Molecular phylogeny for Colias butterflies and their relatives (Lepidoptera:Pieridae)

The sulfur butterflies, Colias spp.. and their relatives in the family Pieridae have been the subjects of diverse behavioral, ecological, and evolutionary studies. However, their phylogeny is uncertain in many respects; We used DNA sequences from 2 mitochondrial gene blocks, 333 bp of the cytochrome oxidase I subunit (CO I) and 1,261 bp from the 2 ribosomal genes and the tRNA between them (rDNA), as character sources to test existing phylogenetic hypotheses and begin to infer others. The I DNA block resolves better at deeper nodes of the phylogeny, and the CO I block at shallower nodes. Our results support sister status for subfamilies Coliadinae and Pierinae within Pieridae; independent tribal status for Euchloini and Pierini within Pierinae; status as sister genera for Colias and Zerene within Coliadinae, and monophyly within subgenus C. (Eucolias) of all North American Colias studied. Our I results suggest that the Neotropical coliad genus Eurema may warrant splitting, as some early workers proposed, but do not support the recently proposed splitting of Eurasian C. erate from subgenus C. (Eriocolias) into the separate subgenus C. (Neocolias).