SummaryUsing phylogenetics and transcriptomics, we show that independent origins of both CAM and C4 photosynthesis in Caryophyllales co-opted the same genes for PEPC through similar adaptive changes.

This study brings much needed clarity to relationships within Montiaceae and confirms that New World and Australian Calandrinia do not form a clade. Australian Calandrinia is a longtime resident of the continent, having diverged from its sister lineage ~30 Ma, concurrent with separation of Australia from Antarctica. Most diversification occurred during the middle Miocene, with lowered speciation and/or higher extinction rates coincident with the establishment of severe aridity by the late Miocene.

Red algal parasites are unusual because the vast majority of them parasitize species with which they share a recent common ancestor. This strategy has earned them the name “adelphoparasites,” from the Greek, adelpho, meaning “kin.” Intracellular adelphoparasites are very rare in nature, yet have independently evolved hundreds of times among the floridiophyte red algae. Much is known about the life history and infection cycle of these parasites but nearly nothing in known about their genomes. We sequenced the mitochondrial genomes of the free-living Gracilariopsis andersonii and its closely related parasite Gracilariophila oryzoides to determine what effect a parasitic lifestyle has on the genomes of red algal parasites. Whereas the parasite genome is similar to the host in many ways, the genes encoding essential proteins ATP8 and SDHC are pseudogenes in the parasite. The mitochondrial genome of parasite from a different class of red algae, Plocamiocolax puvinata, has lost the atp8 gene entirely, indicating that this gene is no longer critical in red algal parasite mitochondria.