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Genetic Lineage
A genetic lineage, also known as genetic pedigree, is a series of mutations which connect an ancestral genetic type (allele, haplotype, or haplogroup) to derivative type. In cases where the genetic tree is very bushy the order of mutations in the lineage is mostly known, examples are the order of mutations between E1b1b and E1b1b1a1a for the human Y-chromosomesal L0 or L1 nodes. A genetic lineage can be contrasted with an evolutionary lineage in that a genetic lineage applies to a locus. An example of the difference is that an ancient African ape evolved into the gorilla-chimpanzee-human ancestor, which further evolved into the chimpanzee-human ancestor and then to humans. While most human lineages coalesce with chimpanzee lineages, which then converge with gorilla lineages, a few human lineages coalesce with gorilla lineages and then converge with chimpanzee lineages (or chimpanzee lineages that coalesce with gorilla lineages and then converge with human lineages). This occurs b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allele
An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chromosomal or genomic location of a gene or any other genetic element is called a locus (plural: loci) and alternative DNA sequences at a locus are called alleles." The simplest alleles are single nucleotide polymorphisms (SNP). but they can also be insertions and deletions of up to several thousand base pairs. Popular definitions of 'allele' typically refer only to different alleles within genes. For example, the ABO blood grouping is controlled by the ABO gene, which has six common alleles (variants). In population genetics, nearly every living human's phenotype for the ABO gene is some combination of just these six alleles. Most alleles observed result in little or no change in the function of the gene product it codes for. However, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplotype
A haplotype ( haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. Many organisms contain genetic material ( DNA) which is inherited from two parents. Normally these organisms have their DNA organized in two sets of pairwise similar chromosomes. The offspring gets one chromosome in each pair from each parent. A set of pairs of chromosomes is called diploid and a set of only one half of each pair is called haploid. The haploid genotype (haplotype) is a genotype that considers the singular chromosomes rather than the pairs of chromosomes. It can be all the chromosomes from one of the parents or a minor part of a chromosome, for example a sequence of 9000 base pairs. However, there are other uses of this term. First, it is used to mean a collection of specific alleles (that is, specific DNA sequences) in a cluster of tightly linked genes on a chromosome that are likely to be inherited together—that is, they are likely to be con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplogroup
A haplotype is a group of alleles in an organism that are inherited together from a single parent, and a haplogroup (haploid from the el, ἁπλοῦς, ''haploûs'', "onefold, simple" and en, group) is a group of similar haplotypes that share a common ancestor with a single-nucleotide polymorphism mutation. More specifically, a haplogroup is a combination of alleles at different chromosomal regions that are closely linked and that tend to be inherited together. As a haplogroup consists of similar haplotypes, it is usually possible to predict a haplogroup from haplotypes. Haplogroups pertain to a single line of descent. As such, membership of a haplogroup, by any individual, relies on a relatively small proportion of the genetic material possessed by that individual. Each haplogroup originates from, and remains part of, a preceding single haplogroup (or paragroup). As such, any related group of haplogroups may be precisely modelled as a nested hierarchy, in which each set (hap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E1b1b
E-M215, also known as E1b1b and formerly E3b, is a major human Y-chromosome DNA haplogroup. It is a division of the macro-haplogroup E-M96, which is defined by the single-nucleotide polymorphism (SNP) mutation M215. In other words, it is one of the major patrilineages of humanity, linking from father-to-son back to a common male-line ancestor ("Y-chromosomal Adam"). It is a subject of discussion and study in genetics as well as genetic genealogy, archaeology, and historical linguistics. The E-M215 haplogroup has two ancient branches that contain all the known modern E-M215, E-M35 and E-M281 subclades. Of the latter two E-M215 subhaplogroups, the only branch that has been confirmed in a native population outside of Ethiopia is E-M35. E-M35 in turn has two known branches, E-V68 and E-Z827, which contain by far the majority of all modern E-M215 subclade bearers. The E-V257 and E-V68 subclades each respectively their highest frequencies in North Africa and the Horn of Africa, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E1b1b1a
Haplogroup E-V68, also known as E1b1b1a, is a major human Y-chromosome DNA haplogroup found in North Africa, the Horn of Africa, Western Asia and Europe. It is a subclade of the larger and older haplogroup, known as E1b1b or E-M215 (also roughly equivalent to E-M35). The E1b1b1a lineage is identified by the presence of a single nucleotide polymorphism (SNP) mutation on the Y chromosome, which is known as V68. It is a subject of discussion and study in genetics as well as genetic genealogy, archaeology, and historical linguistics. E-V68 is dominated by its longer-known subclade E-M78. In various publications, both E-V68 and E-M78 have been referred to by other names, especially phylogenetic nomenclature such as "E3b1a" which are designed to show their place on the family tree of all human males. These various names change as new discoveries are made and are discussed below. Origins E-M78, like its parent clade E-V68, is thought to have an African origin. Based on genetic STR var ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Y-chromosome DNA Haplogroup
In human genetics, a human Y-chromosome DNA haplogroup is a haplogroup defined by mutations in the non- recombining portions of DNA from the male-specific Y chromosome (called Y-DNA). Many people within a haplogroup share similar numbers of short tandem repeats (STRs) and types of mutations called single-nucleotide polymorphisms (SNPs). The human Y-chromosome accumulates roughly two mutations per generation. "one mutation in every 30 million base pairs" Y-DNA haplogroups represent major branches of the Y-chromosome phylogenetic tree that share hundreds or even thousands of mutations unique to each haplogroup. The Y-chromosomal most recent common ancestor (Y-MRCA, informally known as Y-chromosomal Adam) is the most recent common ancestor (MRCA) from whom all currently living humans are descended patrilineally. Y-chromosomal Adam is estimated to have lived roughly 236,000 years ago in Africa. By examining other bottlenecks most Eurasian men (men from populations outside of Afri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplogroup L0 (mtDNA)
Haplogroup L0 is a human mitochondrial DNA (mtDNA) haplogroup. Origin L0 is one of two branches from the most recent common ancestor (MRCA) for the shared human maternal lineage. The haplogroup consists of five main branches (L0a, L0b, L0d, L0f, L0k). Four of them were originally classified into L1 subclades, L1a, L1d, L1f and L1k. In 2014, ancient DNA analysis of a 2,330 year old male forager's skeleton in Southern Africa found that the specimen belonged to the L0d2c1c mtDNA subclade. This maternal haplogroup is today most closely associated with the Ju, a subgroup of the indigenous San people, which points to population continuity in the region. In 2016, a Late Iron Age desiccated mummy from the Tuli region in northern Botswana was also found to belong to haplogroup L0. Distribution L0 is found most commonly in Sub-Saharan Africa. It reaches its highest frequency in the Khoisan people at 73% on average. Some of the highest frequencies are: Namibia ( !Xun) 79%, South Africa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplogroup L1 (mtDNA)
Haplogroup L1 is a human mitochondrial DNA (mtDNA) haplogroup. It is most common in Central Africa and West Africa. It diverged from L1-6 at about 140,000 years ago ( 95% CI). Its emergence is associated with the early peopling of Africa by anatomically modern humans during the Eemian, and it is now mostly found in African pygmies. Distribution Haplogroup L1 is found most commonly in Central Africa and West Africa. It reaches its highest frequency among the Mbenga Pygmies. It is likely that it was formerly more widespread, and was constrained to its current area as a result of the Bantu migration (which is largely associated with haplogroup L2). Haplogroup L1 has been observed in specimens from the island cemetery in Kulubnarti, Sudan, which date from the Early Christian period (AD 550–800). An ancient Beaker culture individual at the Camino de las Yeseras in Spain (San Fernando de Henares, Madrid; 4245 / RISE695F) has also been found to carry the L1b1a mitochondrial hap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lineage (evolution)
An evolutionary lineage is a temporal series of populations, organisms, cells, or genes connected by a continuous line of descent from ancestor to descendant.The Oxford English Dictionary defines biological lineage as "a sequence of species each of which is considered to have evolved from its predecessorOED definition of lineage/ref> Lineages are subsets of the evolutionary tree of life. Lineages are often determined by the techniques of molecular systematics. Phylogenetic representation of lineages 299x299px, A rooted tree of life into three ancient monophyletic lineages: bacteria, archaea, and eukaryotes">archaea.html" ;"title="bacteria, archaea">bacteria, archaea, and eukaryotes based on rRNA genes Lineages are typically visualized as subsets of a phylogenetic tree. A lineage is a single line of descent or linear chain within the tree, while a clade is a (usually branched) monophyletic group, containing a single ancestor and all its descendants. Phylogenetic trees are typica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locus (genetics)
In genetics, a locus (plural loci) is a specific, fixed position on a chromosome where a particular gene or genetic marker is located. Each chromosome carries many genes, with each gene occupying a different position or locus; in humans, the total number of protein-coding genes in a complete haploid set of 23 chromosomes is estimated at 19,000–20,000. Genes may possess multiple variants known as alleles, and an allele may also be said to reside at a particular locus. Diploid and polyploid cells whose chromosomes have the same allele at a given locus are called homozygous with respect to that locus, while those that have different alleles at a given locus are called heterozygous. The ordered list of loci known for a particular genome is called a gene map. Gene mapping is the process of determining the specific locus or loci responsible for producing a particular phenotype or biological trait. Association mapping, also known as "linkage disequilibrium mapping", is a method of ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coalescence (genetics)
Coalescent theory is a model of how alleles sampled from a population may have originated from a common ancestor. In the simplest case, coalescent theory assumes no recombination, no natural selection, and no gene flow or population structure, meaning that each variant is equally likely to have been passed from one generation to the next. The model looks backward in time, merging alleles into a single ancestral copy according to a random process in coalescence events. Under this model, the expected time between successive coalescence events increases almost exponentially back in time (with wide variance). Variance in the model comes from both the random passing of alleles from one generation to the next, and the random occurrence of mutations in these alleles. The mathematical theory of the coalescent was developed independently by several groups in the early 1980s as a natural extension of classical population genetics theory and models, but can be primarily attributed to John K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speciation
Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book ''On the Origin of Species''. He also identified sexual selection as a likely mechanism, but found it problematic. There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric speciation, allopatric, peripatric speciation, peripatric, parapatric speciation, parapatric, and sympatric speciation, sympatric. Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments of speciation, laboratory experiments. Whether genetic drift is a minor or major contributor to speciation is the subject of much ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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