Chromatophores as Evidence of Phylogenetic Evolution

Abstract

The adepidermal melanophores which are situated immediately under the epidermis undergo, in the series of Amphibia, the following evolutionary change In embryos and young larvae they are generally thread-shaped. In Urodela they become flat and movable. In tadpoles of Discoglossus they remain thread-shaped forming, by mutual adhesion, a polygonal network; lose their movability; and assume a supporting function. In Bombina-, Alytes-, and Pelodytes-tadpoles they remain thread-shaped and immovable, form a rectangular network, but do not adhere to one another. In some generations of the Zurich population of Bombina they are pigmentless. In young Alytes-tadpoles they are pigmented, but regularly lose their pigment while growing older. Adepidermal melanophores are entirely absent in higher Anura. Since the adepidermal melanophores have lost their color-regulating function, from Discoglossus on, 2 other kinds of melanophores develop with the physiological properties of the adepidermal melanophores of Urodela, but morpho-logically different from them: the subcut. melanophores in tadpoles, and the intracut. melanophores in adults.