EXPERIMENTAL MANIPULATION OF SEXUAL SELECTION PROMOTES GREATER MALE MATING CAPACITY BUT DOES NOT ALTER SPERM INVESTMENT
EXPERIMENTAL MANIPULATION OF SEXUAL SELECTION PROMOTES GREATER MALE MATING CAPACITY BUT DOES NOT ALTER SPERM INVESTMENT
复制标题
DOI：
10.1111/j.1558-5646.2008.00601.x
复制
发表时间：
2009-04-01
期刊：
影响因子：
3.3
通讯作者：
Snook, Rhonda R.
中科院分区：
文献类型：
--
作者：
Crudgington, Helen S.;Fellows, Sarah;Snook, Rhonda R.
性选择理论对男性生精投资做出了明确的预测。为了验证这些预测，我们对伪眼果蝇（Drosophila pseudobscura）进行了实验性的性选择，这是一种精子异型物种，雄性既能产生可育精子，也能产生不育精子，后者可能在交配后竞争中发挥作用。具体来说，我们确定了两种精子类型的数量和大小，以及相对睾丸质量和附属腺体大小是否会随着精子竞争风险的增加而增加，以及这些变化是否会带来任何健康益处。我们没有发现性选择的历史对精子形态的数量或大小，或相对睾丸质量的影响。然而，经历了更大的性选择机会的雄性进化出了最大的附属腺，具有最大的交配能力，并且产生了最多的后代。这些发现表明，不育精子并不是性选择的直接目标，而辅助腺的大小，而不是睾丸的质量，似乎是男性生殖成功的重要决定因素。我们简要回顾了实验性性选择研究的数据，发现睾丸质量可能不是交配后性选择的常见目标，即使是这样，所产生的变化也并不总是提高适应性。
Sexual selection theory makes clear predictions regarding male spermatogenic investment. To test these predictions we used experimental sexual selection in Drosophila pseudoobscura, a sperm heteromorphic species in which males produce both fertile and sterile sperm, the latter of which may function in postmating competition. Specifically, we determined whether the number and size of both sperm types, as well as relative testis mass and accessory gland size, increased with increased sperm competition risk and whether any fitness benefits could accrue from such changes. We found no effect of sexual selection history on either the number or size of either sperm morph, or on relative testis mass. However, males experiencing a greater opportunity for sexual selection evolved the largest accessory glands, had the greatest mating capacity, and sired the most progeny. These findings suggest that sterile sperm are not direct targets of sexual selection and that accessory gland size, rather than testis mass, appears to be an important determinant of male reproductive success. We briefly review the data from experimental sexual selection studies and find that testis mass may not be a frequent target of postcopulatory sexual selection and, even when it is, the resulting changes do not always improve fitness.