Data from: A species-specific multigene family mediates differential sperm displacement in Drosophila melanogaster

Sperm competition is a post-copulatory sexual selection mechanism in species in which females mate with multiple males. Despite its evolutionary relevance in shaping male traits, the genetic mechanisms underlying sperm competition are poorly understood. A recently originated multigene family specific to D. melanogaster, Sdic, is important for the outcome of sperm competition in doubly-mated females, although the mechanistic nature of this phenotype remained unresolved. Here we compared doubly-mated females, second mated to either Sdic knockout or non-knockout males, and directly visualize sperm dynamics in the female reproductive tract. We found that a less effective removal of first-to-mate male’s sperm within the female’s sperm storage organs is consistent with a reduced sperm competitive ability of the Sdic knockout males. Our results highlight the role young genes can play in driving the evolution of sperm competition.

精子竞争（Sperm competition）是雌性与多只雄性交配的物种中存在的一种交配后性选择机制。尽管其在塑造雄性性状方面具有关键的进化意义，但目前学界对精子竞争背后的遗传机制仍知之甚少。一种新近起源的、黑腹果蝇（D. melanogaster）特异性多基因家族Sdic，对两次交配雌性的精子竞争结果具有重要调控作用，尽管该表型背后的分子机制仍未得到阐明。本研究对两次交配的雌性果蝇开展对照实验：其二度交配的雄性分别为Sdic基因敲除（knockout）型与非敲除型，并直接可视化观测雌性生殖道内的精子动态变化。我们发现，在雌性的精子储存器官中，对首次交配雄性精子的清除效率降低，这与Sdic基因敲除雄性的精子竞争能力下降现象相一致。本研究结果凸显了年轻基因在推动精子竞争演化进程中所发挥的重要作用。