Niche width of parasites in species-rich and species-poor communities

Summary Niche width of ectoparasites of marine fishes, as measured by host range and microhabitat width, is not affected by the number of species in a community. There is no reduction in species numbers of Monogenea due to greater numbers of other parasite species, and frequencies of infection with Monogenea are greater in tropical, species-rich communities.Supported by grants from the Australian Research Grants Committee and the University of New England. M. Heap provided valuable technical assistance, and F. Roubal made his data onAcanthopagrus australis available to me.