Strategic sperm allocation and a Coolidge effect in an externally fertilizing species
Strategic sperm allocation and a Coolidge effect in an externally fertilizing species
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外部受精物种中的战略精子分配和柯立芝效应
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
Carl Smith
中科院分区：
文献类型：
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作者：
R. Spence;M. Reichard;Carl Smith
由于精子昂贵且有局限性，预计男性会根据精子竞争程度、女性生殖质量和女性新颖性在不同的配对中分配精子。我们研究了欧洲苦鱼(Rhodeus Amarus)的精子分配情况，Rhodeus amarus是一种在淡水贻贝的鳃中产卵和孵化的外部受精鱼类。我们预测，雄性会根据贻贝的质量和新鲜度不同地分配精子。占主导地位的雄性对竞争对手的反应是增加精子投入和攻击性，而下属则主要通过精子投入来回应。根据柯立芝效应的预测，占主导地位的雄性将更多的精子投入到新的贻贝中，这种贻贝代表了一个新的受精机会。然而，从属雄性不受贻贝新颖性的影响，但对交配顺序有反应。雄性没有根据贻贝的质量来分配精子，这表明在决定苦涩的精子分配策略时，父子关系的确定性是一个比后代存活更重要的变量。这项研究表明，在外部受精物种中，射精的战略性支出类似于内部肥料，但精子投资在受精部位而不是雌性的水平上运作。
Because sperm is costly and limiting, males are predicted to allocate sperm differentially across matings, according to the level of sperm competition, female reproductive quality, and female novelty. We investigated sperm allocation in the European bitterling (Rhodeus amarus), an externally fertilizing species of fish that spawns and incubates its eggs in the gills of freshwater mussels. We predicted that males would allocate sperm differentially according to the quality and novelty of mussels. Dominant males responded to rivals by increasing both sperm investment and aggression, whereas subordinates responded chiefly through sperm investment. Dominant males invested more sperm in novel mussels in accordance with predictions for a Coolidge effect, the mussel representing a new fertilization opportunity. However, subordinate males were not influenced by mussel novelty but were responsive to order of mating. Males did not allocate sperm according to mussel quality, suggesting that certainty of paternity is a more important variable than offspring survival in shaping bitterling sperm allocation strategies. This study demonstrates strategic ejaculate expenditure in an externally fertilizing species, analogous to that in internal fertilizers, but with sperm investment operating on the level of the site of fertilization rather than the female.