Figure 5

Semi-schematic summarizing a phylogeography and genome evolution of Schistosoma with respect to the evolutionary biogeography of the parasites showing that the genus arose in Central Asia in rodents during the Miocene. The S. japonicum lineage radiates in rodents in China and Southeast Asia. Orientobilharzia acquires artiodactyls as hosts in Central Asia sharing homology with an ancestor that enters Africa during the late Miocene and gives rise to the S. haematobium and S. mansoni lineages. The Pliocene large mammal radiation in Africa triggers the divergence of several lineages of Schistosoma utilizing Artiodactyla. The Plio-Pleistocene large mammal divergence into Asia and the emergence of Bovidae then drives the divergence of the Schistosoma indicum lineage from one of the African artiodactyle Schistosoma clades. Schistosoma of bovids establish on the Indian subcontinent and in Southeast Asia but apparently less so in Central Asia. In Southeast Asia, both S. incognitum and S. spindale undergo near isochronous colonization and radiation from India. The schematic indicates the evolutionary signals that have been produced by genomic data to provide the evidence of the Asian origin of the schistosomes. The ancestor of the African schistosomes shared homology with Orientobilharzia and S. incognitum and a genetic bottleneck occurred, as indicated by the reduction in size of the sex chromosomes and fixed the mt genome rearrangement as the schistosomes moved into Africa. The African schistosomes evolved from a S. mansoni-like ancestor with all African parasites showing the same gene order in the mt genome and all showing karyotypes to be derived from the S. mansoni type, a trend also seen in the S. indicum group as it reinvaded Asia (Adapted from [1]).