Eroding abodes and vanished bridges: historical biogeography of the substrate specialist pebble-mound mice (pseudomys)

Aim To determine whether the pronounced ecological importance of pebble mounds to pebble-mound mice (Pseudomys) is manifest in their continental biogeography. Location Northern Australia. Methods A GIS-based comparison was made between the habitats contained within the potential climatic distributions of mice, representing a null hypothesis of no habitat selection, and their actual distributions based on all known location records. Results All species had a clear preference for hilly, rocky landscapes with a surficial cover dominated by bedrock. Simple vegetation communities with relatively open eucalypt overstorey and grassy understorey were preferred. Highly degraded rocks and aggradational surfaces and plains were avoided. The extent of the summer monsoon may be important in determining the southern limits of the group’s distribution. Major disjunctions between species were attributable to the presence of clay plains and sand sheets. The behavioural requirement of pebble-mound mice for mounds determines their population distribution pattern and the distribution of the different species within the genus. Main conclusions The behavioural need for pebble mounds drives the distributional pattern of populations and species of pebble-mound mice. The initial spread of pebble-mound mice probably occurred during the late Pliocene or earliest Pleistocene. There has predominantly been degradation of the potential distribution of the group since that time due to the stability of Australian landscapes and Pleistocene planation and sand sheet development over large areas of northern Australia. This process is ongoing, and past regions of rocky contact between current distributions have disappeared, while the distributional limits of several species are steadily being reduced by erosion of hills and the spread of dune fields.