Competition between Sibling Species of the Pseudoobscura Subgroup of Drosophila

Abstract

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STUDIES ON NATURAL POPULATIONS OFDROSOPHILAVI. COMPETITION BETWEENDROSOPHILA MELANOGASTERANDDROSOPHILA SIMULANS

“…Females of both species emerged, fly. in general, before males by about one day at 15 C and by a few hours a t 25 C. Similar results have been reported by Sokoloff (1955), Bakker (1961, Furuya andMuri (1961), andMiller (1964) for different species of Drosophila. Figure 2 shows the results of interspecies competition.…”

Intraspecific Competition and the Regulation of Insect Numbers

“…Within a certain density range, larval mortality has been shown to increase in some Diptera [Chrysomyia (130) , Drosophila (11,67,110,121), Lucilia (108,130), Musca (20, 65,137), and Phormia (137)]. The same has been found to occur in some Lepidoptera and Coleoptera This type of relationship has been considered by Andersen (2, 3) in a brief review of the subject.…”

“…(120)]. In some species it was established that pupal or adult weight or size decreased to a minimum value corresponding to the minimum larval weight necessary for pupation [Chry somyia (130); Drosophila (11,24,121); Lucilia (108, 130); Musca (65, 137); Phormia (137) . This minimum size limit has not been found in Ephestia (125,131) and in other experiments with Musca (20) , but this may be due to an abnormal variability between the competitors with respect to this characteristic in the populations studied.…”

Distribution, Coexistence, and Competition of Whirligig Beetles

“…In wasp larvae the entire numerical decline (due to \~~ The fact that larvae of Dineutes nigrior under a food-limited regime display a slowed developmental rate would further moderate the use of cannibalism in population regulation, and allow higher ultimate survival. This extension of larval developmental time has been found in larval competition experiments with certain species of Drosophila (Sokoloff, 1955;Miller, 1964). In Drosophila, a species which possesses this capacity has the advantage in competition with a species possessing an inflexible developmental rate.…”

“…A similar explanation may or may not apply in the case of Drosophila. Sokoloff (1955) has pointed out that it remains problematic whether competition for food ever occurs in natural Drosophila populations.…”