think: if we exchange EITHER "biotic" above with abiotic (non-living environment), what is the result? · Measure in units of chemicals (change over time) or diversity/abundance (change with treatment)? · HEAT IS ENERGY: · Nutrient and energy flow through food web - loss at each level. · Metabolic processes create growth, energy, and heat (lost). · Decomposition allows microbial growth, fission, metabolism also produces heat (lost). · All incoming energy is sunlight or chemical (deep sea hydrothermal vents, caves). · HOW DO WE MEASURE? · Easier to measure if a system is CLOSED and manageable. · Like an aquarium. You can check pH, nitrates, phosphorus, salinity - you control what goes in there. · A "mesocosm" experiment is often chosen for easy ability to replicate TREATMENTS AND CONTROL CONDITIONS · An astonishing amount of ecology relies on kiddie pools, Tupperware, PVC pipe, and jars · Ex. "OA" (ocean acidification) lab at Friday harbor - beer coolers and hardware store supplies. Recreate a system in a way where you can manipulate an important biotic or abiotic factor - separate from the complexity of a natural ecosystem. · ECOLOGICAL STOICHIOMETRY: as food moved through "food web," what is the conversion rate? Termites have a whole-organism C:N ratio of about 5:1, but the wood they consume has C:N ration of 500:1 · What elements are limiting in development and growth - how do organisms find that balance, what resource needs? · For population growth: "r-selected" organisms grow quickly in response to available resources, typically low N:P ratio, because P needed for ribosomes, RNA assembly, rapid growth. · "K-selected" (carrying capacity) biota tend to have high N:P ratio (not about quick growth, more about maintenance). · EXCESS OF NUTRIENTS? · C, N, and P may be LIMITING NUTRIENT for microbial or phytoplankton "blooms" · Fertilizer, laundry detergent - very high anthropogenic inputs of N, P · Hippo feces, dead mammals - nutrient loading in rivers; DOCs taken up by microbial loop, but aerobic respiration requires oxygen · Can result in anoxic/low-oxygen environments in aquatic: fish kills, dead zones · LOSS OF NUTRIENTS: · Average urban tree needs the leaves, grass clippings, bird droppings, mycelium, insects, earthworms, and other microbial diversity to be healthy - notice the many old trees being taken down (or falling) in Athens these days · Arborists study the biology of urban trees (among other things), and just like houseplants, need fertilizer because they otherwise only get water, a big urban tree needs good, nutrient rich soil

Day 19

DAY 19: WE ARE ALL PART OF IT · HEAT IS ENERGY: · Nutrient and energy flow through food web - loss at each level · Metabolic processes create growth, energy, and heat (lost) · Decomposition allows microbial growth, fission, metabolism also produces heat (lost) · All incoming energy is sunlight or chemical (deep sea hydrothermal vents, caves) · HOW DO WE MEASURE? · Easier to measure if a system is closed and manageable · Like an aquarium: can check pH, nitrates, phosphorus, salinity - you control what goes in there · A "mesocosm" experiment is often chosen for easy ability to replicate TREATMENTS AND CONTROL CONIDTIONS · Ex. "OA" (ocean acidification) lab at Friday harbor - beer coolers and hardware store supplies. · Recreate a system in a way you can manipulate a biotic or abiotic factor - separate from the complexity of a natural ecosystem. · ECOLOGICAL STOICHIOMETRY: · As food moves through "food web," what is conversion rate? Termites have a whole-organism C:N ratio of about 5:1, but the wood they consume has C:N ratio of 500:1 · What elements are limiting in development and growth - how do organisms find that balance, what resource needs? · For population growth: "r-selected" organisms grow quickly in response to available resources, typically low N:P ratio because P needed for ribosomes, RNA assembly, rapid growth · "K-selected" (carrying capacity) biota tend to have high N:P ratio (not about quick growth, more about maintenance) · EXCESS OF NUTRIENTS? · C, N, and P may be LIMITING NUTRIENT for microbial or phytoplankton "blooms" · Fertilizer, laundry detergent - very high anthropogenic (mainly pollutants originating in human activity) inputs of N, P · Hippo feces, dead animals - nutrient loading in river; DOCs (dissolved organic compounds) taken on by microbial loop but aerobic respiration requires oxygen. (Bacteria used up all the oxygen). · Can result in anoxic/low oxygen environments in aquatic: fish kills, dead zones · LOSS OF NUTRIENTS · Average urban tree needs leaves, grass clippings, bird droppings, mycelium, insects, earthworms, other microbial diversity to be healthy. Arborists study biology of urban trees and just like houseplants need fertilizer, because otherwise only get water. · ECOSYSTEM ECOLOGY is at the base of many changes in populations and communities · Human activity is ACCELERATING many natural cycles through extraction and use · Pollution, land use limit available resources, habitats as well · BIOMAGNIFICATION: something is consumed/absorbed at low trophic level (producer, primary consumer). Then, next trophic level (secondary consumer) eats those "lower" organisms. Then, next trophic level, then next. So, apex predator has high concentration of DDT, PCBs, or other toxins in the body. Bald eagles nearly went extinct because of biomagnification of DDT! · DDT, PCB, WHAT?? · For us, thankfully, this is mostly historical info. Bald eagle has recovered well so far. · Plastics are a current ecosystem disaster for similar reasons - microfibers, scrubs, as well as big pieces · If biodiversity is considered free and of no importance to us, losing species doesn't matter. Is it free? · ECOSYSTEM SERVICES: Pollination (food), water filtration, storm defense, "forest bathing," medicine, engineering solutions · A recent meta-analysis of insect abundance at national LTER sites (long-term ecological research, funded by NSF) do not necessarily cause such alarm - but those are mostly at protected sites. · Still, it may be important that we recognize the problem while we can identify the cause! · APEX PREDATORS: · In any major ecosystem, apex predators will have a huge impact on the dominance of other consumers. · Recent restoration work considers when we need to re-introduce same or similar diversity to have the effects of balancing the food web. · Apex predators have been hunted exclusively (wolves, coyotes, etc) · Conflicts between ranchers/human populations and predators, but with cascading effects that influence our ecosystem · BIODIVERSITY AND MANAGEMENT: · It has been argued that we should focus on protecting KEYSTONE and FOUNDATION species - because with limited resource, we cannot equally protect all biodiversity. · Role of biologists in exploring, describing, and carefully considering data for making these decisions is a part of how funding/effort is allocated under ENDANGERED SPECIES ACT, funds for Georgia DNR, USFW, and so on · SHARKS! · Concern is that large sharks have been in DECLINE, and we know they have major impacts on the marine fish community · Large sharks eat smaller "mesopredator" elasmobranchs (rays, skates, small sharks) · This study argued that the loss of big sharks was leading to trophic cascade: more rays and small sharks, and they are eating valuable mussels, oysters, scallops... · So, they argue that all of these large sharks are in top decline and the smaller predators are on the increase. And in particular, the cownose ray increases. And bay scallop decreases. Economic consequence. · BAY SCALLOPS: · Bivalve molluscs with amazing behaviors - can swim by clapping hsells together. Blue spots are up to 200 independent eyes watching for predators! · HOMOLOGY ALERT: these eyes are STRCTURALLY not homologous (use mirror protein crystals instead of lenses), but the pigments that absorb light (opsins) are homologous to those in our retina · They estimated that the abundance was increasing in cownose rays, and if each ray eats 0.25 kg of shellfish (bivalve, crab) a day, then as they migrate through area they may collectively eat more than the coastal HUMAN population · One thing we can do: "Eat a Ray, save the bay." · The initial study was done at one location on east coast. Second was able to add additional data source from Virgina Institute of Marine Sciences. · Diff locations can have distinct responses (w/ same species being monitored) because of different context: local environment, size of populations, size of prey populations - even evolutionary variation! · Diff populations WITHIN A SPECIES tell us a lot about how variation is maintained within and among species! · Now thought that the increase in abundance for cownose rays CAME AFTER stocks of oysters, scallops, etc had started to crash in 1980s and 90s. OVERHARVESTING, along with DISEASE decimated oyster and scallop fisheries. · SCIENCE IS HERE TO MAKE PREDICTIONS, AND IMPROVE ON THEM · Severity and trajectory of hurricane Zeta is an opportunity to improve our models. Scientific debates aren't about egos, and aren't just "academic." · We constantly work to know what is really happening to make good decisions about how to manage resources, species, and even epidemics. · Interaction of data from fisheries, disease ecology, knowledge of life history of organisms - helps make better predictions · Overfishing, overharvesting cownose rays will have its own consequences. How do we proceed? · LOSS AND CHANGE OF BIODIVERSITY: · OVERHARVESTING - in particular wild aquatic species, certainly ancient megafauna · Historically, evidence that European cultures believed the ocean contained endless diversity and promise for food · Indigenous cultures have tended toward caution on impact of fishing · MECHANIZED FISHING - "long-line" fishing and trawling have collapsed many fisheries · Fewer large fish because of mechanized harvesting · Larger fish allocate more energy to reproduction · Fish have evolved to become reproductive at smaller sizes - so they reproduce before being caught. · So, populations respond more slowly. · EVOLUTION AND ECOLOGY ARE COMPLETELY INTERTWINED

Day 20

DAY 20: CLIMATE, ECOLOGY, EVOLUTION, CONSERVATION · Trout Diversity. If rivers are not connected to one another - with hundreds to thousands of kilometers between river mouths - how did trout end up in the southwestern US? Why are we focused on the Gila trout, Oncorhynchus gilae? Trout are mostly obligate freshwater salmonid fishes - they don't migrate to sea like true salmon. Trout are salmonids though - their origins are in running to sea to develop and grow on phytoplankton and then become consumers. When the planet was much cooler, salmonids were found all down the Mexican coast. Their descendants are up in rivers flowing in from Sierra Madre Occidental, Grand Canyon, Gila Wilderness... · There are many diff projections of maps of our Earth, and diff projections emphasize diff features, don't match each other · Most phytoplankton and kelps are in temperate/boreal (polar) regions · In Pleistocene, our planet had much cooler glacial periods, where phytoplankton and kelps - primary productivity - would be found down along Baja California peninsula and the west coast of Mexico · Shows how geography isolates populations - and they become evolutionarily distinct! · GILA TROUT · Humans introduced species like rainbow trout and cutthroat trout to their river system. Competition and hybridization (interbreeding) risk. · Significant habitat degradation, even in a sparsely-populated part of the US. · Long history of conservation though! Thanks to the White Mountain Apache tribe, and federal/endangered species act. · We can recognize it as distinct in many different ways. · INTRODUCED/INVASIVE/EXOTIC SPECIES: · We often think of Burmese pythons, Kudzu, green crabs - distinct new forms in an ecosystem that transform the community in some way. · Back to "what is a species?" - when a related, similar organisms is introduced, there are more significant problems of being inter-fertile with the endemic diversity. · Competition for resources, competition for mates. · Offspring may do poorly (intermediate traits not adapted to the environment), or may thrive ("hybrid vigor") · RELATED TROUT SPECIES: · Rainbow (O. mykiss) has been stocked on 6 of 7 continents · Cutthroat, Gila, redband, steelhead, golden - all freshwater variants in radiation of Pacific salmonids (Oncorhynchus) · Diversity evolved through being isolated from each other, so few behavioral or other features affect recognition (identification) or mating · HABITAT DEGREDATION: · Oncorhynchus gilae only lives above 8000' elevation · A crew had to take a horse/mule train into mountains to collect · Cows are affecting their populations, degrading their habitats, in this remote area · Trampled steambanks and removal of shade plants like willows. Damaged riparian areas release sediment into streams rendering them wider and more shallow. Violation of water quality standards for sediment, turbidity, fecal bacteria and excessively high stream water temp are one result; damage to aquatic species which rely on cold water in streams below grazing allotments is another consequence. · HISTORY OF MANAGEMENT: · Almost a century ago, native people recognized that a trout ENDEMIC to their region was disappearing (because of introduced diversity to the area - Europeans and their livestock) · Tribal governments began limiting access/harvest · Federal agencies began assisting, one of the 1st species (the first fish!) placed under protection of ENDANGERED SPECIES ACT (1973, Nixon) · Angling closures; barriers to prevent invasion of non-native salmonids; limiting grazing access · HOW IS BIODIVERSITY LOST? Different ways to express diversity and its loss. · If a species is gone, it is extinct. · If a population disappears from part of the range of a species, it has been EXTIRPATED. · Some species only found in limited regions - we call this ENDEMIC, and so if organism lost there, it is gone! · There is no potential for adaptation to true disaster. · More than 95% of the Gila trout were killed in fires in the late 1980s. · After forest fires killed around 95% of Gila trout, a new recovery plan was implemented in late 1980s. · Recovery possible from HATCHERIES - where fish from particular stocks (POPULATIONS) are maintained, spawned, offspring fed and raised for release to rivers. · Each POPULATION was replicated into multiple streams, even some that had not harbored trout before ("arking," some call it). · Last stage of recovery: ensure no fish remain that are hybrid (from interbreeding), keep distinct population diversity. · GENETIC DIVERSITY: · DNA sequences from portion of MITOCHONDRION are used to identify many species, in addition to their traits. · Other DNA sequences/markers represent more of the genome, and are used to examine introgression (movement of genetic diversity) among populations - here, used to ensure hybrid history. · Here, a PHYLOGENY shows relatedness of trout across western North America. · ANOTHER TYPE OF FIELD GUIDE? · National Center for Biotechnology Information (NCBI) run by national institutes of health (NIH) keeps ALL DNA SEQUENCE DATA THAT HAS BEEN GENERATED. All of it. · Most common "barcode" gene (cytochrome oxidase I) represented many times (for non-animal species, other genes are better) · The characters or TRAITS compared are the order of particular DNA variants in these genes - enough variation to distinguish close relatives with only a tiny piece of fin or other tissue. · The protein may be conserved, but the diversity making it is highly variable (different alleles). · WHAT ABOUT THE REST OF THE GENOME? · Nuclear markers - the "primary" genome - recall that there is allelic diversity at every gene, every locus, with one paternal, one maternal, allele · These genotypes at each locus can be diagnosed in many ways including single nucleotide variants (a mutation from one nucleotide to another) or length variants (a mutation where DNA is repeated or lost) · They key is they follow the rules of Mendelian inheritance, and that allows us to interpret how they behave in a single POPULATION against what happens when populations are mixed. · HARDY-WEINBERG EQUILIBIRUM: · for any ALLELE in a population with frequency p · Individuals HOMOZYGOUS for that allele at frequency p squared (frequency of one parent with that allele forming zygote with another parent with that allele) · DEVIATION FROM EXPECTED FREQUENCY OF GENOTYPES TELLS US WHETHER INDIVIDUALS ARE RANDOMLY MATING OR NOT · POPULATION GENETICS: · We can computationally sort out when individuals represent a POPULATION because their genotype frequencies FIT THAT EXPECTATION, and we can tell when they are mixed together when there is a strong DEVIATION FROM THAT EXPECTATION. · Markers show the painted bunting being 3 distinct populations in their breeding territory, even if they mix together some in winter feeding territory. · BACK TO GILA TROUT: · So, length-variant markers (microsatellites) were used to evaluate whether remaining O. gilae in early 2000s had not only survived, but successfully eliminated introgressed (hybridized) individuals of rainbow trout, cutthroat trout - we would be able to tell because of these genomic markers. · SUCCESS! · July 2006, Oncorhynchus gilae downlisted "threatening" from "endangered," limited sport fishing for first time in 50+ years · Work on many genes representing the whole genome indicate remnant populations are "clean" of other fish diversity · Effort involved dozens of scientists over decades · At right, note that the Arizona populations are often called Apache trout and are genomically just different enough to merit distinct protection as a "subspecies." · Interbreeding/hybridization can be good or bad for offspring, depending on situation · TYPES OF BIODIVERSITY: · NUMBER OF SPECIES (richness) in an area - what is a species? And how are species declared? · GENETIC DIVERSITY includes breadth of DNA sequence diversity - more diversity often suggests greater potential to respond to change. · FUNCTIONAL DIVERSITY - diversity of traits, chemicals, trophic levels · ECOSYSTEM DIVERSITY - how many distinct types of ecosystems in a region (Hawaii has tropical marine and mountain environments very close) · AGRICULTURAL DIVERSITY - huge dependence on biodiversity - different genetic lineages of a crop have distinct tolerances to environment, disease, etc. · SPECIES DIVERSITY: · Species diversity and stability - an active question in ecological research. · Most studies show that more diversity (species, genetic, trait) leads to more STABILITY (less change), more RESILIENCE (ability to recover from disturbances) · GENOMIC DIVERSITY: · 2 ways to think of this: If distinct species are genetically different, means different traits, physiology - this is "phylogenetic diversity" · The diversity within a population or species is itself an indicator of variation in pathogen susceptibility and trait diversity! · A LACK OF GENETIC DIVERSITY IMPLIES: · Inability to respond to selection (must have variation). And possible inbreeding - excess homozygosity for diseases or susceptibility. · Florida puma: restricted range, habitat loss. Endangered. Phenotypic quirks suggests inbreeding. · "Florida" is a population within a species. · The historic range of Felis concolor is huge - from all specimens we know if - used to be connected through Georgia, Alabama, Mississippi, with the rest of the range · Could it help to augment their genomic diversity? · POPULATION GENETICS THEORY: · Mitochondrial and nuclea DNA data suggest "inbred" population · Would introgressing from elsewhere ruin anything unique, ENDEMIC TRAITS of Florida puma? · Would introgressing from elsewhere (Texas) improve chances of survival? · Evolution theory work was used to consider consequences of moving 8 female pumas from Texas, with a few more in following year - make predictions · Population size in Florida is now 4-5 times larger because of this program · Florida-Texas hybrids have 300% survival rate of the "florida" type · GENETIC DIVERSITY... IS the other types of diversity! · AGRICULTURAL DIVERSITY - the text presents the case of potatoes and limited diversity not responding to disease. · Similarly, we are working our way through varieties of bananas as disease wipes them out. · CHEMICAL DIVERSITY: distinct organisms lead us to learn about ehcmicals with functions for: · Agriculture (Bacillus thuringiensis, a bacteria, makes chemical crystals that kill insects - used in GMO crops to limit use of pesticides) · Medicine (aspirin, other drugs from plants) · Technology/research (fluorescent proteins used in cell research derives from jellyfish Aequorea) · ECOSYSTEM DIVERSITY · So many distinct ecosystems: praire, coral reaf, longleaf savannah, alpine meadow, wetland, salt marsh, cave · In some cases, entire ecosystems have been nearly eliminated - ECOLOGY IS ABOUT HOW ALL THE PARTS PLAY A ROLE, AND WE DO NOT KNOW HOW TO RE-ASSEMBLE AN ENTIRE ECOSYSTEM! Soil fungi, micro-invertebrates, tardigrades, worms! And what genomic diversity in the larger organisms was important FOR THAT ECOSYSTEM? · To be fair, diversity changes through time. The climate has changed before, major shifts often involved in major extinctions. · End of Cretaceous, every land animal greater than 25 kg, extinct. Are we on that path now? · LOSS OF DIVERSITY: · HABITAT LOSS (forest destruction, river damming, etc) - huge impact · SPECIES-AREA CURVE - if more diversity in large area, less diversity in small area (less resource, less habitat complexity) · Early experiments took advantage of fragmented habitats to address this. · Tiny islands of varying sizes in Florida Keys. · Fragmentation of Amazon rainforest - how to design reserves optimally · DAMS ON RIVERS - only 30,000 constructed in US alone for hydroelectric, irrigation. Fish cannot reach habitat for spawning, other species rely on flooding for ephemeral food resources (and loss of key algae-eating species in some rivers) · NOT JUST SALMON - southeastern shad, other migratory fish and ecosystems depend on long rivers and habitat · We know it is possible and important to maintain the diversity we have · We know climate change is predicted to change where biodiversity if found · In our next unit we explore "climate velocity," the rate at which many organisms are tracking their optimal habitat - many marine species moving up to 5km per year poleward · Genetic diversity lost through process of selection... So, is it move, adapt, acclimate, or die?

Day 15

Day 15 - ECOLOGY · Last 2 units we will start really learning about those physiological stresses we discussed, the ways that organisms respond, and how their life history and diversity of traits influence what happens next · Species as a whole tend to be moving much more apparently/often than they are adapting · The Distribution of Biodiversity - and the niche: · We have already been discussing these concepts - every cell and every organism has environmental limits within which it can maintain, grow, and reproduce · Outside of those limits, it has to burn more energy to meet these demands, and at some point, there is not enough - it is not able to survive. · As our climate changes, organisms will move their distribution, acclimate to a changing environment, adapt through selection - or disappear · Why is each species not found "everywhere?" · We have focused on temperature - most organisms need a combination of environmental factors · Pinus polustris - temperature, precipitation, soil type (nutrients, structure), interactions between these factors. · How organisms disperse is especially important for organisms that cannot move in their lifetime! · Field guides - birds, butterflies, medicinal plants, fungi... Typically have information on WHERE the organism has been found. · Sometimes, maps will show you boundaries that make sense given physical restriction to movement. · Our empirical observations help us see the limiting factors for the range of a species · Better than a drawn (static) map: actual data points of observation. · GBIF: GLOBAL BIODIVERSITY INFORMATION FACILITY · Koalas express much more cortisol - including chronic stress - in areas of low rainfall. Climate models suggest lower future rainfall and higher variability: these "edge" populations will likely decline. · PHENOLOGY - study the timing of biological events · SPECIES DISTRIBUTION MODELS: observations of where an organism can be found, we can use data from that location. Seasonal temperature, rainfall, elevation, soil type, prey items... To estimate all places that organism SHOULD BE ABLE TO PERSIST - help see limitations to movement, or where the organism may spread towards. · Painted Bunting (diff colored birds): Statistically, it becomes clear there are 3 populations of painted bunting (Passerina ciris) based on genotype frequency differences at 1000s of loci. · LARGE ANIMALS NEED LARGER DISTRIBUTIONS. Near the line on the graph are the observations of pops in danger of extinction because large animals are in a small area. · This unit we expand on this to recognize how organisms INTERACT with one another - both negatively (competition, predation) and POSITIVELY (amelioration, symbiosis) - also influence their numbers and distribution · This is the world of ECOLOGY. At UGA, we have benefited from one of its early pioneers, Eugene Odum (school of Ecology named after him). · Wrote first textbook. Responsible for development of ecosystem ecology, for recognizing the role of symbionts in corals, developing ecotoxicology, gaining our marine lab at Sapelo Island. · Odum argued we cannot hope to understand the environment without first appreciating the complex biological economy of shared resources, competition, and cooperation. The ecosystem, he was fond of saying, is greater than the sum of its parts. · How do we describe nature? It is all around us - so familiar - we have to somehow compress the rich experience down to a set of formal models. Ex. Before ANEMOMETERS, how was wind speed measured? · Scientists make observations, predictions - of mechanism, and of effect: a HYPOTHESIS. "Because X (observation), then Y (prediction)." · Knowing about results of tests of these hypotheses, and quantifying these results, leads us to a model. · "All models are wrong, some are useful." A model is a simplification that approximates how the world works so we can make PREDICTIONS - if the model does a poor job, it can be discarded or improved with more information. · Ecology: Greek study of "house" or "environment." How life interacts with other life and with environment, guiding DISTRIBUTION AND ABUNDANCE. · Null Hypothesis: all organisms are equally likely to be anywhere on the planet (random). Can we reject the null? · Of course we can! Easily. The distribution of most life shows non-random patterns, related to their physiological needs and genomic diversity. · BIOGEOGRAPHY: the study of where life LIVES and how it got there. Spatial platforms and biomes. Physiological tolerances and interactions. Diversity and continental drift. The history of diversity through dispersal and isolation. Latitudinal diversity gradients. And more! · RICHNESS - how many different types of things are there in a sampled area? · ENDEMISM - how many different types of things that are ONLY found in that area? · CLUSTERING OF TYPES: · Ordination and clustering algorithms let us visualize when different parts of the world will have overall very distinct diversity because of the local climate. · Remember, CLIMATE is long-term, weather is short-term... · WEATHER tells you what clothes to wear today, CLIMATE tells you what clothes to have in your closet! · DISPERSAL is another way that related biodiversity is found in multiple regions of the world. · VICARIANCE includes mechanisms that separate populations into discrete areas. CONTINENTAL DRIFT has left records of ancient diversity on multiple continents; other vicariant events happen even now! · Gradient: slope, incline, increase or decrease in the magnitude of a property · For much of life, there is a strong gradient in diversity. Far more diversity in the tropics than close to pols. Ex. In a map, see most warm colors (which represent higher diversity) for terrestrial vertebrates in South America, Africa, east Asia. · So, Diversity Statistics: · 1. How many species (types) can we find in a given area? (RICHNESS). · 2. What is the RELATIVE ABUNDANCE? May be lots of species, but many of them quite rare. · 3. How EVEN (EVENNESS) is that distribution - what is likelier to see when you walk across a UGA campus? Chipmunk? Red-tailed hawk? Rat snake? · Patterns form, we ask why. · There are many observations for which scientists generate hypotheses. Ex: · "If natural selection is so great, why don't most species adapt to live just about anywhere?" · "Why do we see species from the same family of land snails in western Africa and eastern South America?" · "If there are more species in the tropics, do they have smaller distributional ranges? Or similar-sized distributions?" · Environment, evolutionary history, and dispersal influence the distribution of populations and species. · If we learn how these factors control diversity, we can make predictions. Ex. UGA ecologist John Drake 2015 predicted dynamics of Ebola virus accurately. Ex. UGA Marine Institute ecologists study how the salt marsh ecosystem will change with sea level rise. · Throughout nature - from alleles at genes in populations, to species in communities and ecosystems - it is so unusual to have everything at the same abundance! · These distributions tell us about distinct functions or processes that lead to some things being common, others rare - how we count diversity guides our interpretation and is a way to "compress the rich experience down to a set of formal models."