PCB3043 Unit One Material Lectures 1 8 Ecology Final Study Guide Ecology Study of the interactions that determine the distribution and abundance of organisms Population members of the same species living within the same area Population Density Number of organisms per unit area 3 Methods for Counting Pop Size 1 Count 2 Statistical Extrapolation Estimate 3 Tagging Especially when organism is mobile o MRR Mark Release Recapture Marked Recaptured 2nd Sample Total no effect of marking on behavior change of recapture or survival Closed population Size Distribution Vector column showing of individuals in each stage Stable Stage Distribution distribution of individuals among stages that wont change over time The Demographic Transition the shift in human populations from high birth and death rates to low birth and death rates with death rates falling first causing populations to grow rapidly Population Momentum a tendency for population that s growing shrinking will continue growing shrinking after a change in demographic rates Total Environment Impact PAT o People o A verage Resource Use Per Person o Efficiency of Resource Use Technology Trade offs Impacting Populations 1 Current Reproduction and Future Reproduction 2 Reproduction vs Adult Survival 3 Hatchling Size vs Survival Beyond Fledging Human Carrying Capacity of resources needed to sustain human populations Many Populations that Are Unstable Cycle Because 1 Predator Prey Interactions 2 Carrying Capacity Changes Over Time 3 Time lags in how quickly a population can adapt Two Main Reasons Pop Cycles Are Caused By Density Dependence 1 Time lag b c there can t be any instant reactions Stefan Pham 2 High Growth Rate Types of Cycles i ii Damp r is mostly consistent Stable r overshoots and undershoots Pattern Characteristics 1 Chaotic never repeat itself exactly return time of infinity 2 Consistent can repeat itself Heterozygosity of alleles in an individual that are heterozygous Unit One Material Lectures 1 8 Polymorphism of alleles in a population for a certain gene Bottleneck period when a previously large population is at a small size defined by how small the population gets and how long it remains a small size Inbreeding Depression when inbred individuals have lower fitness survival reproduction due to their lower genetic heterozygosity and more homozygous recessives Demography study of human populations Fecundity the potential reproductive capacity of an individual or population Demographic Stochasticity effect of random factors on individual births deaths o Cause population growth rates to be less predictable in small populations Size Structured vs Age Structured Populations o Size structured tracks the dynamics not only of total population but also the distribution of the variables that di erentiate individuals Meanwhile an Age Structured Population focus primarily on the ages that make up a population Difference Between Life Tables and Matrix Models o Life Tables track individuals by age while Matrix Models track by size In a matrix individuals can shrink to a smaller class 7 145 Billion Current Human Population Effect on human Rho if the average age of 1st reproduction increased by a year o It d decrease b c of the few people that die before reproducing Logistic Growth vs Exponential Growth o Main difference logistic growth into begins to level between exponential and is that logistic growth takes account carrying capacity off as it nears it 2 Stefan Pham 3 Stefan Pham 4 Unit Two Material Lectures 9 20 Stefan Pham Metapopulations a population of populations Metapopulations Model dF dt cF 1 F eF C colonization rate F fraction of patches occupied E extinction rate Increasing colonization rates increase in fraction of habitat patches occupied equilibrium f Case Study Voles High extinction rates because they eat their own habitats by eating too much of the available vegetation and resources Colonize by reproducing like crazy and then eat up all of the vegetation o Then when depleted they swim to try and find a new island Big Patches have Bigger Populations Less likely to go extinct Patches Vary in Quality Source Populations high growth rate good habitat o Have colonists to release and send out Sink Populations low neg population growth rate bad habitat Predictions of Source Sink Metapopulations o Sinks need sources o Total population size is higher with sinks Closely related species are NOT the only ones who compete strongly Anything can be competed for but only way to know if competition is driving something is by experimental testing A fugitive species is NOT a good competitor Source populations DO NOT need sinks in order to persist Fish with high parasite loads are avoided by bird predators Commensalism is a term for a 0 species interaction 5 Stefan Pham When predator and prey populations cycle the predator population does NOT always peak before the prey population peaks Fundamental Niche where a species can live Realized Niche where a species does live Unit Two Material Lectures 9 20 Theory of Island Biogeography relationship between c e rates of a species Island Area Effect o As island area increases number of species increases o Extinction rate decreases as islands get larger o Equilibrium Value S increases as island area increases Island Distance Effect o As distance from mainland increases number of species decreases o Colonization rates decreases as islands get further from the mainland o Equilibrium Value S will decrease as an island gets further away Extinction rate can decrease as the area of the island increases however it can increase depending on the amount of resources available and its overall distance from the mainland can greatly affect it as well higher distance away greater the e rate Tests of TB 1 Natural Defaunation Volcanic Eruptions 2 Experimental Size Changes of the Islands 3 Experimental defaunation of islands at diff distances from the mainland Unit Two Material Lectures 9 20 Nature Reserves 1 Protect Species Biodiversity 2 Maintain Ecosystem Services The SLOSS Debate Single Large or Several Species Why might a prey population that lives with a predator have fewer disease outbreaks than a prey population that lives in an area with no predators A prey population without a predator may have fewer outbreaks because they may have a more diverse population that they live with and their population size is most likely lower allowing for transmission to be lower and for them to be less susceptible The Lotka