Social pleiotropy and the molecular evolution of honey bee vitellogenin

In this issue of Molecular Ecology, Kent (2011) describe the adaptive evolution of honey bee vitellogenin that belongs to a phylogenetically conserved group of egg yolk precursors. This glyco-lipoprotein leads a double life: it is central to egg production in the reproductive queen caste, and a regulator of social behaviour in the sterile worker caste. Does such social pleiotropy constrain molecular evolution? To the contrary; Kent et al. show that the vitellogenin gene is under strong positive selection in honey bees. Rapid change has taken place in specific protein regions, shedding light on the evolution of novel vitellogenin functions.