Data from: Discordance between nuclear and mitochondrial genomes in sexual and asexual lineages of the freshwater snail Potamopyrgus antipodarum

The presence and extent of mitonuclear discordance in coexisting sexual and asexual lineages provides insight into 1) how and when asexual lineages emerged, and 2) the spatial and temporal scales at which the ecological and evolutionary processes influencing the evolution of sexual and asexual reproduction occur. Here, we used nuclear single-nucleotide polymorphism (SNP) markers and a mitochondrial gene to characterize phylogeographic structure and the extent of mitonuclear discordance in Potamopyrgus antipodarum. This New Zealand freshwater snail is often used to study the evolution and maintenance of sex because obligately sexual and obligately asexual individuals often coexist. While our data indicate that sexual and asexual P. antipodarum sampled from the same lake population are often genetically similar, suggesting recent origin of these asexuals from sympatric sexual P. antipodarum, we also found significantly more population structure in sexuals vs. asexuals. This latter result suggests that some asexual lineages originated in other lakes and/or in the relatively distant past. When comparing mitochondrial and nuclear population genetic structure, we discovered that one mitochondrial haplotype (‘1A’) was rare in sexuals, but common and widespread in asexuals. Haplotype 1A frequency and nuclear genetic diversity were not associated, suggesting that the commonness of this haplotype cannot be attributed entirely to genetic drift and pointing instead to a role for selection.共存的有性与无性谱系中的线粒体核基因组不一致（mitonuclear discordance）的存在与否与程度，可为两大研究问题提供洞察：其一，无性谱系如何以及何时起源；其二，影响有性与无性生殖演化的生态及演化过程发生的时空尺度。本研究利用核单核苷酸多态性（single-nucleotide polymorphism, SNP）标记与线粒体基因，对新西兰淡水螺Potamopyrgus antipodarum的系统地理结构以及线粒体核基因组不一致的程度进行了表征。该物种因专性有性与专性无性个体常共存于同一环境中，常被用于研究有性生殖的演化与维持机制。我们的数据显示，从同一湖泊种群中采集的有性与无性P. antipodarum通常遗传相似，表明这些无性类群是由同域分布的有性类群新近起源的；但我们同时发现，有性种群的种群结构显著多于无性种群。这一结果提示，部分无性谱系起源于其他湖泊，或起源时间相对久远。在比较线粒体与核基因组的种群遗传结构时，我们发现一种线粒体单倍型（‘1A’）在有性个体中极为罕见，但在无性个体中却常见且分布广泛。单倍型1A的频率与核遗传多样性并无关联，这表明该单倍型的高频率并非完全由遗传漂变导致，反而提示选择作用可能参与其中。