Sperm competition roles and ejaculate investment in a promiscuous mammal
Sperm competition roles and ejaculate investment in a promiscuous mammal
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DOI：
10.1111/j.1420-9101.2012.02511.x
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发表时间：
2012-06-01
影响因子：
2.1
通讯作者：
Stockley, P.
中科院分区：
文献类型：
--
作者：
Lemaitre, J. -F.;Ramm, S. A.;Stockley, P.
精子竞争的理论模型预测男性应该如何分配精子和精液成分射精根据他们的交配角色（占主导地位与从属地位）。在这里，我们根据银鼠（Myodes glareolus）中的雄性角色对射精支出进行了详细分析。精子竞争在这个物种中经常发生，占优势的雄性通常比下属获得更高的受精成功率。与理论预测相反，我们发现，占主导地位的雄性银行田鼠投资更多的精子比下属，无论是绝对的和相对的身体和睾丸质量。主导男性的睾丸也绝对（虽然不是相对）大于下属。然而，我们没有发现任何证据表明，下属男性补偿较低的精子数量，每次射精增加射精频率或精子速度。同样，我们发现没有证据表明，根据男性在精子竞争中的作用，在交配栓大小的差异投资，虽然占主导地位的男性有显着较大的精囊（绝对和相对于体重）相比，下属。我们的结论是，精子竞争的作用，可以有显着的，但意想不到的影响射精投资在哺乳动物与明确定义的差异，男性的社会地位。
Theoretical models of sperm competition predict how males should allocate sperm and seminal fluid components to ejaculates according to their mating role (dominant vs. subordinate). Here, we present a detailed analysis of ejaculate expenditure according to male roles in the bank vole (Myodes glareolus). Sperm competition occurs regularly in this species, and dominant males typically achieve higher fertilization success than subordinates. Contrary to theoretical predictions, we found that dominant male bank voles invest more sperm per ejaculate than subordinates, both absolutely and relative to body and testes mass. The testes of dominant males were also absolutely (although not relatively) larger than those of subordinates. However, we found no evidence that subordinate males compensate for lower sperm numbers per ejaculate by increasing ejaculation frequency or sperm velocity. Similarly, we found no evidence for differential investment in copulatory plug size according to male roles in sperm competition, although dominant males had significantly larger seminal vesicles (both absolutely and relative to body mass) compared with subordinates. We conclude that sperm competition roles can have significant but unexpected influences on ejaculate investment in mammals with clearly defined differences in male social status.