Molecular systematics of armadillos (Xenarthra, Dasypodidae): contribution of maximum likelihood and Bayesian analyses of mitochondrial and nuclear genes

The 30 living species of armadillos, anteaters, and sloths (Mammalia: Xenarthra) represent one of the three major clades of placentals. Armadillos (Cingulata: Dasypodidae) are the earliest and most speciose xenarthran lineage with 21 described species. The question of their tricky phylogeny was here studied by adding two mitochondrial genes (NADH dehydrogenase subunit 1 [ND1] and 12S ribosomal RNA [12S rRNA]) to the three protein-coding nuclear genes (α2B adrenergic receptor [ADRA2B], breast cancer susceptibility exon 11 [BRCA1], and von Willebrand factor exon 28 [VWF]) yielding a total of 6869 aligned nucleotide sites for thirteen xenarthran species. The two mitochondrial genes were characterized by marked excesses of transitions over transversions—with a strong bias toward CT transitions for the 12S rRNA—and exhibited two- to fivefold faster evolutionary rates than the fastest nuclear gene (ADRA2B). Maximum likelihood and Bayesian phylogenetic analyses supported the monophyly of Dasyp...现存的30种犰狳、食蚁兽与树懒（哺乳纲：异关节总目（Xenarthra））是胎盘类哺乳动物的三大主要演化支之一。犰狳（有甲目（Cingulata）：犰狳科（Dasypodidae））是起源最早且物种多样性最高的异关节类群，目前已记述21个物种。本研究针对其复杂的系统发育问题展开分析：将两个线粒体基因——烟酰胺腺嘌呤二核苷酸脱氢酶亚基1（NADH dehydrogenase subunit 1，ND1）与12S核糖体RNA（12S ribosomal RNA，12S rRNA）——与三个蛋白质编码核基因——α2B肾上腺素能受体（α2B adrenergic receptor，ADRA2B）、乳腺癌易感基因外显子11（breast cancer susceptibility exon 11，BRCA1）以及血管性血友病因子外显子28（von Willebrand factor exon 28，VWF）——相结合，最终得到13种异关节类动物的6869个经比对的核苷酸位点。两类线粒体基因均呈现转换位点显著多于颠换位点的特征，其中12S rRNA尤其表现出对CT类型转换的强烈偏好，且其进化速率为演化最快的核基因ADRA2B的2至5倍。最大似然法与贝叶斯系统发育分析均支持犰狳科（Dasypodidae）的单系性……