Optimal body size, density‐dependent selection gradients, and phenotypic variance under asymmetric competition
2004
Kisdi, Éva
I investigate a simple model of asymmetric competition, in which resource‐ holding potential (RHP) correlates with body size, the individuals with the highest RHP obtain the available territories (or other nondividable resources), and the population is regulated by the number of territories. Under these assumptions, I show that there is an optimal size strategy. Challenging a number of intuitive expectations, the model provides the following results: (1) The selection gradient on size may decrease (rather than increase) if population density is higher and competition is more intense; (2) the correlation between size and resource‐holding potential may decrease during evolution, whereby size becomes irrelevant for competitive success; (3) assuming an offspring size–number trade‐off and multiple clutches per year, the optimal size at birth may decrease (rather than increase) during the breeding season.
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