How does environmental variation effect fitness of density-dependent habitat selectors? / by Jody T. MacEachern.

Abstract

The spatial distribution of animals can arise through a variety of habitat-selection strategies. It is unclear which habitat characteristics lead to the evolution of one of these strategies over another. Thus I use an individual-based model of habitat selection to assess how the mean and standard deviation of breeding-site quality in a landscape of two habitats influence the geometric mean fitness of ideal free, ideal pre-emptive and ideal despotic habitat-selection strategies. Computer simulations revealed little difference in fitness among strategies. Most simulated habitats supported large populations that saturated breeding sites and fluctuated around their carrying capacities. Despotism yielded the highest geometric mean fitness when more-or-less homogeneous sites were of low average quality. The rank order of strategies by fitness depended on density and was consistent across all simulations. Despotic habitat selectors consistently possessed the highest geometric mean fitness at low density suggesting that despotism can invade other pure strategies. The results imply that multiple habitat-selection strategies may coexist in the same population. Coexisting strategies are most likely to occur at high population density or under conditions that cause frequent variation in population size.