Developmental noise and phenotypic plasticity are correlated in Drosophila simulans
by Keita Saito | Masahito Tsuboi | Yuma Takahashi | Graduate School of Science and Engineering, Chiba University;RIKEN BDR, Laboratory for Multiscale Biosystem Dynamics | Department of Biology, Lund University | Graduate School of Science, Chiba University
Abstract ID: 29
Event: The 3rd AsiaEvo Conference
Topic: Evolvability: a common currency of evolution, ecology and development
Presenter Name: Keita Saito

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. The former is the reaction norm to environmental changes, thus plasticity is caused by external factors. The latter is phenotypic variation caused by random fluctuations in chemical and physical signaling processes during development. However, unlike plasticity developmental noise depends solely on the local conditions of the developing phenotypes. Therefore, these two sources of non-genetic variation are fundamentally different in their causes, where one depends on external causes and the other on internal fluctuations. 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 due to difficulties in independently accessing the two non-genetic variation. 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. Plasticity must be evaluated by multiple reaction norm, although plasticity was evaluated as the reaction norm to a single environmental cue (e.g., temperature) in most case of previous studies. Therefore, we used three environmental cues, temperature, nutrient condition, and light-dark cycle. In addition, to evaluate accurate developmental noise, we measured fluctuation asymmetry. 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.