Stick Insects Preserve Unused Reproductive System After 1 Million Years of Asexuality

Scientists have discovered that a long‑term asexual stick insect, *Timema*, has evolved a novel genetic strategy to maintain genomic integrity. Dr. Darren Parker, a lecturer in evolutionary biology at Bangor University, led a comparative genomics study of several *Timema* species that have reproduced without sex for up to one million years—the longest documented asexual period in insects. By sequencing and analysing the genomes of these lineages, the team identified a suite of gene‑expression changes that appear to compensate for the lack of meiotic recombination, a process normally essential for correcting DNA damage and preventing the accumulation of deleterious mutations.

The research, published in *Nature Ecology & Evolution*, shows that asexual *Timema* have up‑regulated DNA repair pathways and altered chromatin‑remodeling mechanisms, allowing them to mitigate the mutational load that typically plagues non‑recombining genomes. These adaptations suggest that the insects have evolved a sophisticated molecular toolkit to sustain long‑term survival without sexual reproduction, challenging the prevailing view that asexual lineages inevitably face rapid decline. The findings also provide new insights into how organisms can circumvent the genetic disadvantages associated with asexuality, offering a broader understanding of evolutionary resilience in the face of reproductive constraints.