Licona-Vera Yuyini, Ornelas Juan Francisco
Departamento de Biología Evolutiva, Instituto de Ecología, AC, Xalapa, Veracruz, Mexico.
PLoS One. 2014 Jul 3;9(7):e101870. doi: 10.1371/journal.pone.0101870. eCollection 2014.
The Mexican Sheartail (Doricha eliza), an endangered hummingbird, is endemic to Mexico where two populations have a disjunct distribution. One population is distributed along the northern tip of the Yucatan Peninsula whereas the other is mostly restricted to central Veracruz. Despite their disjunct distribution, previous work has failed to detect morphological or behavioral differences between these populations. Here we use variation in morphology, mtDNA and nuDNA sequences to determine the degree of morphological and molecular divergence between populations, their divergence time, and historical demography. We use species distribution modeling and niche divergence tests to infer the relative roles of vicariance and dispersal in driving divergence in the genus. Our Bayesian and maximum likelihood phylogenetic analyses revealed that Doricha eliza populations form a monophyletic clade and support their sister relationship with D. enicura. We found marked genetic differentiation, with reciprocal monophyly of haplotypes and highly restricted gene flow, supporting a history of isolation over the last 120,000 years. Genetic divergence between populations is consistent with the lack of overlap in environmental space and slight morphological differences between males. Our findings indicate that the divergence of the Veracruz and Yucatan populations is best explained by a combination of a short period of isolation exacerbated by subsequent divergence in climate conditions, and that rather than vicariance, the two isolated ranges of D. eliza are the product of recent colonization and divergence in isolation.
墨西哥剪尾蜂鸟（Doricha eliza）是一种濒危蜂鸟，仅分布于墨西哥，其两个种群呈间断分布。一个种群分布在尤卡坦半岛的北端，而另一个种群主要局限于韦拉克鲁斯中部。尽管它们分布间断，但先前的研究未能发现这些种群之间在形态或行为上的差异。在这里，我们利用形态学、线粒体DNA（mtDNA）和核DNA（nuDNA）序列的变异来确定种群之间的形态和分子分化程度、它们的分化时间以及历史种群动态。我们使用物种分布模型和生态位分化测试来推断地理隔离和扩散在该属物种分化过程中的相对作用。我们的贝叶斯和最大似然系统发育分析表明，墨西哥剪尾蜂鸟的种群形成一个单系类群，并支持它们与D. enicura的姐妹关系。我们发现了显著的遗传分化，单倍型相互单系且基因流高度受限，这支持了过去12万年的隔离历史。种群之间的遗传分化与环境空间缺乏重叠以及雄性之间轻微的形态差异相一致。我们的研究结果表明，韦拉克鲁斯和尤卡坦种群的分化最好由一段短暂的隔离期加上随后气候条件的分化来解释，而且墨西哥剪尾蜂鸟的两个隔离分布范围并非地理隔离的产物，而是近期定殖和隔离分化的结果。
