FEMALE ENCOUNTER RATES AND FIGHTING COSTS OF MALES ARE ASSOCIATED WITH LEK SIZE IN DROSOPHILA-MYCETOPHAGA

Male costs and benefits associated with male display size in field pop ulations of an Australian lekking Drosophila species were examined. Re sults suggested that male mating success increased with display size, since matings appeared to be more common in large displays, and since the probability of males encountering a female increased as displays c ontained more males. Female encounter probabilities did not increase o nce about 20 males or more were present on a display. Male size and fi ghting costs tended to increase with display size. The distribution of males among displays did not follow the ideal free distribution in th e sense that each male did not have equal mating opportunity per unit time. Deviation from an ideal free distribution may have been due to f emale preference for mating in aggregations rather than with solitary males, since in a field experiment females were more willing for matin g in an aggregation of five males than with solitary males.