PARASITE BODY-SIZE DISTRIBUTIONS - INTERPRETING PATTERNS OF SKEWNESS

We examined the distributions of log body sizes of parasite species to test the prediction that the different physical constraints acting on endoparasites and ectoparasites can lead to different size distributi ons, and to see whether the distributions of parasite body sizes diffe r from those of free-living animals. We used body size distributions f rom 19 groups of parasitic or free-living animals, including over 7000 species and almost 2400 genera. There were differences between the bo dy size distributions of male and female parasites, and between the bo dy size distributions of related parasites exploiting different types of hosts. In general, parasite body size distributions were less frequ ently log right skewed than those of free-living animals. Ectoparasite s tended to have more symmetric body size distributions than endoparas ites, in which the most speciose size classes tended to be the smaller ones. Severe space constraints and a greater diversity of small niche s may only allow the diversification of small endoparasites, whereas e ctoparasite body sizes may face less severe limitations. (C) 1997 Aust ralian Society for Parasitology. Published by Elsevier Science Ltd.