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Speciation in the Carbonated Flower-Piercer (Diglossa carbonaria) Complex of the Andes

1982; Oxford University Press; Volume: 84; Issue: 1 Linguagem: Inglês

10.2307/1367812

1938-5129

Gary R. Graves,

Botanical Research and Applications

The evolution, differentiation, and present distribution of the Carbonated Flower-Piercer (Diglossa carbonaria) superspecies were apparently greatly affected by Pleistocene glacial cycles. Populations of the six principal morphotypes are now largely allopatric, although secondary contact occurs in northern Peru (aterrima and brunneiventris) and northwest Bolivia (brunneiventris and carbonaria). A narrow zone of hybridization between brunneiventris and carbonaria occurs northeast of La Paz, Bolivia. The presence of hybrid-like individuals in allopatric populations from eastern Bolivia (carbonaria), Colombia (humeralis), and Venezuela (gloriosa) may be due to past genetic contact and not to present introgression from nearby forms. The forms aterrima, humeralis, and nocticolor are closely related and conspecific (D. humeralis). The form gloriosa is a distinct allospecies (D. gloriosa). The Colombian population of brunneiventris is subspecifically distinct from the nominate form. The forms brunneiventris and carbonaria are closely related, but assuming the existence of a partial isolating mechanism between them, should be recognized as allospecies (D. brunneiventris and D. carbonaria). I present a model of speciation that accounts for the disjunction of similar phenotypes. I propose that differentiation in isolation occurred in a number of high Andean forest refuges during Pleistocene glacials and interglacials, and that dispersal and genetic contact occurred with altitudinal changes in timberline forest at the beginnings and terminations of glacial periods.