Levitan D R
Department of Biological Science, Florida State University, Tallahassee 32306-1100, USA.
Proc Biol Sci. 2000 Mar 22;267(1443):531-4. doi: 10.1098/rspb.2000.1032.
The theoretical prediction that fast sperm should be more effective at fertilizing eggs has never been documented empirically. Interspecific comparisons suggest an inverse relationship between sperm velocity and sperm longevity but this trade-off has never been demonstrated within a species. Here I investigate how sperm velocity and sperm longevity influence the patterns of fertilization in the sea urchin Lytechinus variegatus. In the laboratory I examined 11 male female pairs of sea urchins for variation in sperm velocity and sperm longevity, and determined the correlations of these traits with the percentage of eggs fertilized with serially diluted sperm. Males with faster sperm had higher rates of fertilization than males with slower sperm. Within individual males, as sperm aged they slowed down and showed a reduced percentage activity and lower rates of fertilization. Across males, the average velocity of freshly spawned sperm was inversely related to sperm longevity. These results establish the possibility that sperm traits are adapted for varying conditions along a continuum from sperm limitation to sperm competition.
快速游动的精子在使卵子受精方面更具效力这一理论预测从未得到实证记录。种间比较表明精子速度与精子寿命之间呈负相关，但这种权衡关系从未在一个物种内部得到证实。在此，我研究了精子速度和精子寿命如何影响多棘刺海胆（Lytechinus variegatus）的受精模式。在实验室中，我检查了11对海胆的雌雄个体，以研究精子速度和精子寿命的差异，并确定这些性状与用系列稀释精子使卵子受精的百分比之间的相关性。精子速度较快的雄性比精子速度较慢的雄性具有更高的受精率。在单个雄性个体中，随着精子老化，它们的速度会减慢，活力百分比降低，受精率也会降低。在不同雄性个体之间，刚排出的精子的平均速度与精子寿命呈负相关。这些结果表明，精子性状有可能是为了适应从精子限制到精子竞争这一连续统一体中的不同条件而进化的。
