Final answer:
Reptiles like chameleons can change their skin colors due to cells called chromatophores. Such ability allows for camouflage and social interaction, complemented by their unique vision and keratinous skin adapted for terrestrial life. Genetic changes, like insertions into an intron of the OCA2 gene, can also lead to variations in coloration as seen in certain snake species.
Step-by-step explanation:
Some reptiles, like chameleons, have the remarkable ability to change their skin color thanks to specialized structures called chromatophores. These cells contain pigments that can be redistributed across the skin, allowing the reptile to adapt to different environments for purposes such as camouflage and social signaling. This color change is part of a suite of evolved features that allows reptiles, especially lizards and chameleons, to communicate, survive predation attempts, and adapt to their habitats.
Moreover, reptiles like chameleons also have three-dimensional vision enabled by their independently mobile eyes, and some species have a 'hidden' parietal eye, which further helps them in navigation and perception of their environment. These adaptions, along with their keratinous skin which is adapted to conserve water, make reptiles like chameleons extraordinarily suited to terrestrial life.
In the case of corn snakes, color variations such as amelanism are caused by genetic alterations. Specifically, an insertion of a transposable element into an intron of the OCA2 gene can disrupt its regular function, leading to the absence of melanin and thus the distinct amelanistic coloration displaying red and yellow pigments only.