Ae. Delosmonteros et J. Cracraft, INTERGENERIC RELATIONSHIPS OF THE NEW-WORLD-JAYS INFERRED FROM CYTOCHROME-B GENE-SEQUENCES, The Condor, 99(2), 1997, pp. 490-502
The six genera of corvids endemic to the Americas (i.e., Aphelocoma, C
alocitta, Cyanocitta, Cyanocorax, Cyanolyca, and Gymnorhinus) form the
assemblage that most ornithologists call the New World jays. The inte
rgeneric relationships among these six genera are explored using compl
ete sequences from the cytochrome b gene (1,143 bp) along with 29 morp
hological characters. A consistent phylogenetic hypothesis was obtaine
d when the data sets were analyzed independently or in a total evidenc
e approach. The phylogeny presented in this paper does not corroborate
the existence of two evolutionary lineages as previously proposed by
Hardy (1961, 1969). The most basal genus of the New World jays is Cyan
olyca, which also is supported by independent evidence on cranial anat
omy. The remainder of the genera are embedded within two major clades.
The most derived is formed by Cyanocitta, Aphelocoma, and Gymnorhinus
, being Cyanocitta the most basal genus within this clade. Calocitta a
nd Cyanocorax constitute the other clade. A very close relationship be
tween these two genera is supported by bootstrap values and branch sup
port analysis. These results corroborate the hypothesis that the Pinon
Jay (Gymnorhinus cyanocephalus) is a true New World jay, and a putati
ve relationship with nutcrackers is not supported. The phylogeny obtai
ned is used to infer a biogeographic scenario, as well to explain the
evolution of a very derived jaw articulation present only in the New W
orld jays. The biogeographic scenario agrees with a relatively recent
arrival of a corvine ancestor via Beringia, and a very rapid dispersal
and radiation into the Americas.