Variation in lek return rates between the sexes and selection for mate acquisition traits in a female-ornamented fly, Rhamphmyia longicauda (Loew, 1861)
Tuesday, November 15, 2022
4:54 PM – 5:06 PM PT
Location: Vancouver Convention Centre, Meeting Room 212
Charismatic male traits that improve mate acquisition, despite their viability costs, are well documented. While much less studied, similarly costly traits also occur in females. Typically, males are the sex expected to be under greater sexual selection, with higher time spent competing for mates in mating arenas. Theory predicts that the mating rate of each sex will be a function of their time spent in the mating arena, competition for limited mates, and their investment in mate acquisition traits. In this study we test this theory empirically using the sex role-reversed long-tailed dance fly, Rhamphomyia longicauda; females display sex-specific ornaments while swarming in leks to acquire nuptial gifts that are critical for reproduction. We measured the frequency with which both sexes return to the lek, degree of ornamentation and operational sex ratio (OSR) as a proxy for mate competition intensity. We show that females invest heavily in attractive and costly ornaments, experience strong mating competition (female biased OSR), and have high lek return rates that mirror theoretical predictions for males. We argue that high lek return rates for female dance flies are a function, not of selection for increased mating rates, but of selection for resource acquisition.
