Environmental Issues Exam #3

Tuskless African Elephants?

"Under poaching pressure, elephants are evolving to lose their tusks" - An example of the bottleneck effect - Female elephants only about 2% are tuskless; Poaching impact makes trait go up - Subjected to less poaching than others Good? Less poaching pressure Bad? Difficult for them to get food, tusks have a positive impact on fitness, negatively impact the population because function is now gone (used in defense, protect the trunk, get food and water - especially during drought) - Without tusks, they will need larger ranges. Food resources they can access just went down. Don't have the tools anymore. - Asian female elephants don't have tusks. Different conditions in habitat. Traits evolve relative to the habitat. African savanna occasionally dealing with drought and different food availability.

Immense potential for population growth in many species

- 60 birds released in 1890 in NYC - Ring-necked pheasants - N = 8 to Protection Island, WA - 5 years later: 1,325

Additive vs. Synergistic effects

- Additive: one + one = two (temperature + water), minimal impact for both because they have minimal impacts individually - Synergistic: an effect arising between two or more factors that produces an effect greater than the sum of their individual effects, sometimes these things pair together and have magnified effects (one + one = five); very common when we look at species in nature; produces an effect greater than the sum of their individual effects Example: Salinity and Temperature in the Survival of Mollusks

Other Community Properties

- Already discussed Species composition - richness and relative abundance (cardinal vs. ordinal) Food Webs - Primary Productivity - Ecosystem/Community Stability - Buffering to Disaster? Stability - the ability of a community to maintain its structure Resistance - measure of how much it changes in the face of disturbance Resilience - ability or time it takes to return to original state after disturbance - Dry grassland has poor resistance, but high resilience - Rainforest high resistance, poor resilience - Stability can be their strength, what are they doing best

Eutrophication

- Aquatic ecosystem response to the addition of artificial or natural substances, such as nitrates and phosphates, through fertilizers or sewage - Example is the "algae bloom" or great increase of phytoplankton in a water body as a response to increase nutrients - Negative environmental effects include hypoxia, the depletion of oxygen in the water, which causes a reduction in specific fish and other animals - Too many nutrients in the water leads to no oxygen (probably from sewage or waste dumping in or over fertilization in agriculture) - Eutrophication > "Dead Zones" (can be reversed in scale) - Gulf of Mexico

Predicting Future Population Growth

- Assuming growth rate stays constant, the annual growth rate can be used to predict future population sizes - In 1932, the elk population was 16,000 16,000 x 0.05 = 800 - We would predict that the population would be 16,800 in 1933 - Should also be able to see how growth increases with population size Even slow growth rates can add large numbers of individuals in large populations Pop rebounds in species with slow growth rates

Mutualism

- Both species benefit from the interaction - Flowers and their Pollinators (examples: Bees and hummingbirds gather nectar and spread pollen) - Birds and mammals eat berries and fruits while the plant benefits by dispersal of it seeds - Cleaners eat insect pests from the skin of animals (ex: Egyptian plover cleans giraffes and buffaloes)

Three main cycles on Earth?

- Carbon cycle - Nitrogen cycle - Phosphorus cycle

Carbon Inputs and Outputs

- Carbon cycle: movement of carbon through biotic and abiotic parts of an ecosystem Inputs - Photosynthesis Outputs - Cellular respiration - Burning fossil fuels - Forest fires - Deforestation The inputs and outputs are currently not balanced

Effects of Carrying Capacity on Population Growth

- Carrying capacity is higher for elk than wolves in Yellowstone - Environmental resistance: the environment pushing back on growth, expect this to happen at some point for every population growing rapidly

Carrying Capacity (K)

- Carrying capacity: the maximum population size that a particular environment can support indefinitely - Environment x species interaction

Commensalism

- Commensalism is a relationship between two living organisms where one benefits and the other is neither harmed nor helped - The clownfish lives among the forest of tentacles of an anemone and is protected from potential predators - One animal attaching itself to another for transportation such as barnacles attach to shells or whales or a shrimp riding on a sea slugs - One species uses a second organism for housing such as small mammals or birds that lives in holes in trees or orchids which live in trees

Relationships within Communities

- Communities are all about relationships, and these relationships serve many purposes, including population control and maintaining carrying capacity - Each species is unique and thus interacts in its own unique ways with all the species around it - Some interactions are beneficial and others cause conflict, but all are important I keeping matters and energy flowing through an ecosystem Community Interactions/Relationships Examples? - Predation - Competition - Mutualism - Parasitism - Commensalism

Ecological Communities

- Community Structure - Defined by the patterns of species abundance, species richness, and by the relationships between members - Community structure is not static Communities are dynamic - Can change through time - sometimes predictably (Ecological Succession) Arrival and loss of species Natural processes - the effects of outside forces such as fires and floods

Community Ecology

- Community ecology: the study of all the populations, including plants, animals and other species living and interacting in an area - Each species lives within its specific habitat: the physical environment in which individuals of a particular species can be found - Important application to big picture: How various species contribute to ecosystem services such as pollination, water purification, and nutrient cycling

Ecologists Analyze Growth Factors

- Density-dependent: factors whose impact on a population increases as population size goes up Competition, disease, predation Slow growth, closer to carrying capacity - Density-independent: factors whose impact on a population is not related to population size Density-Dependent Regulation of Aspen Trees in Yellowstone - The population of aspen trees, a preferred food source of elk and deer in Yellowstone, is heavily impacted by the size of the herbivore populations Density-Dependent and Density-Independent Factors Affect Population Size - Understanding density-dependent and density-independent factors gives ecologists tools they can use to monitor and manage populations

Do CO2 levels remain relatively consistent through time naturally?

- Do remain relatively consistent along human time scales, but vary over geologically time - what we see shouldn't be changing Ex. Sunlight or historical condition - Rate of consumption of plants by herbivores - Devonian/Carboniferous - There are fluctuations through geological time but in smaller time frame levels stay pretty consistent - what we see now is not natural - They do fluctuate with the seasons - up in winter, down in summer. Begins when plants use CO2 and convert the carbon into sugar, animals eat sugars and then release it in respiration as CO2, completing the cycle NOTE: I have seen this used to argue against the increase in atmospheric CO2 levels by man and thus global warming - Our carbon levels have been increasing - How does tying up carbon affect the atmosphere? Favorably - ties up carbon - CO2 absorbs heat - greenhouse gas Burn it all > temps up 15-20 degrees, sea levels up > 20 ft

Competition and Release

- Ecological Release - species or populations exhibit greater variation in resource use, and associated morphological characters, in allopatry vs sympatry with competing species Ex. Islands - Reduction in competition leads to ecological opportunity Impact of extinctions Invasives

Core Message

- Ecological communities are complex assemblages of all the different species that can potentially interact in an area. - All the pieces of the ecological community are connected; change one thing, and many others are affected - This means ecosystems are often negatively affected by human impact - Understanding the interconnections within the communities may allow us to better protect and even help restore damaged ecosystems Example: The Florida Everglades - A Community in Crisis - A bird species in the Everglades reveals the intricacies of the threatened ecosystem

Biological vs. Ecological Carrying Capacity

- Ecological: the maximum number of individuals that it should have without doing damage to anything else - Expected to be equal in a natural situation (species evolve relative to one another) - The problem arises when we disrupt the balance

Community Interactions

- Ecologists call relationships between species in a community interspecific interactions These Interspecific interactions affect....what? - Species survival - Reproduction - Where they live - How they live - Behavior - Etc. But what else? - Evolution - Coevolution as we've discussed before

Exponential population growth is very important to populations during the process of:

- Establishment in new environments, natural (trees after ice age, algae in a fish tank) to introduced (Honeybees and collared doves) - During exploitation of transient, favorable conditions - blooms of plankton with seasonal increases to nutrients and light (seasonal or chronic change) - During the process of recovery from some form of exploitation - grey whales after whaling stopped

Ecologically Extinct?

- Exist in nature but not in sufficient numbers to have the impact/effect on the environment and ecosystem that it should (controlling prey numbers) - Example: tigers

Phosphorus Cycle

- Extremely limiting; the primary limiter of productivity of plants; no atmospheric components; erodes off of rocks - Another factor in eutrophication and fish kills - Has gotten better than it used to be - almost all cleaning products contained it but for the most part has been removed "phosphate free" - Important for energy transfer reactions (ATP and ADP for energy transfer and storage between cells), - Important structural component DNA and building block for bones and teeth - Most importantly - Phosphorus has a big impact on productivity. Naturally exists at low levels, limiting factor for growth. - Naturally a very slow cycle - leaches from rocks into the soil where it is used by plants - no atmospheric components

Opportunist Video

- Food is important - quantity and quality - Starvation survival environment - they never know when they are going to starve so they max calorie intake - Grizzly bears: eat everything! Honey, fish, berries, elk - When we hear about them, we hear about their food sources going scarce - But they eat everything, so can't they eat something else? No, because food hierarchy so they need the "good, right food at the right time" - In April, they eat roots. If they are eating them in summer, that's bad because they are supposed to be eating fish - The man in the video says bears are "unfussy" which is FALSE - They are picky eaters because they need to fatten up strategically for hibernation

Exponential Growth

- Growth in which a population becomes progressively large each breeding cycle - Produces a J curve when plotted over time - Typically seen when a species first enters a new environment or there is an influx of new resources Exponential growth occurs when there are no limits on growth - Without predation pressure from wolves, elk numbers in Yellowstone doubled between 1914 and 1932

r-Selected Species

- High biotic potential - Short life span - Early maturity - High fecundity - Thrives in unstable or seasonal environments Adapted to exploit unpredictable environments Will increase quickly as resources become available - Yellowstone examples: deer mice and spotted knapweed - Often overshoot K and crash

Disruptions to the Nitrogen Cycle

- Human impact is disrupting the nitrogen cycle Fertilizers and vehicle emissions are doubling the availability of nitrogen - While nitrogen is no longer a limiting factor for plant growth, the additional nitrogen can disrupt the ecosystem

An Example of Calculating Population Growth

- In 1920, the elk population was 10,000 - In 1921, it was 10,500, which means 500 new individuals were born - B = 500 and N = 10,000 - Annual growth rate = 500/10,000 x 100 = 0.05 or 5%

Why are ecological interactions important?

- Interactions can affect distribution and abundance - Interactions can influence evolution - Interesting part of communities are the interactions and relationships that characterize them - Multiple interests are common in nature Direct vs. indirect Indirect - The outcome of a species interaction can be modified or changed by another species interaction - Do predators increase or decrease the diversity of prey? Increase - if you remove a predator from an ecosystem, the diversity of prey goes down - Predators increase diversity of species below them

What is exponential growth and when does it occur in a population?

- Key Concept: Growth and resistance factors influence population growth, Exponential growth occurs when population growth is unrestricted; however, it will not continue indefinitely.

What are top-down and bottom-up regulation, and which is the most important in determining the size of a population?

- Key Concept: Population size is influenced by factors that decrease it (top down) and factors that increase it (bottom up), but which one has the greatest impact varies from population to population Top-Down Regulation - Control of population size by factors that reduce population size - Predation - Competition - Disease Bottom-Up Regulation - Control of population size by factors that enhance growth and survival - Nutrients - Water - Sunlight - Habitat

What is the importance of population size and density?

- Key Concept: Populations require minimal sizes and densities to reproduce successfully and maintain social ties, but high population density can lead to problems such as disease and overuse of resources - Key Concept: By tracking population size and density, scientists can be alerted to the problems that are causing a decline or be prepared to address or avert overpopulation issues

How do density-dependent and density-independent factors affect population growth?

- Key Concept: The larger and more dense a population is, the greater the impact of density-dependent factors such as predators, competitors or disease - Key Concept: Density-independent factors such as fire or floor will have the same effect on large and small populations alike

What are the life-history strategies of r- and K-selected species, and how do they relate to population growth patterns and their ability to respond to environmental changes?

- Key Concept: The population size of r-selected species can increase or decrease quickly if the environment changes. K-selected species' populations don't fluctuate as widely, but they are less able to respond to environment changes. Life-History Strategies - Classify a species based on biological characteristics that influence how quickly a population can potentially increase in number - Two basic categories r-selected K-selected - Some species such as door and elk have both r and K characteristics

Artificial Carbon Sinks

- Landfills - Carbon Sequestration Proposals Injecting carbon into the ground - Problems? - Lubrication for fault lines - earthquakes more likely - Under pressure; massive carbon dump if released

K-Selected Species

- Low biotic potential - Long life span - Late maturity - Low fecundity - Requires stable environment - Generally shows logistic population growth - Includes many endangered species - Yellowstone examples: wolves and bears

Phosphorus Cycle - Human Impact

- Mainly from mining phosphate ores for fertilizers and detergents - Removing phosphate from forests/tropical rainforest through tree removal - trees are cut and burned, phosphorus and other soil nutrients are washed away leaving unproductive land - soluble in water so washes away easily in run-off - Adding phosphates to aquatic ecosystems through run-off and sewage. Causes effects similar to nitrogen - excessive growth of algae and aquatic plants - a limiting factor for plants, THE limiting factors for algae - Estimates are that we have increased natural rate of phosphorus release into the environment 3.7 times

Food webs

- Many different food chains - Species can exist at multiple different levels - Who eats whom in a community? - Trophic relationships can be diagrammed in a community - What transforms food chains into food webs? - A given species may weave into the web at more than one trophic level

What options do species have to respond to changing abiotic factors?

- Move - Adapt - Die

Mutualism, Parasitism and Commensalism

- Mutualism: a symbiotic relationship between individuals of two species in which both parties benefit Obligate (have to have one another or they die) vs. facultative (species benefit from each other but not being fully dependent that each cannot survive without the symbiotic partner) - Commensalism: a symbiotic relationship between individuals of two species in which one benefits from the presence of the other, but the other is unaffected - Parasitism: a symbiotic relationship between individuals of two species in which one benefits and the other is negatively affected

Carbon Sinks

- Natural or artificial reservoir that accumulates and stores some carbon containing chemical compound for an indefinite period - Keeps carbon out of the atmosphere - Fossilized carbon sinks keep carbon out of the cycle TRUE/FALSE question: Is a carbon sink anything that holds carbon? No.

Nitrogen Inputs and Outputs

- Nitrogen cycle: A continuous series of natural processes by which nitrogen passes from the air to the soil, to organisms, and then returns back to the air or soil - Nitrogen enters an ecosystem through nitrogen fixation: Bacteria convert atmospheric nitrogen (N2) into ammonia (NH3), which is a form of nitrogen that is biologically available to plans - Once in the soil, other bacteria convert some of the ammonia to nitrate which is also biologically available to plants - Nitrogen exits the ecosystem when other bacteria convert nitrate back to molecular nitrogen (N2).

Competitive Exclusion Principle

- No two similar species occupy the same niche indefinitely when resources are limited - Impact of competition? - If your niche is the same, you can't live together - direct competition with one another... one of two things have to happen: do something different to avoid competition (resource partitioning) or go extinct

Parasitism

- One organism, usually physically smaller of the two (the parasite) benefits and the other (the host) is harmed

Populations / Communities

- Population - group of individuals of a single species that live together or inhabit a specific area - individuals of a given species that occur together at one place and time - Community - similar except it applies to all species, so whereas a population is only talking about the members of a single species, a community involves all

Population Density

- Population density: The number of individuals per unit area. Population Size and Density Influence Long Term Population Success - Example: Populations of deer, elk and moose in the United States are increasing, even though their habitat is shrinking. This has resulted in an increase in chronic wasting disease. Too Low (below minimum population size): - Normal social behaviors are deficient (e.g. group foraging or defense) - Unable to find mates - Normal courtship and mating behaviors don't occur - Genetic diversity falls (inbreeding) - Important community connections may be lost, affecting other species Too High (above carrying capacity) - Social behaviors break down with overcrowding - Spread of disease increases - Food supplies are insufficient - Increased chance of conflict with humans - Damage to environmental from overuse of resources

Ecologists Monitor Population Growth

- Population growth rate: the change in population size over time that takes into account the number of births and deaths as well as immigration and emigration numbers - Growth factors: resources individuals need to survive and reproduce that allow a population to grow in number - Resistance factors: things that directly (predators, disease) or indirectly (competitors) reduce population size

Multiple Interactions (Indirect Effects)

- Predation reduces competition Species who cannot coexist alone together often can because predators keep their numbers down - if you remove the predator, a prey species goes extinct - Also parasitism may weaken a superior competitor enough to allow a weaker competitor to survive - Or competition with a superior competitor A keeps species B from driving C into the dumper Rodents and ants (Chihuahua desert) - - Both eat seeds but they do not directly compete because they eat seeds of different sizes. Rodents prefer large seeds. Remove rodents and ant populations rise then crash, why? - Plants with large seeds are competitively superior to plants with small seeds Example reveals the complexity of natural systems - ants numbers increase because of a direct effect of removal of a resource competitor, then fall due to the indirect effect of food loss Simple examples with few species and we get things that are very surprising / don't expect

Predation, Competition and Resource Partitioning

- Predation: species interaction in which one individual, the predator, feeds on another, the prey - Competition: species interaction in which individuals are vying for limited resources Intraspecific competition: occurs between members of the same species Interspecific competition: occurs between members of different species - Resource partitioning: a strategy in which different species use different parts or aspects of a resource rather than compete directly for exactly the same resource - return to this concept with the niche

How Wolves Change Rivers Video

- Reintroduction of wolves to Yellowstone is an example of trophic cascade - Started to hunt elk and changed their behavior (in the presence of wolves, elk have to act differently, have to be closer to cover) (puts elk closer to the bears) - Increase in birds and beavers - Dames their built provided habitats from other species - Rise in mice and rabbits because they hunted coyotes - Changed the behavior of the rivers in response to wolves - regenerating forests stabilized the banks - Transformed the ecosystem and its physical geography - Wolves > decline in Elk (density + behavior) > Plant/Stream Community (more willow/aspen) > More beavers > More ponds > Amphibians - Wolves > decrease in Coyotes > increase small mammals > increase raptors (birds of prey) / increases in foxes and weasels - Wolves > increase in Bears (bears can take kill from wolves and sometimes push off wolves from a kill) (more berries)

Exponential Growth is Not Sustainable

- Resources become scarce - Individuals starve or are unable to find habitat for reproductive - Disease, aggression and competition increase - There is increased pressure from predation

Species Richness and Diversity

- Richness: simply the number of species (10, 50, 100, for example) Why can't we just use richness? It doesn't tell us anything about the size, part of the picture, another part of it is relative abundance or species evenness - Because species can differ in abundance, richness may a poor measure of diversity - A community with an even species abundance is more diverse than one in which one or two species are abundant and the remainder are rare

Species Diversity

- Species diversity of a community is the variety of organisms that make up the community - It has two components: species richness and species evenness Species richness is the total number of different species in the community Relative abundance is the proportion each species represents of the total individuals in the community

Ecological Release and Superman

- Super strong. Alien. Came from somewhere else. In his own world, was nothing special. Comes to our world and he is superman. - Invasives sometimes end up being super species. Bring them over to new world but in their own world they are nothing special. - For many, they die. But some do very well. (cane toads introduced to Australia to control invasive beetle population) Invasive Solution = Biological Control? - Bring other species from that community to control the one that has gone crazy. - Problem is it often goes wrong. Ecosystems with a lot of habitat variety and niches can accommodate more species diversity, and this, in turn, increases the resilience of the community.

Symbiosis

- Symbiosis: a close long-term biological or ecological relationship between two species - Symbiotic interactions show a tremendous interdependency on the part of the participants Three types of symbiosis: - Mutualism - Commensalism - Parasitism Predator/prey? Why not? - No long term relationship between individuals

Fundamental vs. Realized Niche

- The entire niche a species is capable of using based on its physiological requirements and resource needs is the - fundamental niche - The actual niche that a species occupies is the realized niche The difference between fundamental and realized niche can result from species interactions, presence or absence of other species Difference? Biotic component - interactions with other species, may not be able to occupy entire biotic - Example: Interspecific Competition and Barnacles Interferences and Exploitative Competition (In exploitation competition, organisms use up resources directly. Once used, the resource is no longer available for other species to use. In interference competition, one organism prevents other organisms from using the resource.) - Interference Competition - barnacles can fight, grow under each other and try to pop the other off the rock - Realized niches are usually smaller than fundamental because of competition

Wolves of Yellowstone

- The importance of keystone species and their impact - Immediate impact? Wolves are the best elk predator - Elk were overpopulated and not acting right - overgrazed communities around streams and rivers, back to forest dwelling when wolves introduced - More amphibian diversity - beavers come back, restored aquatic ecosystem - Impact on elk Density mediated vs. Trait mediated indirect effects - Density - Indirect Effects are caused by changes in the density of an intermediate species - Trait mediated - Indirect effects caused by changes in traits of an intermediate species Often through changes in feeding behavior - Spiders, grasshoppers, and grass

Biotic Potential

- The maximum rate at which the population can grow due to births if each members of the population survives and reproduces - Example: rats have a high biotic potential

Minimum Viable Population

- The smallest number of individuals that would still allow a population to be able to persist or grow, ensuring long-term survival A population that is too small may fail due to: - Unsuccessful flocking, schooling or courtship Broken social structure - information transfer in foraging - Reduced genetic diversity - Chance events - hurricanes, flood, volcanic eruptions, etc.

Devonian Forest

- The time period when forests evolved (woody plants and trees). - CO2 levels were very high and the Earth was very hot - Bring temperature down and increase oxygen. (so animals could live there) - Then an ice age and extinction event - Change in climate leads to extinction - No herbivores. Matts of decaying plant material. Turned into carbon-based fuels - Huge insects. Absorb oxygen through their skin. Body size limited by oxygen content. Now much smaller because oxygen levels are lower than Devonian.

Our Negative Impacts

- Today we add roughly double the N than all natural terrestrial processes combined Waste fertilizer, and burning fossil fuels - Addition of Nitric Oxide (NO) when fuel is burned - acid rain - damages trees and plants, upset aquatic ecosystems, corrode metals, and even damage stone, marble and other building materials. Also increases weedy species which can out-compete others with the excess nitrogen - Addition of nitrous oxide (N2O) to the atmosphere accelerates global warming - action of anaerobic bacteria on livestock wastes and commercial inorganic fertilizers applied to the soil - Nitrogen removed from topsoil by crops - unavailable to natural cycle - excessive harvest of legumes - Agricultural run-off and discharge of municipal sewage disrupts marine ecosystems - excess plant nutrient causes algae blooms, also other aquatic plant growth that can choke marine ecosystems - prevents sunlight from entering and the breakdown of algae by aerobic decomposers removes oxygen from the water and kills fish - Destruction of wetlands and forests releases large quantities of nitrogen stored in plants - overall humans have doubled the release of fixed nitrogen from the terrestrial portion of earth into the environment Implications - Causes loss of other soil nutrients like calcium and potassium - excess nitrogen compounds in the soil leach out essential nutrients - Acidification of lakes and streams - acid rain - Rising concentration of greenhouse gas, nitrous oxide, - Excess nitrogen causes spread of weeds into prairies and areas occupied by native plants and blooms of algae in coastal areas from run-off through rivers - Eutrophication

Trophic Structure

- Trophic structure is the feeding relationships between organisms in a community - It is a key factor in community dynamics - Food chains link trophic levels from producers to top carnivores - The transfer of food energy from its source in photosynthetic organisms through herbivores and carnivores is called the food chain - Charles Elton first pointed out that the length of a food chain is usually four or five links, called trophic levels - He also recognized that food chains are not isolated units but are hooked together into food webs - Trophic Cascade: if you affect one level of the food chain, you will see impacts below and above both directions

Humans & The Extinction Crisis

- Undebatable relationship - extinction follows increase in population - Impact = Population x Affluence x Technology Consumption has to come down also

Natural Carbon Sinks

- Vegetation / Living things - Ocean: as the ocean absorbs more carbon, it gets more acidic Limestone and calcium carbonate - seashells and marine skeletons - eventually drawn into ground and released by volcano Sea itself holds carbon as CO2 dissolves in water, more released as ocean warms - like a soda - Fossil Fuels Coal and Oil - burning of these fossil fuels (made of remains from living things) releases large amounts of carbon into the atmosphere, these take a long time to form - we have removed deposits that took millions of years to form, which is why fossil fuels are not renewable on a human time scale Why is a biofuel environmentally friendly if it releases the same amount of carbon as a fossil fuel? Can be made of ethanol (corn), algae, waste, etc. Biofuel uses carbon that came from the cycle already Fossil fuels add to the cycle with more carbon

How can you apply cultural carrying capacity to natural populations?

- What humans want to see of a certain species - For deer: overgrazing of people's yards, car accidents, etc. - Sometimes can be higher than ecological carrying capacity Invasive species for example Cocaine hippos - Matters in terms of policy and practice

Possible Outcomes of Competition

1. Extinction of one species 2. Resource Partitioning: splitting the niche - Resource partitioning is differentiation of ecological niches, enabling similar species to coexist in a community - Sympatric species consume slightly different resources or use resources in slightly different ways 3. Character displacement: two similar species evolve in such a way as to become different from each other by accentuating their initial minor differences - Character displacement can be demonstrated by a tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species - An example is variation in beak size between populations of two species of Galapagos finches - Similar beak morphologies and eat similar sized seeds, in contact with one another start to move apart (evolution pushed beak size up and down to accentuate minor different), bigger differences in morphology when they live together

Two Solutions...

1. Need to reduce amount of carbon we are adding to cycle 2. Need to put some back into sinks (carbon sequestration)

Carbon Cycle

2 basic functions for carbon for life: - Essential structural components of cells/life, basic molecule of all organic chemicals - DNA, carbohydrates, fats, proteins, etc. (50% of our dry weight is carbon) - Energy storage in its energy-holding chemical bonds (food and energy) Cycles both abiotically and biotically - Abiotic - cycles through atmospheres, geosphere/pedosphere (land), and hydrosphere (water) Volcanoes release carbon but it is matched by absorption of oceans - Biotic - Ultimate source is CO2, enters the biotic world through photosynthesis 6CO2 + 6H2O = (with light energy, chlorophyll) C6H12O6 + 6O2 - Returned to the atmosphere through respiration of plants and animals, and decomposers who release carbon as they break down the dead material of living organisms

Calculating Annual Population Growth

A simplified way to determine population growth rate utilizes a simple census of a population at two points in time. The equation is: - The number of new births (b) / number of individuals counted in the prior year (N) x 100 = percent change - Population growth = b/N x 100 Growth rates can be positive (population increases), be negative (population decreases), or have no change

Community

All the organisms that live together in a single place (place is subject to being defined) - Example: All the species in a tropical rain forest are a community - Interesting part of communities are the interactions and relationships that characterize them Properties and patterns - Number of species - Relative abundances - Morphology - Trophic links - Succession Processes - Disturbances - Trophic interactions - Indirect effects

Matter Cycles between the Biotic and Abiotic Components of an Ecosystem

Biotic The living (organic) components of an ecosystem; examples include: - Plants - Animals - Waste (dead leaves, feces) Abiotic The nonliving components of an ecosystem; examples include: - Rocks - Water - Soil

"The invasion of Yellowstone Lake by Lake Trout blamed for decline in Yellowstone's elk"

Cutthroat vs. Lake Trout - Lake Trout purposefully introduced for game fishing - Live in deeper waters - inaccessible to the bears - Cutthroat migrate in shallow water - The presence of Lake Trout is dramatically impacting Cutthroat Trout - Causing bears to do other things - increasing predation on elk - the Lake trout invasion led indirectly to elk population decline as the grizzly bears began to seek out elk calves

When might populations grow exponentially?

Does Exponential growth really happen - populations grow at exponential rates for relatively short periods of time under conditions of abundant resources - Small population - Low competition - Ideal conditions Ecological Release - return to this later - Examples of Exponential Growth - we can certainly induce it in the lab but does it ever happen in nature - YES - whales, bees, tree after ice age, algae in your fish tank

Exponential population growth

Exponential growth - A population increases by a fixed percent - Biotic Potential - J-shaped curve Rate of growth is per-capita (per individual) - Growth is multiplicative - Same % increase x large number = large increase Does exponential growth occur in nature? Yes. Grey whales are growing exponentially right now. Cannot happen forever, happens in periods. Checks on growth that are going to kick in and slow that down.

Urban Impact?

How significant? - Overall, cities represent about 2% of available land and 70% of carbon emissions (2011 UN Report) Cities Release Carbon - Directly: consumption of fossil fuels - Indirectly: power consumption, electricity Also through land use changes - Some impacts within but biggest impact is through their effect on land changes elsewhere, food and materials, etc. Urban Expansion - Effect of population density and transportation - New York - wealthy city in a wealthy country - high population size and density with expansive public transport 7.1 tons/capita annually - Washington D.C - more "sprawling" 19.7 tons/capita annually National average - 23.9

Does biodiversity protect lead to high levels of community stability?

In general yes, but there may be an upper limit Implies some level of redundancy - some species duplicating function Does that mean they are unnecessary? No. Redundancy matters. Why? - Represents a back-up (airplane example) - Three or four layers of protection for essential functions - Ecosystems are important, shouldn't design them to a minimal level - Species can pick up function we lost so ecosystem continues to function in the right way - We don't understand how every part of the ecosystem works, don't want to randomly change a system you don't fully understand

Are all species equal in importance to a community?

In general, a few species in a community exert strong control on that community's structure Dominant species: those in a community that have the highest abundance or highest biomass (the sum weight of all individuals in a population). - High in number, top in biomass, very important but not shocking - If we remove a dominant species from a community, it can change the entire community structure Keystone species: species that have particularly strong effects on the composition of a community relative to their abundance - High impact relative to their abundance, low in number but very important, predators keeping dominants in control - Example: top level carnivores - Keystone species determine the ability of large numbers of other species to persist within a biological community

Polar Bears in Trouble

It's about more than Bears More than a Poster Child - Polar bears are a keystone species - keep biological populations in balance - A sign of health for the ecosystem - Eat almost exclusively seals - if they can't hunt for food, could threaten the existence of other Artic species as they compete for resources - Scavengers depend on big kills from polar bears as sources for food - Increase of seals could threaten population of crustaceans and fish - Food source becomes scarce and dismantle food chain could cause wildlife that doesn't eat vegetation to gobble it all depleting that food source for herbivores

What is logistic growth and when does it occur in a population?

Key Concept: As a population's size approaches carrying capacity, exponential growth may transition to logistic growth, slowing population growth rates Logistic Growth - Population size increases rapidly but then slows down as the population becomes larger - Produces an S curve when plotted over time - Occurs when a population nears carrying capacity (K) The maximum sustainable population size Determined by limiting factors

How does carbon cycle through ecosystems, how is this cycle disrupted, and what problems can this disruption cause?

Key Concept: Carbon cycles through the environment via photosynthesis and cellular respiration. Human actions are increasing the amount of atmospheric carbon, unbalancing this cycle.

How does nitrogen cycle through ecosystems, how is this cycle being disrupted, and what problems can this disruption cause?

Key Concept: Nitrogen cycles through the environment in steps that depend on a wide variety of bacteria. Human impact is increasing the amount of usable nitrogen in the environment. Nitrogen is needed to produce proteins and nucleic acids.

How does phosphorus cycle through ecosystems, how is this cycle being disrupted, and what problems can this disruption cause?

Key Concept: Phosphorus moves slowly through the environment, depending on physical and biological processes. Human impact has unbalanced this cycle.

What role do biotic and abiotic factors play in matter cycles?

Key Concept: The matter cycles that move nutrients through ecosystems depend on living organisms and abiotic sinks of those resources.

Huge Urban Impact also represents an enormous opportunity

Key Factors - according to 2011 UN study, "Hot Cities - Battleground for Climate Change" - Geography - Demographics - Urban Form and Density - Urban Economy - Wealth and consumption of residents Cities don't control all factors like geography but almost all areas can be improved

What do we see today?

Major Species shifts + Minor Adaptations + 6th Major Extinction Event - Movement toward the poles and up to mountains ("species falling off mountain tops") - Trees in urban areas evolving heavier seeds (fall where they are, better chance to germinate) Range Shifts Adapt? - Adaptation does not guarantee survival - Shrinking population size, reducing genetic diversity Extinctions from Climate (species already in dire straits from climate factors) Tuskless Elephants?

The Niche

Niche - The sum total of all the ways it utilizes the resources of its environment - Space use - Food consumption - Temperature range - Mating conditions - Moisture requirements - Etc. Synonymous with habitat? No. Habitat is a place - niche is a pattern of living

Understanding Populations

PVA - Population Viability Analysis - A mathematical model that estimates the likelihood of a population surviving into the future - Weakness of model? Things in nature that we can't account for in the model or things we don't understand perfectly not included MVP - Minimum Viable Population - Not a magic number - a guide, does not guarantee success - 3 key aspects of how its expressed Size, probability, time For a given species in a given habitat (under modeled conditions)

Ecologists Monitor Population Dynamics

Population dynamics - Changes over time in population size and composition - The size of a population is determined by factors that simultaneously increase the number of individuals in a population (birth and immigration) and those that decrease numbers (death and emigration) - Immigration not important for species, but within the population Other important population metrics include - Minimum viable population - Carrying capacity - Population density

Back from the Brink?

Probably too strong. Grey wales have slow growth rates. Long generation times, not a lot of offspring. Will take a long time to restore to original.

Are the elk populations in Yellowstone regulated top down or bottom up? Both!

Regulation of Elk Populations in Yellowstone - In Yellowstone, both top-down (predators) and bottom-up regulation (available food sources) are important in controlling elk populations and the plant species on which they feed - The success of the reintroduction program led to the wolf being "delisted" in Montana and Idaho in 2011 - The population dynamics of the Yellowstone wolves will continue to be monitored very closely

Environmental Problems are Human Driven

Root of environmental problems and sustainability = so many people - Recall tragedy of the common The number of people is an unspoken driver of environmental problems - We have removed half of our forests - One quarter of the soil on Earth is eroded - 90% of the fish in the ocean are gone - We consume or use almost one quarter of plant matter on Earth - Fertilizer use makes dominant force in the nitrogen cycle (dead zones in lakes/oceans) - We burn large amounts of fossil fuels Climate change - May affect our food supplies and conflict over resources - Could affect habitability of regions and refugee migration in the future - We know it's affecting biodiversity

Limits on Food Chain Length

Seems to be a limit on how long a food chain tends to be Two hypotheses attempt to explain food chain length: the energetic hypothesis and the dynamic stability hypothesis - The energetic hypothesis suggests that length is limited by inefficient energy transfer - The dynamic stability hypothesis proposes that long food chains are less stable than short ones - Most data support the energetic hypothesis

Ecological Pyramids

Tertiary Consumers Secondary Consumers Primary Consumers Primary Producers About 10% of the energy transfers between levels; 90% lost through use, metabolism, heat, etc. - Would have to eat 10 of individuals below you to survive - Toxins, pollutants, heavy metals transfer 100% between levels - Bioaccumulation: magnifying by a factor of 10 - Major impacts on top level carnivores or species high on the food chain - Always going to feed more people will beans than cows, losing more energy the higher we go up the food chain

Where does the CO2 go?

The missing carbon sink is the idea that we can chart the amount of CO2 we are emitting through fossil fuel use and measure the amount in the atmosphere, but we don't understand where the rest goes? - Ultimately there is a huge percentage that we have no idea where it goes - The theory is forests? "Missing Carbon Sink": In the 90's researchers realized that they could not account for all carbon released, about 25-30% was unaccounted for. - Maybe regrowth of harvested forests - unsure, but could cause a problem in the future if the size of the sink declines it would increase atmospheric CO2 even without increasing emissions - Some have proposed that one explanation for this imbalance was elevated CO2 in the atmosphere causes increased productivity in storage of carbon throughout global ecosystems - Others speculated it was due in part to re-growth of abandoned agricultural land in temperate areas and vegetation thickening in the rangelands and forests - especially forests in Europe where nitrogen deposition from atmospheric pollution is causing nitrogen fertilization

Range of Tolerance

Tolerance: the ability of any organism to survive when subjected to non-ideal biotic or abiotic conditions

Keystone Species

Top-level predators: - In general tend to be a keystone species. They affect multiple species which in turn affect multiple others - removal of top predators often has dramatic and often unforeseen consequences Beavers - Some organisms exert influence by causing physical changes in the environmental that affect community structure - By changing free flowing streams into ponds create new habitat Ecosystem Engineer Alligators - dig deep holes in the bottom, in times of drought they provide refuge for aquatic species that would otherwise perish and provide water for many animals - Nesting mounds provide nesting and feeding sites for herons and egrets - Eat large numbers of gar and help maintain bass and game fish populations - Keep water free of vegetation - otherwise freshwater plants would invade and fill in coastal wetlands Doesn't necessarily make it easier to manage - try telling these things to some whose dog was just eaten by an alligator. Should people have the right to shoot them in their backyard? Certain tropical figs - bear fruit during seasons when no others will. Keep frugivores alive. More than that, if those frugivores were gone, other plants would perish that those organisms are pollinators for.

How do we impact carbon cycle?

Two main ways... 1. Adding carbon dioxide through fossil fuels, wood, etc. - Adds up to "The concentration of CO2 in the atmosphere has increased by about 30% since the start of the industrial revolution sometime around the middle of the 19th century" 2. Land use changes (deforestation) - We remove plants and trees that absorb carbon dioxide - development + forest clearing for agriculture results in immediate release of carbon stored in trees through fire or slower through decomposition All potentially leads to global warming - increased CO2 from burning of fossil fuels, fires, coupled with massive deforestation, and reduced productivity of the oceans

Nitrogen Cycle

Why does it matter? - The most abundant gas in our atmosphere is nitrogen (N2: but can't be used so needs to be converted to forms that can be used by plants through nitrogen fixation) - Issue? The amount of nitrogen that goes into the biotic world is limited; humans are putting too much in the terrestrial and aquatic ecosystems (over nitrification of our ecosystem leads to eutrophication) AND pollution from fossil fuels - Like carbon, it is an essential component of organic molecules Amino acids, peptides, nucleic acids, and proteins all contain Nitrogen - Nitrogen is the most abundant gas in the atmosphere (78%) - Nitrogen in the biotic world comes from producer organisms They get it from soil and incorporate it into their own proteins. Consumers eat the producers and incorporate the nitrogen into their own proteins. - Must be "fixed" for use Bacteria, algae, lightning, some plants (legumes) through a symbiotic relationship with bacteria - Returned through death, decay - denitrification Nitrogen as a pollutant?

Carbon Cycle - Climate

Why is the carbon cycle important? - Key components of nature's thermostat - Removing carbon cools the climate, increasing heats it up - Greenhouse effect is good for environment (warms it up so we can live here) but too much warming is problematic