No abstract

No abstract

We analyzed the genetic profile of 563 individuals from 12 geographically targeted human populations from Europe, Asia and Africa using 27 human-specific polymorphic Alu insertions. Phylogenetic analyses indicated a clear correspondence between genetic profiles and historical patterns of gene flow and genetic drift. Sub-Saharan African populations (Benin, Cameroon, Kenya and Rwanda) formed a visibly differentiated cluster, indicating the role of the Sahara desert as a strong natural barrier to gene flow. Moreover, a higher than expected genetic affinity between populations from Europe, North Africa and Asia was detected, probably reflecting the homogenizing effects of bidirectional migratory processes between Eurasia and North Africa during the Plio-Pleistocene and Neolithic periods or the insensitivity of these markers in discriminating between these groups. The Ami aborigines of Formosa present a distinctive degree of genetic uniqueness from all the other groups, consistent with a pattern of isolation by distance, small population size and, accordingly, substantial genetic drift. We further tested all 27 Alu loci for their potential usefulness as ancestry informative markers (AIMs). On the basis of differences between weighted allelic frequencies (d-values) and F ST values, we propose that 11 of the 27 Alu elements could be useful as part of the current AIM panels to assess phylogenetic relationships.

Neanderthals represent an extinct hominid lineage that existed in Europe and Asia for nearly 400,000 years. They thrived in these regions for much of this time, but declined in numbers and went extinct around 30,000 years ago. Interestingly, their disappearance occurred subsequent to the arrival of modern humans into these areas, which has prompted some to argue that Neanderthals were displaced by better suited and more adaptable modern humans. Still others have postulated that Neanderthals were assimilated into the gene pool of modern humans by admixture. Until relatively recently, conclusions about the relationships between Neanderthals and contemporary humans were based solely upon evidence left behind in the fossil and archaeological records. However, in the last decade, we have witnessed the introduction of metagenomic analyses, which have provided novel tools with which to study the levels of genetic interactions between this fascinating Homo lineage and modern humans. Were Neanderthals replaced by contemporary humans through dramatic extinction resulting from competition and/or hostility or through admixture? Were Neanderthals and modern humans two independent, genetically unique species or were they a single species, capable of producing fertile offspring? Here, we review the current anthropological, archaeological and genetic data, which shed some light on these questions and provide insight into the exact nature of the relationships between these two groups of humans.

Human endogenous retroviruses (HERVs) represent vestiges of ancient infections that resulted in stable integration of the viral genome. These insertional elements of viral origin are in fact molecular fossils and, as such, a source of evolutionary information. A family of HERV insertions designated HERV-K includes members that are still polymorphic for the original insertional event. The goal of this report is to describe a novel genetic marker system based on polymorphic retroviral insertions (PRVIs) and to assess its potential usefulness in human population genetic analyses. The allelic frequencies of four insertionally polymorphic HERV-K loci were analyzed in nine geographically targeted, worldwide populations. A polymerase chain reaction assay was employed to examine the frequencies of the provirus and/or solo long terminal repeat insertions at these four loci. Several statistical and phylogenetic analyses were performed based on the frequency data. The phylogenetic relationships observed among the nine populations based on the four retroviral HERV-K loci are consistent not only with prior genetic analyses with other traditional marker systems but also with reported historical and biogeographical data. These polymorphic endogenous retroviral sequences display features that make them excellent tools for forensic and population genetic studies.

No abstract

The archeology and ethnology of Armenia suggest that this region has acted as a crossroads for human migrations from Europe and the Middle East since at least the Neolithic. Near continual foreign influx has, in turn, led to the supposition that the gene pools of geographically separated Armenian populations may have diverged as differing historical influences potentially left distinct genetic traces in the various regions of the Armenian plateau. In this study, we seek to address whether any evidence for such genetic regional partitioning in Armenians exists by analyzing, for the first time, 15 autosomal short tandem repeat (STR) loci in 404 Armenians from four geographically well-characterized collections (Ararat Valley, Gardman, Sasun, and Lake Van) that represent distinct communities from across Historical Armenia. In addition, to determine whether genetic differences among these four Armenian populations are the result of differential affinities to populations of known historical influence in Armenia, we utilize 27 biogeographically targeted reference populations for phylogenetic and admixture analyses. From these examinations, we find that while close genetic affiliations exist between the two easternmost Armenian groups analyzed, Ararat Valley and Gardman, the remaining two populations display substantial distinctions. In particular, Sasun is distinguished by evidence for genetic contributions from Turkey, while a stronger Balkan component is detected in Lake Van, potentially suggestive of remnant genetic influences from ancient Greek and Phrygian populations in this region.

No abstract