The Enormous Diversity in Genome Sizes of Fish as a Reflection of Nature's Extensive Experiments with Gene Duplication

It appears that nature has experimented extensively with various modes of gene duplication in fish. We witness extreme diversity in the genome size as well as in the degree of gene duplication among fish. There are those that have increased their genome size exclusively by repeated tandem duplication of chromosomal segments. They show no proportional increase in the number of functional gene loci. In this group, the trend for progressive elimination of excessive genetic redundancy appears to have started in modern times. There is another group which went through tetraploid evolution. These fish are endowed with twice the number of gene loci for many of the gene products.