In Drosophila, heterozygous individuals—carrying different forms of the same coloration gene—exhibit greater phenotypic plasticity (the ability to change color in response to the environment) compared to homozygotes. This enhances genetic diversity within populations and facilitates rapid adaptation to environmental changes.
Phenotypic plasticity as a function of genetic polymorphism: thermal dominance reversal in Drosophila species with contrasting melanism
Jean R David , Béatrice Denis , Pascaline Francelle , Alicia Lemaire , Aparup Das , Sujata Mohanty , Patricia Gibert , Amir Yassin
https://doi.org/10.1093/evolut/qpaf225
Evolution, Volume 80, Issue 1, January 2026, Pages 127–142