Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley, WA, Australia.
Evolution. 2023 Nov 2;77(11):2456-2471. doi: 10.1093/evolut/qpad157.
Our understanding of genital evolution comes largely from studies of male genitalia. Females have received far less attention because of the difficulties inherent in quantifying the shapes of their internal genital structures. Here we combine advances in micro-computed tomography with a new landmark free method of quantifying three-dimensional trait shape, to document patterns of divergence in female genital shape, and the correlated divergence of male genitalia among populations of the millipede Antichiropus variabilis. We used single-nucleotide polymorphisms to estimate levels of neutral genetic divergence among seven populations of millipede. Genetic divergence was high and correlated with geographic distance. Comparing phenotypic divergence in genital shape to neutral genetic divergence, we found that genital shape for both females and males has diverged more than would be expected from random drift, consistent with a pattern of directional selection. While there was significant covariation between female and male genital shape across populations, the magnitude of divergence in genital shape between the sexes was not correlated. Our results demonstrate the utility of using three-dimensional scanning technologies to examine female genital traits and add to a small but growing number of studies showing that like male genitalia, female genitalia can be under strong directional selection.
我们对生殖器进化的理解主要来自对雄性生殖器的研究。由于量化女性内部生殖器结构形状所固有的困难，女性受到的关注要少得多。在这里，我们将微计算机断层扫描技术与一种新的无标志三维特征量化方法相结合，记录雌性生殖器形状的发散模式，以及千足虫 Antichiropus variabilis 种群中雄性生殖器的相关发散模式。我们使用单核苷酸多态性来估计 7 个千足虫种群的中性遗传分歧水平。遗传分歧很大，与地理距离相关。将生殖器形状的表型分歧与中性遗传分歧进行比较，我们发现无论是雌性还是雄性，生殖器形状的分歧都超过了随机漂变的预期，与定向选择的模式一致。虽然在种群之间存在雌性和雄性生殖器形状之间的显著协变，但两性之间生殖器形状的分歧程度没有相关性。我们的研究结果表明，使用三维扫描技术来研究女性生殖器特征是有用的，并补充了一小部分但不断增长的研究，这些研究表明，与雄性生殖器一样，女性生殖器可能受到强烈的定向选择。
