Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, CEP 05422-970 São Paulo/SP, Brazil.
Mol Phylogenet Evol. 2009 Dec;53(3):923-34. doi: 10.1016/j.ympev.2009.08.017. Epub 2009 Aug 20.
The toucan genus Ramphastos (Piciformes: Ramphastidae) has been a model in the formulation of Neotropical paleobiogeographic hypotheses. Weckstein (2005) reported on the phylogenetic history of this genus based on three mitochondrial genes, but some relationships were weakly supported and one of the subspecies of R. vitellinus (citreolaemus) was unsampled. This study expands on Weckstein (2005) by adding more DNA sequence data (including a nuclear marker) and more samples, including R. v. citreolaemus. Maximum parsimony, maximum likelihood, and Bayesian methods recovered similar trees, with nodes showing high support. A monophyletic R. vitellinus complex was strongly supported as the sister-group to R. brevis. The results also confirmed that the southeastern and northern populations of R. vitellinus ariel are paraphyletic. R. v. citreolaemus is sister to the Amazonian subspecies of the vitellinus complex. Using three protein-coding genes (COI, cytochrome-b and ND2) and interval-calibrated nodes under a Bayesian relaxed-clock framework, we infer that ramphastid genera originated in the middle Miocene to early Pliocene, Ramphastos species originated between late Miocene and early Pleistocene, and intra-specific divergences took place throughout the Pleistocene. Parsimony-based reconstruction of ancestral areas indicated that evolution of the four trans-Andean Ramphastos taxa (R. v. citreolaemus, R. a. swainsonii, R. brevis and R. sulfuratus) was associated with four independent dispersals from the cis-Andean region. The last pulse of Andean uplift may have been important for the evolution of R. sulfuratus, whereas the origin of the other trans-Andean Ramphastos taxa is consistent with vicariance due to drying events in the lowland forests north of the Andes. Estimated rates of molecular evolution were higher than the "standard" bird rate of 2% substitutions/site/million years for two of the three genes analyzed (cytochrome-b and ND2).
巨嘴鸟属 Ramphastos（佛法僧目：巨嘴鸟科）一直是新热带古生物地理假说形成的模式。Weckstein（2005）基于三个线粒体基因报告了该属的系统发育历史，但有些关系的支持力度较弱，而且黄嘴巨嘴鸟的一个亚种（citreolaemus）没有采样。本研究通过添加更多 DNA 序列数据（包括核标记）和更多样本（包括 R. v. citreolaemus）扩展了 Weckstein（2005）的研究。最大简约法、最大似然法和贝叶斯法重建的树相似，节点具有高支持度。黄嘴巨嘴鸟复合体的单系性得到了强烈支持，是短嘴巨嘴鸟的姐妹群。结果还证实，黄嘴巨嘴鸟的东南和北部种群 ariels 是并系的。R. v. citreolaemus 与黄嘴巨嘴鸟复合体的亚马逊亚种关系密切。使用三个蛋白质编码基因（COI、细胞色素-b 和 ND2）和贝叶斯松弛时钟框架下的区间校准节点，我们推断佛法僧目属起源于中中新世至早更新世，巨嘴鸟种起源于上新世晚期至更新世早期，种内分歧发生在整个更新世。基于简约法的祖先区重建表明，四个跨安第斯山脉的巨嘴鸟属（R. v. citreolaemus、R. a. swainsonii、R. brevis 和 R. sulfuratus）的进化与从安第斯山脉内部区域的四次独立扩散有关。安第斯山脉最后一次隆升可能对 R. sulfuratus 的进化很重要，而其他三个跨安第斯山脉的巨嘴鸟属的起源与由于安第斯山脉北部低地森林的干燥事件而产生的隔离有关。分析的三个基因中的两个（细胞色素-b 和 ND2）的分子进化率估计高于“标准”鸟类的 2%替换/位点/百万年。
