Habitat loss is not the only threat faced by koalas (Phascolarctos cinereus; pictured). Around half of captive koalas die from cancers associated with retroviruses — viral invaders that insert their DNA into the host’s genome. When such foreign DNA becomes integrated into reproductive cells, it is passed to future generations. Although this evolutionary process occurred millions of years ago in humans, evidence suggests it is ongoing in koalas, leaving them susceptible to diseases caused by disruptions in gene activity.
Competing Interests
The author declares no competing interests.
