THE FIXED SAMPLE SEARCH RULE AND USE OF AN INDICATOR CHARACTER TO EVALUATE MATE QUALITY

The phenotypic correlation observed between mated males and females is a direct result of the decision rules that individuals employ during search for a mate. We generalize the fixed sample search rule and exam ine how the functional relationship between a male indicator character and the fitness benefit of a mating decision influences female search behavior. If the phenotypes of males and females combine additively t o influence the benefit of a mating decision and fitness is a highly i nclined function of phenotypic values the optimal value of n, the numb er of males that females sample during search, is relatively large. Th e phenotype of the searcher has no impact on the optimal value of n if fitness is a linear function; the optimal n increases with the phenot ype of females if the fitness function is convex; and a concave fitnes s function induces females with high trait values to sample relatively few males. Because females that sample many potential mates are expec ted to encounter a male with a high expression of the indicator trait linear, convex and concave fitness functions induce a random, assortat ive and disassortative combination of phenotypes between mated individ uals, respectively. Thus, the fixed sample search tactic can produce t he variety of phenotypic correlations observed between mated individua ls in natural systems and our ability to derive rule-specific predicti ons of search behavior may generally require information on how charac ters used to evaluate potential mates are related to fitness. (C) 1998 Academic Press.