School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull, United Kingdom ; Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas, Castellón, Spain.
Instituto de Acuicultura de Torre de la Sal, Consejo Superior de Investigaciones Científicas, Castellón, Spain.
PLoS One. 2013 Dec 20;8(12):e83348. doi: 10.1371/journal.pone.0083348. eCollection 2013.
There is wide interest in understanding how genetic diversity is generated and maintained in parthenogenetic lineages, as it will help clarify the debate of the evolution and maintenance of sexual reproduction. There are three mechanisms that can be responsible for the generation of genetic diversity of parthenogenetic lineages: contagious parthenogenesis, repeated hybridization and microorganism infections (e.g. Wolbachia). Brine shrimps of the genus Artemia (Crustacea, Branchiopoda, Anostraca) are a good model system to investigate evolutionary transitions between reproductive systems as they include sexual species and lineages of obligate parthenogenetic populations of different ploidy level, which often co-occur. Diploid parthenogenetic lineages produce occasional fully functional rare males, interspecific hybridization is known to occur, but the mechanisms of origin of asexual lineages are not completely understood. Here we sequenced and analysed fragments of one mitochondrial and two nuclear genes from an extensive set of populations of diploid parthenogenetic Artemia and sexual species from Central and East Asia to investigate the evolutionary origin of diploid parthenogenetic Artemia, and geographic origin of the parental taxa. Our results indicate that there are at least two, possibly three independent and recent maternal origins of parthenogenetic lineages, related to A. urmiana and Artemia sp. from Kazakhstan, but that the nuclear genes are very closely related in all the sexual species and parthenogegetic lineages except for A. sinica, who presumable took no part on the origin of diploid parthenogenetic strains. Our data cannot rule out either hybridization between any of the very closely related Asiatic sexual species or rare events of contagious parthenogenesis via rare males as the contributing mechanisms to the generation of genetic diversity in diploid parthenogenetic Artemia lineages.
人们对了解单性生殖谱系中遗传多样性的产生和维持方式非常感兴趣，因为这有助于澄清关于有性繁殖的进化和维持的争论。有三种机制可以负责单性生殖谱系遗传多样性的产生：接触性单性生殖、重复杂交和微生物感染（例如沃尔巴克氏体）。卤虫属（甲壳纲，鳃足亚纲，无甲目）的卤虫是一个很好的模型系统，可以研究生殖系统之间的进化转变，因为它们包括有性物种和不同倍性水平的强制性单性生殖种群的谱系，这些物种和谱系经常共存。二倍体单性生殖谱系偶尔会产生完全功能性的稀有雄性个体，种间杂交已知会发生，但无性系起源的机制尚未完全了解。在这里，我们对来自中亚和东亚的广泛二倍体单性生殖卤虫和有性物种的一个线粒体和两个核基因片段进行了测序和分析，以研究二倍体单性生殖卤虫的进化起源以及亲代分类群的地理起源。我们的结果表明，至少有两个，可能有三个独立的、近期的单性生殖谱系母系起源，与来自哈萨克斯坦的 A. urmiana 和 Artemia sp. 有关，但除了 A. sinica 之外，所有有性物种和单性生殖谱系的核基因都非常密切相关，A. sinica 可能没有参与二倍体单性生殖株系的起源。我们的数据既不能排除任何密切相关的亚洲有性物种之间的杂交，也不能排除稀有雄性通过罕见雄性进行接触性单性生殖作为导致二倍体单性生殖卤虫谱系遗传多样性产生的机制。
