Cramer Emily, Krauss Nicole, Rowlison Tricia, Comizzoli Pierre
Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC 20008, USA.
Cornell Lab of Ornithology, Cornell University, Ithaca, NY 14850, USA.
Animals (Basel). 2020 Jul 10;10(7):1175. doi: 10.3390/ani10071175.
Extra-pair paternity may drive selection on spermatozoa and ejaculate characteristics through sperm competition and cryptic female choice. Here, we examine sperm morphology in the black-throated blue warbler (), an ecological model species where extra-pair paternity is frequent and is linked with male age. We test whether sperm morphology relates to several aspects of male phenotype known or suspected to affect extra-pair paternity success. Sperm morphology did not correlate with the size of the white wing spot, a social status signal, nor with the volume of the cloacal protuberance. However, older males tended to have longer sperm cells. Although the sample size was limited, this pattern is intriguing, as longer cells may be advantageous in post-copulatory sexual selection and older males have larger testes and higher extra-pair paternity success in this species. Changes in sperm morphology with age are not observed in other birds, though they have been observed in insects and fishes. More research on sperm morphology is needed to clarify its role in extra-pair fertilizations in this well-studied species.
婚外父权可能通过精子竞争和雌性隐秘选择推动对精子及射精特征的选择。在此，我们研究了黑喉蓝林莺的精子形态，这是一种生态模式物种，婚外父权现象频繁且与雄性年龄有关。我们测试了精子形态是否与已知或疑似影响婚外父权成功的雄性表型的几个方面相关。精子形态与白色翅斑大小（一种社会地位信号）以及泄殖腔突起的大小均无关联。然而，年龄较大的雄性往往拥有更长的精子细胞。尽管样本量有限，但这种模式很有趣，因为较长的精子细胞在交配后的性选择中可能具有优势，而且在该物种中，年龄较大的雄性具有更大的睾丸和更高的婚外父权成功率。在其他鸟类中未观察到精子形态随年龄的变化，不过在昆虫和鱼类中观察到了这种变化。需要对精子形态进行更多研究，以阐明其在这个经过充分研究的物种的婚外受精中的作用。
