title: Long-Distance Dispersal Shaped Patterns of Human Genetic Diversity in Eurasia.
abstract: Most previous attempts at reconstructing the past history of human populations did not explicitly take geography into account or considered very simple scenarios of migration and ignored environmental information. However, it is likely that the last glacial maximum (LGM) affected the demography and the range of many species, including our own. Moreover, long-distance dispersal (LDD) may have been an important component of human migrations, allowing fast colonization of new territories and preserving high levels of genetic diversity. Here, we use a high-quality microsatellite data set genotyped in 22 populations to estimate the posterior probabilities of several scenarios for the settlement of the Old World by modern humans. We considered models ranging from a simple spatial expansion to others including LDD and a LGM-induced range contraction, as well as Neolithic demographic expansions. We find that scenarios with LDD are much better supported by data than models without LDD. Nevertheless, we show evidence that LDD events to empty habitats were strongly prevented during the settlement of Eurasia. This unexpected absence of LDD ahead of the colonization wave front could have been caused by an Allee effect, either due to intrinsic causes such as an inbreeding depression built during the expansion or due to extrinsic causes such as direct competition with archaic humans. Overall, our results suggest only a relatively limited effect of the LGM contraction on current patterns of human diversity. This is in clear contrast with the major role of LDD migrations, which have potentially contributed to the intermingled genetic structure of Eurasian populations.
authors.affiliation: Computational and Molecular Population Genetics Lab, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland Swiss Institute of Bioinformatics, Lausanne, Switzerland Population and Conservation Genetics Group, Instituto Gulbenkian de Ciência, Oeiras, Portugal isabel.alves@iee.unibe.ch laurent.excoffier@iee.unibe.ch.
authors.forename: Isabel
authors.initials: I
authors.lastname: Alves
authors.affiliation: Computational and Molecular Population Genetics Lab, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland Swiss Institute of Bioinformatics, Lausanne, Switzerland Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal.
authors.forename: Miguel
authors.initials: M
authors.lastname: Arenas
authors.affiliation: Anthropology, Genetics and Peopling History Lab, Department of Genetics & Evolution-Anthropology Unit, University of Geneva, Geneva, Switzerland.
authors.forename: Mathias
authors.initials: M
authors.lastname: Currat
authors.affiliation: Computational and Molecular Population Genetics Lab, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland Swiss Institute of Bioinformatics, Lausanne, Switzerland.
authors.forename: Anna
authors.initials: A
authors.lastname: Sramkova Hanulova
authors.affiliation: Computational and Molecular Population Genetics Lab, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland Swiss Institute of Bioinformatics, Lausanne, Switzerland.
authors.forename: Vitor C
authors.initials: VC
authors.lastname: Sousa
authors.affiliation: EnviroSPACE Lab, Institute for Environmental Sciences, University of Geneva, Geneva, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Ray
authors.affiliation: Computational and Molecular Population Genetics Lab, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland Swiss Institute of Bioinformatics, Lausanne, Switzerland isabel.alves@iee.unibe.ch laurent.excoffier@iee.unibe.ch.
authors.forename: Laurent
authors.initials: L
authors.lastname: Excoffier
mesh_terms: D001208:Asia; D003710:Demography; D017753:Ecosystem; D005060:Europe; D051456:Gene Flow; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D005843:Geography; D063426:Human Migration; D006801:Humans; D007178:Inbreeding; D011157:Population Dynamics
keywords: human evolution; last glacial maximum; long-distance dispersal; out of Africa.