Phylogeography of the tepui brush finch, Atlapetes personatus (Passeriformes: Passerellidae): Extensive differentiation on the sky islands of the Venezuelan Pantepui

The biogeography and genetic structure of species endemic to the high
elevation sky islands (tepuis) of the Guiana Shield in eastern and
southern Venezuela and adjacent areas of Brazil and Guyana are poorly
known. We investigated the phylogeography and population structure of the
tepui brush finch (Atlapetes personatus) as an exemplar of that biota.
Mitochondrial DNA sequences revealed three monophyletic clades that
correspond to major morphological subspecies groups occurring in eastern,
southern, and northwestern regions of the Pantepui. Differentiation among
the clades accounted for 95% of the total genetic variance. DNA sequences
from three nuclear loci also showed marked divergence among those three
regions. Estimates of gene flow between regions and sampled populations
were all less than one individual per generation. Consequently, these
subspecies groups ought to be recognized as species-level taxa. The
results suggest there is more large-scale biogeographic structure within
the Pantepui region than generally recognized. Additionally, within two of
the three regions, genetic variance among tepuis was substantial at both
mitochondrial and nuclear loci. Many of the sampled populations appear to
be genetically independent units that are nearly cryptic morphologically.
The sampled tepuis may be islands of habitat for this taxon and for
conservation purposes.