Zarza Eugenia, Reynoso Víctor H, Faria Christiana M A, Emerson Brent C
Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
Grupo Académico de Biotecnología Ambiental, El Colegio de la Frontera Sur, Unidad Tapachula, Tapachula, Chiapas, Mexico.
PeerJ. 2019 Apr 23;7:e6744. doi: 10.7717/peerj.6744. eCollection 2019.
Introgression, the transmission of genetic material of one taxon into another through hybridization, can have various evolutionary outcomes. Previous studies have detected signs of introgression between western populations of the Mexican endemic and threatened spiny-tailed iguana, . However, the extent of this phenomenon along the geographic distribution of the species is unknown. Here, we use multilocus data together with detailed geographic sampling to (1) define genotypic clusters within ; (2) evaluate geographic concordance between maternally and biparentally inherited markers; (3) examine levels of introgression between genotypic clusters, and (4) suggest taxonomic modifications in light of this information. Applying clustering methods to genotypes of 341 individuals from 49 localities of and the closely related , we inferred the existence of five genotypic clusters. Contact zones between genotypic clusters with signatures of interbreeding were detected, showing different levels of geographic discordance with mtDNA lineages. In northern localities, mtDNA and microsatellites exhibit concordant distributions, supporting the resurrection of . Similar concordance is observed along the distribution of , confirming its unique taxonomic identity. Genetic and geographic concordance is also observed for populations within southwestern Mexico, where the recognition of a new species awaits in depth taxonomic revision. In contrast, in western localities a striking pattern of discordance was detected where up to six mtDNA lineages co-occur with only two genotypic clusters. Given that the type specimen originated from this area, we suggest that individuals from western Mexico keep the name . Our results have profound implications for conservation, management, and forensics of Mexican iguanas.
基因渗入是指一个分类群的遗传物质通过杂交传递到另一个分类群中，它可能产生各种进化结果。先前的研究已经在墨西哥特有的濒危刺尾鬣蜥的西部种群之间检测到基因渗入的迹象。然而，这种现象在该物种地理分布范围内的程度尚不清楚。在这里，我们使用多位点数据以及详细的地理采样来（1）定义该物种内的基因型簇；（2）评估母系遗传和双亲遗传标记之间的地理一致性；（3）检查基因型簇之间的基因渗入水平，以及（4）根据这些信息提出分类学修改建议。将聚类方法应用于来自该物种49个地点的341个个体以及密切相关物种的基因型，我们推断出存在五个基因型簇。检测到具有杂交特征的基因型簇之间的接触区，显示出与线粒体DNA谱系不同程度的地理不一致。在北部地区，线粒体DNA和微卫星表现出一致的分布，支持了[物种名称]的恢复。沿着[另一物种名称]的分布也观察到类似的一致性，证实了其独特的分类身份。在墨西哥西南部的种群中也观察到遗传和地理一致性，在那里一个新物种的认定有待深入的分类学修订。相比之下，在西部地区检测到一种明显的不一致模式，多达六个线粒体DNA谱系与仅两个基因型簇同时出现。鉴于模式标本源自该地区，我们建议来自墨西哥西部的个体保留[物种名称]。我们的结果对墨西哥鬣蜥的保护、管理和法医学具有深远意义。
