We still don’t know how strange celibate animals evolve

A new study has cast doubt on leading theory for how tiny creatures have evolved for tens of millions of years - without ever having sex. Most animals reproduce sexually, a process which shuffles genes from parent to offspring. This makes natural selection more efficient and allows animals to evolve defences against changing environmental conditions more rapidly, especially new diseases. We thought we were understanding more about these creatures, but this is a spanner in the works. Professor Tim Barraclough Bdelloid rotifers however appear to be an exception to this rule: they are all female, and their offspring are clones of their mothers. Bdelloids are microscopic animals that live in freshwater and damp habitats across the world. Despite their apparent lack of sex, we know they have evolved for tens of millions of years into more than 500 species.