Cytonuclear evidence for hybridogenetic reproduction in natural populations of the Australian carp gudgeon (Hypseleotris: Eleotridae).

Although most vertebrates reproduce sexually, a small number of fishes, amphibians, and reptiles are known in which reproduction is asexual i.e. without meiotic recombination. In fishes, these so-called “unisexual” lineages usually comprise only females, and utilize co-occurring males of a related sexual species to reproduce via gynogenesis or hybridogenesis. Here we examine patterns of microsatellite and mitochondrial DNA (mtDNA) variation in a widespread group of freshwater fishes (carp gudgeons; Hypseleotris spp.) to investigate a long-standing proposal that this group includes unisexual forms. We show that the mtDNA genome of most carp gudgeons in tributaries of the Goulburn River belong in one of two deeply divided clades (~10% cyt b divergence) and that nuclear variation divides the same individuals into four distinct groups. Group 1 exhibits the genotypic proportions of a random mating population and has a 1:1 sex ratio. Two other groups are extremely sex-biased (98% male, 96% fe...尽管绝大多数脊椎动物均以有性方式繁殖，目前已发现少量鱼类、两栖类与爬行类可进行无性繁殖，即不经历减数分裂重组的繁殖方式。在鱼类中，这类被称为“单性”的演化支通常仅包含雌性个体，并借助同域分布的近缘有性物种雄性个体，通过雌核发育（gynogenesis）或杂交发育（hybridogenesis）完成繁殖。本研究针对一类分布广泛的淡水鱼类——鲤鰕虎（carp gudgeons；Hypseleotris spp.），分析其微卫星DNA与线粒体DNA（mtDNA）的变异模式，以验证该类群包含单性繁殖类群这一长期存在的学术假说。研究结果显示，古尔本河支流中绝大多数鲤鰕虎的线粒体基因组可归入两个高度分化的演化支之一（细胞色素b [cyt b] 序列分歧度约为10%），而核基因变异则将同一批个体划分为四个截然不同的类群。类群1的基因型比例符合随机交配种群的特征，且性别比例为1:1。其余两个类群则存在极严重的性别偏向（98%为雄性，96%为雌...）