Betters Melissa, Levitan Don R
Biol Bull. 2018 Oct;235(2):63-70. doi: 10.1086/699406. Epub 2018 Sep 27.
Although the benefits to males mating with multiple females have been well documented, the benefits to females mating with multiple males (polyandry) are less studied, particularly the mechanism that might drive these potential benefits. Benefits of polyandry might stem from increasing the chance of mating with a high-quality or compatible male or stem from the ability of multiple males to fertilize more eggs than any single male. We examine the fertilization consequences of polyandry in the sea urchin Lytechinus variegatus. This species has variation in spine color, and we conducted matings between individual and pooled sperm from two males that matched or mismatched in color. The results indicate that (1) males with white spines achieved higher fertilization and were more likely to cause polyspermy than males with purple spines, and there was no effect of female spine color on fertilization; (2) when comparing the average success of individual matings with pooled-sperm matings, there was a net benefit to polyandry when purple-spine males were pooled, a net cost when white-spine males were pooled, and no difference when mismatched spine color males were pooled; and (3) the success under pooled-sperm trials, with any of the spine color combinations, never exceeded the success of the more successful male in the individual-male trials. Together these results suggest that the consequences of polyandry depend on the relation between sperm availability and the sensitivity of eggs to sperm limitation and polyspermy with respect to the specific set of available males. The potential fertilization consequences of a female spawning with multiple males might be associated primarily with increasing the amount of sperm available to fertilize her eggs and secondarily with increasing the chances of mating with a higher-quality or more compatible male, as opposed to a diversity of males.
尽管雄性与多个雌性交配的益处已有充分记录，但雌性与多个雄性交配（多配偶制）的益处却较少被研究，尤其是可能驱动这些潜在益处的机制。多配偶制的益处可能源于增加与高质量或适配雄性交配的机会，或者源于多个雄性使更多卵子受精的能力，而这超过任何单个雄性。我们研究了多配偶制在海胆（Lytechinus variegatus）中的受精后果。该物种的棘刺颜色存在差异，我们让来自两只颜色匹配或不匹配的雄性个体的精子单独或混合后与雌性交配。结果表明：（1）白色棘刺的雄性比紫色棘刺的雄性实现了更高的受精率，且更有可能导致多精入卵，而雌性棘刺颜色对受精没有影响；（2）当比较单个交配与混合精子交配的平均成功率时，混合紫色棘刺雄性的精子时多配偶制有净益处，混合白色棘刺雄性的精子时有净成本，混合棘刺颜色不匹配的雄性精子时则没有差异；（3）在任何棘刺颜色组合的混合精子试验中，成功率从未超过单个雄性试验中更成功的雄性的成功率。这些结果共同表明，多配偶制的后果取决于精子可用性与卵子对精子限制和多精入卵的敏感性之间的关系，具体针对一组特定的可用雄性。雌性与多个雄性产卵的潜在受精后果可能主要与增加可用于使卵子受精的精子数量有关，其次与增加与更高质量或更适配雄性交配的机会有关，而不是与雄性的多样性有关。
