Abstract

Genetic variation and phylogeographic studies have been crucial for understanding mechanisms of speciation. We analyzed genetic variation and phylogeography to reconstruct the demographic history of the Rivoli’s Hummingbird (Eugenes fulgens) species complex and also evaluated their morphological differentiation. This widely distributed species inhabits the highlands of Mexico and northern Central America, with 2 subspecies separated by the Isthmus of Tehuantepec (west: E. f. fulgens, east: E. f. viridiceps). We surveyed genetic variation in 2 mitochondrial DNA markers (mtDNA, with 129 individuals) and nuclear DNA (6 microsatellites, with 85 individuals). We also inferred the demographic history, estimated divergence times, and analyzed morphological variation using 470 vouchered specimens. We modeled the current potential distribution of the species using ecological niche modeling and projected it into the past to model the effects of the Pleistocene climatic cycles. Haplotype networks, pairwise F_ST comparisons, AMOVA, and morphological analysis revealed differences between geographically isolated populations separated by the Isthmus of Tehuantepec (IT; corresponding to the 2 recognized subspecies: fulgens and viridiceps), and by the Motagua-Polochic-Jocotán (MPJ) system fault. Demographic scenarios revealed a contraction in distribution during the last interglacial, and expansion during the Last Glacial Maximum (LGM) with little change since the LGM. Divergence between groups separated by the Isthmus of Tehuantepec ~59,600 yr ago occurred in the presence of gene flow, suggesting that the Isthmus of Tehuantepec is a semipermeable barrier to gene flow. STRUCTURE analyses of microsatellite data detected 3 genetically differentiated groups. Several results fit a model of recent lineage divergence, including a significant signal of genetic differentiation, demographic expansion, decreased gene flow from past to present, and northward expansion during the LGM and contraction during the interglacial periods. We conclude that the genetic differentiation of E. fulgens in the Madrean Pine-Oak Woodlands resulted from recent geographical isolation of populations separated by natural barriers (IT and MPJ).

中文翻译：

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里沃利蜂鸟（Eugenes fulgens）物种群（Aves：Trochilidae）的种群之间的遗传和形态分化

摘要

遗传变异和系统地理学研究对于理解物种形成机制至关重要。我们分析了遗传变异和植物谱，以重建Rivoli蜂鸟（Eugenes fulgens）物种复合体的人口历史，并评估了它们的形态分化。这种广泛分布的物种栖息于墨西哥和中美洲北部的高地，有2个亚种分离的特万特佩克地峡（西：。E.˚Ffulgens，东部：E.˚Fviridiceps。）。我们调查了2个线粒体DNA标记（mtDNA，有129个个体）和核DNA（6个微卫星，有85个个体）的遗传变异。我们还推论了人口统计学历史，估计的发散时间，并使用470份带凭证的标本分析了形态变异。我们使用生态位模型对当前物种的潜在分布进行了建模，并将其投影到过去以对更新世气候周期的影响进行建模。单倍型网络，成对的F _ST比较，AMOVA和形态学分析揭示了被Tehuantepec（IT;地峡）隔开的地理上分离的种群之间的差异；对应于2个公认的亚种：fulgens和viridiceps），以及由Motagua-Polochic-Jocotán（MPJ）系统故障引起的。人口统计情况表明，在最后一次冰期之间的分布在收缩，而在最后一次冰期最大值（LGM）期间则在扩张，自LGM以来变化不大。在基因流存在的情况下，由特万特佩克地峡隔开的群体之间存在分歧，大约在59,600年前，这表明特万特佩克的地峡是基因流的半渗透性屏障。微卫星数据的结构分析检测到3个遗传分化组。一些结果符合近期谱系差异的模型，包括遗传分化，人口膨胀，从过去到现在的基因流减少以及在LGM期间北向扩张和间冰期收缩的重要信号。我们得出的结论是Madrean橡树栎林地中的E. fulgens是由于最近被自然屏障（IT和MPJ）分隔的人口地理隔离所致。