The relationship between developmental instability of gudgeonGobio gobioand abundance or morphology of its ectoparasiteParadiplozoon homoion(Monogenea)

Abstract

GudgeonGobio gobio(Cyprinidae) were collected monthly from the Vlara Stream (Czech Republic) during 2004 and examined for the presence of the ectoparasiteParadiplozoon homoion(Diplozoidae; Monogenea). Over 26% ofP. homoionshowed abnormalities of the attachment sclerites, indicating either a stressful environment or that the quality of the fish host was suboptimal for parasite development. Here, the hypotheses that parasite abundance and the occurrence of morphological abnormalities are correlated with fluctuating asymmetry (FA, the random deviation from the perfect bilateral symmetry) in its fish host were tested. The FA and morphological abnormality are estimators of developmental instability. To estimate fish developmental instability nine meristic and two morphometric bilateral characters on the right and the left sides of the fish were measured. In general, there was no correlation between mean fish FA and parasite abundance or the proportion of parasites with abnormalities. There was, however, a significant relationship between the proportion of abnormalP. homoionand the number of asymmetric meristic traits per individual fish. This study thus indicates that developmental instability ofP. homoion, measured as morphological abnormality of the attachment apparatus, is only weakly dependent on the fish quality as measured by FA.