Genetic diversity and gene flow among southeastern Queensland koalas (Phascolarctos cinereus)

Habitat fragmentation and destruction associated with the rapid urban and r ural development of southeast Queensland presents an immediate threat to th e survival of koala populations within this region. A sensitive method comb ining heteroduplex analysis (HDA) with temperature gradient gel electrophor esis (TGGE) was optimized to detect within-species variation in a mitochond rial DNA (mtDNA) control-region fragment, approximate to 670 bp in length, from the koala. Eight different haplotypes were characterized in koalas, of which four were novel. Analysis of mtDNA diversity in 96 koalas from five populations in southeast Queensland revealed that the number of haplotypes in a single population ranged from one to five, with an average within-popu lation haplotype diversity of 0.379 +/- 0.016, and nucleotide diversity of 0.22 +/- 0.001%. Nucleotide divergence between populations averaged 0.09 +/ - 0.001% and ranged from 0.00 to 0.14%. Significant genetic heterogeneity w as observed among most populations, suggesting that koala populations may b e spatially structured along matrilines, although this may not be universal . The limited distribution of the central phylogenetic haplotype suggested the possibility of historical population bottlenecks north of the Gold Coas t, while the presence of two highly divergent haplotypes at the Moreton sit e may indicate the occurrence of one or more undocumented translocation eve nts into this area.