Australasian Science: Australia's authority on science since 1938

Genetic Clues to Managing Koala Demise

Genetic patterns in koala populations have revealed that the right balance between tree cover and roads is required to save koala populations from urban growth.

While koalas spend most of their time in trees, they move between trees on the ground.

“When they move across landscapes to mate, they transfer their genes across the landscape too,” says Dr Jonathan Rhodes of The University of Queensland. “By identifying koalas’ genetic connectivity – how their genes are distributed across landscapes – scientists can establish how viable a population is. We can also identify the main landscape features that influence this gene flow.”

The study found that genetic connectivity drops rapidly once the percentage of forest cover falls below 30%. Areas with little or no forest cover had rates of gene flow three times lower than areas where foliage cover was 100%. “We also found that the presence of highways reduces gene flow dramatically compared to areas without roads,” Rhodes says. “If you throw in a major highway, genetic dispersal is greatly impeded regardless of how much forest cover is present.”

To enhance gene flow, Rhodes says “habitat bridges and underpasses beneath highways need to be implemented as they can play an important role, particularly where highways are adjacent to koala habitats”.