VARIATION IN SPERM LENGTH IN THE YELLOW DUNG FLY SCATHOPHAGA-STERCORARIA (L)

We examine the relationship between a male's body size and the length of his sperm in the yellow dung fly Scathophaga stercoraria (L). Sperm length could affect the outcome of sperm competition, which is known to be important in this species. Sperm were monomorphic but varied sig nificantly amongst males. However, there was no significant relationsh ip between a male's size and the mean length of his sperm. We conclude that variation in sperm length will not affect conclusions about sper m competition drawn for S. stercoraria