Jarne Philippe, Auld Josh R
Centre d'Ecologie Fonctionnelle et Evolutive, Centre National de la Recherche Scientifique, 1919 route de Mende, 34293, Montpellier 5, France.
Evolution. 2006 Sep;60(9):1816-24. doi: 10.1554/06-246.1.
Excluding insects, hermaphroditism occurs in about one-third of animal species, providing numerous opportunities for the evolution of selfing. Here we provide an overview of reproductive traits in hermaphroditic animal species, review the distribution of selfing rates in animals, and test for ecological correlates of selfing. Our dataset (1342 selfing-rate estimates for 142 species) is 97% based on estimates derived from the analysis of population structure (F(IS)-estimates) using genetic markers. The distribution of selfing is slightly U-shaped and differs significantly from the more strongly U-shaped plant distribution with 47% of animal t-estimates being intermediate (falling between 0.2 and 0.8) compared to 42% for plants. The influence of several factors on the distribution of selfing rates was explored (e.g., number of populations studied per species, habitat, coloniality, sessility, or fertilization type), none of which significantly affect the distribution. Our results suggest that genetic forces might contribute to the evolution of self-fertilization to the same extent in animals and plants, although the high proportion of intermediate outcrossing suggests a significant role of ecological factors (e.g., reproductive assurance) in animals. However, we caution that the distribution of selfing rates in animals is affected by various factors that might bias F(IS)-estimates, including phylogenetic underrepresentation of highly selfing and outcrossing species, various genotyping errors (e.g., null alleles) and inbreeding depression. This highlights the necessity of obtaining better estimates of selfing for hermaphroditic animals, such as genotyping progeny arrays, as in plants.
除昆虫外，雌雄同体现象在约三分之一的动物物种中出现，为自体受精的进化提供了众多机会。在此，我们概述了雌雄同体动物物种的生殖特征，回顾了动物中自体受精率的分布情况，并测试了自体受精的生态关联因素。我们的数据集（针对142个物种的1342个自体受精率估计值）97%基于使用遗传标记对种群结构进行分析得出的估计值（F(IS)估计值）。自体受精的分布呈轻微的U形，与植物中更强的U形分布显著不同，动物的t估计值中有47%处于中间水平（介于0.2和0.8之间），而植物为42%。我们探讨了几个因素对自体受精率分布的影响（例如，每个物种研究的种群数量、栖息地、集群性、固着性或受精类型），但没有一个因素对分布有显著影响。我们的结果表明，遗传因素在动植物中对自体受精进化的贡献程度可能相同，尽管中间杂交的高比例表明生态因素（例如生殖保障）在动物中起着重要作用。然而，我们提醒，动物中自体受精率的分布受到各种可能使F(IS)估计值产生偏差的因素影响，包括高度自体受精和异交物种在系统发育上的代表性不足、各种基因分型错误（例如无效等位基因）以及近亲繁殖衰退。这凸显了像在植物中那样，通过对后代阵列进行基因分型等方式，更好地估计雌雄同体动物自体受精率的必要性。
