Phylogenomics of coral-infecting corallicolids reveal multiple independent losses of chlorophyll biosynthesis in apicomplexan parasites

Second, it is unclear if chlorophyll or a metabolic intermediate is synthesized, as most chlorophyll biosynthesis enzymes are encoded in the nucleus. To address these questions we have sequenced transcriptomes from two corallicolids, infecting Parazoanthus swiftii and Madracis mirabilis. Phylogenomic data strongly support a late-branching relationship with coccidians, perhaps specifically to the protococcidians.

We also find evidence for the expression of nucleus-encoded enzymes involved in chlorophyll biosynthesis in corallicolids and protococcidians. Overall, we conclude that photosynthesis was lost at the origin of apicomplexans, but chlorophyll synthesis was nonetheless retained through most of the early evolution of the group, and then lost approximately nine times independently, emphasizing the impact of parallel evolutionary changes in parasitic transitions.