Meeting Abstract

50.3  Saturday, Jan. 5  Hox Gene Evolution in North American Suckers (Cypriniformes: Catostomidae), a Tetraploid Family of Fishes MERNER, M.J.*; BERENDZEN, P.B.; Univ. of Northern Iowa; Univ. of Northern Iowa

Most eukaryotic organisms are diploid, containing two sets of chromosomes, one from each parent. However, having more than two sets of chromosomes, a condition known as polyploidy, is prominent in some taxa such as vascular plants. Members of Catostomidae, a fifty million-year-old monophyletic family comprising sucker fishes, have four sets of chromosomes. This condition, known as tetraploidy, presents interesting questions in regard to the fate of the duplicated genome. In particular, Hox genes in a diploid organism are normally highly conserved due to their role in orientation and morphology of organisms. The duplication of Hox genes in Catostomidae may lead to a higher rate of mutation. This is due to the presence of the extra copy which would mask a normally detrimental effect. This study tests the hypotheses that 1) fourteen Hox clusters will be present in Catostomidae rather than the seven clusters found in most teleost fishes; 2) some Hox genes within the clusters will not be conserved but silenced through the formation of stop codons; 3) Hox genes that are silenced will show a phylogenetic pattern across the catostomids; and 4) the species of catostomids with more derived traits will have more changes to their Hox genes. To test this, thirteen degenerate primer sets were used to target and isolate specific regions of Hox genes. Subsequent amplification through PCR, cloning of plasmid DNA, and sequencing of the clones were performed on a diversity of species across the catostomid phylogeny. Preliminary results will be presented.