Male phenotype predicts insemination success in guppies
Male phenotype predicts insemination success in guppies
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雄性表型预测孔雀鱼授精成功
DOI：
10.1098/rspb.2002.2017
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
A. Bisazza
中科院分区：
文献类型：
--
作者：
A. Pilastro;J. Evans;S. Sartorelli;A. Bisazza
理论预测，如果女性用来评估男性质量的第二性征与交配过程中转移的精子数量不同，那么配偶选择可能会导致女性生殖力的增加。在雌性交配繁殖的地方，雄性吸引力和射精大小之间的这种关系可能会额外(或替代地)通过偏向于优先选择的雄性来增强间接选择的效果。在任何一种情况下，男性的吸引力与交配时射精的大小之间都是正相关的。到目前为止，这一预测的一些最令人信服的(间接)证据来自孔雀鱼，这是一种表现出无资源交配系统的鱼类，在这种系统中，漂亮的雄性往往拥有更大的精子储备。我们发现，在主动交配的过程中，具有首选表型的雄性孔雀鱼实际上比装饰较少的雄性孔雀鱼转移了更多的精子给雌性孔雀鱼，而不管它们最初储存的精子的大小。我们的结果还表明，在强制交配过程中，射精大小和雄性表型之间的关系被打破。后一个结果，再加上我们发现交配速度--雌性控制的一个因素--是射精大小的重要预测因素，我们推测，雌性可能至少部分控制了在合作交配过程中受精的精子数量。
Theory predicts that mate choice can lead to an increase in female fecundity if the secondary sexual traits used by females to assess male quality covary with the number of sperm transferred during copulation. Where females mate multiply, such a relationship between male attractiveness and ejaculate size may, additionally (or alternatively), serve to augment the effect of indirect selection by biasing paternity in favour of preferred males. In either case, a positive correlation between male attractiveness and the size of ejaculates delivered at copulation is predicted. To date, some of the most convincing (indirect) evidence for this prediction comes from the guppy, a species of fish exhibiting a resource–free mating system in which attractive males tend to have larger sperm reserves. We show that, during solicited copulations, male guppies with preferred phenotypes actually transfer more sperm to females than their less–ornamented counterparts, irrespective of the size of their initial sperm stores. Our results also reveal that, during coercive copulations, the relationship between ejaculate size and the male's phenotype breaks down. This latter result, in conjunction with our finding that mating speed—a factor under the female's control—is a significant predictor of ejaculate size, leads us to speculate that females may exert at least partial control over the number of sperm inseminated during cooperative matings.