MITOCHONDRIAL PHYLOGENY OF THE GENUS REGULUS AND IMPLICATIONS ON THE EVOLUTION OF BREEDING-BEHAVIOR IN SYLVIOID SONGBIRDS

We tested four hypotheses about the relationships of the kinglets (gen us Regulus) to seven closely related genera of the songbird superfamil y Sylvioidea using mitochondrial DNA sequences. The kinglets were sugg ested to be closely related to the tits (Parus) or to the Old World Wa rblers (Phylloscopus) and were also suggested to constitute the, or at least one of the, most ancestral splits among the sylvioids. Our phyl ogenetic analysis grouped the kinglets as the sister group of a clade comprising Parus and Phylloscopus and including the genera Sylvia, Aeg ithalos, and Leptopoecile. Two of the taxa mere placed more ancestral to the kinglets: Sitta and Certhia. We also identified the endemic kin glet species from the Canary Islands as the sister group of R. regulus . The superimposition of breeding behavior on the phylogeny suggests t hat hole nesting is ancestral and various other patterns of nest const ruction have evolved from it. The placement of Parus implies that hole nesting in the Paridae is likely to have originated secondarily. Furt her, Leptopoecile and Aegithalos, two genera for which a helper system of elder offspring in breeding was described, were resolved as a clad e. (C) 1998 Academic Press.