Dobler Ralph, Charette Marc, Kaplan Katrin, Turnell Biz R, Reinhardt Klaus
Animal Evolutionary Ecology Institute of Evolution and Ecology Eberhard Karls University of Tubingen Tübingen Germany.
Applied Zoology Institute of Zoology Technische Universität Dresden Dresden Germany.
Ecol Evol. 2022 Feb 16;12(2):e8567. doi: 10.1002/ece3.8567. eCollection 2022 Feb.
Sexually selected traits may also be subject to non-sexual selection. If optimal trait values depend on environmental conditions, then "narrow sense" (i.e., non-sexual) natural selection can lead to local adaptation, with fitness in a certain environment being highest among individuals selected under that environment. Such adaptation can, in turn, drive ecological speciation via sexual selection. To date, most research on the effect of narrow-sense natural selection on sexually selected traits has focused on precopulatory measures like mating success. However, postcopulatory traits, such as sperm function, can also be under non-sexual selection, and have the potential to contribute to population divergence between different environments. Here, we investigate the effects of narrow-sense natural selection on male postcopulatory success in . We chose two extreme environments, low oxygen (10%, hypoxic) or high CO (5%, hypercapnic) to detect small effects. We measured the sperm defensive (P1) and offensive (P2) capabilities of selected and control males in the corresponding selection environment and under control conditions. Overall, selection under hypoxia decreased both P1 and P2, while selection under hypercapnia had no effect. Surprisingly, P1 for both selected and control males was higher under both ambient hypoxia and ambient hypercapnia, compared to control conditions, while P2 was lower under hypoxia. We found limited evidence for local adaptation: the positive environmental effect of hypoxia on P1 was greater in hypoxia-selected males than in controls. We discuss the implications of our findings for the evolution of postcopulatory traits in response to non-sexual and sexual selection.
性选择的性状也可能受到非性选择的影响。如果最优性状值取决于环境条件，那么“狭义”（即非性）自然选择会导致局部适应，在特定环境下选择的个体中，处于该环境时的适应性最高。这种适应反过来又可以通过性选择推动生态物种形成。迄今为止，大多数关于狭义自然选择对性选择性状影响的研究都集中在交配前的措施，如交配成功率。然而，交配后的性状，如精子功能，也可能受到非性选择的影响，并且有可能导致不同环境之间的种群分化。在这里，我们研究狭义自然选择对雄性交配后成功率的影响。我们选择了两个极端环境，低氧（10%，缺氧）或高二氧化碳（5%，高碳酸血症）来检测微小影响。我们在相应的选择环境和对照条件下测量了选择组和对照组雄性的精子防御（P1）和进攻（P2）能力。总体而言，缺氧条件下的选择降低了P1和P2，而高碳酸血症条件下的选择没有影响。令人惊讶的是，与对照条件相比，在环境性缺氧和环境性高碳酸血症条件下，选择组和对照组雄性的P1都更高，而在缺氧条件下P2更低。我们发现局部适应的证据有限：缺氧对P1的正向环境效应在缺氧选择的雄性中比在对照组中更大。我们讨论了我们的发现对交配后性状响应非性选择和性选择进化的意义。
