AUTHOR=Bargues María Dolores , Halajian Ali , Artigas Patricio , Luus-Powell Wilmien J. , Valero M. Adela , Mas-Coma Santiago 

TITLE=Paleobiogeographical origins of Fasciola hepatica and F. gigantica in light of new DNA sequence characteristics of F. nyanzae from hippopotamus

JOURNAL=Frontiers in Veterinary Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.990872

DOI=10.3389/fvets.2022.990872

ISSN=2297-1769

ABSTRACT=<p>Fascioliasis is a highly pathogenic disease affecting humans and livestock worldwide. It is caused by the liver flukes <italic>Fasciola hepatica</italic> transmitted by <italic>Galba</italic>/<italic>Fossaria</italic> lymnaeid snails in Europe, Asia, Africa, the Americas and Oceania, and <italic>F. gigantica</italic> transmitted by <italic>Radix</italic> lymnaeids in Africa and Asia. An evident founder effect appears in genetic studies as the consequence of their spread by human-guided movements of domestic ruminants, equines and Old World camelids in the post-domestication period from the beginning of the Neolithic. Establishing the geographical origins of fasciolid expansion is multidisciplinary crucial for disease assessment. Sequencing of selected nuclear ribosomal and mitochondrial DNA markers of <italic>F. nyanzae</italic> infecting hippopotamuses (<italic>Hippopotamus amphibius</italic>) in South Africa and their comparative analyses with <italic>F. hepatica</italic> and <italic>F. gigantica</italic>, and the two <italic>Fascioloides</italic> species, <italic>Fs. jacksoni</italic> from Asian elephants and <italic>Fs. magna</italic> from Holarctic cervids, allow to draw a tuned-up evolutionary scenario during the pre-domestication period. Close sequence similarities indicate a direct derivation of <italic>F. hepatica</italic> and <italic>F. gigantica</italic> from <italic>F. nyanzae</italic> by speciation after host capture phenomena. Phylogenetic reconstruction, genetic distances and divergence estimates fully fit fossil knowledge, past interconnecting bridges between continents, present fasciolid infection in the wild fauna, and lymnaeid distribution. The paleobiogeographical analyses suggest an origin for <italic>F. gigantica</italic> by transfer from primitive hippopotamuses to grazing bovid ancestors of Reduncinae, Bovinae and Alcelaphinae, by keeping the same vector <italic>Radix natalensis</italic> in warm lowlands of southeastern Africa in the mid-Miocene, around 13.5 mya. The origin of <italic>F. hepatica</italic> should have occurred after capture from primitive, less amphibious <italic>Hexaprotodon</italic> hippopotamuses to mid-sized ovicaprines as the wild bezoar <italic>Capra aegagrus</italic> and the wild mouflon <italic>Ovis gmelini</italic>, and from <italic>R. natalensis</italic> to <italic>Galba truncatula</italic> in cooler areas and mountainous foothills of Asian Near East in the latest Miocene to Early Pliocene, around 6.0 to 4.0 mya and perhaps shortly afterwards.</p>