Morphological and Physiological Colour Changes in the Animal Kingdom
Résumé
Colour change is the ability of an organism to modify its colouration in response to specific stimuli. Several biological functions have been proposed to explain colour changes, including ultraviolet (UV) protection, thermoregulation, crypsis, inter- and intraspecific communication. Changes in body colouration are mainly performed through two types of mechanisms referred to as morphological and physiological. Mechanistically, these two types of colour changes differ in their speed and the way coloured structures are altered. The proximal causes of these colour changes are identified in a handful number of species and demonstrate that common physiological, cellular and molecular actors are at play. However, the reasons why both colour-change types are widespread in the animal kingdom and how they have evolved are still unknown. This is partly due to a lack of knowledge about the fitness implications of colour changes, particularly their energetic costs.