PDF(Pubmed)
Abstract：
Parthenogenesis, or virgin birth, describes a mode of reproduction where an egg develops into an offspring without fertilization, and is observed across various vertebrate taxa, excluding mammals. Obligate parthenogenesis, found in around 100 vertebrate species and 1000 invertebrate species, is relatively rare. Conversely, facultative parthenogenesis, where females can reproduce both sexually and parthenogenetically, is observed in some vertebrates, including elasmobranchs. Notably, this phenomenon in elasmobranchs is mainly documented in captivity, allowing for detailed long-term observation. Specifically, this study reports the first case of facultative parthenogenesis in the common smooth-hound shark Mustelus mustelus, a species classified by IUCN as endangered. Here we show that the juvenile M. mustelus were born through parthenogenesis, exhibiting homozygosity at each genetic marker, consistent with terminal fusion automixis. Remarkably, this finding reveals that parthenogenesis can occur annually in these sharks, alternating between two females, and conclusively excludes long-term sperm storage as a cause. Consequently, this enhances our understanding of parthenogenesis in elasmobranchs and highlights the reproductive flexibility of M. mustelus. Overall, these results contribute to our broader understanding of reproductive strategies in elasmobranchs, which could inform conservation efforts for endangered species.
摘要：
孤雌生殖,或处女出生，描述了一种繁殖模式，其中卵子在没有受精的情况下发育成后代，并在各种脊椎动物类群中观察到，不包括哺乳动物。专性孤雌生殖，在大约100种脊椎动物和1000种无脊椎动物中发现，相对罕见。相反，兼性孤雌生殖，雌性可以有性和孤雌生殖繁殖，在一些脊椎动物中观察到，包括弹枝。值得注意的是,这种现象主要记录在圈养中，允许详细的长期观察。具体来说,这项研究报告了常见的光滑猎犬Mustelusmustelusmustelus的兼性孤雌生殖的第一例，被世界自然保护联盟归类为濒危物种。在这里，我们显示了幼年的M.mustelus是通过孤雌生殖出生的，在每个遗传标记上表现出纯合性，与终端融合自动机一致。值得注意的是,这一发现表明，这些鲨鱼每年都会发生孤雌生殖，在两个雌性之间交替，并最终排除了长期精子储存的原因。因此,这增强了我们对弹枝孤雌生殖的理解，并突出了芥菜的生殖灵活性。总的来说,这些结果有助于我们更广泛地理解弹性枝的生殖策略，这可以为濒危物种的保护工作提供信息。
