This is an interesting article where the authors compare divergence at different taxonomic levels: between ecotypes within a species and between different species. The results indicate that niche dimensionality is important in evolutionary divergence of these insects, i. e. the number of niche dimensions along which divergence has taken place. Apparently, colouration differences evolve first, followed by subsequent diversification of host-plant related physiological adaptations.

The results are suggestive and the study makes good use of an already well-explored system. A criticism raised by some referees is that the number of comparisons are few (only one between-species comparison), which means that the generality of the results needs to be verified in a future study encompassing additional species in a broader phylogenetic framework of these stick insects.