To develop wings is an important evolutionary decision for an insect. Wings are part of central adaptation mechanisms allowing insects to escape predators, exploit scattered resources, and disperse into new niches — resulting in radiations into vast numbers of species. Although insects can subsequently evolve to wingless forms, an evolutionary reversal from a flightless insect to a volant form has been thought unlikely. In the January 16 Nature, Michael F. Whiting and colleagues at Brigham Young University, Utah, USA, show that stick insects (Order Phasmatodea) diversified as wingless insects and that wings were derived secondarily, perhaps on many occasions (Nature, 421: 264-267, January 16, 2003).

Whiting et al. examined the phylogeny of Phasmatodea on the basis of DNA sequence data from 22 outgroup and 37 ingroup taxa representing all Polyneoptera and 14 of the 19 recognized phasmid subfamilies. They observed that there is a 95% probability that the ancestral phasmid was wingless, that the first six basal phasmid lineages are entirely wingless, and that fully developed wings were derived later in phasmid evolution, on as many as four occasions.

"To our knowledge, this is the first example of a complex feature being lost and later recovered in an evolutionary lineage, and it is possible that the reacquisition of complex features may have an important role in evolutionary diversification", conclude the authors.