Data from: Rapid genetic assimilation of native wall lizard populations (Podarcis muralis) through extensive hybridization with introduced lineages

The Common Wall Lizard (Podarcis muralis) has established more than 150 non-native populations in Central Europe, stemming from eight geographically distinct evolutionary lineages. While the majority of these introduced populations are found outside the native range, some of these populations also exist at the northern range margin in south-western Germany. In order to a) infer the level of hybridization in contact zones of alien and native lineages and b) compare the genetic diversity among purebred introduced, native and hybrid populations we used a combination of maternally inherited markers (mtDNA: cytb) and Mendelian markers (microsatellites). Our results suggest a rapid genetic assimilation of native populations by strong introgression from introduced lineages. Discordant patterns of mtDNA and nDNA variation within hybrid populations may be explained by directed mate choice of females towards males of alien lineages. In contrast to previous studies we found a non-linear relationship between genetic diversity and admixture level. The genetic diversity of hybrid populations was substantially higher than in introduced and native populations belonging to a single lineage, but rapidly reaching a plateau of high genetic diversity at an admixture level of two. However, even introduced populations with low founder sizes and from one source population retained moderate levels of genetic diversity and no evidence for a genetic bottleneck was found. The extent of introgression and the dominance of alien haplotypes in mixed populations indicate that introductions of non-native lineages represent a serious threat to the genetic integrity of native populations due to the rapid creation of hybrid swarms.

普通壁蜥（Podarcis muralis）已在中欧建立150余个非本土种群，这些种群源自8个地理上独立的演化支系。尽管此类引入种群大多分布于原生分布范围之外，但其中部分种群也见于德国西南部的北部分布边缘地带。为实现两项研究目标：a）推断外来与本土支系接触区的杂交水平；b）比较纯种引入种群、本土种群及杂交种群的遗传多样性，本研究联合使用了母系遗传标记（mtDNA：cytb）与孟德尔遗传标记（微卫星（microsatellites））。研究结果显示，引入支系的强力基因渐渗可快速导致本土种群发生遗传同化。杂交种群中线粒体DNA与核DNA（nDNA）变异模式的不一致性，可通过雌性对外来雄性的定向择偶行为加以解释。与既往研究不同，本研究发现遗传多样性与混合度之间存在非线性关联：杂交种群的遗传多样性显著高于仅含单个支系的引入种群与本土种群，但当混合度为2时，其高遗传多样性会快速趋于平稳。即便如此，即使是奠基者种群规模较小且仅源自单个源种群的引入种群，仍保留了中等水平的遗传多样性，未发现存在遗传瓶颈的证据。混合种群中基因渐渗的程度与外来单倍型的主导地位表明，非本土支系的引入会因快速形成杂交集群，对本土种群的遗传完整性构成严重威胁。