Helminth community structure in Rattus leucopus (Gray) (Muridae) from Australia, Papua New Guinea and Papua

This study describes the helminth community in 28 Rattus leucopus, from Australia, Papua New Guinea and Papua ( formerly Irian Jaya), and compares the community in Australian R. leucopus with those known from two other Australian endemics, R. sordidus and R. fuscipes. In total, 28 parasite species were found: one acanthocephalan, five cestodes, one trematode and 21 nematodes as well as two lots of unidentified spirurid nematode larvae. The diversity of helminths in R. leucopus was high but equitable; the reciprocal of Simpson's Index was 1.75. The distribution of prevalence of helminth species was not indicative of a core-satellite structure. No species occurred at a prevalence >30% and more than half the species occurred at prevalences of <10%. Only 10% of the helminth species identified were unique to R. leucopus. Helminth community structure in R. leucopus differed from that observed in R. sordidus and the community in R. fuscipes was markedly different from those in R. leucopus and R. sordidus. Determinants of the diversity of the helminth community in R. leucopus include the time intervals between the three waves of migration of Rattus spp. to Australia, biogeographic factors related to immigration and adaptive radiation of the host genus, and associated with coevolution, speciation and host switching of the helminths.