Ecology Exam 4
lotic ecosystems
flowing water (streams and rivers)
Assuming a consistent patch shape, the ratio of interior to edge habitat should __________ with increasing patch size.
increase
autochthonous
inputs of organic matter that are produced by algae and aquatic plants inside an ecosystem Produced within the system
Regional extinction
the whole metapopulation goes extinct because all patches blink out at the same time
Biogeography
study of the distribution of organisms around the world
Why does the Latitudinal diversity gradient (LDG) exist?
-Age of the community -Area -Climate -Available Environmental Energy -Primary productivity -Species interactions
What affects the rate of decomposition?
-Quality of plant litter as a food source -Oxygen Availability -Climate (Temperature and humidity)
To what other types of ecosystems does the theory of island biogeography apply?
-areas fragmented by humans -oasis in desert -Coral reefs -Mountaintops -Caves -ponds, rivers -hosts
What happens to the energy a heterotroph consumes?
...some is lost as waste (W) ...some is used to produce new tissue (P) - babies put a lot of energy toward production of new tissue ...Some is lost to the surrounding environment as heat (R)
If we have three local populations, each with e = 0.7, what are the chances that at least one will persist for one year? That is, what are the chances of regional persistence?
1 - (0.7)^3 = 0.657 = 65% of regional persistence For ten local populations: 1-(0.7)^10 = 3% chance of regional extinction 97% chance of persistence
What is the equilibrium number of species affected by in the theory of island biogeography?
1) Distance of island from mainland -Islands close to the mainland have more than islands far from the mainland 2) Island size -Bigger islands have more species than smaller islands
If e=0.7, what are the chances that a local population will persist for two years?
1- 0.7 = 0.3 = probability of persistence (0.3)^2 = 0.09 = 9% chance of persistence
In a traditional metapopulation model, each of four local populations has a 60% (0.6) chance of extinction in any given year. 1. What are the chances of regional persistence of the metapopulation over a 1 year period? 2. What are the chances of regional persistence of the metapopulation over a 5 year period?
1. 1-(0.6)^4 = 87% chance of persistence 2. (0.87)^5 = 50%
soil microbial loop
1. Plant roots exude energy-rich carbon compounds 2. Bacteria/fungi grow and immobilize nitrogen 3. Protozoa and nematodes consume bacteria.fungi and excrete NH3 4. NH3 is taken up by plants
How many described eukaryotes are on earth?
1.7 million There is more described beetles (22%) than any other species Wasps make up 8% Vertebrates make up 1% Plants/algae make up 18%
In most ecosystems, what percentage of the energy stored as biomass in a given trophic level is converted into biomass at the next higher trophic level?
10% of the energy stored as biomass in a given trophic level is converted to biomass at the next higher trophic level 90% of the energy is lost as heat
Metapopulation
A group of spatially separated populations of the same species which exchange individuals through immigrant and emigration "a population of pops" Intermediate levels of dispersal is key
Patch size
A large patch has more interior habitat relative to a small patch As you can see in the image, the interior (core area) increases as patch size increases. As the patch size increases, the area of the edge decreases.
Production efficiency
A measure of how efficiently the consumer incorporates assimilated energy into secondary production (P/A)
Gamma diversity
A measure of overall diversity for different ecosystems within a region
The landscape model
A model of spatial population structure in which the effects of differences in habitat quality within the habitat matrix are considered. It takes into account landscape features that might affect dispersal Ex: Collared lizard exist in a metapopulation with dispersal occurring between glades (habitat patches). Fire suppression threatened this species because the Eastern red cedar encroached, preventing dispersal.
Rhizosphere
A region of soil where plant roots function Intense microbial activity occurs here It is involved in decomposition and nutrient cycling in terrestrial ecosystems
Corridor
A route that facilitates movement between patches
Theory of island biogeography
A theory that demonstrates the dual importance of habitat size and distance in determining species richness The number of species found on an island is determined by the equilibrium between the immigration of new species and the extinction of those species already present The model predicts that at some point the rates of immigration and extinction will reach an equilibrium point that determines the island's average number of different species (species diversity).
Based on the figure, which species would you expect to have a higher lignin content?
A. Oak Oak would have the higher lignin (low-quality carbon source) content because it decomposes at a slower rate
Patch
An area of habitat that differs from surroundings and has sufficient resources to allow a population to persist
Ecosystem services
Any benefit that wildlife or ecosystems provide to people Food, freshwater, wood and fiber, fuel Aesthetic, spiritual, educational, and recreational Climate regulation, flood regulation, disease regulation, and water purification Nutrient cycling, soil formation, and primary production
Parasite conservation
As host density declines, parasites go extinct before their hosts do There is available evidence that says parasites are extremely important in ecosystems
LDG and Climate
At the poles, climate is variable. This could hinder speciation Near the equator, climate is stable. This could facilitate speciation. More sunlight and consistently warmer temperatures at the equator
Types of Decomposers
Bacteria, Protozoans, Fungi (dominant composer of plant material), and Invertebrate detritivore
Dilution effect
Biodiversity protect against infectious disease as the number of individuals in a group increases, the chance of being the one attacked by a predator decreases
Edge effect
Boundary habitat often has biodiversity than surrounding areas
Population decline and habitat fragmentation
Breakup of a habitat into smaller pieces, usually as a result of human activities. Fragmentation reduces animal ranges and restricts movement, increasing extinction risk
What limits NPP in terrestrial ecosystems?
Climate Nutrient Availability Four principal abiotic factors usually limit the amount of NPP on land - light, water, temperature, and mineral nutrients - and all these abiotic factors are changing rapidly as a result of human activity, with highly uncertain implications for global and local NPP.
Landscape model example: Collared lizard
Collared lizard exist in a metapopulation with dispersal occurring between glades (habitat patches). Fire suppression threatened this species because the Eastern red cedar encroached, preventing dispersal. Controlled burns started in 1994 and restored dispersal between glades. The lizard population recovered and the number of occupied glades increased
Population decline and Habitat Destruction
Damage done to a habitat that results in the loss of resources that organisms need to survive, like food, water, and shelter Humans exploit habitats and threaten the species that live there For example: humans clear rainforest to create plantations made to produce palm oil
Many species are experiencing population __________
Declines Populations of vertebrates have declined by 60% on average over the last 40 years The Global Living Planet Index (1970-2014) notes that the average abundance of 16,704 populations representing 4,005 species monitored across the globe declined by 60%. The white line shoes the index values and the shaded areas represent the statistical certainty surrounding the trend (range: -50% to -67%)
Oxygen availability and the rate of decomposition
Decomposition proceeds faster when oxygen is available In Aerobic conditions (with O2 present), decomposition rate is faster In Anaerobic conditions (without oxygen), decomposition rate is slower
Show an example of how species richness varies over time
Diversity of land plants has increased almost continuously throughout evolutionary history, but dominant groups have shifted
LDG and Age of the community
Due to ice ages, ecosystems in the tropics are "older" than those in temperate zones
What is a source of iron in aquatic ecosystems
Dust storms Dust storms play a key role in fueling phytoplankton blooms by delivering iron to the Gulf of Alaska
Patch shape
Edge area increases as patch gets less circular A square or circular patch has more interior habitat relative to a skinny patch
Population decline and climate change
Elevated temperatures cause corals to expel symbiotic zooxanthellae -Some species are laying eggs earlier now than they have in the past (Phenology) -Northern house martins arrive earlier and depart earlier from breeding grounds than they have in the past (Phenology)
Gross primary productivity (GPP)
Energy fixed pr unit area by photosynthetic activity standing crop does not equal GPP
Latitudinal diversity gradient (LDG)
Example of how species richness varies over space Species richness is highest near the equator (latitude = 0) and declines as you move toward the poles Deviations from the general pattern are often driven by abiotic conditions and various taxonomic groups exhibit patterns that differ from the general pattern Generally, latitude is negatively correlated with species richness
LDG and species interactions
Explanations for the paradox of the plankton: 1. Predation/parasitism 2. Mutualism 3. Spatial variability 4. Temporal variability 5. Multiple resources
According to the theory of island biogeography, a small island should have low species richness because?
Extinction rates are high
Plants encourage bacterial growth around their roots by _________________?
Exuding carbohydrate-rich compounds
Why does patch size matter?
Generally, large areas support more species than small areas do. The increase in patch size is related to several factors. Many species are area sensitive; they require large, unbroken blocks of habitat. Large areas typically encompass a greater number of microhabitats and thus support a greater array of animal species. There are also differences between the habitats provided by boundary and interior environments Conclusions: 1. Only when a patch is large enough to be deeper than its boundary can it develop interior conditions 2. When designing an experiment, carefully consider the proper scale for the organism your'e studying.
What are the two food chains that every ecosystem has?
Grazing and detrital A grazing food chain is a food chain that starts with green plants as the main source of energy. A detritus food chain is a food chain that starts with the dead remains of organisms as a main source of energy.
Source habitat
High quality habitat where population maintains a positive growth rate Birth rates are higher than death rates. Surplus individuals can migrate to new locations.
Mineralization
It is the microbial breakdown of organic matter in soil to organic substances The process by which fungal and bacterial decomposers break down the organic matter found in dead bodies and waste products and convert it into inorganic compounds It is involved in decomposition and nutrient cycling in terrestrial ecosystems
In trophic efficiency, the pattern is different in some ecosystems, Why?
In ecosystems like lakes and the open seas, primary production is concentrated in phytoplankton. These microscopic organisms have a short life cycle and rapid reproduction. They are heavily grazed by herbivorous zooplankton that are larger and long-lived. Thus, despite the high productivity of algae, their biomass is low compared to that of zooplankton herbivores which results in an inverted pyramid with a lower standing biomass of primary produces and herbivores.
Species accumulation curve
It measures species richness It is a graph showing the cumulative number of species recorded in a particular environment as a function of the cumulative effort spent searching for them x axis = cumulative number of sample y axis = estimated number of species It does not involve area
Nutrient spiraling
It occurs in lotic habitats (rivers and streams) one spiral represents the uptake of an atom of a nutrient, its passage through the food chain, and its return to water, where it's available for reuse.
What do corridors facilitate?
In this example, for both butterfly species, corridors facilitate movement between high quality habitat patches Movement between patches declines with increasing distance between patches
Which of the following is NOT among the leading hypotheses put forward to explain the LDG?
Intermediate levels of disturbance occur at low latitudes (NOT TRUE) Climate is more stable at low latitudes, There's more area at low latitudes, and Areas at low latitude were not subject to recent glaciation (these are true)
Population decline and invasive species
Invasive species threaten the native species And microorganisms can also be an invasive species Ex: Chytrid's spread through Central America reduced the Amphibian population
What do variations in microclimates affect?
It effects the biota
Where is NPP particularly low?
It is particularly low in lotic ecosystems but there is plenty of organic C in lotic systems Allocthonous inputs of organic carbon are important, particularly in lotic ecosystems
What limits NPP in aquatic ecosystems?
Light and Nutrient availability
How does light limit NPP in aquatic ecosystems?
Light declines exponentially with increasing water depth ...so photosynthesis does not occur below a certain depth
Sink habitat
Low quality habitat where populations maintains a negative growth rate birth rates are less than death rates and the species would disappear if not replenished from a source
Rate of decomposition and quality of plant litter as a food source
Low-quality sources of carbon (e.g., lignins) are broken down slowly High-quality sources of carbon (e.g. simple sugars) are broken down quickly These high-quality plant material decomposes faster. For example, Red maple decomposes faster than a sycamore tree because red maple have more high-quality carbon sources.
Population decline and Exploitative hunting/fishing
Many species were hunted to extinction by humans for food or other reasons The dod was hunted to extinction by humans and the last accepted sighting was in 1662 The American Bison were hunted almost to extinction by the late 1800s Shark-finning is banned in many countries, but remains a significant threat to shark populations
Decomposition and nutrient cycling in lotic (flowing water) aquatic ecosystems
Microbes colonize POM Shredders fragment organic particles and consume microbes Collectors gather fine particles and fecal material Scrapers feed on algae, microbes, organic matter on rocks Predators eat shredders, collectors, and scrapers Diatoms take up DOM from the water
Where do microclimates vary?
Microclimates varies between edge and interior habitat They can vary in temperature, light or humidity These variations affects biota
LDG and primary productivity
More productive environments may give rise to increased plant diversity over evolutionary time As primary production increases and Terrestrial NPP increases, so does species richness .
Terrestrial and aquatic biomes differ in their _______
NPP
Estimating GPP
NPP = GPP - R Therefore, NPP-R=GPP In the light bottle, there is a water sample containing phytoplankton. There is O2 produced by photosynthesis and the O2 consumed in respiration that = NPP In the dark bottle, there is a water sample containing phytoplankton. This the the O2 consumed in respiration = Respiration The light bottle - the dark bottle = the O2 produced by photosynthesis = GPP
How does nutrient availability limit NPP in terrestrial ecosystems
NPP increases with increasing Nitrogen availability in terrestrial ecosystems As Nitrogen availability increases, so does NPP
How does climate limit NPP in terrestrial ecosystems
NPP increases with increasing precipitation and temperature in terrestrial ecosystems As temp and water rises, so does NPP
How does nutrient availability limit NPP in aquatic ecosystems?
Nitrogen and iron are particularly limiting in marine environments There is an Iron hypothesis that states if you add iron to iron-deficient parts of the ocean, it should remove more carbon dioxide from the atmosphere This can be measured by estimating the concentration of chlorophyll in the water since it is a proxy for the amount of photosynthetic plankton, or phytoplankton present in the ocean.
Tertiary production in marine aquatic ecosystems
Oceanic Food Webs - Synthesis of World Productivity Food webs in the water column of oceans vary: 1. Primary productivity (e.g., upwelling vs gyre center) 2. Food chain efficiency 3. Number of trophic levels 4. Area of ocean covered
Local extinction
One patch in the metapopulation blinks out because all individuals living in that patch die e= probability of local extinction in a given year 0< e < 1
Allochthonous
Produced outside the system inputs of organic matter, such as leaves, that come from outside of an ecosystem
Example: P=BE^n. Use food chain efficiency to calculate energy available to highest trophic level. Let B = 1, E = 0.1 If n = 5, P = ?
P = 1 x (0.1)3 = 1 x 0.1 x 0.1 x 0.1x.1 = 0.0001 P= 0.0001
Example: P=BE^n. Use food chain efficiency to calculate energy available to highest trophic level. Let B = 1, E = 0.1 If n = 2, P = ?
P= 1 x (o.1)^2 = 1 x 0.01 = 0.01
Given several trophic levels (e.g., L1, L2, L3). How do we use food chain efficiency to calculate energy availability to highest trophic level (P)?
P=BE^n P= production at highest level B= Primary production E=Food chain efficiency n=number of links between trophic levels
Nutrient cycling
Pathway of an element thru an ecosystem, from assimilation by organisms to release by decomposition Nutrient cycling is an essential feature of all ecosystems. Most Nutrients are recycled within the ecosystem. Nutrients from decomposition go the soil. Then taken up by plants and plant tissue. It is then retranslated and nutrients succumb to litter-fall which makes dead organic matter that is decomposed. Cycle continues.
LDG - primary production and marine environments
Patterns of NPP are different in marine environments so this doesn't explain the LDG in marine environments Marine NPP is actually low at the equator, but higher at some coastlines and differ between Austral (southern hemisphere) and Boreal (northern hemisphere) summer
Conservation
Protecting and preserving natural resources and the environment The integrated study of ecology, evolutionary biology, physiology, molecular biology, and genetics to sustain biological diversity at all levels.
Matrix
The area that surrounds patches on landscape unusable habitat
Alpha, beta, and gamma diversity
Shows that species richness varies by scale Site A alpha diversity = 3 Site B alpha diversity = 3 Site C alpha diversity = 2 A and B Beta diversity = 3-2) + (3-2)=2 B and C Beta Diversity = 3 Gamma diversity = 5
Alpha diversity
Species diversity at the local or community scale. It is the diversity within a particular area or ecosystem
Phenological mismatches
Species interactions are affected by changes in phenology Timing of the availability of an important resource changes in response to climate but the timing of the demand of the resource does not change. Examples: -environmental cues for egg laying do not change-but cues for insect emergence do-resulting in chicks fledgling when food supply is low -Differential climate change between summer and winter ranges leads to problems in the transition for migratory birds Plant phenology has shifted, but caribou phenology has not. As a result, many calves die of starvation
LDG and the available environmental energy
Species richness is positively correlated with thermal energy for many taxonomic groups in terrestrial habitats It is the same for marine environments. Sea surface temperature is positively correlated with species richness in two groups of marine crabs
What other nutrients are involved in nutrient cycling besides nitrogen?
Sulfur, Calcium, and Magnesium
Climate and the rate of decomposition
Temperature and Humidity Decomposition proceeds faster at warmer temperatures For example, in Virginia, decomposition is faster compared to New Hampshire where is it colder Decomposition also proceeds faster at high humidity. faster in Florida than in New York
Decomposition
The breakdown of chemical bonds formed during the construction of plant and animal tissues It reverses the process of photosynthesis It converts organic compounds to inorganic compounds
Beta diversity
The change in species diversity between ecosystems
Decomposition and Nutrient Cycling in terrestrial ecosystems
The circulation of chemicals necessary for life, from the environment (mostly from soil and water) through organisms and back to the environment. There is leaching, mineralization, and immobilization The amount of nitrogen remaining in decaying leaf litter changes through the decomposition process When immobilization is greater than mineralization, the nitrogen increases. When Immobilization is less than mineralization the nitrogen decreases.
What is the sixth mass extinction?
The current rapid extinction of many modern species due to human activities
Boundary
The edge of a patch (edge-habitat)
Guinea worm
The first macroparasite of humans to be eliminated It is a deadly and painful parasite, so it's good that some parasites go extinct. But they all can't go
Iron hypothesis
The hypothesis proposes that, in parts of the ocean that are deficient in iron, this deficiency limits phytoplankton growth, so adding iron should promote it Specifically, it states that an effective way of increasing productivity in the ocean is to fertilize the ocean by adding the only nutrient that appears to be lacking-iron. Adding iron to the ocean also increases the amount of carbon dioxide removed from the atmosphere.
What do multiple patches do?
The spread the risk! As you can see from the graph, more patches increases the probability of regional persistence
In trophic efficiency, what is the effect of trophic chain length?
The length of food chains can also influence higher trophic level production longer length means more nutrients
What order has the most described species?
The order containing beetles (Coleoptera) currently has more described species than any other, but the order containing wasps, bees, and ants (Hymenoptera) is probably more diverse
Decomposition and nutrient cycling in estuarine ecosystems
The pycnocline helps to retain nutrients within an estuary, rather than flushing them out to sea The salt wedge is affected by dredging
secondary productivity
The rate at which heterotrophs produce biomass per unit area per unit time. Think about it as the heterotrophic equivalent of net primary production by autotrophs. Primary productivity limits secondary productivity and the amount of herbivore biomass than an ecosystem can support depends on NPP
Net Primary Productivity (NPP)
The rate of energy storage as organic matter after respiration NPP = GPP - R NPP is measured in units of weight of plant biomass per unit area per unit time
Trophic efficiency
The rate of energy transfer from one trophic level to the next higher level In most ecosystems, about 10% of the energy stored as biomass within a trophic level is converted to biomass at the next higher trophic level P=BE^n
Assimiliation efficiency
The ratio of assimilation to ingestion (A/I)
Consumption efficiency
The ratio of ingestion to production at the next-lower trophic level
Enemy Release Hypothesis
The success of introduced species occurs because they are freed from predators, parasites, and competitors in their introduced range Ex: invasive black rates threaten native species of Hawaii
Empirical test of the theory of island biogeography
The theory of island biogeography was experimentally tested by E. O. Wilson and his student Daniel Simberloff in the mangrove islands in the Florida Keys. Species richness on several small mangroves islands were surveyed. The islands were fumigated with methyl bromide to clear their arthropod communities The mangrove islands in the FL Keys were fumigated to clear arthropod communities Arthropod communities recovered more quickly on islands close to the mainland than on islands far from the mainland
Immobilization
The uptake and assimilation of mineral nitrogen by microbial decomposers
Hopkins Bioclimatic Law
There is a parallel relationship between elevational and latitudinal gradients of species richness Species richness declines with increasing altitude for many taxonomic groups. In general, as altitude increases, species richness decreases ...but this is changing due to climate change
What happens in deep water ecosystems?
There is a seasonal pulse f productivity due to upwelling High productivity in spring and summer when there is high levels of temperature and light
LDG and Area
There is more area in the tropics than at the poles Recall that larger areas have lower extinction rates
What are landscapes made out of?
They are made up of habitat patches surrounded by matrix These definitions depend on the organism or process being examined
What's a reality of patches?
They are not of equal quality think if the source-sink model
In terrestrial and some aquatic systems, what do plants bridge?
They bridge the physical gap between zones of production and decomposition.. ...But not in deep water ecosystems
How upwellings affect nutrient availability and limit NPP in aquatic ecosystems?
Upwellings are wind-driven motion of dense, cooler, and nutrient-rich water towards the ocean surface, replacing the warmer, nutrient-depleted surface water The wind and the Coriolis effect replaces surface water with the deep water
Currently, what group is in trouble?
Vertebrates are in trouble Current extinction rates are much higher than background rates in earlier years
LDG - Area and diversity
We usually do not see higher diversity where there's greater area
Source-sink model
a structure in which subpopulations in high quality (source) habitat patches produce excess offspring that disperse subpopulations to low quality (sink) habitat patches Ex: Bay Checkerspot butterfly It is essential to preserve the source population because it "rescues" sink populations
Does biodiversity protect against disease?
Yes Higher rates of biodiversity have been linked to an increase in human health Ex: Humans have a greater risk of infection in late spring and summer with ticks -the nymphs (middle stage) of a tick are the ones most likely to give humans lyme disease Risk is high in a low biodiversity system because most larval ticks bite mice, which are competent host Risk is low in a high biodiversity system because many larval ticks bite less competent hosts
DOM
dissolved organic matter It is a component in lentic aquatic ecosystems in the microbial loop: 1. Autotrophs excrete photosynthate as DOM 2. Heterotrophic bacteria consume DOM 3. Heterotrophic nano-flagellates consumer heterotrophic bacteria 4. Etc.
Metapopulation theory
examines the colonization and local extinction of local populations of a species on an array of patches in a broader landscape
POM
particulate organic matter It is dead organisms and other organic material that drifts toward the bottom It is a component of decomposition and nutrient cycling n lentic (still water) aquatic ecosystems
primary productivity
rate at which organic matter is created by producers in an ecosystem photosynthesis
Lentic Ecosystems
still water (ponds, lakes and wetlands)
Ecosystem energetics
study of how energy is fixed by autotrophs and made available to heterotrophs Measures of energy provide summaries of ecosystem structure and function
Standing crop biomass
the amount of accumulated organic matter found in an area at a given time Where do you think this happens in terrestrial systems? -in forests like the amazon
mass extinction events
the extinction of a large proportion of the world's species in a very short time period due to some extreme and rapid change or catastrophic event. Two notable periods are the end of the Permian, when more than 90% of marine invertebrates disappeared from the fossil record, and the cretaceous period, which saw the extinction of dinosaurs
Phenology
the timing of seasonal activities e.g migration, termination of dormancy, onset of reproductive activity
IUCN Red List
world's most comprehensive inventory of the global conservation status of biological species The list is heavily biased toward vertebrates, but this is because invertebrates are understudied, not because they are not threatened. For example, 67% of vertebrates or being monitored but only 2% of invertebrates are being monitored
What are the main drivers of population declines and extinction?
•Habitat destruction •Exploitative hunting/fishing •Invasive species •Climate change
Amplification effect
where an increase in species diversity leads to increased disease risk. an amplification effect occurs when increased biodiversity is related to an increase in prevalence