Molecular data reveal some major adaptational shifts in the early evolution of the most diverse avian family, the Furnariidae

Abstract

A robust phylogeny estimate for the family Furnariidae (sensu lato) was obtained using sequences of two nuclear introns and one mitochondrial gene (cyt b). Contrary to the widely accepted sister-group relationship of ovenbirds (Furnariinae) and woodcreepers (Dendrocolaptinae), a basal clade is suggested for Sclerurus and Geositta, while Xenops, hitherto considered an aberrant ovenbird, was found to occupy a basal position on the woodcreeper lineage. The morphological variation is re-interpreted in view of this revised phylogenetic hypothesis. Presumably, the remarkable adaptive radiation in this family started as primitive, Sclerurus-likes forms, which used the tail as a prop during terrestrial feeding, lured up to seek food on tree-trunks. The two basal woodcreeper genera, Xenops and then Glyphorynchus, show strong cranial specializations for hammering in wood, thus presenting a remarkable parallelism with the family Picidae, Xenops resembling a piculet, Glyphorynchus, a diminutive woodpecker. However, this specialization was lost in other woodcreepers, which show a more normal passerine skull, adapted for probing and prying in tree-trunk crevices and sallying for escaping insects. The ovenbirds developed a more flexible (rhynchokinetic) bill, well suited for probing and retrieving hidden prey in dead-leaf clusters and debris suspended in the vegetation, and in epiphyte masses. Adaptations to live in open terrain are secondary.