Department of Biology, Boston University, Boston, MA, USA; Biology Department, Boston College, Chestnut Hill, MA, USA.
Department of Biology, Villanova University, Villanova, PA, USA; Sam Noble Oklahoma Museum of Natural History and Department of Biology, University of Oklahoma, Norman, OK, USA.
Mol Phylogenet Evol. 2019 Jul;136:196-205. doi: 10.1016/j.ympev.2019.04.016. Epub 2019 Apr 15.
The West Indian avifauna has provided fundamental insights into island biogeography, taxon cycles, and the evolution of avian behavior. Our interpretations, however, should rely on robust hypotheses of evolutionary relationships and consistent conclusions about taxonomic status in groups with many endemic island populations. Here we present a phylogenetic study of the West Indian thrashers, tremblers, and allies, an assemblage of at least 5 species found on 29 islands, including what is considered the Lesser Antilles' only avian radiation. We improve on previous phylogenetic studies of this group by using double-digest restriction site-associated DNA sequencing (ddRAD-seq) to broadly sample loci scattered across the nuclear genome. A variety of analyses, based on either nucleotide variation in 2223 loci recovered in all samples or at 13,282 loci confidently scored as present or absent in all samples, converged on a single well-supported phylogenetic hypothesis. Results indicate that the resident West Indian taxa form a monophyletic group, exclusive of the Neotropical-Nearctic migratory Gray Catbird Dumetella carolinensis, which breeds in North America; this outcome differs from earlier studies suggesting that Gray Catbird was nested within a clade of island resident species. Thus, our findings imply a single colonization of the West Indies without the need to invoke a subsequent 'reverse colonization' of the mainland by West Indian taxa. Additionally, our study is the first to sample both endemic subspecies of the endangered White-breasted Thrasher Ramphocinclus brachyurus. We find that these subspecies have a long history of evolutionary independence with no evidence of gene flow, and are as genetically divergent from each other as other genera in the group. These findings support recognition of R. brachyurus (restricted to Martinique) and the Saint Lucia Thrasher R. sanctaeluciae as two distinct, single-island endemic species, and indicate the need to re-evaluate conservation plans for these taxa. Our results demonstrate the utility of phylogenomic datasets for generating robust systematic hypotheses.
西印度群岛的鸟类为岛屿生物地理学、分类群循环和鸟类行为进化提供了重要的见解。然而，我们的解释应该依赖于进化关系的稳健假设，并对具有许多特有岛屿种群的分类群的分类地位得出一致的结论。在这里，我们展示了一项关于西印度鸣禽、颤禽和它们的近缘物种的系统发育研究，这些物种至少有 5 种，分布在 29 个岛屿上，包括被认为是小安的列斯群岛唯一的鸟类辐射区的物种。我们通过使用双酶切限制位点相关 DNA 测序（ddRAD-seq）广泛地对散布在核基因组中的基因座进行采样，从而改进了对该组的先前系统发育研究。基于在所有样本中回收的 2223 个基因座中的核苷酸变异或在所有样本中均能可靠地记录为存在或缺失的 13282 个基因座的分析，各种分析都集中在一个单一的、支持良好的系统发育假说上。结果表明，居留西印度的分类群形成一个单系群，与新热带-近北极的候鸟灰猫鸟 Dumetella carolinensis 不同，后者在北美洲繁殖；这一结果与早期的研究结果不同，早期的研究结果表明灰猫鸟嵌套在一个岛屿居留物种的分支中。因此，我们的研究结果表明，西印度群岛是一次单一的殖民，而不需要假设随后西印度的分类群会反向殖民到大陆。此外，我们的研究首次对濒危白胸鸣禽 Ramphocinclus brachyurus 的两个特有亚种进行了采样。我们发现这些亚种具有长期的进化独立性，没有基因流的证据，而且彼此之间的遗传差异与该组中的其他属一样大。这些发现支持将 R. brachyurus（仅限于马提尼克岛）和圣卢西亚鸣禽 R. sanctaeluciae 确认为两个不同的、单一岛屿特有物种，并表明需要重新评估这些类群的保护计划。我们的研究结果表明，基因组数据集在生成稳健的系统发育假设方面具有实用性。
