Faculty of Sciences, University of Antwerp
Department of Biology
Evolutionary Ecology group
Abstracts (first author)
Contrasting evolutionary patterns in recent and deep time suggest old origins for East-African arenaviruses and strong specificity to their multimammate mouse hosts
To understand the relationship between evolutionary histories of zoonotic RNA viruses and their hosts, we study patterns of viral divergence across a host geographic range structured by both recent and ancient events. We focus on East African arenaviruses closely related to the virus causing human Lassa fever in West Africa and which infect the same natural host, the multimammate mouse Mastomys natalensis. We sampled at regular intervals along a 200 km transect in Tanzania, capturing a total of 1284 multimammate mice, of which 57 harbored arenaviruses. Multilocus microsatellite, mitochondrial and Y chromosome markers reveal a cryptic host contact zone between two M. natalensis taxa along the transect, with one admixed central locality and the surrounding 11 localities dominated by one of either taxon. The host mitochondrial lineages split about 1 million years ago and the current zone is likely the outcome of secondary contact of M. natalensis geographic isolates some thousands of years ago, driven by Holocene climate oscillations. We show that each M. natalensis taxon hosts a very distinct arenavirus, yet both arenavirus species are present in the host-admixed locality. Both hosts and viruses show further genetic differentiation within each host-taxon’s ranges, but on this level the geographic patterns of host and virus structure are not correlated. These observations suggest that recent host evolutionary history has little effect on recent arenaviral divergence (despite similar differentiation time scales), yet host-virus associations at a deeper taxonomic level have likely persisted since their shared isolation during the last glacial cycle, predating current ancestry estimates for these RNA viruses. Furthermore, if arenavirus species are unable to cross between pairs of taxonomically cryptic host sister taxa in geographic contact, a rapid arenavirus spread across M. natalensis’ pan-African range, likely home to many such cryptic taxa, seems remote.