Stick insects that are normally asexual may occasionally have sex

Two supposedly asexual species of stick insects may engage in occasional bouts of sex, helping to widen their gene pool and avoid harmful mutations.

A handful of animals reproduce asexually, primarily through a process known as parthenogenesis, which involves creating embryos from unfertilised eggs. Species that do this include some insects, reptiles and fish.

“All members of a parthenogenetic population can produce offspring, so they have this huge demographic advantage,” says Darren Parker at Bangor University in the UK. This is because …