Article Abstract:
Allozyme electrophoresis was used in the evaluation of genetic variation among four Mexican populations each of Common Bush-tanagers (Chlorospingus ophthalmicus) and Chestnut-capped Brush-finches (Atlapetes brunneinucha). Within-population genetic variation in Chlorospingus and Atlapetes is typical of bird species diversity, but among-populations of both species are strongly genetically differentiated. Geographic distance among populations is does not affect variation. Both species have sufficient genetic isolation so that most of the populations must differentiate by genetic drift alone.
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Article Abstract:
Parus (P.) bicolor and P. inornatus are more evolutionarily related than P. wollweberi, which diverged earlier in the geologic timescale. The patterns of mitochondrial DNA divergence among the three titmice species provides a critical assessment of genetic divergence in the present taxonomy of titmice. A high mitochondrial DNA divergence existed between two subspecies of P. inornatus in contrast to the low divergence between subspecies of bicolor and wollweberi. Further research may separate the interior and coastal P. inornatus as two distinct species.
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Article Abstract:
Mitochondrial sequences were employed to investigate the phylogenetic relationships among species of chat-tyrants scattered along the length of the Andes. Findings showed large divergence and multiple base substitutions at some locations between geographically overlapping species. The diversity may have occurred even before the Pleistocene Era while the vicariance patterns may indicate events during the lower Pleistocene. Findings are in agreement with the monophyly of all chat-tyrants but with a distinctive internal structure.
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