Evolutionary Genetics, Centre for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands.
PLoS One. 2013 Apr 2;8(4):e60459. doi: 10.1371/journal.pone.0060459. Print 2013.
An attractive way to improve our understanding of sex determination evolution is to study the underlying mechanisms in closely related species and in a phylogenetic perspective. Hymenopterans are well suited owing to the diverse sex determination mechanisms, including different types of Complementary Sex Determination (CSD) and maternal control sex determination. We investigated different types of CSD in four species within the braconid wasp genus Asobara that exhibit diverse life-history traits. Nine to thirteen generations of inbreeding were monitored for diploid male production, brood size, offspring sex ratio, and pupal mortality as indicators for CSD. In addition, simulation models were developed to compare these observations to predicted patterns for multilocus CSD with up to ten loci. The inbreeding regime did not result in diploid male production, decreased brood sizes, substantially increased offspring sex ratios nor in increased pupal mortality. The simulations further allowed us to reject CSD with up to ten loci, which is a strong refutation of the multilocus CSD model. We discuss how the absence of CSD can be reconciled with the variation in life-history traits among Asobara species, and the ramifications for the phylogenetic distribution of sex determination mechanisms in the Hymenoptera.
一种能够增进我们对性别决定进化理解的有吸引力的方法是在系统发育的角度下，研究密切相关物种的潜在机制。膜翅目昆虫非常适合进行相关研究，因为它们具有多样化的性别决定机制，包括不同类型的互补性别决定（CSD）和母体控制性别决定。我们研究了具有不同生活史特征的四种茧蜂属（Asobara）中的不同类型的 CSD。我们监测了 9 到 13 代的近交，以观察二倍体雄性产生、幼虫大小、后代性别比例和蛹死亡率等指标，作为 CSD 的指示。此外，我们还开发了模拟模型，将这些观察结果与预测的具有多达 10 个位点的多基因座 CSD 模式进行了比较。近交不会导致二倍体雄性产生、幼虫大小减少、后代性别比例大幅增加或蛹死亡率增加。模拟进一步使我们能够拒绝多达 10 个位点的 CSD，这强烈反驳了多基因座 CSD 模型。我们讨论了缺乏 CSD 如何与 Asobara 物种之间的生活史特征的变化相协调，以及这对膜翅目昆虫性别决定机制的系统发育分布的影响。
