Effects of multiple mating and male eye span on female reproductive output in the stalk-eyed fly, Cyrtodiopsis dalmanni

Females of the stalk-eyed fly, Cyrtodiopsis dalmanni, mate repeatedly during their lifetime and exhibit mating preference for males with large eye span. How these mating decisions affect female fitness is not fully understood. In this study, we examined the effects of multiple mating and male eye span on short-term reproductive output in this species. Experiments that manipulated the number of copulations and partners a female received suggested that obtaining a sufficient sperm supply is an important benefit associated with multiple mating. The average percentage of fertile eggs laid by females increased as a function of mating frequency and ranged from 40% for females mated once, to 80% for females mated continuously. In addition, a high proportion of copulations in this species appeared to be unsuccessful. One-third of all females mated once laid less than 10% fertile eggs. There was no significant difference in reproductive performance between females mated to multiple partners and females mated to a single partner. There was also no indication that females received any short-term reproductive benefits from mating with males with large eye span. In fact, females mated to males with short eye span laid a higher percentage of fertile eggs than females mated to large eye span males.