A case of rapid diversification in the neotropics: Phylogenetic relationships among Cranioleuca spinetails (Aves, Furnariidae)

Relationships among the 18-19 species of spinetaiIs of the genus Cranioleuc a are difficult to establish. Attempts based on traditional taxonomic chara cters have failed because of a high degree of homoplasy. Most morphological characters vary independently, producing leap-frog patterns of variation a long the Eastern Brazilian Andean track, and behavior and vocalizations var y little. We use mtDNA sequence data from the cyt b and ND2 genes in an att empt to clarify relationships within the genus. We show (i) that Cranioleuc a represents a recent burst of speciation and (ii) that a set of species th ought by Maijer and Fjelds (a) over circle (1997) to form a natural group i s in fact a paraphyletic assemblage which also includes humid forest specie s with different pigmentations and vocalizations. However, synapomorphic va riation in the sequences is not sufficient to unambiguously resolve the rel ationships within the genus. Several species (C. baroni, C. antisiensis, C. pyrrhophia, C. albiceps) show more than one haplotype, without any obvious correlation between genetic and geographic or morphological variation, and the different species do not always show reciprocal monophyly in haplotype diversity. Nevertheless, low genetic differentiation characterizes not onl y allopatric taxa but also some forms which are essentially sympatric, supp orting species rank for the former. Our data suggest a recent diversificati on and proliferation possibly linked to Pleistocene climatic variation and its consequent vegetational shifts, at least in the Andean species. (C) 199 9 Academic Press.