Genetic versus census estimators of the opportunity for sexual selection in the wild

The existence of a direct link between intensity of sexual selection and mating system type is widely accepted. However, the quantification of sexual selection has proven problematical. Several measures of sexual selection have been proposed, including the operational sex ratio (OSR), breeding sex ratio (BSR) and opportunity for sexual selection (Imates). For a wild population of pronghorn (Antilocapra americana), we calculated OSR and BSR. We estimated Imates from census data on the spatial and temporal distribution of receptive females in rut and from a multi-generational genetic pedigree. OSR and BSR indicated weak sexual selection on males, but census and pedigree Imates suggested stronger sexual selection on males than on females. OSR and BSR correlated with census but not pedigree estimates of Imates, and census Imates did not correlate with pedigree estimates. This suggests that the behavioral mating system, as deduced from the spatial and temporal distribution of females, does n...

性选择强度与交配系统类型之间存在直接关联这一观点已被广泛认可。然而，性选择的量化一直是个难题。目前已提出多种性选择量化指标，包括操作性别比（operational sex ratio, OSR）、繁殖性别比（breeding sex ratio, BSR）以及性选择机会（opportunity for sexual selection, Imates）。针对野生叉角羚（Antilocapra americana）种群，我们计算了OSR与BSR。我们利用发情期可受孕雌性的时空分布普查数据，以及多世代遗传谱系数据，对Imates进行了估算。OSR与BSR显示雄性受到的性选择较弱，但基于普查和谱系数据的Imates结果则表明，雄性受到的性选择强度高于雌性。OSR与BSR与基于普查数据的Imates估算值相关，但与基于谱系数据的Imates估算值无关；同时，两种数据来源的Imates估算值之间也不存在相关性。这表明，通过雌性时空分布推断出的行为交配系统，does n...