Several factors have been proposed as drivers of species diversification in the Neotropics, including environmental heterogeneity, the development of drainage systems and historical changes in forest distribution due to climatic oscillations. Here, we investigate which drivers contributed to the evolutionary history and current patterns of diversity of a polymorphic songbird (Arremon taciturnus ) that is widely distributed in Amazonian and Atlantic forests as well as in Cerrado gallery and seasonally‐dry forests. We use genomic, phenotypic and habitat heterogeneity data coupled with climatic niche modelling. Results suggest the evolutionary history of the species is mainly related to paleoclimatic changes, although changes in the strength of the Amazon river as a barrier to dispersal, current habitat heterogeneity and geographic distance were also relevant. We propose an ancestral distribution in the Guyana Shield, and recent colonization of areas south of the Amazon river at ~380 to 166 kya, and expansion of the distribution to southern Amazonia, Cerrado and the Atlantic Forest. Since then, populations south of the Amazon River have been subjected to cycles of isolation and possibly secondary contact due to climatic changes that affected habitat heterogeneity and population connectivity. Most Amazonian rivers are not associated with long lasting isolation of populations, but some might act as secondary barriers, susceptible to crossing under specific climatic conditions. Morphological variation, while stable in some parts of the distribution, is not a reliable indicator of genetic structure or phylogenetic relationships.

中文翻译：

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古气候演变是当前广泛存在且多态的新热带歌鸟Arremon taciturnus中基因组多样性的主要驱动力。

提出了一些因素作为新热带地区物种多样化的驱动力，包括环境异质性，排水系统的发展以及由于气候振荡而造成的森林分布的历史变化。在这里，我们调查了哪些驱动因素对多态鸣禽（Arremon taciturnus）广泛分布于亚马逊和大西洋森林，塞拉多画廊和季节性干燥的森林中。我们使用基因组，表型和生境异质性数据以及气候位模型。结果表明，该物种的进化历史主要与古气候变化有关，尽管亚马逊河作为扩散障碍的强度变化，当前生境异质性和地理距离也很重要。我们建议在圭亚那盾构中进行祖先分布，并在约380至166 kya的亚马逊河以南地区进行近期殖民化，并将分布范围扩展到南部的亚马孙地区，塞拉多和大西洋森林。自那时候起，由于气候变化影响了栖息地的异质性和种群连通性，亚马逊河以南的种群经历了孤立和可能的二次接触循环。大多数亚马孙河流与长期隔离人口没有关系，但有些可能充当次生屏障，在特定气候条件下易越境。形态变异虽然在分布的某些部分稳定，但不是遗传结构或系统发育关系的可靠指标。