Results of fitting evolutionary models for differences in N/S ratios.

LBD and DBD indicate ligand and DNA binding domains, respectively. O, O, O and O are the O. mykiss ER, ER, ER and ER genes, respectively. S indicates all of the salmonid ER genes. and indicate ER and ER from all fish, respectively. is the number of parameters in the model, is the log likelihood calculated by PAML, and AIC is the Akaike Information Criterion value [35]. Models labeled with an asterisk are the best fitting models based upon the AIC values.LBD与DBD分别指代配体结合域（Ligand Binding Domain）与DNA结合域（DNA Binding Domain）。四个标记为O的序列依次对应虹鳟（Oncorhynchus mykiss）的四种ER基因。S指代所有鲑科鱼类的ER基因。二者分别指代所有鱼类的两种ER基因。k为模型的参数数量，lnL为通过PAML软件计算得到的对数似然值，AIC即赤池信息准则（Akaike Information Criterion）值[35]。带有星号标注的模型为基于AIC值筛选得到的最优拟合模型。