Department of Zoology, Stockholm University, Svante Arrhenius väg 18b, 106 91 Stockholm, Sweden.
Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Crawley, WA 6009, Australia.
Cells. 2021 Apr 29;10(5):1062. doi: 10.3390/cells10051062.
In polyandrous species, males face reproductive competition both before and after mating. Sexual selection thus shapes the evolution of both pre- and postcopulatory traits, creating competing demands on resource allocation to different reproductive episodes. Traits subject to strong selection exhibit accelerated rates of phenotypic divergence, and examining evolutionary rates may inform us about the relative importance and potential fitness consequences of investing in traits under either pre- or postcopulatory sexual selection. Here, we used a comparative approach to assess evolutionary rates of key competitive traits in two artiodactyl families, bovids (family Bovidae) and cervids (family Cervidae), where male-male competition can occur before and after mating. We quantified and compared evolutionary rates of male weaponry (horns and antlers), body size/mass, testes mass, and sperm morphometrics. We found that weapons evolve faster than sperm dimensions. In contrast, testes and body mass evolve at similar rates. These results suggest strong, but differential, selection on both pre- and postcopulatory traits in bovids and cervids. Furthermore, we documented distinct evolutionary rates among different sperm components, with sperm head and midpiece evolving faster than the flagellum. Finally, we demonstrate that, despite considerable differences in weapon development between bovids and cervids, the overall evolutionary patterns between these families were broadly consistent.
在多雄交配物种中，雄性在交配前后都面临着生殖竞争。因此，性选择塑造了交配前和交配后特征的进化，对不同生殖事件的资源分配产生了竞争需求。受到强烈选择的特征表现出更快的表型分化速度，而研究进化速度可以让我们了解在交配前或交配后性选择下投资特征的相对重要性和潜在适应度后果。在这里，我们使用比较方法评估了两种偶蹄目动物家族（牛科和鹿科）中关键竞争特征的进化速度，在这些家族中，雄性间的竞争可以发生在交配前后。我们量化并比较了雄性武器（角和鹿角）、体型/质量、睾丸质量和精子形态的进化速度。我们发现武器的进化速度快于精子尺寸。相比之下，睾丸和身体质量以相似的速度进化。这些结果表明，在牛科和鹿科中，对交配前和交配后特征都有强烈但不同的选择。此外，我们记录了不同精子成分之间不同的进化速度，精子头部和中段比鞭毛进化得更快。最后，我们证明，尽管牛科和鹿科在武器发育方面存在很大差异，但这些家族之间的总体进化模式大致一致。
