Courtship behavior and the kinetics of mating in three lines ofDrosophila simulans and their hybrids

Mating inDrosophila is precisely characterized by an exponential phase based on second-order kinetics coupled with an initial lag phase based on zeroth-order kinetics. In this model, the two separate kinetic phases are quantified by separate parameters. Three genetically distinct lines ofDrosophila simulans differing in male and female mating propensities (measured by the relative frequencies of animals mating after a fixed interval of time) also differed sharply in both parameters of mating kinetics. One line was highly outcrossed and the other two, derivatives of the first, had been subjected to genetic drift. The lines and their F₁ hybrids were studied in no-choice mating tests with a control line to determine the two parameters describing mating kinetics and were observed in pair matings to measure four courtship traits. The two parameters of mating kinetics (L, which describes the lag phase, andK, which describes the exponential phase) and the mean percentage mating varied widely across the nine types, in both sexes. The logarithm ofL was linearly related to the percentage mating (r²=0.732);L andK were not significantly correlated. Among female genotypes, only one courtship trait varied significantly—the latency from coconfinement of female and male to initiation of courtship; among male genotypes, the duration of the two wing displays, scissor and vibrate, varied significantly. LogK was significantly (P<0.01) correlated with the latency to courtship (r=–0.626) and with the duration of two components, orient (r=0.701) and scissor (r=0.698), whereas logL and percentage mating were not significantly correlated with components of courtship. There was evidence of inbreeding depression forL, but not forK, in both sexes of the drift lines.The research was supported in part by NSF Grant DEB 7903866 and a grant from the University of Maine and by the Computing Center of the University of Maine.