Geographic ranges, sympatry and the influence of environmental factors on the distribution of species of an endemic Tasmanian freshwater crayfish

Abstract

The Tasmanian endemic freshwater crayfish genus Parastacoides is presently under review and 14 species have been recognised. The distributions of the putative species have been mapped using museum data. The distribution of geographical ranges of the species is highly skewed. Most species are local or short-range endemics, with 11 of the 14 species (nearly 79%) having geographical ranges of less than 20 km². Many sympatric contact zones exist where distributions of species meet and in some cases the sympatric species partition the habitat. The majority of species appear to be capable of exploiting a wide variety of habitat types. Ecological factors such as climate, vegetation, substrate, baseline geology and burrow type do not seem to be major determinants of species distributions, but adequate rainfall and a low evaporation rate appear to be the major factors determining the eastern boundary of Parastacoides. It is likely that historical factors have played an important role in determining the present distribution patterns.