Department of Biology, Indiana University, Bloomington, Indiana 47405 E-mail:
Evolution. 2012 Mar;66(3):919-926. doi: 10.1111/j.1558-5646.2011.01488.x. Epub 2011 Nov 6.
Cyclical parthenogens are a valuable system in which to empirically test theoretical predictions as to the genetic consequences of sexual reproduction in natural populations, particularly if the frequency of sexual relative to asexual reproduction can be quantified. In this study, we used a series of lake populations of the cyclical parthenogen, Daphnia pulicaria, that vary consistently in their investment in sexual reproduction, to address the questions of whether the ecological variation in investment in sex is detectable at the genetic level, and if so, whether the genetic patterns seen are consistent with theoretical predictions. We show that there is variation in the genetic structure of these populations in a manner consistent with their investment in sexual reproduction. Populations engaging in a high frequency of sex were in Hardy-Weinberg and gametic phase equilibrium, and showed little genotypic differentiation across sampled years. In contrast, populations with a lower frequency of sex deviated widely from equilibrium, had reduced multilocus clonal diversity, and showed significant temporal genotypic deviation.
周期性孤雌生殖是一个有价值的系统，可以在自然种群中对有性生殖的遗传后果进行实证检验，特别是如果可以量化有性相对于无性生殖的频率。在这项研究中，我们使用了一系列周期性孤雌生殖的 Daphnia pulicaria 湖种群，这些种群在性生殖投资方面始终存在差异，以解决投资于性的生态变异是否可以在遗传水平上检测到的问题，以及如果可以检测到，那么所看到的遗传模式是否与理论预测一致。我们表明，这些种群的遗传结构存在变异，这种变异与它们的性生殖投资方式一致。进行高频率性生殖的种群处于哈迪-温伯格和配子相平衡状态，并且在采样年份之间表现出很少的基因型分化。相比之下，性生殖频率较低的种群偏离平衡状态很大，具有较低的多位点克隆多样性，并且表现出显著的时间基因型偏离。
