What is the environmental variable that affects wing color?

The environmental variable that most significantly affects wing color in many species, particularly in insects and birds, is temperature. Temperature influences pigmentation through metabolic processes and can affect the presence of pigments like melanin. Additionally, UV radiation and habitat conditions, such as light exposure and humidity, can further influence wing coloration by impacting how pigments are produced and expressed. This adaptability in wing color can play a crucial role in thermoregulation and camouflage.