Melospiza melodia

Exhibits a well-structured continental pattern of morphological variation, but mtDNA variation is not geographically structured and subspecies are not identifiable by mtDNA analysis (Zink and Dittman 1993, Ball and Avise 1992). MtDNA data indicate that there may be barriers to gene flow between island and mainland populations in Alaska that are more severe than barriers of some populations in the contiguous U.S., but not effective enough, or ancient enough, to have produced deep branches in the intraspecific mtDNA phylogeny; genetic distance is small, even among subspecies with very divergent phenotypes; phenotypic differences used to define subspecies may have evolved fairly rapidly or they may be environmentally induced (Hare and Shields 1992).

BREEDING: southern Alaska and southern Mackenzie to northern Saskatchewan and Newfoundland, south to southern Baja California, southern Mexico, northern New Mexico, northern Arkansas, northeastern Alabama, and South Carolina. NON-BREEDING: southern Alaska, coastal and southern British Columbia, northern U.S., and southeastern Canada south through the breeding range and the southeastern U.S.

Subspecies GRAMINEA of Santa Barbara Island, California, is extinct, due to habitat destruction by introduced hares followed by an extensive fire (Ehrlich et al. 1992).