Lecture 18

Lecture 18 - Lecture 18: Movements Strategies in Space I....

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Lecture 18: Movements Strategies in Space I. Key Words A. Dispersion – how individuals arranged in space B. Random - C. Clumped - D. Uniform - E. Metapopulation - F. Rescue Effect - G. Population Sinks - H. Migration - I. Dispersal - II. Key Concepts A. The dispersion pattern of organisms is scale-dependent, and can be random, clumped, or uniform. B. A metapopulation consists of subpopulations connected by the movement of individuals. 1. Subpopulations are exposed to different environmental conditions and react more-or-less independently of one another. 2. Although subpopulations go extinct, the population as a whole can be stable because immigrants from subpopulations colonize patches left open by the extinction of previous populations. C. Migration is a mechanism whereby organisms try to maximize (benefits - costs), but it entails substantial risk. D. Dispersal is a mechanism whereby organisms try to maximize (benefits - costs), and it also entails risk. E. Whether an organism migrates or disperses depends upon the (benefits - costs) of moving, given the context and constraints of the organism’s biology and environment. F. The r- and K- selection continuum is a useful model for explaining some (but not all) life history strategies. III. General Outline A. Types of Movements 1. dispersion and within-population movements 2. migration (from one place and back again) 3. dispersal B. Dispersion Patterns 1. Organisms can be arranged in space (dispersion) in only three basic ways a. Random (the position of one individual has no effect on the positions of the other individuals) b. Clumped
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c. Uniform (regularly spaced) Which is most common? Depends on the scale (how big?) At small scales, orgs
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Lecture 18 - Lecture 18: Movements Strategies in Space I....

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