DEVELOPMENT TIME AND PUPATION BEHAVIOR IN THE DROSOPHILA-MELANOGASTER SUBGROUP (DIPTERA, DROSOPHILIDAE)

This study is an in-depth analysis of intersexual, intraspecific, and interspecific variability in larvopupal developmental time, pupation site preference, and larval and pupal survival of a number of isofemale lines of the species Drosophila mauritiana, D. melanogaster, D. sechellia, D. simulans, D. teissieri, and D. yakuba. There was no significant sex differences in pupation height, but females eclosed significantly earlier than males in all species. In addition, the suggestion of a strong negative correlation between larval developmental time and pupation height could not be confirmed in this study. The hypothesis that differences in pupation height provide a basis for niche partitioning between closely related species with overlapping distributions was tested by three planned orthogonal contrast analyses of variance. First, the two species D. teissieri and D. yakuba, with largely overlapping distribution, were significantly different in pupation height. Second, the two allopatric, nonoverlapping island species D. mauritiana and D. sechellia did not significantly differ in pupation height. However, the absence of a significant difference in the final contrast between the two cosmopolitan species D. melanogaster and D. simulans, which are often found together, makes us cautious to accept the hypothesis.