Non-competitive phenotypic differences can have a strong effect on ideal free distributions

1. We present a model of the ideal free distribution (IFD) where difference s between phenotypes other than those involved in direct competition for re sources are considered. We show that these post-acquisitional differences c an have a dramatic impact on the predicted distributions of individuals. 2. Specifically, we predict that, when the relative abilities of phenotypes are independent of location, there will be a continuum of mixed evolutiona rily stable strategy (ESS) distributions (where all phenotypes are present in all patches). 3, When the relative strengths of the post-acquisitional trait in the two p henotypes differ between patches, however, we predict only a single ESS at equilibrium. Further, this distribution may be fully or partially segregate d (with the distribution of at least one phenotype being spatially restrict ed) but it will never be mixed. 4, Our results for post-acquisitional traits mirror those of Parker (1982) for direct competitive traits. This comparison illustrates that it does not matter whether individual differences are expressed before or after compet ition for resources, they will still exert considerable influence on the di stribution of the individuals concerned.