Early developmental processes limit socially mediated phenotypic plasticity in an ant

Caste determination in social insects has long been considered to exemplify socially mediated phenotypic plasticity: young larvae can develop into queens or workers depending on the social environment. However, recent studies have challenged this view by showing that, in some species, larval development can be biased early by factors such as larval genotype. We analyzed this issue in the ant species Aphaenogaster senilis. First, we found that the probability that a larva develops into a queen or a worker varies consistently among colonies. Next, we conducted a cross-fostering experiment in which larvae from colonies with relatively low queen production were transferred to colonies with relatively high queen production and vice versa. The results show a strong significant interaction between early determination and worker control of larval caste fate. Therefore, our study shows that socially mediated phenotypic plasticity is limited by processes occurring at an early developmental stage that possibly include direct or indirect genetic effects or non-genetic maternal effects.