Stick Insect Genomes Reveal Natural Selection’s Role in Parallel Speciation

Stick to the Bush Can the underlying genetic changes driving the divergence of populations into new species be predicted or repeated? Soria-Carrasco et al. (p. 738 ) investigated the genetic changes observed after one generation when stick insect ( Timema cristinae ) populations were transplanted from their preferred host plants to alternative hosts. Diverged genetic regions were relatively small, with most loci showing divergence in a single population pair. However, the number of loci showing parallel divergence was greater than expected by chance. Thus, selection can drive parallel phenotypic evolution via parallel genetic changes.