The 4R genome duplication in salmonine fishes: insights from conserved non-coding elements
Gene and genome duplications are important processes in evolution. Salmonids are ideal animal model systems in which to study these processes, as they originated from a tetraploid ancestor. Conserved non-coding elements (CNEs) are of interest because of their highly conserved DNA consensus motifs spanning lineages as diverse and divergent as humans and fish. The main goal of this study is to test CNEs as a tool to study genome duplications and to revisit the "4R" hypothesis and phylogeny of Salmonine fishes (Salmonidae) 'Salmo salar, Salvelinus alpinus' and ' Oncorhynchus mykiss' through the study of copy number and nucleotide variation in six pairs of CNEs. Allele numbers for most CNE sequence pairs are consistent with the 4R hypothesis, as is the symmetric phylogenetic topology shown by some CNE pairs; the estimated date of CNE duplication is consistent with the only reported range of 25-100Mya. However, the phylogenetic relationships within Salmoninae remain unresolved.