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

Females of the stalk-eyed fly, Cyrtodiopsis dalmanni, mate repeatedly durin g their lifetime and exhibit mating preference for males with large eye spa n. How these mating decisions affect female fitness is not fully understood . In this study, we examined the effects of multiple mating and male eye sp an on short-term reproductive output in this species. Experiments that mani pulated 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 femal es increased as a function of mating frequency and ranged from 40% for fema les 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 f rom 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 m ated to large eye span males.