Zamudio-Beltrán Luz E, Hernández-Baños Blanca E
Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
Departamento de Biología Evolutiva, Facultad de Ciencias, Museo de Zoología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
PeerJ. 2018 Oct 19;6:e5733. doi: 10.7717/peerj.5733. eCollection 2018.
Cloud forests are one of the most endangered ecosystems in the Americas, as well as one of the richest in biological diversity in the world. The species inhabiting these forests are susceptible to environmental changes and characterized by high levels of geographic structure. The Garnet-Throated Hummingbird, mainly inhabits cloud forests, but can also be found in other habitats. This species has a highly restricted distribution in Mesoamerica, and five disjunct regions have been delimited within the current geographic distribution of the species from Mexico to Honduras. According to variation in size and color, three subspecies have been described: restricted to the Mexican highlands and Guatemala, distributed in Guerrero (Mexico), and , distributed in the highlands from Honduras and El Salvador. We analyzed the levels of geographic structure in and its taxonomic implications. We used mitochondrial and nuclear DNA to analyze genetic variation, demographic history, divergence times, reconstructed a multilocus phylogeny, and performed a species delimitation analyses. We also evaluated morphological variation in 208 specimens. We found high levels of genetic differentiation in three groups, and significant variation in morphological traits corresponding with the disjunct geographic populations. presents population stability with the highest genetic variation explained by differences between populations. Divergence time estimates suggest that split from its sister group around 10.55 million years ago, and the diversification of the complex was dated ca. 0.207 Mya. The hypotheses tested in the species delimitation analyses validated three independent lineages corresponding to three disjunct populations. This study provides evidence of genetic and/or morphometric differentiation between populations in the complex where four separate evolutionary lineages are supported: (1) populations from the Sierra Madre Oriental and the highlands of Oaxaca (), (2) populations from the highlands of Guerrero (), (3) populations from the highlands of Chiapas and Guatemala (this is a non-previously proposed potential taxon: ), and (4) populations from the highlands of Honduras and El Salvador (). The main promoters of the geographic structure found in the complex are likely the Isthmus of Tehuantepec as a geographic barrier, isolation by distance resulting from habitat fragmentation, and climatic conditions during the Pleistocene.
云雾森林是美洲最濒危的生态系统之一，也是世界上生物多样性最丰富的生态系统之一。栖息在这些森林中的物种易受环境变化影响，且具有高度的地理结构特征。石榴喉蜂鸟主要栖息在云雾森林中，但也能在其他栖息地被发现。该物种在中美洲的分布范围极为有限，在从墨西哥到洪都拉斯的当前地理分布范围内已划定了五个不连续的区域。根据大小和颜色的差异，已描述了三个亚种：局限于墨西哥高地和危地马拉，分布于格雷罗（墨西哥），以及分布于洪都拉斯和萨尔瓦多高地。我们分析了石榴喉蜂鸟的地理结构水平及其分类学意义。我们使用线粒体和核DNA来分析遗传变异、种群历史、分歧时间，重建了多位点系统发育，并进行了物种界定分析。我们还评估了208个标本的形态变异。我们发现三组之间存在高度的遗传分化，并且与不连续地理种群相对应的形态特征存在显著差异。石榴喉蜂鸟呈现出种群稳定性，种群间差异解释了最高的遗传变异。分歧时间估计表明，石榴喉蜂鸟与其姐妹群大约在1055万年前分化，该复合体的多样化可追溯到约20.7万年前。在物种界定分析中测试的假设验证了对应于三个不连续种群的三个独立谱系。本研究提供了石榴喉蜂鸟复合体种群间遗传和/或形态测量分化的证据，支持四个独立的进化谱系：（1）来自东马德雷山脉和瓦哈卡高地的种群（），（2）来自格雷罗高地的种群（），（3）来自恰帕斯高地和危地马拉的种群（这是一个先前未提出的潜在分类单元：），以及（4）来自洪都拉斯和萨尔瓦多高地的种群（）。在石榴喉蜂鸟复合体中发现的地理结构的主要促成因素可能是特万特佩克地峡作为地理屏障、栖息地破碎化导致的距离隔离以及更新世期间的气候条件。
