Post-spawning sexual selection in red and white Chinook salmon (Oncorhynchus tshawytscha)

Post-copulatory processes, including sperm competition and cryptic female choice (CFC), can play important roles in the maintenance of polymorphisms. In Chinook salmon (Oncorhynchus tshawytscha), color morphs (red and white) exist due to genetic polymorphisms affecting carotenoid deposition in flesh, skin, and gametes. We investigated the role of post-spawning sexual selection in maintaining the polymorphism in a mixed population. First, we compared sperm velocity differences in water between morphs. Next, we measured color-based CFC via 2 methods: 1) sperm velocity in ovarian fluid and 2) in vitro competitive fertilization using paired red and white males. We found that red males had marginally faster sperm relative to white males in water, suggesting that carotenoid storage may affect sperm performance. However, ovarian fluid of red and white females influenced sperm velocity of red and white males differently, indicative of color-based CFC on sperm velocity. Furthermore, we found evi...

交配后过程，涵盖精子竞争与隐蔽雌性选择（cryptic female choice, CFC），在遗传多态性的维持中发挥着关键作用。在奇努克鲑（Oncorhynchus tshawytscha）中，由于调控肌肉、皮肤及配子中类胡萝卜素沉积的遗传多态性，存在红色与白色两种体色形态。本研究针对混合种群内产卵后性选择对多态性的维持效应展开了探究。首先，我们比较了不同体色形态个体的精子在水体中的运动速度差异。随后，我们通过两种方法量化了基于体色的隐蔽雌性选择：其一为检测卵巢液中的精子运动速度；其二为利用配对的红色与白色雄性个体开展体外竞争性受精实验。研究结果显示，在水体中红色雄性的精子运动速度略快于白色雄性，这表明类胡萝卜素储存或可影响精子功能。然而，红色与白色雌性的卵巢液对红色与白色雄性的精子运动速度的影响存在差异，这表明基于体色的隐蔽雌性选择可作用于精子运动速度。此外，我们发现了相关证据（原文此处未完整展示）。