High-Altitude Drosophila of Colombia (Diptera: Drosophilidae)

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Abstract
Collections of Drosophila made in 5 parts of Colombia at altitudes above 6700 ft are compared. D. mesophragmatica Duda and D. sucinea Patterson and Mainland were the dominant species, the percentage of the former decreasing and that of the latter increasing with decreasing altitude. At 5 sites near Bogotá the dominant species were D. mesophragmatica, D. viracochi Brncic and Koref, and D. pseudoobscura Frolova, but in specific ecological sites they might be replaced by other, rarer species. In Bogotá, 2 sites 164 ft apart were compared over a 20-month period; the relative frequencies of the species differed in the same way in nearly all months. These differences are interpreted as being related to ecological preferences. In general, fewer Drosophila were collected in the months following (by 1 month) dry seasons than in those following rainy seasons. Paired comparisons of 2 “wild” sites ¼ mile apart showed differences in the numbers of the various species collected, and also in the relative frequencies. The number of D. mesophragmatica collected monthly in these 2 sites during 1962–3 varied cyclically with relation to the wet-dry seasons.