BIOL 180 Exam 4 Study Guide
BIOL 180 Exam 4 Study Guide BIOL 180
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This 9 page Study Guide was uploaded by Angel Lee on Thursday December 10, 2015. The Study Guide belongs to BIOL 180 at University of Washington taught by Scott Rider Freeman in Summer 2015. Since its upload, it has received 168 views. For similar materials see Biology in Biology at University of Washington.
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Date Created: 12/10/15
BIOL 180 Exam 4 Study Guide Lecture 31: Populations A. Age structure: relative # of individuals in various age classes that helps you understand population history and future B. Geographic structure: allows you to calculate how much gene flow is occurring 1. Common patterns – a. Clumped: “patchy” b. Overdispersed (uniform): well spread out population c. Random: combination of clumped and overdispersed 2. Factors for distribution patterns a. Quality and resources of habitat b. Social behavior (do they travel in herds?) c. Presence of competitors or predators 3. Patterns are NOT mutually exclusive. – the same species can have be over dispersed locally, but distributed in a clumpy pattern regionally 4. Ranges – dynamic, because abiotic and biotic factors change over time 5. Metapopulation: population of populations connected by migration; group of relatively small and geographically isolated populations Consequences of Metapopulation Structure Inbreeding Depression Habitat fragmentation leads to a metapopulation structure. Small populations become Genetic Drift Small, geographically inbred because individuals isolated populations inside the populations Loss of Genetic Variation migration.by limited have fewer mates to As the population choose from. inbreeding depression, Homozygosity increases, they become more Genetic variation is smallTINCTION! decreasing fitness susceptible to genetic in small population, but drift. even more limited by Alleles are randomly fixednetic drift and Species go extinct. or lost. inbreeding depression. This decrease in geneticHowever, in variation, limits naturametapopulation structure, selection to select fromwith gene flow, it is smaller variety of allelpossible for the species to environment. changes in return via recolonization. a. Importance of unoccupied habitats and wild life corridors – they are needed so that individuals can colonize new sites and start new populations and induce gene flow to reduce the effects of inbreeding and drift in isolated populations. C. Competition or Fundamental Niche - The absence of species A and the presence of species B in a specific region may be due to a variety of reasons. 1. Competition – a. Under this hypothesis - “Species B eliminates species A.” b. Prediction – “There is an inverse relationship between the survival of species A and the density of species B.” c. Species to species interactions and arms race. – Traits that increase the survival of species A by decreasing the likelihood of predation from species B will increase in allele frequency due to natural selection. 2. Fundamental Niche – a. Under this hypothesis - “Species A cannot grow due to the conditions of this region.” b. Prediction – “Survival of species A is low in the specific region.” Lecture 32: Disease Ecology Coevolutionary A. Coevolutionary arms race: adaptations due to predator and prey Arms Race interactions between species – the species interact in a way such as their adaptive traits select against one another; an advantage to one species creates a selective advantage for an adaptation Parasitism/ in the other species that negates this advantage Predator/ parasite predation - - Predator: short lived, complete consummation of adapts selection against prey/ host victim - Parasite: long lived, gradual consummation of victim B. Parasites and host manipulation - Every species represents a resource that may be exploited by an array of parasites - Studies support natural selection that favors alleles that Natural selection allow parasites to manipulate host behavior in a way that for predator/ increases their transmission to new hosts. parasite that Prey/host adapts negates adaptation - Warmer climates tend to have more parasites and more types of parasites C. Evolution of virulence - Virulence: tendency to cause illness/death. - Parasites are expected to become extremely virulent when transmission rates to new hosts are high. Lecture 33: Consumption A. How does predation affect prey populations? - Predators can reduce prey populations below the level that can be supported by available resources B. How do prey respond to predators? Standing Defenses: defensive Are NOT mutually exclusive – they can all be correct. Inducible defenses: defensive traits that are always present traits that develop in response to Traits that result from defenses are a threat A standing defense can also be an phenotypic, not genotypic changes. inducible defense by increasing in response to the presence a threat. Therefore, they are NOT HERITABLE - However the ability to have defenses is a heritable trait. C. How do predators affect communities of species? 1. Keystone species: species that has an extraordinarily large impact on the surrounding community, relative to tis abundance D. Why is the world green? 1. Top-down hypothesis: predators control herbivore populations 2. Bottom up limitation hypothesis: a. Poor nutrition hypothesis: plant tissues offer poor nutrition or a lack of nitrogen. Nitrogen limits reproductive success in herbivores because it is expensive in terms of predation risk, time, and energy. Organisms benefit from eating plant species with a higher ratio of nitrogen. b. Plant defense hypothesis: plant tissues are well defended The presence of toxins or indigestible compounds makes many plant tissues inedible. Lecture 34: Competition A. How does competition work? Symmetric/ Asymmetric Niche Overlap Competition May lead to... Natural selection favors Character displacement: evolutionary change in traits or individuals that do not compete morphology that increase fitness by reducing competition AND/ OR NIche differentiation/ resource partitioning: evolutionary change in resources exploited by each species in order to reduce competition AND/ OR Competitive exlcusion: "species with the same or overlapping niches cannot coexist. If this occurs, the more competitive species will drive the less competitive species out." 1. Fundamental v. realized niches - Niche: range of resources used by a species a. Fundamental niche: maximum/ total theoretical range of resources and environmental conditions a species can exploit b. Realized niche: the portion of the fundamental niche that species actually exploits 2. Types of competition – natural selection favors individuals that do not compete with other species for the same food resources. If so, then over time different species should evolve to use different resources. - Competitive exclusion: two species that share that exact same fundamental niche cannot exist; one species is wiped out in that habitat. - Coevolution: evolutionary change in response to species interactions a. Interspecific competition: competition between different species b. Intraspecific competition: competition within a species c. Symmetric competition: when both species experience similar decrease in fitness due to niche overlap d. Asymmetric competition: when one species is a stronger competitor and has a lower reduction in fitness Good competitors can drive other bad competitors to extinction. Why don’t the best competitors take over the world? Although good competitors have higher fitness, they are still limited by fitness tradeoffs. They suck at other things. Lecture 35: Mutualism A. Mycorrhizal and endophytic fungi - Fungi grows on plant roots. - Fungi: transfer N or P from dead plants to live plants - As the plant benefits N and P from the fungi, the fungi gets photosynthate or products of photosynthesis. B. N-fixing bacteria: bacteria that converts molecular nitrogen to amino groups that can be used to build proteins, nucleic acids, and other key molecules - N-fixation is extremely energy intensive. - N-fixing bacteria live on the roots cells of plants. - As plants provide bacteria protection and nutrients, the bacteria fixes nitrogen. - However, interaction between n-fixing bacteria and host plants is extremely specific. A series of complex events occur, each requiring certain signaling molecules. This prevents parasitic species that mimic n-fixing bacteria from gaining entry. Lecture 36: Communities A. Community Structure 1. Community: collection of species in a particular area 2. Types of species interactions: a. Mutualism b. Parasitism c. Competition d. Consumption e. Commensalism- (“doesn’t exist in the real world. If it does exist, the chances of it becoming parasitism or some other type of species interaction is high.” –Professor Dooley) 3. Coevolution: evolutionary change in response to species interactions 4. Are communities “Super-organisms” - collection of organisms that work together to create an organized. productive unit (removal of one subunit greatly disturbs the entire system)? Gaia Hypothesis: life facilitate life Medea hypothesis: life kills life. Earth forms a self- regulating complex system Multicellular life is suicidal Contributes to maintaining the conditions for life Microbial triggered extinctions are attempts to on the planet. return the Earth to microbial-dominated state. Prediction: Biomass or productivity increases as Prediction: As species diversity increases, biomass species diversity increases. or productivity decreases. 5. Are communities highly structured of loose assemblages of species? Cleaments Hypothesis: Communities are highly structured due to coGleason Hypothesis: Communities are loose assemblages of species due to a (the evolution of one species depends on another). lack of coevolution ( evolution of species are independent of each other). Prediction: Community composition is predictable by Prediction: Community composition is not predictable and is observing species interactions. a result of mere chance events. What this means: What this means: (1) Communities lead to same "climax" stage. (1) Communities are dynamic and unstable. (2) If the community is disturbed, it will reconstitute itself by (2) If a community is disturbed, a different community will reiterating "developmental stages". emerge. A: The best supported hypothesis depends on the scale. On a small scale, the highly structured hypothesis is supported. On the other hand, on a large scale, the loose assemblages of species is supported. B. Disturbances and communities 1. Disturbance: any change that removes biomass or change abiotic conditions a. Type – different types of disturbances affects different species and changes different features of the environment. b. Severity – as severity increase the number of species that are wiped out increases c. Frequency - disturbances that are more frequent tend to be less severe while disturbances that are rare tend to more severe. C. Community Response to Disturbances - Succession Early Succession - Late Succession - Succession - different short-lived species that long-lived species that, Disturbance species succeed each grow rapidly and thrive grow slowly but are other in harsh autobiotic better competitors than conditions. early species. 1. Early successional species alter the physical environment in ways that favor late successional species. - They add nutrients to the environment producing organic material and also making the environment unfavorable for their own kind. a. Weed: species that is adapted to growing in disturbed soils 2. Late successional species are much better competitors than early successional species. They produce larger offspring and live longer. 3. Primary succession: take place in the absence of soil 4. Role of chance – certain species may show up early or late in the process, or not at all 5. Role of history – species present now depend on what disturbance occurred in the past, and which species happened to arrive Lecture 37: Biodiversity and Ecosystem A. Species Richness and productivity – Measurements of Biodiversity NPP increases with species richness Genetic diversity Number and relative frequency of allele - Primary productivity: total energy Species Richness Number of species harvested Species diversity Number and relative frequency of each species Functional diversity Number and of functional groups - Net primary productivity (NPP): total energy used to make Phylogenetic diversity Number of different common ancestors biomass (total organic matter); amount of new biomass produced by plants and other primary producers in a certain amount of time - Importance of NPP – biomass fuels other species Resource Use Efficiency:since different species use different resources, there is an increase overall use of resources Sampling effect: some plant species are more productive than others. The more species Facilitation:faciliated species grow there are, the higher the better in the presence versus absence of the other speices . probability of choosing a "big HYPOTHESES - producer". "As biodiversity increases, NPP increases" B. Importance of biodiversity NPP: total energy used to make biomass •biodiversity increases NPP, which is especially important for growing human populations which need a lot of resources such as food. Resistance: degree of change during and after a disturbance •biodiversity increases resistance to disturbances and invasions by exotic species. Resilience: ability to bounce back after •biodiversity increases resilience and ensures faster recovery from stochastic conditions disturbance to the original condition such as hurricanes and earthquakes. Ecosystem function/ services: improves the •Biodiversity increases NPP, which is especially important for growing human ability of abiotic environment to support lipopulations which need a lot of resource such as food. Aesthetics and morality •Biodiversity is of extreme economic value because it provides beauty and tourism •Genetic resporitory for drugs or other products; source of alleles to introduce to Genetic Repository domesticate varieties. Lecture 38: Ecosystems I – Energy and Nutrients A. How energy flows through ecosystems - Consumer: eats living stuff - Decomposer: eats dead stuff - The flow of nutrients and energy links producers, consumers, decomposers, and the abiotic environment. Patterns in NPP – NPP is significantly higher on land than in water Land Water Highest in – the tropics Highest in – coastal lines (due to nutrient run off and upwelling in these areas) Limited by – sunlight and water Limited by – nutrients Contrast – small area, but very large productivity Contrast – small productivity, but very large area B. Trophic levels in a food chain or food web - Food chain: one possible pathway of energy flow among trophic levels in an ecosystem - Food web: multiple food chains embedded 1. Pyramid of productivity: biomass production declines at ~1% of incident sunlight to primary production each higher trophic level a. Each level of the pyramid represents a trophic level Start: 1000 grams of primary producer b. The width of each level of the pyramid represent the amount of biomass. 200 grams of primary consumer (20% efficiency) c. Energy is lost at each transfer because organisms are spending more energy on life processes other than 30 grams of secondary consumer (~15% efficiency) growth such as warmth, movement, defense, transporting fluids, digestion, and cellular respiration. 3 grams of tertiary consumer (~10% efficiency) d. Warm blooded animals are particularly inefficient compared to cold blooded ones e. Tertiary consumers move around a lot more than secondary or primary consumers C. How nutrients flow through ecosystems A: biogeochemical cycles – nutrients and energy move through ecosystems, from organisms to organisms in food webs and to/from the abiotic environment 1. N cycle – although the adding more N into the cycle may decrease CO2 with by increasing NPP…. Blooms of NO3- using O2 used up Increase in anoxic Unknown increase in N NO3- using primary Decompos by H2S, killing areas or effects on primary producers ers bloom decompos eukaryotic "dead food webs producers die ers life zones" a. Humans add enormous amounts in the form of ammonia based fertilizers or amino groups in N fixing crops. 2. Water cycle 3. Carbon cycle a. Humans add enormous amounts of carbon into the cycles through activities such as deforestation, burning fossil fuels. Lecture 39: Global Climate Change A. How humans are changing the Carbon Cycle 1. Carbon Cycle in Terrestrial Ecosystems v. Carbon Cycle in Marine Ecosystems a. When decomposer are decomposing, they release CO2, a process known as a cellular respiration (red circles) b. Burning of fossil fuels (green arrow) c. Photosynthesis (green circles) d. Death (purple circles) e. Herbivory/ predation (orange circles) f. Sinks (green boxes) g. NOTE: the atmosphere is not considered a carbon sink. h. Processes in marine environments are much faster than terrestrial environments. This is due to the nature of primary producers in the ocean which are algae. Generally both share the same compartments. i. Carbon by itself does not cause death… increased Microbial world Increase in CO2 Warpolest the differeces in Dof convectiond roxygenon in anoxia in ocean that creates temperature more H2S j. With the decreased speed convection, more methane gets released from the poles and the bottom of the ocean adding positive feedback. k. Carbon “sinks” (a repository or compartment or part of the cycle where something accumulates) in terrestrial environments – SOM - soil organic matter; peat - semi-decayed organic matter; coal – compressed peat that is turned into a rock like state in marine environments – DOM – dissolved organic matter; benthos or bottom of water 2. Human Impacts on the Carbon Cycle – humans are altering most biogeochemical cycles in massive ways a. Average global temperature increased about 0.8 Celsius degrees. b. Average global sea level increased over 175 to 200 m. B. Consequences of Global Warming - Climate: long term trends in temp, precipitation, sunlight, and wind conditions - Weather: short term trends in temp, precipitation, sunlight, and wind conditions - Greenhouse gas: absorbs and traps energy from IR radiation reflected from the Earth’s surface - Phenology: timing of season events 1. Increase in catastrophic events such as storms, foods, and other weather-related events 2. Economic costs 3. Changes in climate are causing changes in phenology and a chain effect among species interactions. 4. Increased temperature pose stressful conditions to many species 5. Climate changes are shifting the ranges in which species reside. 6. Increase in CO2 in the oceans are making oceans more acidic and harder for organisms like shellfish to develop thick shells. 7. Feedback a. Positive feedback: increases CO2 levels in the atmosphere and ocean b. Negative feedback: reduces CO2 levels in the atmosphere and ocean C. Mechanisms to mitigate climate change Lecture 40: Threats A. Threats to biodiversity 1. Many species are undergoing extinction rates that are far greater than the background extinction rates. 2. % of known species threatened with extinction: amphibians > gymnosperms > mammals > birds a. Amphibians are particularly affected by the chemical changes in the environment due to their semi- permeable skin. They are also more sensitive to temperature changes. 3. As human population are increasing, habitat fragmentation increases, causing more habitats to be lost and species loss to be greater. 4. There are biases and assumptions to extinction rates. a. Ascertainment bias: when the “effort” or criteria for identifying or diagnosing changes or varies among study groups. b. Extinction rates are affected by the assumption that every species that becomes endangered will become extinct c. Species extinction rates tend to be more conservative rather than inflated because they are quicker than the actual observed. B. Why are species going extinct - Habitat fragmentation: division of a large, contiguous habitat into many small pockets or fragments. 1. Anthropocene extinction – time of rapid climate change, chemical composition of the atmosphere, change in rock layers, lots of extinction. a. Destruction of habitat b. Over-fishing c. Harvesting organisms for traditional medicines 2. Invasive species: anthropogenic introduced species that outcompete the native species 3. Biggest threats a. For terrestrial species – habitat loss b. For marine species – overexploitation 4. Extinction vortex/ domino effect – as population become smaller and more isolated, inbreeding depression increases and genetic drift affects the population more. In addition, continuous changes or stochastic disturbances in the environment become more effective at affecting the fitness of the populations. 5. Net loss = total change including reforestation C. How can we reduce threats? 1. Wildlife corridor: strip of habitat that connects two preserved areas 2. Ex situ conservation: preserving species in zoos, botanic gardens, or aquaria 3. Genetic restoration: artificial gene flow that counteracts the effect of inbreeding and drift. 4. Ecological restoration: efforts by humans to increase biodiversity and biomass indegraded habitats Lecture 41: Strategies A. Designing effective protected areas 1. Efficiency issue – protecting the largest number of species in the smallest possible areas a. Goals: maximizing the interactions between species, understanding the human communities surrounding the habitats, maximizing the number of habitats, and identifying the locations with the most species richness. b. Measured variable: increase in species richness. Resilience. Inbreeding depression by examining genetic structures. 2. Map biodiversity hotspots or areas of high level of threat a. Biodiversity hotspots: area where species richness is extremely high b. The amazon is not included because it still has a lot of habitat c. Japan is included because of high level of industrialization in addition to geographic isolation which decreases gene flow between other populations. 3. Establishing wildlife corridors a. Species richness for connected environments will increase and then level off at some point. b. Species richness for unconnected environment will gradually decrease. B. Reducing threats 1. Overexploitation and habitat loss 2. Controlling invasive species C. Restoring damaged ecosystems D. Decreasing ecological “footprints” 1. Footprint: an estimate of how many hectares of productive land it takes to support your life style; usually assess food, transportation, shelter, goods/services 2. ¾ of all agricultural land goes to feeding livestock Review Session: If temperatures increase on the surfaces, why is the upwelling events decreasing? The density of the water decreases, making it harder for the water to push up the gradients Fewer upwelling in the oceans decreases NPP in the oceans, and the circulation of water, decreasing oxygen, creating dead zones, positive feedback. Decrease in circulation is a positive feedback
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