A: Intraspecies comparison of porcine selenoproteins; B: Comparisons of porcine selenogenome with that of humans and rodents; C: Comparison of porcine selenogenome with that of domestic rabbit, sheep, chicken, cat, horse, ass, dog and cattle; D: Comparison of GPX1 among different species. The distance scale in substitutions per position is indicated at the bottom left in A, D.