Genomes of an entire Plasmodium subgenus reveal paths to virulent human malaria

Plasmodium falciparum, the most virulent agent of human malaria, shares a recent common ancestor with the gorilla parasite P. praefalciparum. Although there are further gorilla and chimpanzee-infecting species in the same (Laverania) subgenus as P. falciparum, none are known to be able to establish repeated infection and transmission in humans. To elucidate underlying mechanisms and the evolutionary history of this subgenus, we have analysed multiple genomes from all known Laverania species. Here we estimate the timings of Laverania speciation events, placing P. falciparum speciation 40,000-60,000 years ago followed by a recent population bottleneck. We show that interspecific gene transfers as well as convergent evolution were important in the evolution of these species. Striking copy number and structural variations were observed within gene families and for the first time, features in P. falciparum are revealed that made it the only member of the Laverania able to infect and spread in humans.