Recent theoretical models predict that the evolutionary diversification of the weapons and ornaments of pre-mating sexual selection should be influenced by trade-offs with male expenditure on ejaculates. However, the patterns of association between secondary sexual traits and ejaculate expenditure are frequently inconsistent in their support of this prediction. We show why consideration of additional life-history, ecological, and mating-system variables is crucial for the interpretation of associations between secondary sexual traits and ejaculate production. Incorporation of these ‘missing variables’ provides evidence that interactions between pre- and post-mating sexual selection can underlie broad patterns of diversification in male weapons and ornaments. We call for more experimental and genetic approaches to uncover trade-offs, as well as for studies that consider the costs of mate-searching.

最近的理论模型预测，早婚性选择的武器和装饰物的进化多样化应受到男性射精支出的权衡取舍的影响。然而，次要性格特征与射精支出之间的关联模式在支持这一预测方面常常不一致。我们证明了为什么要考虑额外的生活史，生态和交配系统变量对于解释继发性特征和射精之间的关系至关重要。这些“缺失变量”的结合提供了证据，表明交配前和交配后的性选择之间的相互作用可能是男性武器和装饰品多样化的广泛模式的基础。我们呼吁采用更多实验性和遗传性方法来发现折衷方案，