Fig 2. Evolutionary history of ExoR is congruent with speciation history of Rhizobiales.

ML and Bayesian phylogenetic patterns support the existence of an ExoR ancestor that arose prior to diversification among the Rhizobiales and five Rhodobacterales species identified in our genomic searches. The ExoR gene was maintained among these species, giving rise to the ortholog set. Phylogenetic reconstruction of ExoR orthologs agrees with currently accepted speciation patterns.