Fig. 1

Numbers of OlfC genes in the genome sequences of 13 species of fish. “I,” “T,” and “P” indicate the numbers of intact genes, truncated genes, and pseudogenes, respectively. Branch shades represent the different groups of fishes: ostariophysan fishes (light blue); ostariophysan fishes having the fright reaction (deep blue); ostariophysan fishes lacking the fright reaction (deep green). Species tree was taken from previous studies^2,4,50