The Phenotypic Effects of Royal Jelly on Wild-Type D. melanogaster Are Strain-Specific

Phenotypic extremes or extreme phenotypes? On the use of large and small-bodied "phenocopied" Drosophila melanogaster males in studies of sexual selection and conflict

In the fruit fly, Drosophila melanogaster, variation in body size is influenced by a number of different factors and may be strongly associated with individual condition, performance and success in reproductive competitions. Consequently, intra-sexual variation in size in this model species has been frequently explored in order to better understand how sexual selection and sexual conflict may operate and shape evolutionary trajectories. However, measuring individual flies can often be logistically complicated and inefficient, which can result in limited sample sizes. Instead, many experiments use large and/or small body sizes that are created by manipulating the developmental conditions experienced during the larval stages, resulting in "phenocopied" flies whose phenotypes resemble what is seen at the extremes of a population's size distribution. While this practice is fairly common, there has been remarkedly few direct tests to empirically compare the behaviour or performance of phenocopied flies to similarly-sized individuals that grew up under typical developmental conditions. Contrary to assumptions that phenocopied flies are reasonable approximations, we found that both large and small-bodied phenocopied males frequently differed from their standard development equivalents in their mating frequencies, their lifetime reproductive successes, and in their effects on the fecundity of the females they interacted with. Our results highlight the complicated contributions of environment and genotype to the expression of body size phenotypes and lead us to strongly urge caution in the interpretation of studies solely replying upon phenocopied individuals.

Beyond Royalactin and a master inducer explanation of phenotypic plasticity in honey bees

Distinct female castes produced from one genotype are the trademark of a successful evolutionary invention in eusocial insects known as reproductive division of labour. In honey bees, fertile queens develop from larvae fed a complex diet called royal jelly. Recently, one protein in royal jelly, dubbed Royalactin, was deemed to be the exclusive driver of queen bee determination. However, this notion has not been universally accepted. Here I critically evaluate this line of research and argue that the sheer complexity of creating alternate phenotypes from one genotype cannot be reduced to a single dietary component. An acceptable model of environmentally driven caste differentiation should include the facets of dynamic thinking, such as the concepts of attractor states and genetic hierarchical networks.

In honeybees, genotypically identical females develop into queens or sterile workers, depending on their diets. In this review, Ryszard Maleszka discusses the controversial role of the royal jelly protein Royalactin in caste determination and provides a framework for moving beyond the master inducer concept.