Parasite-mediated sexual selection may arise as a consequence of 1) females avoiding mates with directly transmitted parasites, 2) females choosing less-parasitized males that provide parental care of superior quality, or 3) females choosing males with few parasites in order to obtain genes for parasite resistance in their offspring. Studies of specific host-parasite systems and comparative analyses have revealed both supportive and conflicting evidence for these hypotheses. A meta-analysis of the available evidence revealed a negative relationship between parasite load and the expression of male secondary sexual characters. Experimental studies yielded more strongly negative relationships than observations did, and the relationships were more strongly negative for ectoparasites than for endoparasites. There was no significant difference in the magnitude of the negative effect for species with and without male parental care, or between behavioral and morphological secondary sexual characters. There was a significant difference between studies based on host immune function and those based on parasite loads, with stronger effects for measures of immune function, suggesting that the many negative results from previous analyses of parasite-mediated sexual selection may be explained because relatively benign parasites were studied. The multivariate analyses demonstrating strong effect sizes of immune function in relation to the expression of secondary sexual characters, and for species with male parental care as compared to those without, suggest that parasite resistance may be a general determinant of parasite-mediated sexual selection.

Cestodes from four badgers (Meles meles) and eight raccoons (Procyon lotor) were studied. The badgers and seven of the raccoons were taken from the wild near the city of Berlin, Germany. This paper is the first record of Atriotaenia incisa (Railliet, 1899) (Cestoda: Anoplocephalidae) from P. lotor in Europe. Atriotaenia incisa is redescribed and compared with morphological descriptions of the North American species Atriotaenia procyonis (Chandler, 1942), a common parasite of the raccoon in Canada and the United States. No morphological differences were found between the two species and it is suggested that they may be conspecific.