Comparison of BAC insert size frequency distributions. Insert sizes calculated by sea bass BAC-ES, consistently mapped to stickleback chromosomes, show a shift to lower insert sizes compared to the observed insert size of the library published by Whitaker et al. . This observation can be explained by genome size evolution in teleosts. As the genome of sea bass is known to be larger than the stickleback genome the lower insert size of mapped BACs reflects the average size difference of orthologous loci. By dividing the insert sizes at the maxima of the distributions, it can be concluded that the sea bass genome is about 1.3 fold larger than the stickleback genome.