Godwin Joanne L, Spurgin Lewis G, Michalczyk Łukasz, Martin Oliver Y, Lumley Alyson J, Chapman Tracey, Gage Matthew J G
School of Biological Sciences University of East Anglia Norwich NR4 7TJ UK.
Department of Entomology Institute of Zoology Jagiellonian University 30-387 Kraków Poland.
Evol Lett. 2018 Aug 16;2(5):511-523. doi: 10.1002/evl3.80. eCollection 2018 Oct.
Despite limitations on offspring production, almost all multicellular species use sex to reproduce. Sex gives rise to sexual selection, a widespread force operating through competition and choice within reproduction, however, it remains unclear whether sexual selection is beneficial for total lineage fitness, or if it acts as a constraint. Sexual selection could be a positive force because of selection on improved individual condition and purging of mutation load, summing into lineages with superior fitness. On the other hand, sexual selection could negate potential net fitness through the actions of sexual conflict, or because of tensions between investment in sexually selected and naturally selected traits. Here, we explore these ideas using a multigenerational invasion challenge to measure consequences of sexual selection for the overall net fitness of a lineage. After applying experimental evolution under strong versus weak regimes of sexual selection for 77 generations with the flour beetle , we measured the overall ability of introductions from either regime to invade into conspecific competitor populations across eight generations. Results showed that populations from stronger sexual selection backgrounds had superior net fitness, invading more rapidly and completely than counterparts from weak sexual selection backgrounds. Despite comprising only 10% of each population at the start of the invasion experiment, colonizations from strong sexual selection histories eventually achieved near-total introgression, almost completely eliminating the original competitor genotype. Population genetic simulations using the design and parameters of our experiment indicate that this invasion superiority could be explained if strong sexual selection had improved both juvenile and adult fitness, in both sexes. Using a combination of empirical and modeling approaches, our findings therefore reveal positive and wide-reaching impacts of sexual selection for net population fitness when facing the broad challenge of invading competitor populations across multiple generations.
尽管在后代繁殖方面存在限制，但几乎所有多细胞物种都通过有性生殖来繁衍后代。有性生殖引发了性选择，这是一种广泛存在的力量，通过繁殖过程中的竞争和选择发挥作用。然而，性选择对整个谱系适应性是有益的，还是起到了限制作用，目前仍不清楚。性选择可能是一种积极的力量，因为它能选择改善个体状况并清除突变负荷，从而使谱系的适应性更强。另一方面，性选择可能会通过性冲突的作用，或者由于在性选择特征和自然选择特征上的投资之间的矛盾，抵消潜在的净适应性。在这里，我们通过多代入侵挑战来探讨这些观点，以衡量性选择对一个谱系整体净适应性的影响。在用面粉甲虫在强性选择和弱性选择条件下进行了77代的实验进化后，我们测量了来自这两种条件下的引入群体在八代时间里侵入同种竞争群体的总体能力。结果表明，来自较强性选择背景的群体具有更高的净适应性，比来自弱性选择背景的群体入侵得更快、更彻底。尽管在入侵实验开始时，每个群体中来自强性选择背景的个体仅占10%，但具有强性选择历史的群体最终几乎完全渗入，几乎完全消除了原来的竞争基因型。使用我们实验的设计和参数进行的群体遗传模拟表明，如果强性选择提高了两性的幼年和成年适应性，那么这种入侵优势就可以得到解释。因此，通过结合实证和建模方法，我们的研究结果揭示了在面临跨多代侵入竞争群体这一广泛挑战时，性选择对群体净适应性具有积极且广泛的影响。
