Data from: Differential sperm storage by female zebra finches Taeniopygia guttata

When females mate promiscuously, female sperm storage provides scope to bias the fertilization success towards particular males via the non-random acceptance and utilization of sperm. The difficulties observing post-copulatory processes within the female reproductive tract mean that the mechanisms underlying cryptic female choice remain poorly understood. Here, we use zebra finches Taeniopygia guttata, selected for divergent sperm lengths, combined with a novel technique for isolating and extracting sperm from avian sperm storage tubules (SSTs), to test the hypothesis that sperm from separate ejaculates are stored differentially by female birds. We show that sperm from different inseminations enter different SSTs in the female reproductive tract, resulting in almost complete segregation of the sperm of competing males. We propose that non-random acceptance of sperm into SSTs, reflected in this case by sperm phenotype, provides a mechanism by which long sperm enjoy enhanced fertilization success in zebra finches.

当雌性采取多配性交配策略时，其体内的精子储存机制为雌性通过非随机接受与利用精子，使特定雄性的受精成功获得偏向性优势提供了可行空间。由于难以在雌性生殖道内观测交配后过程，学界对隐蔽雌性选择（cryptic female choice）背后的核心机制仍知之甚少。本研究以精子长度存在显著分化的斑胸草雀（Taeniopygia guttata）为实验对象，结合一种全新的鸟类精子储存小管（SSTs）内精子分离提取技术，验证“雌性鸟类会差异化储存不同射精来源的精子”这一假说。研究结果显示，不同授精事件产生的精子会进入雌性生殖道内不同的精子储存小管，从而使竞争雄性的精子几乎完全彼此分离。我们提出，精子向精子储存小管的非随机接受（本研究中体现为精子表型差异），为斑胸草雀中长精子获得更高受精成功率提供了潜在机制。