DNA fingerprint analysis of a free-range koala population.

Thirty-six koalas in a free-range Queensland population were fingerprinted using an M13 probe in combination with MspI digestion. The technique was found to be highly repeatable, with estimates of 0.1-1.6% within-gel error and 0.1-2.5% between-gel error. Of the 43 different-size fingerprint bands produced in the population, only 2 bands were common to all 36 koalas. Ten bands were quite rare, occurring at a frequency of 0.2 or less. All 36 koalas had unique DNA fingerprints (probability of 1.88 x 10(-7)), which enabled them each to be uniquely identified. Despite this, there was still a high level of band sharing in the population (mean number of shared bands = 0.749). This level is much higher than that reported for humans, birds, cats, dogs, and cattle but not as high as that reported previously for Victorian koalas. This lack of genetic variation may influence the ability of the population to respond to stress situations, such as lack of food, habitat destruction, and disease.