I have a protein of interest, which is conserved from bacteria, archaea to eukaryotes.

After aligning the sequence a highly conserved domain of the homologs, I have divided the sequences into three groups which differ by a significant number of the aligned position that shared a common trend, in terms of the percentage of the amino acid composition at the respective position, for illustration:

For aligned residue position 1,

group 1 : 100% lysine

group 2 : 50% lysine, 50% arginine

group 3 : 100% arginine

Interestingly, for some positions the mutation is less conservative, for example:

group 1 : 100% histidine

group 2 : 50% histidine, 50% aspartate

group 3 : 100% aspartate

Does anyone know how do we call such a phenomenon in evolution?

Thank you.