Data from: No association between sperm competition and sperm length variation across dung flies (Scathophagidae)

Sperm length is extremely variable across species, but a general explanation for this variation is lacking. However, when the risk of sperm competition is high, sperm length is predicted to be less variable within species, and there is some evidence for this in birds and social insects. Here, we examined intraspecific variation in sperm length, both within and between males, and its potential associations with sperm competition risk and variation in female reproductive tract morphology across dung flies. We used two measures of variation in sperm size, and testis size was employed as our index of sperm competition risk. We found no evidence of associations between sperm length variation and sperm competition or female reproductive tract variation. These results suggest that variation in sperm competition risk may not always be associated with variation in sperm morphology, and the cause(s) of sperm length variation in dung flies remains unclear.不同物种间的精子长度差异极大，但目前尚无针对该变异的普适性解释。不过，当精子竞争风险较高时，物种内部的精子长度变异程度预计会降低，且该结论已在鸟类与社会性昆虫中得到部分实证支持。本研究以粪蝇为研究对象，探究了精子长度在雄性个体内部以及雄性个体间的种内变异，及其与精子竞争风险、雌性生殖道形态变异的潜在关联。本研究采用两种指标量化精子大小的变异程度，并以睾丸大小作为精子竞争风险的衡量指标。研究结果显示，精子长度变异与精子竞争风险或雌性生殖道形态变异之间未发现显著关联。上述结果表明，精子竞争风险的变异并非总能与精子形态变异存在关联，粪蝇精子长度变异的具体成因仍未明晰。