. The biology of the amphibia. Amphibians. 90 THE BIOLOGY OF THE AMPHIBIA. characters of pupil form, skin rugosity, and body size have independently evolved in the derived species on these islands (Fig. 28). In many groups of animals the reappearance of the same character in species not closely related has given rise to the suggestion that one species may be mimicking another which has certain other characters of survival value. This mummery has been brought about by the action of natural selection on small mutations. In the Amphibia many characters of denti- tion, pupil form, pectoral girdle,
. The biology of the amphibia. Amphibians. 90 THE BIOLOGY OF THE AMPHIBIA. characters of pupil form, skin rugosity, and body size have independently evolved in the derived species on these islands (Fig. 28). In many groups of animals the reappearance of the same character in species not closely related has given rise to the suggestion that one species may be mimicking another which has certain other characters of survival value. This mummery has been brought about by the action of natural selection on small mutations. In the Amphibia many characters of denti- tion, pupil form, pectoral girdle, tongue form, digital scutes, digital loss, etc., have reappeared in groups not closely related. It would seem that the various families of Amphibia had only a limited repertoire of germ- inal changes. Many of these parallel changes have no known functional significance. In some cases the retention of a character once it has re- appeared in a different stock may be aided by natural selec- tion. Some polypedatid and hylid tree frogs from different parts of the world may appear almost identical externally, ntx â " . . , , and it is possible that the Fig. 29.âMimicry in salamanders. 1 A reddish cheek patch is characteristic slow weeding Out of natural of Plethodon jordani (B) and appears as a variation in specimens of Desmognathus fuscus carolinensis (A) living in the Great a b O U t Smoky Mountains, the habitat of the however, would seem to have former species. 7 had little effect on shaping the color pattern of some Amphibia. For example, Plethodon jordani of the Great Smoky Mountains is dark bluish with a conspicuous reddish cheek. Desmognathus fuscus carolinen- sis of the same region occasionally shows an almost identical color pattern (Fig. 29). It would seem remarkable that this distinc- tive color pattern should have occurred in two species in the same region, but at Durbin, West Virginia, bright orange specimens have been found, others with a stripe on each side and
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