Developmental noise and phenotypic plasticity are correlated in Drosophila simulans

Non-genetic variation is the phenotypic variation induced by the differential expression of a genotype in response to varying environmental cues and is broadly categorized into two types: phenotypic plasticity and developmental noise. These variation aspects have been suggested to play an important role in adaptive evolution; however, the mechanisms by which these two types of non-genetic variations influence the evolutionary process are currently poorly understood. Using a machine-learning based phenotyping tool, we independently quantified the phenotypic plasticity and developmental noise in the wing morphological traits of a fruit fly Drosophila simulans. Utilizing a rearing experiment, we demonstrated plastic responses in both wing size and shape as well as non-zero heritability of both phenotypic plasticity and developmental noise, which suggests that adaptive phenotypic plasticity can evolve via genetic accommodation in the wing morphology of D. simulans. We found a positive correlation between phenotypic plasticity and developmental noise, while the correlation between the plastic response to three kinds of environmental factors that were examined (nutrient condition, temperature, and light-dark cycle) were poor. These results suggest that phenotypic plasticity and developmental noise contribute to evolvability in a similar manner, however, the mechanisms that underlie the correspondence between these two variation types remains to be elucidated. Lay SummaryNon-genetic variations consist of phenotypic plasticity and developmental noise, and these variations have been suggested to influence the direction and the rate of evolution. However, the role of phenotypic plasticity and developmental noise in evolutionary process is still poorly understood. Using a rearing experiment, we examined the heritability of plasticity and developmental noise, the correlation of the strength of plastic response to three kinds of environmental factors, and the relationship between plasticity and developmental noise in wing size and wing shape in Drosophila simulans. We found that the degree of phenotypic plasticity and developmental noise were heritable, and positively correlated with each other. Our results suggest that there two non-genetic variations dependently affect the direction and the rate of evolution together.