University of California, Santa Barbara - EEMB 131eemb 131 final

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Lecture 12 Biodiversity and Ecosystem Packing I. General points -Simple models developed to explain island biogeography or to characterize the growth of populations…substitution of speciation (... a) for colonization or birth rates and of extinction (b) for local extirpation or death rates. - number of living species (N*) can be an equilibrium state, and that N* can be substantially less than the carrying capacity (N*max) if extinctions are not completely diversity-dependent. Based on value proportional to the ratio a/b - extinction not competitive exclusion= open niches - m (where dN*/dt = 0) the ratio N*/N*max = 1-b/a; since we know N*, b and a, we can calculate N*max II. What determines N*max? -N*max is equivalent to K in population biology, but is the number of species limited by resources -Plate tectonics illustrates that the amount of physical space can vary by ca. 30x (species are apportioned among a variable number of continents and climatic zones), and a latitude effect on diversity increases this range to ca. 100x -annexation-organisms can evolve to occupy new environments - partitioning- ecological interactions can evolve such that a system contains more or fewer species - resource-based criterion that might include interspecific competition as a causal mechanism - compilation of the numbers of families, pattern of increase, stasis and decline involving three successive faunas (Cambrian, Paleozoic and Modern) - logistic curve [Show More]

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