Sperm competition risk affects ejaculate strategy in terms of sperm number but not sperm size in squid
Sperm competition risk affects ejaculate strategy in terms of sperm number but not sperm size in squid
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DOI：
10.1111/jeb.13894
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发表时间：
2021-07-04
影响因子：
2.1
通讯作者：
Shaw, Paul W.
中科院分区：
文献类型：
--
作者：
Iwata, Yoko;Sato, Noriyosi;Shaw, Paul W.
在一夫多妻制物种中，雌性精子的储存方式影响精子数量和质量性状的进化，因为它为精子竞争、隐蔽的雌性选择和受精过程提供了舞台。在这项研究中，我们比较了两种鱿鱼，异色乌贼和雷诺乌贼的射精特性。这两个物种都表现出与另一种生殖策略相关的二态精子特征，即配偶和运动鞋雄性将精子转移到雌性体内的不同存储位置(分别在输卵管和嘴巴附近)。由于生殖行为和精子放置的不同，预计运动鞋中的精子竞争风险比这两个物种的同类更高，雷诺迪龙虾的总体风险也更高。我们的结果表明，通过精心设计的精子包，释放的精子的瞬时数量被调整到预期的精子竞争风险。配偶精子在大小上相似；然而，运动鞋精子的鞭毛明显长于雷诺罗非鱼，这很可能是由于与精子存储条件相关的战术内冲突。从不同的交配策略考虑，我们认为精子竞争水平决定数量性状，而精子质量性状更多地取决于精子的储存和受精方式。
In polygamous species, the mode of sperm storage in females influences evolution of sperm quantitative and qualitative traits because it provides the arena for sperm competition, cryptic female choice and fertilization processes. In this study, we compared ejaculate traits of two squid species, Heterololigo bleekeri and Loligo reynaudii. Both species show dimorphic sperm traits associated with alternative reproductive tactics where consort and sneaker males transfer sperm to different storage sites within a female (on the oviduct and near the mouth, respectively). Due to differences in reproductive behaviours and sperm placement, sperm competition risk is expected to be higher in sneakers than in consorts of both species and higher overall in L. reynaudii. Our results demonstrate that the instantaneous number of released sperm is adjusted to the expected sperm competition risk via an elaborate sperm package. Consort sperm are similar in size; however, sneaker sperm have a significantly longer flagellum in H. bleekeri than in L. reynaudii, most likely due to intra-tactic conflicts associated with sperm storage conditions. From consideration of the different mating tactics, we suggest that while levels of sperm competition determine quantitative traits, sperm quality traits are determined more by the mode of sperm storage and fertilization.