Male dimorphism, sperm traits and immunology in the corkwing wrasse (Symphodus melops L.)
Male dimorphism, sperm traits and immunology in the corkwing wrasse (Symphodus melops L.)
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塞翅濑鱼 (Symphodus melops L.) 的雄性二态性、精子特征和免疫学
DOI：
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发表时间：
2001
影响因子：
2.3
通讯作者：
I. Folstad
中科院分区：
文献类型：
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作者：
I. Uglem;T. Galloway;G. Rosenqvist;I. Folstad
摘要：另类雄性交配表型的进化不可避免地涉及精子竞争风险或强度的变化。据预测，通常在不受欢迎的角色(即运动鞋/寄生虫雄性)中交配的男性会经历比在受欢迎角色(更倾向于雌性/表现出配偶垄断)中交配的男性经历更高程度的精子竞争。在这里，我们研究了两种不同的雄性表型在精子数量、精子活力和受精能力方面是否在适应精子竞争方面存在差异。我们发现，表现出女性模仿(不受欢迎的角色)的男性的性腺绝对和相对都比具有典型第二性特征(受欢迎的角色)的男性大。此外，与领地雄性精子相比，来自雌性模仿者的精子在激活5分钟后具有更高比例的活动精子。然而，在精子密度或体外受精能力方面，这两种雄性变异体之间没有差异。我们还检查了男性表型在某些免疫参数上是否存在差异，以及这种差异是否与精子特征有关。目前的理论预测射精质量应该与免疫活性水平呈负相关。雄鼠的脾相对比雌鼠重，但这是否反映了不同的免疫活性还不确定，因为脾也是储存红细胞的重要器官。此外，循环中淋巴细胞和粒细胞的密度没有差异，免疫参数与精子性状没有相关性。因此，免疫活性的差异不太可能为软骨鱼精子特征的差异提供主要的近似解释。
Abstract.The evolution of alternative male mating phenotypes inevitably involves variation in risk or intensity of sperm competition. Males that typically mate in disfavoured roles (i.e. sneakers/parasitic males) are predicted to experience higher magnitudes of sperm competition than males mating in favoured roles (preferred by females/exhibiting mate monopolisation). Here, we investigated whether two distinct male phenotypes in corkwing wrasse (Symphodus melops) differ with respect to adaptations for sperm competition in terms of sperm quantity, sperm motility and fertilising capacity. We found that males exhibiting female mimicry (disfavoured role) had both absolutely and relatively larger gonads than males with typical secondary sexual characters (favoured role). Moreover, a higher proportion of sperm from female mimics was motile 5 min after activation compared to sperm of territorial males. There were, however, no differences in sperm concentration or in in vitro fertilisation ability between the two male morphs. We also examined whether the male phenotypes differed in some immune parameters and if any such variation is associated with sperm traits. Current theories predict that ejaculate quality should be negatively correlated with the level of immunocompetence. Territorial males had relatively heavier spleens than female mimics, but whether this reflects differing immunocompetence is uncertain, since the spleen is also an important organ for erythrocyte storage. Furthermore, there were no differences in the densities of circulating lymphocytes or granulocytes, and the immune parameters did not covary with the sperm traits. Differences in immunocompetence are therefore unlikely to provide a major proximate explanation for variations in sperm traits in corkwing wrasse.