Proulx Stephen R, Day Troy, Rowe Locke
Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada.
Proc Biol Sci. 2002 Nov 22;269(1507):2291-9. doi: 10.1098/rspb.2002.2129.
The hypothesis that females prefer older males because they have higher mean fitness than younger males has been the centre of recent controversy. These discussions have focused on the success of a female who prefers males of a particular age class when age cues, but not quality cues, are available. Thus, if the distribution of male quality changes with age, such that older males have on average genotypes with higher fitness than younger males, then a female who mates with older males has fitter offspring, which allows the female preference to spread through a genetic correlation. We develop a general model for male display in a species with multiple reproductive bouts that allows us to identify the conditions that promote reliable signalling within an age class. Because males have opportunities for future reproduction, they will reduce their levels of advertising compared with a semelparous species. In addition, because higher-quality males have more future reproduction, they will reduce their advertising more than low-quality males. Thus, the conditions for reliable signalling in a semelparous organism are generally not sufficient to produce reliable signalling in species with multiple reproductive bouts. This result is due to the possibility of future reproduction so that, as individuals age and the opportunities for future reproduction fade, signalling becomes more reliable. This provides a novel rationale for female preference for older mates; older males reveal more information in their sexual displays.
雌性偏好年长雄性是因为它们比年轻雄性具有更高的平均适合度，这一假设一直是近期争议的焦点。这些讨论集中在当存在年龄线索而非质量线索时，偏好特定年龄组雄性的雌性的成功情况。因此，如果雄性质量的分布随年龄变化，使得年长雄性平均具有比年轻雄性更高适合度的基因型，那么与年长雄性交配的雌性就会有更适合的后代，这使得雌性偏好能够通过遗传相关性得以传播。我们为具有多次繁殖周期的物种中的雄性展示建立了一个通用模型，该模型使我们能够确定在一个年龄组内促进可靠信号传递的条件。由于雄性有未来繁殖的机会，与一次性繁殖物种相比，它们会降低广告宣传水平。此外，由于高质量雄性有更多未来繁殖机会，它们会比低质量雄性更多地减少广告宣传。因此，一次性繁殖生物中可靠信号传递的条件通常不足以在具有多次繁殖周期的物种中产生可靠信号传递。这一结果是由于未来繁殖的可能性，所以随着个体年龄增长以及未来繁殖机会减少，信号传递变得更加可靠。这为雌性偏好年长配偶提供了一个新颖的理论依据；年长雄性在其求爱展示中透露了更多信息。
