PDF(Pubmed)
Abstract：
Factors that increase reproductive variance among individuals act to reduce effective population size (Ne), which accelerates the loss of genetic diversity and decreases the efficacy of purifying selection. These factors include sexual cannibalism, offspring investment and mating system. Pre-copulatory sexual cannibalism, where the female consumes the male prior to mating, exacerbates this effect. We performed comparative transcriptomics in two spider species, the cannibalistic Trechaleoides biocellata and the non-cannibalistic T. keyserlingi, to generate genomic evidence to support these predictions. First, we estimated heterozygosity and found that genetic diversity is relatively lower in the cannibalistic species. Second, we calculated dN/dS ratios as a measure of purifying selection; a higher dN/dS ratio indicated relaxed purifying selection in the cannibalistic species. These results are consistent with the hypothesis that sexual cannibalism impacts operational sex ratio and demographic processes, which interact with evolutionary forces to shape the genetic structure of populations. However, other factors such as the mating system and life-history traits contribute to shaping Ne. Comparative analyses across multiple contrasting species pairs would be required to disentangle these effects. Our study highlights that extreme behaviours such as pre-copulatory cannibalism may have profound eco-evolutionary effects.
摘要：
增加个体间生殖差异的因素会降低有效种群规模(Ne)，这加速了遗传多样性的丧失并降低了纯化选择的功效。这些因素包括性食人,后代投资和交配系统。交配前的性相食,雌性在交配前吃掉雄性，加剧了这种影响。我们对两种蜘蛛进行了比较转录组学，食人族的生物白种人和非食人族的T.keyserlingi，产生支持这些预测的基因组证据。首先,我们估计了杂合度，发现食人物种的遗传多样性相对较低。第二,我们计算了dN/dS比率作为纯化选择的量度；较高的dN/dS比率表明食人族物种的纯化选择宽松。这些结果与以下假设一致：性食人行为会影响性别比和人口统计过程，它们与进化力量相互作用以塑造种群的遗传结构。然而,其他因素，如交配系统和生活史特征也有助于塑造Ne。需要对多个对比物种对进行比较分析才能解开这些影响。我们的研究强调了极端行为，例如交配前的同类相食可能会产生深远的生态进化影响。
