When black plus white equals gray: the nature of variation in the Variable Seedeater complex (Emberizinae: Sporophila)

Wing-barred Seedeater (Sporophila americana) Science Article 1

abstract

The degree of relationship between the Variable (Sporophila aurita) and Wing-barred (S. americana) Seedeaters has been debated for over 80 years. The discovery of a zone of hybridization between the former and the Gray Seedeater (S. intermedia), not previously considered to be closely related because of its gray rather than black-and-white adult 0′ plumage, prompted me to reexamine this question. M y working hypothesis of a close relationship between all of these forms was supported by their very similar morphology and almost perfectly complementar y distributions, the recognition of another zone of limited overlap and hybridization, and by heretofore unappreciated variation within S. intermedia itself. I conclude that S. intermedia is in effect a member of an enlarged Variable Seedeater complex, a monophyletic unit best recognized at the superspecies level. Patterns of morphological differentiation and distribution lead me to propose the recognition of four allospecies: S. corvina ( = ‘aurita’), Variable Seedeater; S. intermedia, Gray Seedeater; S. murallae, Caqueta Seedeater; and S. americana, Wing-barred Seedeater. Quantitative analysis of the variation within S. i. intermedia indicates that the subspecies agustini is not recognizable; likewise, synonynuzation of S. c. chocoana, suggested in a previous study, is supported. A tentative hypothesis for the historical zoogeography of the group is proposed

F. Gary Stiles, ORNITOLOGIA NEOTROPICAL 7: 75-107,

Download article


Updated: December 27, 2011 — 9:53 am

Leave a Reply