We focus on reconstructing a spatiotemporal scenario of diversification of a widespread South American species, the Pectoral Sparrow Arremon taciturnus (Aves: Passerellidae). This species is widely distributed in both the humid and the dry forests of South America and therefore provides an interesting model for understanding the connection between different biomes of South America. We examined nucleotide sequences of the mitochondrial genes Cytochrome b (cyt‐b) and NADH subunit 2 (ND2) from 107 specimens, and one nuclear marker (intron 7 of the β‐fibrinogen gene) from a subset of samples collected across the distribution ranges of A. t. taciturnus and A. t. nigrirostris. Six major lineages were recovered in the phylogenies that displayed high levels of variance of allele frequencies and corresponded to distinct geographical locations. The estimation of divergence times provided evidence that diversification of the six lineages of the Pectoral Sparrow occurred throughout the Late Pleistocene across major cis‐Andean biomes and Amazonian interfluves. Our dataset for A. taciturnus provides further evidence that rivers in Amazonia constitute barriers promoting allopatric speciation, with occasional sharing of alleles among lineages, particularly those with adjacent distributions.

中文翻译：

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胸麻Arremon taciturnus的进化史：晚更新世期间多样化的证据

我们专注于重建时空情景下的南美广泛物种（胸鳍麻雀Arremon taciturnus（Aves：Passerellidae））的多样化。该物种广泛分布在南美的潮湿和干旱森林中，因此为理解南美不同生物群落之间的联系提供了一个有趣的模型。我们检查了107个标本中线粒体基因Cytochrome b（cyt-b）和NADH亚基2（ND2）的核苷酸序列，以及一个在整个分布范围内收集的样本子集中的一个核标记（β-纤维蛋白原基因的7号内含子）的A.吨。taciturnus和A. t。黑眉毛。在系统发育中恢复了六个主要谱系，这些谱系显示等位基因频率的高水平变异并对应于不同的地理位置。的分歧时间估计提供的证据表明，胸鳍麻雀的六个谱系的多样化整个晚更新世发生重大跨越顺-Andean生物群落和亚马逊的分野。我们的数据集A. taciturnus提供了进一步的证据表明，亚马逊河流域的河流构成障碍，促进异域成种，与谱系中的等位基因偶尔共享，特别是那些与相邻的分布。