Résumé
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 Dasypodinae, Tolypeutinae, and Euphractinae, with the latter
two armadillo subfamilies strongly clustering together. Conflicting
branching points between individual genes involved relationships within
the subfamilies Tolypeutinae and Euphractinae. Owing to a greater number
of informative sites, the overall concatenation favored the mitochondrial
topology with the classical grouping of Cabassous and Priodontes within
Tolypeutinae, and a close relationship between Euphractus and
Chaetophractus within Euphractinae. However, low statistical support
values associated with almost equal distributions of apomorphies among
alternatives suggested that two parallel events of rapid speciation
occurred within these two armadillo subfamilies.