Gomendio M, Roldan E R
Sub-Department of Animal Behaviour, University of Cambridge, Madingley, U.K.
Proc Biol Sci. 1991 Mar 22;243(1308):181-5. doi: 10.1098/rspb.1991.0029.
Among mammals sperm competition leads to selection for increased sperm numbers but it is not known whether it also leads to changes in sperm size. Two contrasting theoretical predictions have been made. The first hypothesis relies on the assumption that there is a trade-off between sperm numbers and sperm size and predicts that, in species confronting sperm competition, there will be a concomitant decrease in sperm size as sperm numbers increase. In contrast, the second hypothesis suggests that longer sperm may outcompete rival sperm; if longer sperm may swim faster, they will reach the ova sooner and will be selected when sperm competition prevails. We tested these hypotheses in both primates and rodents. We report that males from species in which females mate promiscuously have longer sperm than species in which females mate with one male. In addition, we also found that sperm length is positively correlated with maximum sperm velocity. Our findings thus support the view that longer sperm may be adaptive in the context of sperm competition.
在哺乳动物中，精子竞争会促使精子数量增加，但目前尚不清楚它是否也会导致精子大小的变化。人们提出了两种截然不同的理论预测。第一种假设基于精子数量与精子大小之间存在权衡这一前提，并预测在面临精子竞争的物种中，随着精子数量的增加，精子大小会相应减小。相比之下，第二种假设表明较长的精子可能会在与对手精子的竞争中胜出；如果较长的精子游动速度更快，它们将更快到达卵子，并且在精子竞争占主导时会被选择。我们在灵长类动物和啮齿动物中对这些假设进行了测试。我们报告称，雌性滥交的物种中的雄性精子比雌性与单一雄性交配的物种中的雄性精子更长。此外，我们还发现精子长度与最大精子速度呈正相关。因此，我们的研究结果支持了这样一种观点，即在精子竞争的背景下，较长的精子可能具有适应性。
