ORNAMENTATION PREDICTS REPRODUCTIVE SUCCESS IN FEMALE PIPEFISH

In the sex-role reversed pipefish Syngnathus typhle females compete fo r access to males and males are choosy. Females develop a temporary or nament when competing over mates with other females and when performin g nuptial dances with males. This ornament is an amplification of the normal striped pattern in these fishes. We here show experimentally th at (1) the contrast of this normal pattern forecasts the extent to whi ch the ornament is shown, (2) contrast and ornamentation honestly sign al female quality (egg numbers), (3) contrast and ornamentation accura tely predict female mating success, (4) contrast is a phenotypically p lastic trait specifically exaggerated under situations of female - fem ale competition, and (5) neither contrast nor ornament. are energetica lly expensive to the females (i.e., they are independent of short-term nutritional status). Hence, as predicted in sex-role reversed species , ornament design is constrained by costs to female fecundity: an ener getically demanding ornament would impair on a female's ability to pro duce eggs. The type of ornament described here is the expected one, co stly for reasons other than being energetically expensive to produce.