LOW GENETIC-VARIABILITY OF THE KOALA PHASCOLARCTOS-CINEREUS IN SOUTH-EASTERN AUSTRALIA FOLLOWING A SEVERE POPULATION BOTTLENECK

Genotyping of koalas at CA-repeat microsatellite loci has revealed sig nificant differences in the levels of allelic diversity (A) and expect ed heterozygosity ((H) over bar(E)) between populations from north-eas tern and south-eastern Australia. In the 10 populations studied, allel ic diversity ranged from 8.0 in the Nowendoc population to 1.7 in the Kangaroo Is. population, and values of (H) over bar(E) ranged from 0.8 31 in the Nowendoc population to 0.331 in the Kangaroo Is. population. Data from pooled populations revealed koalas from the northeastern re gion had significantly higher levels of allelic diversity (A = 11.5+/- 1.4) than those from south-eastern Australia (A = 5.3+/-1.0). Furtherm ore significantly higher heterozygosity levels were found in the north -eastern ((H) over bar(E) = 0.851) vs. the south-eastern ((H) over bar (E) = 0.436) regions of Australia. Following a near-extinction bottlen eck in the 1920s, mainland Victorian and Kangaroo Is. koalas have been involved in an extensive program of relocations. The source populatio ns of the relocated animals were islands in Westernport Bay, which wer e founded by very few individuals in the late 1800s and early 1900s. T he significantly lower levels of variation between south-eastern Austr alian populations suggests that human intervention has had a severe ef fect on levels of genetic diversity in this region, and this may have long-term genetic consequences.