approaching significanceP =0.9352
RESULTS The final model for brain mass indicated that age group ( F 1,4,114 =204.6, P <0.0001), rearing treatment ( F 1,4,110 =5.626, P =0.0194), and the interaction of age group×rearing treatment ( F 1,4,110 =3.909, P =0.0505) were all significant (or approaching significance at α=0.05), whereas population was not ( F 1,4,110 =0.0070, P =0.9352).