Genetics, morphology, and ecological niche modeling do not support the subspecies status of the endangered Southwestern Willow Flycatcher (Empidonax traillii extimus)

[摘要] ABSTRACT The Willow Flycatcher (Empidonax traillii) breeds throughout much of the United States, northwestern Mexico, and southeastern and southwestern Canada. A subspecies found in the southwestern United States and northwestern Mexico, E. t. extimus (Southwestern Willow Flycatcher), is listed as endangered under the U.S. Endangered Species Act (ESA). This subspecies was described in 1948, based on comparisons of a few external morphological characters from an unstated number of specimens and localities, although it was excluded from the last official list of subspecies by the American Ornithologists' Union. Like most avian subspecies, its validity has not been tested with modern morphological or genetic methods. Recent assessments of the subspecies have assumed it to be a distinct taxon, and some authors have limited their comparisons to E. t. extimus versus E. t. adastus (the subspecies immediately to the north of E. t. extimus), excluding comparison to western (E. t. brewsteri) and eastern (E. t. trai...

[学科分类] 动物科学

[关键词] Endangered Species Act;mitochondrial DNA;niche modeling;plumage coloration;subspecies;Willow Flycatcher