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The concepts of island biogeography and metapopulations in the context of ecology. Topics such as logistic population growth, the impact of island size on species diversity, the effects of habitat patch size and isolation on population dynamics, and the rescue effect. The document also discusses the traits of metapopulations and provides examples of metapopulations in butterflies.
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Announcements Logistic growth reconsidered Island Biogeography The Metapopulation Colonization and Extinction Patch size and isolation Habitat heterogeneity The rescue effect
!Less genetic diversity !Closer to “minimum” population where alee effect becomes important.
! Islands are similar to isolated patches on the landscape. " Ecologists now apply this concept to terrestrial habitats. ! Refined Definition: " The number of species established on an island represents a dynamic equilibrium between the immigration of new colonizing species and the extinction of previously established ones.
!As species began to accumulate, rate of immigration would decline since fewer arrivals would be new species.
" Presence of more species creates a larger pool of potential extinctions. " As number of species increases, population size of each must diminish. " As number of species increases, potential for competitive interactions between species will increase.
!Population partially maintained by immigration.
Butterfly Populations
!Rate of movement of individuals between subpopulations can affect species persistence in a landscape.
General definition: Metapopulation : population divided into discrete subpopulations linked by movement of individuals. Subpopulation : because the landscape is heterogeneous, individuals can form smaller groups, with much less interaction between groups than if the habitat were homogeneous.
! Why might this be critical?
!Sandy areas not always available in smaller patches
CV=St.dev/mean
" An increase in population size and a decrease in the risk of extinction brought about by an increase of immigration into a population.
" Single habitat is the dominant source of immigrants. " Many non-island populations have a similar structure.