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1·Synonymous substitution rate nearly is neutral, which not chang amino acids of protein;

同义替代不引起氨基酸改变，它们基本是中性替代速率；

2·Nosynonymous substitution rate is lower than that of synonymous substitution, which lead to changing of amino acids in protein.

非同义替代引起氨基酸变化，替代速率常常比同义替代速率低。