GENE DUPLICATION AND THE EVOLUTION OF PHOTOSYNTHETIC REACTION-CENTER PROTEINS

We investigate the evolutionary relationships between photosynthetic r eaction center proteins (D1, D2, L and M) and demonstrate that the pat tern of nucleotide substitution in these is more complicated than has been assumed in previous phylogenetic analyses, We show that there are serious violations of methodological assumptions in previous publishe d studies, We conclude that there is equal support for hypotheses indi cating (i) a single gene duplication of an ancestral reaction center p rotein followed by diversification and (ii) two independent gene dupli cations giving rise to proteins in oxygenic and anoxygenic systems.