P0655 Genome Expansion in Zebrafish is Mediated by Recent Tandem Duplications

Jianguo Lu , Auburn University, Auburn, AL
Eric Peatman , Auburn University, Auburn, AL
Haibao Tang , J. Craig Venter Institute, Rockville, MD
Joshua Lewis , Auburn University
Huseyin Kucuktas , Auburn University, Auburn, AL
John Liu , Auburn University, Auburn, AL
Gene duplication plays a major role in genome evolution. One of important gene duplication type, tandem duplication, results from two major mechanisms including unequal crossing over and whole genome duplication for vertebrate genome evolution. Although lots of researches were related to whole-genome duplication events in teleost species, less study were available on gene duplications and their effect on the population size, gene content, functional bias and overall duplication pattern of teleost genomes. Here, four teleost model species with chromosomal coordinate information, zebrafish, medaka, stickleback and Tetraodon were analyzed using Markov clustering algorithm (MCscan). Based on our analyses of gene duplication set size, duplication type, synonymous substitution rate (Ks), GO enrichment, and lineage-specific patterns of genome evolution, our analyses highlight the extraordinary duplication and retention rate of recent  duplicates in zebrafish and their likely role in the structural and functional expansion of the zebrafish genome. We find that the zebrafish genome is remarkable in its large number of duplicated genes, small duplicate set size, biased Ks distribution toward minimal mutational divergence, and proportion of tandem and intra-chromosomal duplicates when compared with the other teleost model genomes. The observed gene duplication patterns have played significant roles in shaping the architecture of teleost genomes and appear to have contributed to the recent functional diversification and divergence of important physiological processes in zebrafish.