Morphology and coexistence of congeneric ectoparasite species:reinforcement of reproductive isolation?
|Title in English||Morphology and coexistence of congeneric ectoparasite species: reinforcement of reproductive isolation?|
|Year of publication||2002|
|Type||Article in Periodical|
|Magazine / Source||Biological Journal of the Linnean Society|
|MU Faculty or unit|
|Keywords||competition; host specificity; morphometric distances; niche segregation; reproductive barriers; reinforcement|
|Description||Several hypotheses to explain morphological differences among congeneric parasite species were tested, assuming that differences or similarities in morphology among congeners living in the same habitat are not a random pattern. These hypotheses were (1) reproductive isolation, (2) niche restriction due to competition, and (3) niche specialisation. Congeneric monogenean (platyhelminth) ectoparasites parasitising the gills of one host species were used as an ecological model. Morphometric distances of the attachment organ and morphometric distances of the copulatory organ between species pairs were used. Levins niche size and Renkonen niche overlap indices were calculated. Our results support the prediction that niche segregation has the function to achieve reproductive isolation of related species in order to prevent hybridisation (reinforcement of reproductive barriers). Parasite species living in the same niche greatly differ in the size of the copulatory organ. Moreover, species coexistence is facilitated by an increase in morphometric distances of copulatory organ and niche centres distances. Our results also show that species living in overlapping niches have similar attachment organs which supports the prediction that morphologically similar species have the same ecological requirements within one host and suggests small effects of interspecific competition for the evolution of morphological diversity of attachment organs. Specialist adaptations also seem to facilitate species coexistence and affect the niche distribution within host species. Parasite species that can colonise more than one host species, i.e. generalists, occupy more distant niches within host species than strictly host specific parasites.|