Wright Timothy F, Schirtzinger Erin E, Matsumoto Tania, Eberhard Jessica R, Graves Gary R, Sanchez Juan J, Capelli Sara, Müller Heinrich, Scharpegge Julia, Chambers Geoffrey K, Fleischer Robert C
Department of Biology, New Mexico State University, Las Cruces, NM, USA.
Mol Biol Evol. 2008 Oct;25(10):2141-56. doi: 10.1093/molbev/msn160. Epub 2008 Jul 24.
The question of when modern birds (Neornithes) first diversified has generated much debate among avian systematists. Fossil evidence generally supports a Tertiary diversification, whereas estimates based on molecular dating favor an earlier diversification in the Cretaceous period. In this study, we used an alternate approach, the inference of historical biogeographic patterns, to test the hypothesis that the initial radiation of the Order Psittaciformes (the parrots and cockatoos) originated on the Gondwana supercontinent during the Cretaceous. We utilized broad taxonomic sampling (representatives of 69 of the 82 extant genera and 8 outgroup taxa) and multilocus molecular character sampling (3,941 bp from mitochondrial DNA (mtDNA) genes cytochrome oxidase I and NADH dehydrogenase 2 and nuclear introns of rhodopsin intron 1, tropomyosin alpha-subunit intron 5, and transforming growth factor ss-2) to generate phylogenetic hypotheses for the Psittaciformes. Analyses of the combined character partitions using maximum parsimony, maximum likelihood, and Bayesian criteria produced well-resolved and topologically similar trees in which the New Zealand taxa Strigops and Nestor (Psittacidae) were sister to all other psittaciforms and the cockatoo clade (Cacatuidae) was sister to a clade containing all remaining parrots (Psittacidae). Within this large clade of Psittacidae, some traditionally recognized tribes and subfamilies were monophyletic (e.g., Arini, Psittacini, and Loriinae), whereas several others were polyphyletic (e.g., Cyclopsittacini, Platycercini, Psittaculini, and Psittacinae). Ancestral area reconstructions using our Bayesian phylogenetic hypothesis and current distributions of genera supported the hypothesis of an Australasian origin for the Psittaciformes. Separate analyses of the timing of parrot diversification constructed with both Bayesian relaxed-clock and penalized likelihood approaches showed better agreement between geologic and diversification events in the chronograms based on a Cretaceous dating of the basal split within parrots than the chronograms based on a Tertiary dating of this split, although these data are more equivocal. Taken together, our results support a Cretaceous origin of Psittaciformes in Gondwana after the separation of Africa and the India/Madagascar block with subsequent diversification through both vicariance and dispersal. These well-resolved molecular phylogenies will be of value for comparative studies of behavior, ecology, and life history in parrots.
现代鸟类（今鸟亚纲）最初是何时开始多样化的问题，在鸟类分类学家中引发了诸多争论。化石证据总体上支持第三纪的多样化观点，而基于分子定年法的估计则倾向于白垩纪时期更早的多样化。在本研究中，我们采用了一种替代方法，即推断历史生物地理模式，来检验鹦形目（鹦鹉和凤头鹦鹉）的初始辐射起源于白垩纪冈瓦纳超大陆这一假说。我们利用了广泛的分类采样（82个现存属中的69个属的代表以及8个外类群分类单元）和多位点分子特征采样（来自线粒体DNA（mtDNA）基因细胞色素氧化酶I和NADH脱氢酶2的3941碱基对，以及视紫红质内含子1、原肌球蛋白α亚基内含子5和转化生长因子β-2的核内含子）来构建鹦形目的系统发育假说。使用最大简约法、最大似然法和贝叶斯准则对组合特征分区进行分析，得到了分辨率良好且拓扑结构相似的树，其中新西兰的鸮鹦鹉属和啄羊鹦鹉属（鹦鹉科）与所有其他鹦形目动物互为姐妹群，凤头鹦鹉科进化枝与包含所有其余鹦鹉（鹦鹉科）的进化枝互为姐妹群。在这个庞大的鹦鹉科进化枝中，一些传统上认可的族和亚科是单系的（如锥尾鹦鹉族Arini、鹦鹉族Psittacini和吸蜜鹦鹉亚科Loriinae），而其他一些则是多系的（如侏鹦鹉族Cyclopsittacini、玫瑰鹦鹉族Platycercini、鹦鹉亚科Psittaculini和鹦鹉亚科Psittacinae）。利用我们的贝叶斯系统发育假说和各属当前分布进行的祖先区域重建，支持了鹦形目起源于澳大拉西亚的假说。分别使用贝叶斯宽松分子钟和惩罚似然法构建的鹦鹉多样化时间分析表明，基于鹦鹉基部谱系白垩纪定年的时间线图中，地质事件和多样化事件之间的一致性，比基于该谱系第三纪定年的时间线图更好，尽管这些数据更具不确定性。综合来看，我们的结果支持鹦形目在非洲与印度/马达加斯加地块分离后起源于冈瓦纳白垩纪，随后通过隔离和扩散实现多样化。这些分辨率良好的分子系统发育树对于鹦鹉行为、生态和生活史的比较研究将具有重要价值。
