Rapid divergence in genital structures among nascent species has been posited to be an early-evolving cause of reproductive isolation, although evidence supporting this idea as a widespread phenomenon remains mixed. Using a collection of interspecific introgression lines between two Drosophila species that diverged ∼240,000 years ago, we tested the hypothesis that even modest divergence in genital morphology can result in substantial fitness losses. We studied the reproductive consequences of variation in the male epandrial posterior lobes between Drosophila mauritiana and D. sechellia and found that divergence in posterior lobe morphology has significant fitness costs on several pre-fertilization and post-copulatory reproductive measures. Males with divergent posterior lobe morphology also significantly reduced the life span of their mates. Interestingly, one of the consequences of genital divergence was decreased oviposition and fertilization, which suggests that a sensory bias for posterior lobe morphology could exist in females, and thus posterior lobe morphology may be the target of cryptic female choice in these species. Our results provide evidence that divergence in genitalia can in fact give rise to substantial reproductive isolation early during species divergence, and they also reveal novel reproductive functions of the external male genitalia in Drosophila. This article is protected by copyright. All rights reserved.

中文翻译：

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种间基因渗入揭示了雄性生殖器形态在果蝇生殖隔离进化过程中的作用

新生物种之间生殖器结构的快速分化被认为是生殖隔离的早期演变原因，尽管支持这一观点的证据仍然是一种普遍现象。使用大约 240,000 年前分化的两个果蝇物种之间的种间渗入系的集合，我们测试了即使生殖器形态的适度差异也会导致显着的健康损失的假设。我们研究了 Drosophila mauritiana 和 D. sechellia 之间雄性外皮后叶变异的生殖后果，发现后叶形态的差异对几种受精前和交配后的生殖措施具有显着的适应性成本。具有不同后叶形态的雄性也会显着缩短其配偶的寿命。有趣的是，生殖器分化的后果之一是产卵和受精减少，这表明雌性可能存在后叶形态的感觉偏差，因此后叶形态可能是这些物种中雌性选择的目标。我们的结果提供证据表明，在物种分化的早期，生殖器的分化实际上会导致大量的生殖隔离，并且它们还揭示了果蝇外部雄性生殖器的新生殖功能。本文受版权保护。版权所有。因此，后叶形态可能是这些物种中神秘雌性选择的目标。我们的结果提供证据表明，在物种分化的早期，生殖器的分化实际上会导致大量的生殖隔离，并且它们还揭示了果蝇外部雄性生殖器的新生殖功能。本文受版权保护。版权所有。因此，后叶形态可能是这些物种中神秘雌性选择的目标。我们的结果提供证据表明，在物种分化的早期，生殖器的分化实际上会导致大量的生殖隔离，并且它们还揭示了果蝇外部雄性生殖器的新生殖功能。本文受版权保护。版权所有。