Reproductive mode is predicted to influence the form of sexual selection. The viviparity-driven conflict hypothesis posits that a shift from lecithotrophic (yolk-nourished) to matrotrophic (mother-nourished or placental) viviparity drives a shift from precopulatory towards post-copulatory sexual selection. In lecithotrophic species, we predict that precopulatory sexual selection will manifest as males exhibiting a broad distribution of sizes, and small and large males exhibiting contrasting phenotypes (morphology and coloration); conversely, in matrotrophic species, an emphasis on post-copulatory sexual selection will preclude these patterns. We test these predictions by gathering data on male size, morphology and coloration for five sympatric Costa Rican poeciliid species that differ in reproductive mode (i.e. lecithotrophy vs. matrotrophy). We find tentative support for these predictions of the viviparity-driven conflict hypothesis, with some interesting caveats and subtleties. In particular, we find that the three lecithotrophic species tend to show a broader distribution of male sizes than matrotrophic species. Furthermore, large males of such species tend to exhibit proportionately large dorsal and caudal fins and short gonopodia relative to small males, while these patterns are expressed to a lesser extent in the two matrotrophic species. Finally, large males in some of the lecithotrophic species exhibit darker fins relative to small males, a pattern not evident in either matrotrophic species. One unexpected finding was that even in the matrotrophic species Poeciliopsis retropinna and Poeciliopsis paucimaculata, which lack courtship and dichromatic coloration, some morphological traits exhibit significant allometric relationships, suggesting that even in these species precopulatory sexual selection may be present and shaping size-specific male phenotypes in subtle ways.

中文翻译：

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雌性繁殖模式塑造了活鱼（Poeciliidae 科）雄性特征的异速生长。

预计生殖模式会影响性选择的形式。胎生驱动的冲突假说认为，从卵磷脂（卵黄营养）向母体营养（母体营养或胎盘）的转变推动了从交配前向交配后性选择的转变。在卵磷脂物种中，我们预测交配前的性选择将表现为雄性表现出广泛的体型分布，而小型和大型雄性则表现出不同的表型（形态和颜色）；相反，在营养型物种中，强调交配后的性选择将排除这些模式。我们通过收集有关生殖模式不同的五种同域哥斯达黎加 poeciliid 物种的雄性大小、形态和颜色的数据来测试这些预测（即卵磷脂与母体营养）。我们找到了对胎生驱动冲突假说的这些预测的初步支持，但有一些有趣的警告和微妙之处。特别是，我们发现三个卵形营养物种往往比营养物种表现出更广泛的雄性大小分布。此外，与小型雄性相比，此类物种的大型雄性往往表现出成比例的大背鳍和尾鳍以及较短的足足，而这些模式在两种嗜养性物种中的表现程度较低。最后，一些卵形营养物种中的大型雄性相对于小型雄性显示出更深的鳍，这种模式在任何一种营养型物种中都不明显。一个意外的发现是，即使是在缺乏求偶和双色着色的营养物种 Poeciliopsis retropinna 和 Poeciliopsis paucimaculata 中，