Comparative karyology in nine-primaried oscines (Aves).

Abstract

The group known as the new world nine-primaried oscines is a large and diverse group containing about 10% of the living species of birds. The group is poorly known karyologically and phylogenetic relationships of some species within the group remain uncertain. In this paper, karyological data relating to the relationships of three species are presented. The data is also useful for exploring the nature of chromosomal evolution in birds. Two species of Parulinae were studied, with other warblers for comparison. Karyological data strongly supported removal of the Olive Warbler, Peucedramus taeniatus, from Parulinae. The Yellow-breasted Chat, Icteria virens, was found to be aberrant but properly a member of Parulinae. The genus Dendroica was found karyotypically conservative, with no differences between four species. The genus Vermivora was distinguished from other genera by large blocks of heterochromatin at the centromeres of most macrochromosomes. It appears that the Five-striped Sparrow, Amphispiza quinquestriata, is properly placed in its genus according to analysis of a data set that combined karyological and morphological data. This work strongly suggests that Chromosomal evolution is decoupled from the speciation process in Emberizidae. More intrageneric karyotypic variation was found within Emberizinae than has been previously reported from any bird taxon. There was a great deal of karyotypic rearrangement between species in Thraupinae and Cardinalinae. The rearrangements appear to be due to pericentric inversion. The heteromorphisms in the karyotypes of A. quinquestriata and Pipilo erythrophthalmus when combined with reports of heteromorphisms in other nine-primaried oscine species suggest this group has mechanisms to avoid meiotic irregularities usually associated with pericentric inversion. Further karyological studies of the nine-primaried oscines are required to improve our understanding of chromosomal evolution in the group.