Chapters 13-14 Notes
Chapters 13-14 Notes 301
Popular in Ecology and Evolution
verified elite notetaker
Popular in Biology
This 6 page Class Notes was uploaded by Morgan Deal on Monday October 26, 2015. The Class Notes belongs to 301 at University of South Carolina taught by Dr. April South in Summer 2015. Since its upload, it has received 30 views. For similar materials see Ecology and Evolution in Biology at University of South Carolina.
Reviews for Chapters 13-14 Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 10/26/15
CHAPTER 13 Population Dynamics Over Time and Space Population Fluctuations ALL populations uctuate Small organisms o Reproduce faster 0 Respond faster to variable conditions high SAV ratio 0 Large organisms small SAV ratio allows for homeostasis in the face of adverse conditions Age Structure Fluctuations 0 Age group with high or low numbers usually corresponds with high birth or death rates in the past Forests longterm uctuations in age structure can be determined by examining tree rings Overshoots and DieOffs Does every population reach k and then level off NO 0 What model would this follow LOGISTIC Overshoot when population exceeds k 0 Occurs when k decreases from 1 year to the next usually due to low resources 0 Ngtk Dieoff decrease in density typically well below k following an overshoot Cyclic Population Fluctuations Population cycles regular oscillation of population over long periods of time 0 Patterns of oscillation some populations have regular oscillation 0 Can occur across large geographic areas among related species 0 Cyclic behavior of populations most cycles are inherent Delayed density dependence density dependence occurs based on population density at some time in the past 0 Based off of logistic growth model 0 Incorporate time delay T dN NH rN1 dt k As T increases density dependence is delayed population slows growth as population size approaches k 0 Amount of cycling in population depends on r and T r1 lt 37 no oscillations 37 lt rt lt 157 l damped oscillations magnitude of oscillations decreases over time rt gt 157 l stable limit cycle large oscillations over time Cycles in lab populations other reasons for delayed density dependence 0 Storage of energynutrient reserves 0 Time delays in development from 1 life stage to another ExUncUon Small populations are more vulnerable Due to growth rates growth rates have variation 0 Deterministic model designed to predict without accounting for random variation in population growth rate 0 Stochastic model incorporates random variation in population growth rate Demographic stochasticity variation in birth and death rates due to random differences among individuals Environmental stochasticity due to random changes in environmental conditions Habitat Fragmentation All habitats are NOT equal 0 Habitat fragmentation breaking up large habitats into a smaller habitats Sourcesink metapopulation model 0 Source habitats high quality high number of individuals emigrate o Sink habitats low quality rely on source populations to avoid extinction Basic Metapopulation Model Assumptions 0 Habitats are of equal quality 0 Each occupied patch has the same subpopulation size 0 Each subpopulation supplies the same number of dispersers to other patches 0 p fraction of habitat patches that are occupied e probability of each patch becoming unoccupied c probability of each patch becoming colonized phat proportion of occupied patches when colonization and extinction are at equilibrium A 6 o p C Patch Size and Isolation Patches are rarely equal Small patches 0 Increased rate of extinction can t support a large population 0 Less likely to be occupied than large patches More isolated patches have lower probability of being occupied than closer patches 0 Inverse relationship between dispersal success and distance of dispersal Unoccupied patches close to occupied patches are more likely to be colonized Rescue effect dispersers supplement declining subpopulation to prevent extinction CHAPTER 14 Predation and Herbivory Effects of Predators Predators have large effects on prey Introduced nonnative or exotic species 0 Invasive species introduced species that spread rapidly and have negative effects on other species Parasitoids unique predators that limit abundance of prey o Larvae kill animal from inside out Mesopredator smaller predators that consume herbivores Top predator larger predator that consumes herbivores and mesopredators o Interfere with human agricultural activities 0 Decline of top predators can increase abundance of mesopredators 0 Bene ts of removing a top predator do not outweigh resulting mesopredator damage Herbivores Also have large effects on the species they consume 0 Example cactus moths decimated cacti crop in 3 years Modeling PredatorPrey Cycles 0 Stable cycles can occur when environment is complex so predators cannot easily nd prey LotkaVolterra model incorporates oscillations in abundance of predator and prey populations dN 0 Growth of Prey EZrNCNP o rN exponential growth rate of prey population 0 cNP loss of individuals due to predation dr 0 Growth of predator population EZaCNP mp o acNP birth rate 0 mP death rate 0 N prey P predators C probability of an encounter between predator and prey leading to capture of prey A efficiency of predator converting consumed prey into offspring M per capita mortality rate of predators Modeling Prey Prey population is stable when dNdt 0 0 Addition of prey consumption rNgtcNPPltrc o Prey population increases rNltcNPPgtrc o Prey population decreases Modeling Predators dPdt 0 o Predator population stabIe addition of predators mortality mP lt acNP l N gt mac o Predator population increases mP gt acNP lN lt mac o Predator population decreases Modeling PredatorPrey Cycles Equilibrium isocline population size of 1 species causes population of another to be stable Prey l P rc Predators l N mac Joint population trajectory simultaneous trajectory of predator and prey population 0 joint equilibrium point point at which equilibrium points of predatory and prey populations cross Predator Response LV model doesn t incorporate 0 Time delays 0 Density dependence 0 Realistic foraging behavior 0 Functional response relationship between prey density and predator s rate of food consumption 0 Type I predator rate of consumption increases until satis ed uncommon 0 Type II predator rate of consumption decreases as prey density decreases then plateaus Any prey density increase causes consumption to slow 0 Type III low rapid slowing prey consumption under low moderate and high prey density Most common in the wild Prey can nd places to hide Predators have less practice nding prey but can develop search image helps locate and capture food Predators may exhibit prey switching Typel Typell o 0 Numerical response change in number of predators through population growth or movement