Gene action in fish of tetraploid origin. II. Cellular and biochemical parameters in clupeoid and salmonoid fish.

By use of cell size, protein and hemoglobin content, and enzyme activities as markers, it becomes apparent that in the course of evolution the gene expression of anciently tetraploid fish of the order Ostariophysi was diploidized, but no such regulatory mechanism has evolved in the phylogenetically tetraploid species of the order Isospondyli. This finding is discussed in terms of possible selective neutrality of tetraploid expression and the phylogenetic age of Isospondyli.