Comparing measures of breeding inequality and opportunity for selection with sexual selection on a quantitative character in bighorn rams

The reliability and consistency of the many measures proposed to quantify sexual selection have been questioned for decades. Realized selection on quantitative characters measured by the selection differential i was approximated by metrics based on variance in breeding success, using either the opportunity for sexual selection Is or indices of inequality. There is no consensus about which metric best approximates realized selection on sexual characters. Recently, the opportunity for selection on character mean OSM was proposed to quantify the maximum potential selection on characters. Using 21 years of data on bighorn sheep (Ovis canadensis), we investigated the correlations between seven indices of inequality, Is, OSM and i on horn length of males. Bighorn sheep are ideal for this comparison because they are highly polygynous, sexually dimorphic, ram horn length is under strong sexual selection, and we have detailed knowledge of individual breeding success. Different metrics provided c...数十年来，学界始终对诸多用于量化性选择的测量指标的可靠性与一致性提出质疑。此前，研究人员常基于繁殖成功率的方差，采用性选择机会（opportunity for sexual selection, *I*_s）或不平等性指数，对通过选择微分（selection differential, *i*）测得的数量性状实际选择强度进行近似估算。目前学界尚未就何种指标能最优近似性选择性状的实际选择强度达成共识。近期，有研究提出性状均值选择机会（opportunity for selection on character mean, *OSM*）以量化性状的最大潜在选择强度。本研究依托盘羊（*Ovis canadensis*）长达21年的观测数据，针对雄性角长相关的7种不平等性指数、*I*_s、*OSM*以及选择微分*i*之间的相关性展开了探究。盘羊是开展此类对比研究的理想类群：它们具有高度的多配制特征，存在显著的两性异形，公羊角长受到强烈的性选择作用，且本研究已掌握个体繁殖成功率的详细资料。不同指标所得到的相关结果存在……