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r- and K-Selection in a Completely Chaotic Population Model
The American Naturalist
Vol. 113, No. 4 (Apr., 1979), pp. 499-510
Stable URL: http://www.jstor.org/stable/2460271
Page Count: 12
You can always find the topics here!Topics: Population size, Genotypes, Population growth, Chaos theory, Natural selection, Haploidy, Population dynamics, Population growth rate, Gene frequency, Logarithms
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A model of discrete-generations population dynamics originally due to M. H. Williamson is analyzed. In this model, the negative effect of population density acts suddenly and completely as the population size passes a threshold. The model almost always yields chaotic fluctuation of population size. When it does, this chaos ensues whatever the initial population size. The average population cycle length is found, as well as the distribution of population sizes over time. One can readily analyze r- and K-selection in this model. Natural selection will favor cycles with more time spent above the threshold population size, and will favor increase of the threshold. When r- and K-selection oppose each other, protected polymorphism is possible in an asexual or haploid population, but only if the genotype which would be lost if there were no K-selection has the greater population fluctuation when present alone. Conditions for protected polymorphism in a two-allele diploid population are also given.
The American Naturalist © 1979 The University of Chicago Press