Contemporary genetic structure reflects historical drainage isolation in an A ustralian snapping turtle, E lseya albagula

Effective spatial classification of freshwater biodiversity remains a worldwide conservation challenge. The isolating nature of catchment boundaries over evolutionary timescales makes them potentially important in defining natural units for biodiversity management. We sought to clarify biogeographical relationships amongst drainages within A ustralia's biodiverse mid‐eastern coastal region ( F itzroy, B urnett, and M ary C atchments) where freshwater communities face considerable urban pressure, using a locally endemic riverine specialist, the white‐throated snapping turtle, E lseya albagula . Mitochondrial and nuclear microsatellite data sets were employed to investigate past and present influences on population connectivity and to identify units for management. Populations within catchments were largely well connected genetically. However, the F itzroy C atchment contained a distinct genetic lineage, deeply divergent from a second lineage present across the B urnett and M ary C atchments. The two lineages can be considered evolutionarily significant units that reflect historical isolation of the F itzroy and recent coalescence of the B urnett‐ M ary C atchments during lowered Pleistocene sea levels. Congruence with geological evidence and patterns reported for fish and macroinvertebrates supports a shared biogeographical history of a diverse regional biota. This work highlights the need for better spatial classification of freshwater biodiversity at local as well as regional scales, including recognition of potentially cryptic diversity amongst individual river drainages. © 2013 The Linnean Society of London