Uniparental markers-Mitochondrial DNA and Y chromosomes, which are transmitted exclusively maternally or paternally without recombination.įine-mapping-The processes of refining the location of trait-associated variants in the genomic region of interest to identify likely causal variants based on association statistics and linkage disequilibrium patterns. Paleolithic (Old Stone Age)-The period of time in human evolution when people initially started using stone tools, extending from ∼3.3 million years ago (Mya) to 12 kya. Neolithic (New Stone Age)-The period of time when people began using more sophisticated stone tools, leading to the emergence of farming and herding, extending from ∼12 kya to 6.5 kya in Africa. Iron Age-The period of time during human prehistory when people began making tools from iron and steel, extending from ∼4 to 1.5 kya in Africa. Holocene-The current geological epoch that started after the Last Glacial Maximum ∼12 kya. Introgression-The interbreeding of individuals from two or more populations that were isolated for a long evolutionary time but are not yet reproductively isolated. Gene flow-The movement of individuals and their genetic material from one population to another population. Principal components-A set of uncorrelated variables derived from the original data set through linear transformations, which maximize the variance between samples and reduce the dimensionality of the data while preserving the most important information. Individuals with shared genetic ancestry tend to be more genetically similar. Genetic ancestry-The genealogical paths through which an individual inherits DNA from specific ancestors in a reference population. Genetic cline-A gradual change of allele frequencies over a specified geographic area. Population bottleneck-An event that drastically reduces the effective size of a population, leading to increased genetic drift. Haplotype-A set of linked genetic variants that are coinherited.
#Pinpoint mapping serial
Serial founder effect-The successive loss of genetic variation when populations are sequentially founded by a small number of individuals. Out-of-Africa (OOA) model -Hypothesis that anatomically modern humans evolved in Africa and subsequently peopled the rest of the world. Population structure-Systematic differences in allele frequencies between subpopulations.Īdmixture-The interbreeding of individuals from two or more subpopulations that were isolated for a relatively short evolutionary time. N e determines the strength of genetic drift acting on a population. Linkage disequilibrium (LD)-The nonrandom association of two alleles at different loci.Įffective population size ( N e)-The number of breeding individuals in an idealized randomly mating population. Finally, we explore the biomedical implications of population structure in Africa on health and disease and call for more ethically conducted studies of genetic variation in Africa. Third, we highlight how natural selection has shaped patterns of genetic variation across the continent, noting that gene flow provides a potent source of adaptive variation and that selective pressures vary across Africa. Furthermore, the genomic signatures of more recent admixture can be found in the Cape Peninsula and throughout the African diaspora.
This includes gene flow between different click-speaking Khoe-San populations, the stepwise spread of pastoralism from eastern to southern Africa, multiple migrations of Bantu speakers across the continent, as well as admixture from the Middle East and Europe into the Sahel region and North Africa. Second, we describe the genetic legacies of admixture events that have occurred during the past 10,000 years. First, we give a brief overview of genetic variation in Africa and examine deep population structure within Africa, including the evidence of ancient introgression from archaic “ghost” populations. Each of these historical vignettes paints a recurring picture of population divergence followed by secondary contact. In this review, we view population genetics through the lens of admixture, highlighting how multiple demographic events have shaped African genomes. Importantly, African genomes are heterogeneous: They contain mixtures of multiple ancestries, each of which have experienced different evolutionary histories. As the ancestral homeland of our species, Africa contains elevated levels of genetic diversity and substantial population structure.
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