Sexual Dichromatism in North American Freshwater Fish: Do Parasites Play a Role?

North American freshwater fish were scored for parasites and sexual dichromatism to test the interspecific prediction of the Hamilton-Zuk hypothesis that more sexually dichromatic fish species should harbour more parasites. We used two measures of parasite load, the mean number of helminth species per individual host and the total number of parasite genera reported per host species.Data were collected on 68 species of indigenous, non driadromous North American freshwater fishes