Fitness consequences of artificial selection on relative male genital size.
Fitness consequences of artificial selection on relative male genital size.
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DOI：
10.1038/ncomms11597
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发表时间：
2016-05-18
影响因子：
16.6
通讯作者：
Jennions MD
中科院分区：
文献类型：
--
作者：
Booksmythe I;Head ML;Keogh JS;Jennions MD
雄性生殖器在大小、形状和复杂程度上往往在近缘种之间表现出显著的差异。雄鱼用来使雌鱼受精的细长鳍（gonopodium）占体长的18%到53%。因此，不同物种的相对生殖器大小差别很大。相比之下，物种内部通常存在紧密的异速尺度，这表明强烈的选择反对偏离物种自然异速线的生殖器-身体大小组合。我们通过人工选择异速截距来测试这一限制，在给定体型的食蚊鱼Gambusia holbrooki中，创造出性腺相对较长或较短的雄性品系。研究表明，相对生殖器长度是可遗传的，在上选系和下选系之间的差异为7.6-8.9%，体型也发生了相关变化。然而，偏离异速生长的自然线并不影响男性在吸引力、游泳表现和最重要的生殖成功（父权）测试中的成功。在物种内部，生殖器官大小和体型大小之间往往存在紧密的关系，这表明了强大的稳定选择。在这里，Booksmythe等人为地选择了食蚊鱼的相对生殖器尺寸，并发现新的生殖器尺寸-身体尺寸组合不会导致预期的适应性降低。
Male genitalia often show remarkable differences among related species in size, shape and complexity. Across poeciliid fishes, the elongated fin (gonopodium) that males use to inseminate females ranges from 18 to 53% of body length. Relative genital size therefore varies greatly among species. In contrast, there is often tight within-species allometric scaling, which suggests strong selection against genital–body size combinations that deviate from a species' natural line of allometry. We tested this constraint by artificially selecting on the allometric intercept, creating lines of males with relatively longer or shorter gonopodia than occur naturally for a given body size in mosquitofish, Gambusia holbrooki. We show that relative genital length is heritable and diverged 7.6–8.9% between our up-selected and down-selected lines, with correlated changes in body shape. However, deviation from the natural line of allometry does not affect male success in assays of attractiveness, swimming performance and, crucially, reproductive success (paternity). Within species, there tends to be a tight relationship between genital size and body size, suggesting strong stabilizing selection. Here, Booksmythe et al. artificially select relative genital size in mosquitofish and find that novel genital size-body size combinations do not lead to expected fitness reductions.