van Tuinen M, Sibley C G, Hedges S B
Department of Biology, Pennsylvania State University, University Park 16802, USA.
Mol Biol Evol. 1998 Apr;15(4):370-6. doi: 10.1093/oxfordjournals.molbev.a025933.
The origin of the flightless ratite birds of the southern continents has been debated for over a century. Whether dispersal or vicariance (continental breakup) best explains their origin depends largely on their phylogenetic relationships. No consensus has been reached on this issue despite many morphological and molecular studies. To address this question further we sequenced a 2.8-kb region of mitochondrial DNA containing the ribosomal genes in representative ratites and a tinamou. Phylogenetic analyses indicate that Struthio (Africa) is basal and Rhea (South America) clusters with living Australasian ratites. This phylogeny agrees with transferrin and DNA hybridization studies but not with sequence analyses of some protein-coding genes. These results also require reevaluation of the phylogenetic position of the extinct moas of New Zealand. We propose a new hypothesis for the origin of ratites that combines elements of dispersal and vicariance.
南半球不会飞的平胸鸟类的起源问题已经争论了一个多世纪。扩散还是隔离（大陆分裂）能更好地解释它们的起源，这在很大程度上取决于它们的系统发育关系。尽管进行了许多形态学和分子研究，但在这个问题上尚未达成共识。为了进一步解决这个问题，我们对包含核糖体基因的线粒体DNA的2.8 kb区域进行了测序，样本包括代表性的平胸鸟类和一种䳍形目鸟类。系统发育分析表明，鸵鸟属（非洲）是基部类群，美洲鸵属（南美洲）与现存的澳大拉西亚平胸鸟类聚在一起。这个系统发育关系与转铁蛋白和DNA杂交研究结果一致，但与一些蛋白质编码基因的序列分析结果不同。这些结果也需要重新评估新西兰已灭绝恐鸟的系统发育位置。我们提出了一个关于平胸鸟类起源的新假说，该假说结合了扩散和隔离的因素。
