Genes and Linkage Groups in Genetics

Abstract

IN the flatfishes “mutations” are not uncommon; albinos, piebalds, etc., reversed examples (sinistral individuals of dextral species and dextral individuals of sinistral species), and ambicolorate fish. There are many degrees of ambicoloration, from specimens with a small coloured patch or a few scattered spots on the blind side to others in which the whole blind side is coloured like the eyed side. When ambicoloration is complete, or nearly so, it appears always to be associated with other variations; the migration of the eye is delayed, so that it gets in the way of the dorsal fin as it is growing forward on the head, the scales of the blind side resemble those of the eyed side in structure, the asymmetry of the paired fins is less marked. It is clear that the one thing that holds these variations together is that they are variations towards symmetry, and it is interesting to note that the head, which is the most asymmetrical part of the fish, is the last to be affected; thus it often happens that the whole blind side is coloured except a patch in the orbital region, and that the scales of the blind side are as rough as those of the eyed side except on the head.