Asexual reproduction can have negative effects on genome evolution in stick insects, study finds

The results have been published on 23 February under the title 'Convergent consequences of parthenogenesis on stick insect genomes' inScience Advances.

Offspring are produced via two main reproductive pathways: sexual, i.e. fertilization between male and female gametes, or asexual, for example parthogenesis. In parthenogenesis, females pass on their genes without a male being involved.Timemaare a genus of stick insects native to western North America, and includes both sexually and asexually reproducing species. The biologists discovered that in asexually reproducingTimema, beneficial mutations cannot be passed on as efficiently in the long term.

Like humans,Timemahave a double set of chromosomes. The extent to which these two genome copies differ is described as heterozygosity. During parthenogenesis, however, this difference is lost and the two genome copies become very similar. This reduces variability, which can be important for species to adapt to their environment.

The research team analysed the genomes of five asexualTimemaspecies and closely related sexually species that reproduce sexually. "The results show that genetic exchange during sexual reproduction promotes the speed of adaptation and genetic diversity in the insects' natural populations," said Dr Jens Bast.