Reproductive behavior of Drosophila melanogaster and D. nigrospiracula in the field and in the laboratory.

Publisher Website
Google Scholar
Abstract
The reproductive behaviors of two species of fruit fly, Drosophila melanogaster and D. nigros- piracula, were compared in field and laboratory populations. A number of differences were observed in the behavior of the two species in their natural habitats. D. melanogaster, which was observed on citrus, mates at its feeding site, whereas D. nigrospiracula, which is cactiphilic. mates on a non-resource-based male territory adjacent to its feeding site. In both species large male size is important for reproductive success. However, in D. melanogaster smaller males tended to be excluded from the breeding site and were therefore not among the pool of potential mates to which females were exposed. Sex ratios were biased toward females in both species, but the high frequency of female remating in D. nigrospiracula may have provided more mating opportunities for the males of this species. Field observations differed from laboratory observations, and I discuss the importance of these differences for understanding the evolution of Drosophila mating systems. Organisms in natural populations usually exhibit differen- tial reproductive success, because some individuals are more successful in obtaining mates than others. Because differential mating success may influence the genetic composition o f subsequent generations, evolutionary biologists are concerned with understanding the mechanisms underlying nonrandom mating (Thornhill & Alcock, 1983). The relevant mechanisms may be morphologically (Eberhard, 1985) and behaviorally based (Thornhill & Alcock, 1983). Drosophila has been a popular organism in empirical stud- ies of the basis of differential mating success. Numerous laboratory investigations o f sexual selection i n Drosophila have revealed strong correlations of certain traits with male mating success. Among factors reportedly associated with success in Drosophila melanogaster are increased male body size (Ewing, 1961; Markow, 1987; Partridge & Farquhar, 1983), superior status in aggressive encounters with other males (Dow & von Schilcher, 1975), the ability to defend a territory, such as patch of food or a drop of feces (Jacobs, 1978), and overall courtship vigor or persistence (Markow, 1987). Many of these traits are associated with male success in other insect species as well (Thornhill & Alcock, 1983), but the majority of observations on other insects have been made under field conditions, allowing researchers to make evolu- tionary interpretations with more confidence. Studies in other insect groups have shown that traits associated with mating success differ depending on the ecology of the organisms in question. Although Drosophila mating systems have rarely been studied in natural populations, laboratory findings are unfortunately discussed as though they represent field behav-

This publication has 0 references indexed in Scilit: