A MULTIFACTORIAL BEHAVIORAL STUDY OF COEXISTING DROSOPHILID SPECIES IN NATURE

A multifactorial experiment was performed to differentiate among sympatric drosophilid species by their responses to several variable factors when selecting an oviposition site in nature. D. busckii, D. affinis, and S. pallida were significantly more photonegative when ovipositing 150 cm above the ground than when ovipositing 30 cm above the ground. D. busckii showed the greatest effect of height on photoresponse. D. affinis was the most photonegative at either height. There was no evidence for photobehavioral differentiation of the four species studied between two collecting sites within the habitat. Similarly, there was no difference in oviposition-site preference between flies laying eggs in the morning and the afternoon. Three of the four sympatric species can be distinguished from the others by their unique behavioral profiles, which are probably responsible for maintaining niche separation.