NAMED SUBSPECIES AND THEIR SIGNIFICANCE IN CONTEMPORARY ORNITHOLOGY

Subspecies, or geographic races, are diagnosable populations that, at least during the breeding season, are largely allopatric with other subspecies of the same species. In attempts to give objectivity to the subspecies concept, arbitrary rules have been applied for the recognition of subspecies (e.g., the "75% rule," whereby 75% of the individuals should be identifiable to subspecies; there are several other rules). As a case study, I examined the usefulness of the subspecies concept in describing geographic variation of a polytypic American songbird, the Savannah Sparrow (Passerculus sandwichensis). About 21 subspecies of this species have been recognized in the taxonomic literature, but much of the geographic variation is clinal. I argue that there is little value in subdividing a clinal continuum into different subspecies. Rather, the use of subspecies is best restricted to distinctive, and usually geographically isolated, populations. I show that this has been done for only a few of the named subspecies of Savannah Sparrows. [PUBLICATION ABSTRACT]