The importance of being plastic: Evolutionary and ecological correlates of phenotypic plasticity

Phenotypic plasticity allows individuals to cope with different environmental conditions without the need for genetic adaptation. Consequently, plasticity affects the nature and strength of selection on traits. Plasticity enables individuals to experience novel selection pressures, for example through migration, possibly leading to genetic adaptation. At the same time, plasticity may shield the genotype from selection, impeding genetic adaptation. Plasticity, therefore, can have opposing effects on evolutionary change and population divergence.The visual system of cichlid fish is a suitable model trait to study the relationship between plasticity and evolutionary change, because of the high species richness and the variation among species in visual habitat. Furthermore, plasticity in the expression of genes involved in the cichlid’ visual system is well established. Here, we test whether visual plasticity is correlated to the degree of ecological specialisation and clade species richness. We quantify plasticity in the expression of these genes in species from species-poor and species-rich clades, inhabiting different visual habitats in nature, by exposing individuals to different light conditions and determining light-induced variation in gene expression. Preliminary results indicate that expression indeed differs among light treatments, in multiple species. We expect our study to provide a better understanding of the impact of phenotypic plasticity on divergent evolution.