Effects of alternative male mating strategies on characteristics of sperm production in the Atlantic salmon (Salmo salar): Theoretical and empirical investigations
Effects of alternative male mating strategies on characteristics of sperm production in the Atlantic salmon (Salmo salar): Theoretical and empirical investigations
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DOI：
10.1098/rstb.1995.0173
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发表时间：
1995-12-29
影响因子：
6.3
通讯作者：
Parker, GA
中科院分区：
文献类型：
--
作者：
Gage, MJG;Stockley, P;Parker, GA
大西洋鲑鱼（萨尔莫salar）男性成熟的小早熟parr前向海迁移，或作为老年人和较大的溯河产卵男性。溯河产卵的雄性主宰着产卵的红鱼，并积极地保护雌性免受幼鱼的入侵。当溯河产卵的雄性和雌性产卵时，帕尔通过潜入射精来获得受精。这种交配优势的差异产生了雄性策略之间精子竞争风险的不对称性。理论精子竞争模型预测，男性通常交配不利的角色（在这里，帕尔策略）应被选择，以抵消这一劣势，投资更多的精子发生，以实现受精成功。首先，我们提出了一个理论模型，分析鲑鱼幼鱼和溯河产卵男性生殖策略的配子支出。然后，我们使用自然的变化，在这个物种内的交配模式比较经验如何男性投资精子发生。一系列的生殖特征进行了测量，这两个男性的战略。当然，溯河产卵的雄性比幼鱼有更大的睾丸，产生更多的精子。然而，结果表明，parr投资相对更多的总精子发生，并有一个较大的性腺指数比溯河产卵男性。相对于体型，帕尔产生的精子数量和剥离的射精量更大。两种雄性策略之间的精子长度没有差异。然而，更多的精子是能动的parr射精，这些精子比溯河产卵的男性精子寿命长。我们的研究结果可以解释男性parr，在精子竞争的风险升高，占据不利的交配角色（parr体重只有0.15%的平均体重的溯河产卵男性）实现不成比例的高受精成功。
Atlantic salmon (Salmo salar) males mature as either tiny precocious parr before seaward migration, or as older and larger anadromous males. Anadromous males dominate the spawning redds and aggressively defend females against parr intrusions. Parr gain fertilizations by sneaking in to ejaculate while anadromous males and females spawn. Such differences in mating advantage generate asymmetries in risk of sperm competition between the male strategies. Theoretical sperm competition models predict that males typically mating in disfavoured roles (here, the parr strategy) should be selected to offset this disadvantage by investing more into spermatogenesis to achieve fertilization success. First, we present a theoretical model which analyses gametic expenditure for salmon parr and anadromous male reproductive strategies. We then use the natural variance in mating pattern within this species to compare empirically how males invest in spermatogenesis. A range of reproductive traits were measured for both male strategies. Absolutely, anadromous males have larger testes and produce greater numbers of sperm than parr males. However, results show that parr invest relatively more heavily into total spermatogenesis, and have a larger gonosomatic index than anadromous males. Relative to body size, parr produced greater numbers of sperm and volumes of stripped ejaculate. There was no difference in sperm length between the two male strategies. However, more sperm were motile in parr ejaculates, and these sperm lived longer than anadromous male sperm. Our findings may explain how male parr, under elevated risks of sperm competition and occupying a disfavoured mating role (parr weigh only 0.15% of the average body mass of anadromous males) achieve disproportionately high fertilization success.