Condition-dependent expression of pre- and postcopulatory sexual traits in guppies
Condition-dependent expression of pre- and postcopulatory sexual traits in guppies
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孔雀鱼交配前和交配后性特征的条件依赖性表达
作者：
Md Moshiur Rahman;J. Kelley;J. Evans
雌性选择可以对雄性的性选择特征施加持续的定向选择，然而这些特征往往表现出高水平的表型变异。对这一悖论的一种解释是，如果性选择的特征是昂贵的，只有最适合的雄性才能获得和分配表达这些特征所需的资源。此外，由于男性状况依赖于资源分配，性特征的条件依赖性可能是生殖和其他生活史功能之间权衡的基础。在这项研究中，我们通过实验控制孔雀鱼（Poecilia reticulata）的饮食质量（类胡萝卜素水平）和数量来验证这些观点，孔雀鱼是一种生活的淡水鱼，是理解交配前和交配后性选择性状之间关系的重要模型。具体来说，我们测试了交配前和交配后性特征（行为、纹饰、精子特征）表达的条件依赖性，并确定饮食操纵是否介导了这些特征之间的关系。与先前的工作一致，我们发现饮食量对交配前和交配后雄性性状的表达都有显著影响；饮食限制的雄鱼的性行为较少，精子的颜色纹饰、精子质量、精子数量和精子长度都比随意喂食的雄鱼明显减少。然而，与我们的预期相反，我们没有发现类胡萝卜素对这些性状的表达有显著影响，也没有证据表明交配前和交配后的性选择在资源分配上存在权衡。我们的研究结果进一步强调了行为、观赏和射精性状对饮食应激的敏感性，并强调了条件依赖在维持男性性性状的高度可变性方面的重要作用。
Female choice can impose persistent directional selection on male sexually selected traits, yet such traits often exhibit high levels of phenotypic variation. One explanation for this paradox is that if sexually selected traits are costly, only the fittest males are able to acquire and allocate the resources required for their expression. Furthermore, because male condition is dependent on resource allocation, condition dependence in sexual traits is expected to underlie trade-offs between reproduction and other life-history functions. In this study we test these ideas by experimentally manipulating diet quality (carotenoid levels) and quantity in the guppy (Poecilia reticulata), a livebearing freshwater fish that is an important model for understanding relationships between pre- and post-copulatory sexually selected traits. Specifically, we test for condition dependence in the expression of pre- and postcopulatory sexual traits (behavior, ornamentation, sperm traits) and determine whether diet manipulation mediates relationships among these traits. Consistent with prior work we found a significant effect of diet quantity on the expression of both pre- and postcopulatory male traits; diet-restricted males performed fewer sexual behaviors and exhibited significant reductions in color ornamentation, sperm quality, sperm number, and sperm length than those fed ad libitum. However, contrary to our expectations, we found no significant effect of carotenoid manipulation on the expression of any of these traits, and no evidence for a trade-off in resource allocation between pre- and postcopulatory episodes of sexual selection. Our results further underscore the sensitivity of behavioral, ornamental, and ejaculate traits to dietary stress, and highlight the important role of condition dependence in maintaining the high variability in male sexual traits.
影响因子：
7.1
作者：
PRINCE, MR;FRISOLI, JK
通讯作者：
FRISOLI, JK