Genetic effects of habitat contraction on Lumholtz's tree-kangaroo ( Dendrolagus lumholtzi ) in the Australian Wet Tropics

Abstract

Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi) is one of two species of tree-kangaroo resident in the tropical rainforests of north-eastern Australia. The species is confined to the Wet Tropics region, with its distribution centred on the Atherton Tablelands. While D. lumholtzi was exposed to periodic large-scale climatic fluctuations during the Quaternary that have effectively acted as natural fragmentation events, the species is currently under pressure from anthropogenic disturbance and habitat fragmentation. This study aimed to assess the level of genetic diversity in D. lumholtzi by examining hypervariable microsatellite loci and the control region of mitochondrial DNA (mtDNA) in 21 individuals from a single 20 ha forest fragment, and from a further 24 animals collected throughout the Atherton Tablelands. Results suggest that D. lumholtzi has relatively low levels of genetic diversity which is uniformly distributed throughout the Atherton Tablelands; a pattern congruent with data from many other vertebrates endemic to the Australian Wet Tropics. It is suggested that Pleistocene climatic fluctuations, which resulted in large-scale rainforest contractions, have imposed an ancient population bottleneck on the ancestral D. lumholtzi population. The apparent over-riding influence of these natural, historical effects on the genetic structure of D. lumholtzi populations, will complicate attempts to assess the genetic impact of current anthropogenic habitat loss and fragmentation.