The Sensory Basis of Mate Selection Indrosophila

have studied the relationship between the relative frequencies of two types of Drosophila males in a confined space and their mating efficiency. They all found that the less abundant males achieve mating more frequently than do these same males when they are the majority. This phenomenon has now been observed in Drosophila melanogaster, D. pseudoobscura, D. persimilis, D. tropicalis, D. wiUistoni, and D. equinoxialis using strains carrying different chromosomes, of different geographic origins, mutants versus wild types, and even strains raised at different temperatures. But the physiological basis of the mating advantage of rare forms was totally unknown. Initial attempts to identify the signals which allow Drosophila females to perceive the relative frequency of males courting them were inconclusive (Ehrman, 1967). This present paper will report the results of additional experiments undertaken to probe more accurately, the sensory basis of the relationship between genotype frequency and mating success in Drosophila pseudoobscura. To express the problem more simply, "How does a Drosophila female know which males are rare?"