Testing potential mechanisms of conspecific sperm precedence in Drosophila pseudoobscura

Drosophila pseudoobscura females that co-occur with sister species D. persimilis show elevated fertilization by conspecific sperm when they mate with both a heterospecific and a conspecific male. This phenomenon, known as conspecific sperm precedence (CSP), has evolved as a mechanism to avoid maladaptive hybridization with D. persimilis. In this study, we assessed pericopulatory (during mating) and postcopulatory (after mating) traits in crosses with sympatric or allopatric D. pseudoobscura females and conspecific or heterospecific males to evaluate potential mechanisms of CSP in this system. We observed shorter copulation duration in crosses with sympatric females, but found no difference in quantity of sperm transferred or female reproductive tract toxicity between sympatry and allopatry. Our data show some support for the hypothesis that parasperm, a short, sterile sperm morph, can protect fertile eusperm from the D. pseudoobscura female reproductive tract, though it is unclear how t...

与姊妹种拟相似果蝇（D. persimilis）同域分布的拟暗果蝇（Drosophila pseudoobscura）雌性个体，若同时与异种雄性和同种雄性交配，其同种精子的受精成功率将显著升高。这一现象被称为同种精子优先（CSP），是为避免与拟相似果蝇发生适应性劣化的杂交而演化出的生殖隔离机制。本研究通过设置同域或异域拟暗果蝇雌性与同种、异种雄性的交配组合，对交配期间（pericopulatory）及交配后（postcopulatory）的相关性状开展评估，以解析该系统中同种精子优先现象的潜在作用机制。实验结果显示，同域雌性参与的交配组合其交配时长更短，但在精子转移量与雌性生殖道毒性方面，同域与异域组间未检测到显著差异。本研究数据为"副精子（parasperm）——一种短小的不育精子形态——可保护可育真精子（eusperm）免受拟暗果蝇雌性生殖道的损害"这一假说提供了部分支持，但目前其具体作用机制仍尚不明确。