Data from: Evolution of Dendrocolaptes platyrostris (Aves: Furnariidae) between the South American open vegetation corridor and the Atlantic forest

The open vegetation corridor of South America is a region dominated by savanna biomes. It contains forests, i.e. riverine forests, that may act as corridors for rainforest specialist between the open vegetation corridor and its neighboring biomes, the Amazonian and Atlantic forests. A prediction for this scenario is that populations of rainforest specialists in the open vegetation corridor and in the forested biomes show no significant genetic divergence. We addressed this hypothesis by studying plumage and genetic variation of the Planalto woodcreeper Dendrocolaptes platyrostris Spix (1824) (Aves: Furnariidae), a forest specialist that occurs in both the open habitat and in the Atlantic forest. Our questions are: (1) is there any evidence of genetic continuity between populations of the open habitat and the Atlantic forest? and (2) is plumage variation congruent with patterns of neutral genetic structure or with ecological factors related to habitat type? We used cytochrome b and mtDNA control region sequences to show that D. platyrostris is monophyletic and that presents substantial intraspecific differentiation. We found two areas of plumage stability: one associated to Cerrado and the other associated to southern Atlantic Forest. Multiple Mantel tests showed that most of the plumage variation followed transition of habitats but not phylogeographic gaps, suggesting that selection may be related to the evolution of the species plumage. Results were not compatible with the idea that forest specialist in the open vegetation corridor and in the Atlantic forest are linked at the population level because birds from each region were not part of the same genetic unit. Divergence in the presence of gene flow across the ecotone between both regions might explain our results. Also, our findings indicate that the southern Atlantic forest may have been significantly affected by Pleistocene climatic alteration, but that those events did not cause local extinction of most taxa, as occurred in other regions of the globe where forests were significantly affected by global glaciations. Finally, our results neither supported subspecies nor regions of stability of plumage as species.

南美洲开阔植被廊道（open vegetation corridor）是一片以稀树草原生物群系（savanna biomes）为主的区域。该区域内分布有河岸林（riverine forests），此类森林可作为雨林特化种（rainforest specialist）在开阔植被廊道与其相邻生物群系——亚马孙森林与大西洋森林之间扩散的廊道。针对这一情境的一项预测是：开阔植被廊道内及森林生物群系中的雨林特种种群不会出现显著的遗传分化。本研究以同时栖息于开阔生境与大西洋森林的森林特化种——巴西砍林鸟（Planalto woodcreeper，学名*Dendrocolaptes platyrostris* Spix, 1824，隶属于鸟纲（Aves）灶鸟科（Furnariidae））的羽色与遗传变异为研究对象，对上述假说进行验证。本研究旨在解答两个问题：（1）开阔生境种群与大西洋森林种群之间是否存在遗传连续性？（2）羽色变异是否与中性遗传结构模式相符，抑或与生境类型相关的生态因子相关？本研究通过细胞色素b（cytochrome b）与线粒体DNA控制区（mtDNA control region）序列分析，证实*D. platyrostris*为单系群（monophyletic），且存在显著的种内分化（intraspecific differentiation）。研究发现两处羽色稳定区域：一处与塞拉多稀树草原（Cerrado）相关，另一处与南大西洋森林相关。多组曼特尔检验（Mantel tests）结果显示，绝大多数羽色变异与生境过渡模式相符，而非与系统地理间隙（phylogeographic gaps）一致，这表明选择作用可能与该物种的羽色演化相关。研究结果与“开阔植被廊道内与大西洋森林中的森林特化种在种群水平上存在关联”这一观点不相符，因为两个区域的个体并不属于同一遗传单元。两区之间生态交错带（ecotone）存在基因流的情况下仍发生分化，这或许可以解释本研究的结果。此外，本研究结果表明南大西洋森林曾受到更新世（Pleistocene）气候剧变的显著影响，但此类事件并未像全球其他受全球冰期（glaciations）严重影响的森林区域那样，导致多数类群发生本地灭绝。最后，本研究结果既未支持该物种存在亚种分化，也未支持羽色稳定区域可作为物种划分的依据。