BIOLOGY 197FH Lecture Notes - Lecture 19: Improved Sanitation, Population Ecology, Logistic Function
25 Apr 2016
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Document Summary
Logistic growth model the per capita rate of increase declines as carrying capacity is approached. Expression that reduces per capita rate of increase as n approaches k dn/dt = rmaxn(k-n)/k. Difficult to get laboratory population to model this because situation is artificial. At high densities, each individual has few resources and slow growth. At low densitites, per capita resources are abundant and rapid growth. At high densities, selection favors adaptations that enable organisms to survive and reproduce with few resources. At low densities, adaptations that promote rapid reproduction are selected for. Selects for diversity r selection: r selected species do best in unpredictable environments, where specialized adaptations are unhelpful. Selected during early phase where organisms reproduced quickly. Better to be a generalist not specialized for environment. Mosquitos, shrimp k-selection: selection for life history traits that re sensitive to population density density dependent selection. Do well in predictable environment, adapt to environment for advantages.
