The Spatial Pattern of Natural Selection When Selection Depends on Experience

Apostatic (frequency- or density-dependent) selection, aposematic signals, and mate choice behavior generally require that the mean prey or potential mate density m value be high enough (above a threshold T) to result in sufficient encounter rates for the searcher to learn or retain the association between conspicuous signals and prey unprofitability, to forage apostatically, or to choose among mates. This assumes that all searchers experience, m > T which implicitly assumes an even dispersion of targets among searcher territories. Uneven dispersion generates new phenomena. If m < T, then only territories with local density x values that are m > T greater than T favor experience-based behavior, leading to spatially variable frequency-or density-dependent selection intensity. As aggregation increases, the increase in percentage of targets in favorable territories (x > T) is greater than the increase in the percentage of territories that are favorable. The relationship is reversed when m > T. In both cases, because as few as 10% of the territories can contain 80% of the targets, only a few territory holders may account for most of the selection on most of the target population; accidents of experience in only a few searchers can have unexpectedly large effects on the target population. This also provides an explanation for high searcher behavior variation (personalities): individuals from favorable territories will behave differently in behavioral experiments than those from unfavorable territories, at least with respect to similar kinds of targets. These effects will generate spatial heterogeneity in natural and sexual selection in what are otherwise uniform environments.