Department of Biology, University of Virginia, Charlottesville, VA, USA.
Department of Biology, James Madison University, Harrisonburg, VA, USA.
Mol Biol Evol. 2022 Jun 2;39(6). doi: 10.1093/molbev/msac121.
Species across the tree of life can switch between asexual and sexual reproduction. In facultatively sexual species, the ability to switch between reproductive modes is often environmentally dependent and subject to local adaptation. However, the ecological and evolutionary factors that influence the maintenance and turnover of polymorphism associated with facultative sex remain unclear. We studied the ecological and evolutionary dynamics of reproductive investment in the facultatively sexual model species, Daphnia pulex. We found that patterns of clonal diversity, but not genetic diversity varied among ponds consistent with the predicted relationship between ephemerality and clonal structure. Reconstruction of a multi-year pedigree demonstrated the coexistence of clones that differ in their investment into male production. Mapping of quantitative variation in male production using lab-generated and field-collected individuals identified multiple putative quantitative trait loci (QTL) underlying this trait, and we identified a plausible candidate gene. The evolutionary history of these QTL suggests that they are relatively young, and male limitation in this system is a rapidly evolving trait. Our work highlights the dynamic nature of the genetic structure and composition of facultative sex across space and time and suggests that quantitative genetic variation in reproductive strategy can undergo rapid evolutionary turnover.
生命之树上的各种物种都可以在无性和有性繁殖之间切换。在兼性有性物种中，切换繁殖模式的能力通常依赖于环境，并受到局部适应的影响。然而，影响与兼性性别相关的多态性维持和更替的生态和进化因素仍不清楚。我们研究了兼性性模型物种，Daphnia pulex 中的生殖投资的生态和进化动态。我们发现，无性系多样性的模式，但不是遗传多样性在池塘之间存在差异，与预期的短暂性和无性系结构之间的关系一致。使用实验室生成和野外采集的个体重建多年系谱表明，存在着在雄性生产投资上存在差异的克隆共存。使用实验室生成和野外采集的个体对雄性生产的定量变异进行映射，确定了该性状的多个潜在数量性状基因座 (QTL)，并确定了一个合理的候选基因。这些 QTL 的进化历史表明它们相对较新，并且该系统中的雄性限制是一个快速进化的特征。我们的工作强调了兼性性别在空间和时间上的遗传结构和组成的动态性质，并表明生殖策略的数量遗传变异可以经历快速的进化更替。
