A single pleiotropic locus influences the rate of hybridisation between two sibling species of Lygaeus bugs

The evolution of reproductive isolation lies at the heart of understanding the process of speciation. Of particular interest is the relationship between pre- and post-zygotic reproductive isolation, and the genetic architecture of traits that contribute to one or both forms of reproductive isolation. The sibling species of seed bug Lygaeus equestris and L. simulans show a classic pattern of asymmetric pre-zygotic reproductive isolation, with female L. equestris hybridising with male L. simulans, but with no hybridisation in the reciprocal direction. We have recently described a mutant pale colour form of L. simulans, that inherits as a single Mendelian locus and is pleiotropic for a number of other life history and behavioural traits. Here we tested whether this locus also influences pre- and post-zygotic reproductive isolation. Two sets of experimental crosses revealed that behavioural isolation varied with mutant versus wild-type phenotype for male L. simulans, with the pale form less...生殖隔离（reproductive isolation）的演化是理解物种形成（speciation）过程的核心议题。其中，合子前生殖隔离（pre-zygotic reproductive isolation）与合子后生殖隔离（post-zygotic reproductive isolation）之间的关联，以及调控两类生殖隔离相关性状的遗传结构，尤为引人关注。长蝽（seed bug）的姊妹种（sibling species）绮丽长蝽（Lygaeus equestris）与模拟长蝽（L. simulans）呈现出典型的不对称合子前生殖隔离模式：雌性绮丽长蝽可与雄性模拟长蝽完成杂交，但反向杂交（雄性绮丽长蝽与雌性模拟长蝽）则无法发生。我们近期报道了模拟长蝽的一类浅色突变体色表型，该性状由单个孟德尔基因座（Mendelian locus）遗传，且对多种其他生活史（life history）与行为性状存在多效性（pleiotropic）影响。本研究旨在探究该基因座是否同时影响合子前与合子后生殖隔离。两组实验杂交结果显示，雄性模拟长蝽的行为隔离（behavioural isolation）程度因突变型与野生型（wild-type）表型而异，浅色突变型的……