Promiscuity and elongated sperm storage organs work cooperatively as a cryptic female choice mechanism in an earwig
Promiscuity and elongated sperm storage organs work cooperatively as a cryptic female choice mechanism in an earwig
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DOI：
10.1016/j.anbehav.2012.11.010
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发表时间：
2013-02-01
期刊：
影响因子：
2.5
通讯作者：
Kamimura, Yoshitaka
中科院分区：
文献类型：
--
作者：
Kamimura, Yoshitaka
女性生殖器通常表现出复杂的形态，不能用精子的接收和储存功能来解释。然而，我们对女性生殖器夸张背后的力量的理解是有限的。雌性地蜈蚣（Euborellia plebeja）是滥交的，它们高度伸长的精子储存器官只允许被较短的雄性生殖器部分移除和取代储存的精子，导致每次与精子饱和的雌性交配只增加20%的父权。本研究考察了限制精子置换对女性的意义和最佳性。一项分阶段的交配实验和父权成功分析显示，大型雄性在争夺雌性洞穴的竞争中占主导地位，导致与同一雌性重复交配。尽管每次交配获得的父权收益很低，但这种重复交配导致具有更高资源持有潜力的较大雄性的父权显著增加。基于雄性体型与交配频率关系的数值模拟表明，限制精子位移（每次交配约20%）是滥交雌性有效地从较大雄性那里积累精子的最佳选择。由于这个物种中雄性的体型是可遗传的，估计雌性会从其儿子的交配成功率增加1.4%中受益。当假设每只雄性和雌性相遇只有一次交配时，这种遗传优势就消失了。由于在这个物种中没有检测到雌性交配的可测量成本，因此滥交和精子位移受限的结合最好用雌性选择假说来解释。(C) 2012动物行为研究协会。Elsevier Ltd.出版。版权所有。
Female genitalia often show complex morphologies that cannot be explained by sperm reception and storage functions. However, our understanding of the forces underlying genital exaggeration in females is limited. Female earwigs, Euborellia plebeja, are promiscuous and their highly elongated sperm storage organs allow only partial removal and displacement of stored sperm by shorter male genitalia, resulting in only a 20% gain in paternity per copulation with a sperm-saturated female. This study examined the significance and optimality of restricted sperm displacement for females. A staged mating experiment with a paternity success analysis revealed that large males dominated male-male competition for burrows housing females, resulting in repeated copulations with the same female. Despite the low paternity gain per copulation, such repeated copulations resulted in a significant increase in paternity for larger males with higher resource-holding potential. A numerical simulation based on the relationship between male body size and copulation frequency showed that restricted sperm displacement (about 20% per copulation) is optimal for promiscuous females to accumulate sperm effectively from larger males. Because male body size is heritable in this species, females were estimated to benefit from a 1.4% increase in their sons' mating success. This genetic benefit disappeared when only a single copulation per male-female encounter was assumed. Since no measurable costs of mating for females have been detected in this species, the combination of promiscuity and restricted sperm displacement is best explained by the cryptic female choice hypothesis. (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.