BIO 373 1st Edition Lecture 13 Outline of Last Lecture I Influences on Population Size a Weather b Intraspecific competition c Density dependent factors II Logistic Growth a Carrying capacity b Compare to exponential growth III Simple and complex population dynamics a Exponential and logistic growth b Population fluctuations Outline of Current Lecture I Delayed Density Dependence II Population Dynamics a Extinction i Factors ii Spatial dynamics b Metapopulation Current Lecture Delayed Density Dependence when r tau is small logistic growth when r tau is intermediate exhibits oscillations when r tau is large stable limit cycle Population Dynamics populations can go extinct o just as all populations can grow exponentially factors chance events o genetic factors genetic drift chance of propensity of alleles to be lost can lead to fixation of an allele These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute inbreeding less diversity similar alleles decreased genetic variation in small populations o demographic stoichaciticity chance events affect survival and reporoduction of individual birth rate and death rate frequencies may be unequal P extinction d b No o Environmental stoicasticity Good years and bad years for population growth hence r changes through time Optimal vs suboptimal conditions on intrinsic rate of growth Fluctuations effects are much greater in small populations Natural catastrophes Spatial Dynamics o Can be patchy distributions as opposed to continuous o Patchiness is increased due to human impact o Metapopulation concept we see population in habitats that are suitable Persistence 0 or 1 not there or there probability of persistence of a population Regional or landscape scale Dp dt cp 1 p ep E extinction p proportion of habitat patches occupied c colonization of patches Know metapopulation assumptions Some patches go extinct while others get colonization or recolonized and grow again Immigration into empty patches can sustain metapopulation o Application of metapopulation concept Habitat fragmentation As patches get smaller and more isolated colonization rate decreases and extinction rate increases If e c 1 metapopulation will go extinct A critical habitat threshold exists to avoid extinction
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