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BIOL 180 FINAL EXAM
Lectures 25-32
| Question | Answer |
|---|---|
| What is an ecosystem function? | Productivity (amount of biomass produced by primary producers Nutrient retention: to what extent nitrogen and phosphorous are retained Resistance/Resilience: How long it would take for the ecosystem to recover after a disaster or disease epidemic |
| Biodiversity Ecosystem Function experiment in Minnesota- example of what? | Do patches with more species function different than those with less? -Species compete for different kinds of resources at different times of the growing system, so more diversity means better ecosystem function. |
| How does biodiversity influence the health of the ecosystem? Examples? | Disease is more likely to spread to neighbors of the same species if they are close together Also, legumes fix nitrogen that leaks out and benefits neighbors |
| What is a functional group? | Species united by physiological or morphological traits that makes them function similarly (legumes, forbs, c3 and c4 grasses) |
| What were the results of the diversity experiment in Minnesota? | Diversity = productivity Relationship gets stronger over time More species, less disease within the community |
| What is biodiversity? | Species richness (number of species) and evenness |
| What are the four hypotheses for NPP? | 1. Big producer sampling effect- when big producer is present there is more total biomass 2. Resource use efficiency 3. Facilitation- plants leak out nitrogen over time which helps their neighbors 4. Number of individuals |
| Invasive species- what do they demonstrate about the distribution of organisms? | The barriers to dispersal (history) prevent species from occurring everywhere they can. |
| Three factors of biogeography (how organisms are distributed geographically) | 1. Abiotic factors (things that are not living like environment, climate, and soils) 2. Biotic interactions 3. History (chance, dispersal limitation) |
| What are the biotic factors of biogeography? | Biotic factors: the distribution of a species is often limited by biotic factors-- interactions with other organisms (remember- realized niche) -competitive exclusion, consumption, mutualism |
| Give an example of competitive exclusion | Example of competitive exclusion: tsetse fly and distribution of cattle- the fly has such a negative impact that the two rarely overlap in area |
| Are species everywhere they can be? | No, most species could occur in many more places than they do, but they are prevented because of dispersal limitations. -Subfield of historical biogeography- speciation, emigration, and extinction of species |
| What are the abiotic factors of biogeography? | Can every organism live everywhere? No- vary in their ability to tolerate climatic conditions You wouldn't see a christmas tree in a tropical rainforest, and you wouldn't see a coconut tree in Alaska |
| Biomes: characteristics and influence | Characterized by specific vegetation types- structure morphology Influenced by climate: 1. Amount of precipitation, mean temperature 2. Seasonal variation 3. Whether the time of maximum precipitation corresponds with the warmest time of the year |
| What are climatographs? | Biomes are assessed by the average temperature and the annual precipitation. --Tropical wet forest: lush vegetation, structural complexity, diverse --Subtropical desert: much less vegetation, plants are far apart, adaptations |
| What is an endemic species? | Biodiversity hotspots: Endemic species: species that only occur in a narrow geographic location In what areas do we have the most amount of species in the most area? -Areas that are rapidly decreasing |
| What is a disturbance? | Any change that removes biomass from an area --Examples: fire, herbivory, disease, mudslide, clearing land for farming purposes |
| Disturbance regime | 1. Type- consequences? 2. Extent- how large an area 3. Frequency- how often does it come back? 4. Severity- what proportion of biomass does it remove? Everything or just a bit? 5. Selectivity- does it impact a certain species or every species in the a |
| Example of how disturbances can mold species through evolution | Example: serotinous pine cone has really tight scales that protect the seeds until a fire opens it and the seeds pop out --Adaptation for coping with fire- have a mechanism that arises right after a disturbance so there's no other competition |
| In the past, bison grazed on tall grass prairies until they were hunted to near extinction. How might this effect tall grass prairies today that experience little grazing by bison, compared to the past? | Tall grass prairies today contain fewer species with tough leaves, bitter alkaloids, and re-sprout readily. |
| Intermediate Disturbance Hypothesis | Richness is highest when disturbance is intermediate. |
| Example of the intermediate disturbance hypothesis | Boulder fields in intertidal zones: 1. Small boulders saw high disturbance, large saw low (makes sense- waves) 2. If disturbance is too severe- good competitors at a disadvantage; too low- good colonizers are at a disadvantage |
| Succession: primary and secondary | Sequence or species that colonize an area after a disturbance. Types: 1. Primary: used to describe cases where pretty much everything living is removed 2. Secondary: a portion of living biomass is removed |
| Factors that influence succession | 1. Species traits: ability to get a site and hold onto it. --Early successional species: grow faster, produce lots of seeds, tolerant of stressful conditions, tend not to be good competitors. --Late successional species-- total opposite (good competitor |
| What is an ecosystem and what contributes to it? | A group of interacting organisms in a particular area and their abiotic environment 1. External energy source- where the energy that organisms use comes from (ex: the sun) 2. Primary producers- autotrophs capture abiotic energy 3. Consumers 4. Decompo |
| Gross Primary Productivity: Energy flow (production) | Energy Flow (production): Net amount of productivity that is produced or fixed by the autotrophs (primary producers) in the system: not 100% efficient because plants need to use some of the energy too. |
| Net Primary Productivity: Energy flow (production) | NPP = GPP - R (costs of maintaining)- within an ecosystem feeds consumers and decomposers --All energy depends on primary producers (which varies) --Climate and vegetation affect; different biomes (have different NPP) |
| Patterns of energy flow and production | More net primary productivity along the equator due to high temperature and moisture --Most productive biomes per unit area: Tropical wet forest, tropical seasonal forest, temperate evergreen (also consider area covered by ecosystem to know total NPP) |
| What is meant by “trophic level?” What is the difference between chains and webs? | -Feeding level in a food chair: primary producer at bottom (goes bottom up) -Chains vs. webs: most organisms don't eat just one particular organisms, so webs are more accurate because of the complex relationships |
| Energy transfer between trophic levels is always inefficient- you never get 100% of the energy that moves between those levels. Why? | 1. energy devoted to maintenance (ex: seeds) 2. lignin- not available for higher levels 3. endotherms devote a lot of energy to maintaining their body temperatures (insects are more efficient at converting energy to biomass) |
| Implications of inefficient energy transfer: pyramid of productivity | 1. Less biomass produced as you go up the food chain 2. Limited number of trophic levels, because you'll eventually run out of biomass (no more than 6 trophic levels) -Generally, population sizes also tend to go down the higher trophic level |
| What is a trophic cascade and why do we care? | What is it? Removing or adding a top consumer changes the abundance/density/biomass in lower trophic level -Mess with one part of the food chain, the rest gets messed up. Why do we care? --invasions (adding top predators), extinct (removing top predato |
| Examples of trophic cascades | 1. Sharks eat rays, rays eat bivalves (mollusks) -Sharks decline due to bycatch and sharkfin soup -Rays increased -Bivalves decreased 2. Wolves in Yellowstone went locally extinct, then reintroduced -Wolves increase, elk decrease, aspen are growing |
| What is nutrient cycling? Examples? | Movement of nutrients between the biotic components (producers, consumers, decomposers) and abiotic components (soils, aquatic environments) of the ecosystem. Examples: Nitrogen, carbon, phosphorous, sulfur, water |
| What is biogeochemistry? | The global flow of elements between various ecosystems and various biotic and abiotic components. |
| What are some fundamental questions ecosystem ecologists would ask? | 1. Reservoirs: Where, how big, what kind of pools? 2. Rates: What are the fluxes btwn pools? What changes them/how fast? 3. Interactions: btwn biogeochemical cycles 4. Anthropogenic impacts: How do humans influence the pools, what are consequences? |
| Summarize the nitrogen cycle. | 1. Atmospheric nitrogen (N2) gets fixed by bacteria & turned into a form available to other organisms 2. Producers can then take up N 3. Consumers eat N 4. Decomposers decompose the compounds diff. forms of N 5. Bacteria can transform N back to nitr |
| What are the nitrogen cycle’s most important sinks (reservoirs)? Also, what are the rates? | 1. Reservoirs: Largest reservoir is the atmosphere-- about 79% nitrogen in the form of N2, but organisms can't use until bacteria/n-fixers turn it into nitrates. 2. Rates: Transformations between different forms of nitrogen is largely mediated by bacteri |
| What organisms are involved in transformations during the nitrogen cycle? | Bacteria: fix atmospheric nitrogen (N2) into nitrate Producers: take up nitrogen Consumers: eat nitrogen Decomposers: decompose compounds into various forms of nitrogen |
| Anthropogenic impacts of the nitrogen cycle: Humans have nearly doubled the input of nitrogen through nitrogen fixation. How? (#1) | 1. Burning fossil fuels like natural gas and coal -Our impacts on the nitrogen cycle are not geographically constant (certain parts are more effected than others) |
| Anthropogenic impacts of the nitrogen cycle: Humans have nearly doubled the input of nitrogen through nitrogen fixation. How? (#2) | Growing a lot of n-fixing crops (peas & soybeans- mutualistic w/ n-fixing bacteria -Aquatic systems- phytoplankton blooms- when they die, they lower oxygen and create hypoxic zones which can lead to dead organisms (can make toxic chemicals, like red tide |
| Anthropogenic impacts of the nitrogen cycle: Humans have nearly doubled the input of nitrogen through nitrogen fixation. How? (#3) | 3. Fix nitrogen ourselves by making fertilizers -In areas where nitrogen deposition was high, there was a decrease in plant diversity. An increase in nitrogen benefits only a few weedy fast-growing species that dominate and take over diversity. |
| Summarize the carbon cycle. | 1. Start in atmosphere, plants take in carbon through photosynthesis 2. Consumers eat plants & each other (C moves between them) 3. Some material makes it to decomposers 4. Goes back into the atmosphere and the oceans via respiration |
| What are the carbon cycle’s most important sinks (reservoirs)? | Ocean is largest reservoir, then terrestrial, then atmosphere -Carbon in living organisms, some in woody biomass which stays for a very long time -Carbon from dead & decaying organisms can turn into fossil fuels (geological inactive reservoirs of carb |
| What are the carbon cycle’s rates? | Plants take CO2 from the atmosphere and turn it into organic carbon based compounds -All organisms return CO2 back to the atmosphere when they die -Plants are very important mediators |
| What organisms are involved in carbon cycle transformations? | Plants: take up carbon through photosynthesis Consumers: eat plants Decomposers: make soil out of consumers and plants |
| What are some anthropogenic impacts on the carbon cycle? | Ex. carbon based fuels: petroleum, coal, and natural gas -Started using them as a source of energy- increasing the rate of flux of pools returning to the atmosphere -CO2 and fossil fuel burning increased since industrial rev. -land clearing &burning tr |
| What was the Mauna Loa volcano example talked about in class? | Mauna Loa Observatory: 1958 measure atmospheric CO2 -Co2 has been increasing -Data fluctuates with seasons- Reduces in spring and summer when plants are active -More land mass in the N. Hemisphere (reason to have it in Mauna Loa- also no civilization) |
| Feedbacks: positive | Instability: banks -If a bank isn't doing so well financially, people will freak out and withdraw all their money, then eventually the bank goes out of business A affects B which turns around and affects A again- a change will lead to more change |
| Feedbacks: negative | Stability: thermostat -When it gets warmer than a certain temp, it will stop and not heat. If its colder, it will kick on. |
| Extrapolation example: What is the number of insects in tropical forests? | B: # unique beetles species=160 T: # tree species in tropical forests=50,000 P(b):proportion of insects that are beatles=0.4 P(t):proportion of insects that are tree dwelling=0.666 160 beatle species per tree (160x50,000) Divide by 0.4 and 0.66 Get |
| Species area curve | S=cA^z Sampled number of plant species in areas of different sizes and found a relationship S: number of species A: area C: parameter z: parameter (slope) Describes how species accumulate with area |
| Recent earth extinctions | 1. Since year 1000, about 1,000 bird species have gone extinct. This is 100x the normal (background) rate. 2. 122 amphibian species have gone extinct in the past 25 years; this is 211x the background rate. |
| IUCN Redlist | keep lists of species that are in one of Three categories of how soon they are going to become extinct 1. critical 2. endangered 3. vulnerable |
| Why are species going extinct? | 1. Less area: reduction/destruction and fragmentation -Population size will go down 2. Less connectivity: less able to disperse from one patch to another- inbreeding depression, vulnerable to extinctions 3. More edges: edges are not great |
| What was learned from the Biological Dynamics of Forest Fragments (BDFF) experiment? | -Edge effects can penetrate a long distance into the patches- 300 meters- functioning and species are detrimentally affected -Specialized organisms are reduced the most, generalist species do better -Top predators tend to be detrimentally impacted |
| What are some examples of invasive species? | Brown tree snake introduced to Guam: caused extinction of all native birds Feral cat: 15% of their diet is native species that are endangered |
| Why are island ecosystems more vulnerable to non-native species? | -Tend to have a lot of endemic (unique) species -A lot of island species are naive to predators |
| What is exploitation? | -Bison hunting- pile of skulls -Hunters shooting at passenger pigeons that went extinct- were very abundant but were hunted to extinction What kind of species are affected? -Fisheries tend to "fish down the food chain"- large fish go extinct so eat sma |
| What is the difference between conservation biology and restoration biology? | Conservation bio: Focus on species and population, try to understand where biodiversity is threatened and what to do. Restoration bio: Focus on ecosystem and community, restoring degraded ecosystems |
| Habitat destruction: what it causes and what methods can be used to fix it | --Leads to small populations and inbreeding depression --Use captive breeding and corridors --Prairie chickens: monitored small population, overtime it led to poor breeding performance. More were introduced and population saw better performance. |
| Invasive species: Examples and conservation strategies | --Channel Island Fox: Bald eagles went extinct from DDT, golden eagle took over,preyed on foxes and competed for feral pigs. --Captive breeding program for foxes --Eradication of feral pigs |
| What is biocontrol? | A technique of introducing nonnative species that preys on the invasive species you want removed -Make sure the species you introduce won't become an invasive species itself and eat the native vegetation! (Cactoblastis moths and Opuntia) |
| Direct hunting and exploitation: what is it and example | Reducing the population sizes can have cascading and direct effects on other species Ex: removal of wolves from Yellowstone Park which caused elk to increase which caused Aspen trees to decrease |
| What are range shifts? How are scientists trying to combat it? | Species having to shift and move to keep up with areas that are suitable for them- scientists are worried species won't be able to keep up with rapid climate change 1. Reserve design carefully 2. Assisted migration/colonization (but will displace others |
| Nitrogen deposition: what does it cause and what can you do about it? | Causes a loss in species diversity. To decrease it, remove nitrogen/pollutants and add carbon and plant species that take up a lot of nitrogen. |
Created by:
amilo