Boxplot of the body sizes as a function of the size classes for each sex. Body size was measured as the standard length, from the tip of the mouth to the caudal peduncle. Females (grey boxes) were assigned to two size classes: small (n = 20) and large (n = 20). Males (white boxes) were assigned to three size classes: small (n = 20), medium (n = 20), and large (n = 20). For a given size class, the black dot depicts the mean, the thick line the median, and the box the interquartile range. Within a pair of females or within a triplet of males, there was a difference of at least 1 cm between each individual.