Animal Behaviour Research Group, Washington Singer Labs, University of Exeter, Perry Road, Exeter, United Kingdom.
Am Nat. 2009 Mar;173(3):E62-78. doi: 10.1086/596528.
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 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.
反选择(频率或密度依赖)、警戒信号和配偶选择行为通常要求平均猎物或潜在配偶密度 m 值足够高(高于阈值 T),以便搜索者有足够高的遭遇率来学习或保留显眼信号与猎物无利可图之间的关联,从而进行反选择觅食或在配偶之间进行选择。这假设所有搜索者都经历 m>T,这隐含地假设目标在搜索者领地中的分布是均匀的。不均匀的分布会产生新的现象。如果 m<T,那么只有局部密度 x 值大于 T 的领地有利于基于经验的行为,从而导致空间上可变的频率或密度依赖选择强度。随着聚集程度的增加,有利于目标的领地(x>T)的百分比增加大于有利于领地的百分比增加。当 m>T 时,情况就会逆转。在这两种情况下,由于多达 10%的领地可能包含 80%的目标,因此只有少数领地持有者可能对大多数目标种群产生大部分选择;少数搜索者的偶然经验可能对目标种群产生出乎意料的大影响。这也解释了为什么搜索者行为会有很高的变异性(个性):来自有利领地的个体在行为实验中的表现与来自不利领地的个体不同,至少在类似的目标方面是不同的。这些效应将在原本均匀的环境中产生自然和性选择的空间异质性。