Clustering of genes showing P. latipinna-biased expression in P. formosa. Allelic expression of two contigs that are enriched of P. latipinna-biased genes in all organs are plotted. The x-axis is the order of gene on contig, and the y-axis represents normalized allelic expression of P. latipinna (above the x-axis), P. mexicana (below the x-axis) alleles. Solid lines of different colors (red: P. latipinna allele; blue: P. mexicana allele) represent both parental allelic expression in the P. formosa, and the faint lines of different colors (red: P. latipinna allele; blue: P. mexicana allele) represent allelic expression in the artificial interspecies hybrid. Red squares designate the P. latipinna alleles that show dominant expression in clonal fish but equal expression as P. mexicana alleles in the F₁ hybrids.