Figure 4.

The phylogenetic hypothesis presented here alters our understanding of malaria parasite host-switching and life-history evolution. (a) All topologies that we recovered from across phylogenetic analyses that were corrected for base composition bias suggest a single switch to mammalian hosts from sauropsid-infecting ancestors, followed by one additional switch back to sauropsid hosts in the Plasmodium lineage. (b) This topology suggests two alternative scenarios for the evolution of blood schizogony (asexual reproduction in the host bloodstream) and vector use. One scenario (left) posits a single gain of blood schizogony and a switch to mosquito (Culicidae) vectors in the lineage leading to all mammalian malaria parasites, followed by loss of blood schizogony and a vector switch in three lineages: Polychromophilus, Hepatocystis and Nycteria. Alternatively (right), the four lineages of Plasmodium identified in our analysis could have evolved blood schizogony and switched to mosquito vectors independently.