Raj Pant Sara, Hammers Martijn, Komdeur Jan, Burke Terry, Dugdale Hannah L, Richardson David S
Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, UK.
Groningen Institute for Evolutionary Life Sciences, Faculty of Science and Engineering, University of Groningen, Groningen, The Netherlands.
Mol Ecol. 2020 Oct;29(19):3731-3746. doi: 10.1111/mec.15563. Epub 2020 Sep 26.
Extra-pair paternity (EPP) is often linked to male age in socially monogamous vertebrates; that is, older males are more likely to gain EPP and less likely to be cuckolded. However, whether this occurs because males improve at gaining paternity as they grow older, or because "higher quality" males that live longer are preferred by females, has rarely been tested, despite being central to our understanding of the evolutionary drivers of female infidelity. Moreover, how extra-pair reproduction changes with age within females has received even less attention. Using 18 years of longitudinal data from an individually marked population of Seychelles warblers (Acrocephalus sechellensis), we found considerable within-individual changes in extra-pair reproduction in both sexes: an early-life increase and a late-life decline. Furthermore, males were cuckolded less as they aged. Our results indicate that in this species age-related patterns of extra-pair reproduction are determined by within-individual changes with age, rather than differences among individuals in longevity. These results challenge the hypothesis-based on longevity reflecting intrinsic quality-that the association between male age and EPP is due to females seeking high-quality paternal genes for offspring. Importantly, EPP accounted for up to half of male reproductive success, emphasizing the male fitness benefits of this reproductive strategy. Finally, the occurrence of post-peak declines in extra-pair reproduction provides explicit evidence of senescence in infidelity in both males and females.
在社会性一夫一妻制的脊椎动物中，婚外父权（EPP）往往与雄性年龄有关；也就是说，年龄较大的雄性更有可能获得婚外父权，而被戴绿帽的可能性较小。然而，这种情况的发生是因为雄性随着年龄增长在获得父权方面有所提高，还是因为寿命更长的“高质量”雄性更受雌性青睐，尽管这是我们理解雌性不忠进化驱动因素的核心，但很少有人进行过测试。此外，雌性体内的婚外繁殖如何随年龄变化受到的关注更少。利用来自一个有个体标记的塞舌尔莺（Acrocephalus sechellensis）种群的18年纵向数据，我们发现两性的婚外繁殖在个体内部都有相当大的变化：生命早期增加，生命后期下降。此外，雄性随着年龄增长被戴绿帽的情况减少。我们的结果表明，在这个物种中，与年龄相关的婚外繁殖模式是由个体随年龄的变化决定的，而不是个体在寿命方面的差异。这些结果挑战了基于寿命反映内在质量的假设，即雄性年龄与婚外父权之间的关联是由于雌性为后代寻找高质量的父本基因。重要的是，婚外父权占雄性繁殖成功的比例高达一半，强调了这种繁殖策略对雄性适应性的益处。最后，婚外繁殖在达到峰值后下降的情况为雄性和雌性不忠的衰老提供了明确证据。
