Data from: Lineages evolved under stronger sexual selection show superior ability to invade conspecific competitor populations

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 Tribolium castaneum, 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.尽管后代产出存在限制，几乎所有多细胞物种（multicellular species）均通过有性生殖繁衍。有性生殖催生了性选择（sexual selection）——一种通过繁殖过程中的竞争与选择广泛发挥作用的演化力量，但目前学界仍未明确，性选择究竟对谱系总适合度有益，还是会成为演化制约因素。性选择可能是正向演化力量：通过对个体优良状态的选择以及突变负荷的清除，最终使谱系获得更优适合度；另一方面，性选择也可能通过性冲突的作用，或是性选择性状与自然选择性状间的投资冲突，抵消潜在的净适合度收益。本研究借助多代入侵实验，探究性选择对谱系整体净适合度的影响。研究以赤拟谷盗（Tribolium castaneum）为实验对象，在强、弱两种性选择强度处理下开展77代实验演化后，通过8代实验测定了两类处理组种群入侵同种种群竞争者的整体能力。结果显示，源自强性选择背景的种群具备更优的净适合度，其入侵速度更快、入侵程度也显著高于弱性选择背景的对照种群。尽管在入侵实验初始阶段，强性选择种群仅占每个混合种群的10%，但最终其定殖群体实现了近乎完全的基因渐渗（introgression），几乎彻底清除了原始竞争者基因型。结合本实验设计与参数开展的种群遗传模拟（population genetic simulations）表明，若强性选择同时提升了两性的幼体与成体适合度，则可解释本次实验观察到的入侵优势。综上，本研究结合实验与建模方法发现，当面临跨多代入侵竞争者种群的广谱挑战时，性选择对种群净适合度具有正向且广泛的影响。