Mitochondrial Phylogeny of the GenusRegulusand Implications on the Evolution of Breeding Behavior in Sylvioid Songbirds

Abstract

We tested four hypotheses about the relationships of the kinglets (genusRegulus) to seven closely related genera of the songbird superfamily Sylvioidea using mitochondrial DNA sequences. The kinglets were suggested to be closely related to the tits (Parus) or to the Old World Warblers (Phylloscopus) and were also suggested to constitute the, or at least one of the, most ancestral splits among the sylvioids. Our phylogenetic analysis grouped the kinglets as the sister group of a clade comprisingParusandPhylloscopusand including the generaSylvia, Aegithalos,andLeptopoecile.Two of the taxa were placed more ancestral to the kinglets:SittaandCerthia.We also identified the endemic kinglet species from the Canary Islands as the sister group ofR. regulus.The superimposition of breeding behavior on the phylogeny suggests that hole nesting is ancestral and various other patterns of nest construction have evolved from it. The placement ofParusimplies that hole nesting in the Paridae is likely to have originated secondarily. Further,LeptopoecileandAegithalos,two genera for which a helper system of elder offspring in breeding was described, were resolved as a clade.