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In the study of molecular evolution, a haplogroup (from the Greek: ἁπλοῦς, haploûs, "onefold, single, simple") is a group of similar haplotypes that share a common ancestor with a single nucleotide polymorphism (SNP) mutation. Because a haplogroup consists of similar haplotypes, this is what makes it possible to predict a haplogroup from haplotypes. An SNP test confirms a haplogroup. Haplogroups are assigned letters of the alphabet, and refinements consist of additional number and letter combinations, for example R1b1. Y-chromosome and mitochondrial DNA haplogroups have different haplogroup designations. Haplogroups pertain to deep ancestral origins dating back thousands of years.[1]
In human genetics, the haplogroups most commonly studied are Y-chromosome (Y-DNA) haplogroups and mitochondrial DNA (mtDNA) haplogroups, both of which can be used to define genetic populations. Y-DNA is passed solely along the patrilineal line, from father to son, while mtDNA is passed down the matrilineal line, from mother to offspring of both sexes. Neither recombines, and thus Y-DNA and mtDNA change only by chance mutation at each generation with no intermixture between parents' genetic material.
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Mitochondria are small organelles that lie in the cytoplasm of eucaryotic cells, such as those of humans. Their primary purpose is to provide energy to the cell. Mitochondria are thought to be reduced descendants of symbiotic bacteria that were once free living. One indication that mitochondria were once free living is that each contains a circular DNA, called mitochondrial DNA (mtDNA), whose structure is more similar to bacteria than eukaryotic organisms (see endosymbiotic theory). The overwhelming majority of a human's DNA is contained in the chromosomes in the nucleus of the cell, but mtDNA is an exception. An individual inherits their cytoplasm and the organelles it contains exclusively from their mother, as these are derived from the ovum (egg cell), sperm only carry chromosomal DNA due to the necessity of maintaining motility. When a mutation arises in mtDNA molecule, the mutation is therefore passed in a direct female line of descent. These mutations are derived from copying mistakes, when the DNA is copied it is possible that a single mistake occurs in the DNA sequence, these single mistakes are called single nucleotide polymorphisms (SNPs).
Human Y chromosomes are male-specific sex chromosomes; nearly all humans that possess a Y chromosome will be morphologically male. Y chromosomes are therefore passed from father to son; although Y chromosomes are situated in the cell nucleus, they only recombine with the X chromosome at the ends of the Y chromosome; the vast majority of the Y chromosome (95%) does not recombine. When mutations (SNPs) arise in the Y chromosome, they are passed on directly from father to son in a direct male line of descent. The Y chromosome and mtDNA therefore share specific properties.
Other chromosomes, autosomes and X chromosomes in women, share their genetic material (called crossing over leading to recombination) during meiosis (a special type of cell division that occurs for the purposes of sexual reproduction). Effectively this means that the genetic material from these chromosomes gets mixed up in every generation, and so any new mutations are passed down randomly from parents to offspring.
The special feature that both Y chromosomes and mtDNA display is that mutations can accrue along a certain segment of both molecules and these mutations remain fixed in place on the DNA. Furthermore the historical sequence of these mutations can also be inferred. For example, if a set of ten Y chromosomes (derived from ten different men) contains a mutation, A, but only five of these chromosomes contain a second mutation, B, it must be the case that mutation B occurred after mutation A. Furthermore all ten men who carry the chromosome with mutation A are the direct male line descendants of the same man who was the first person to carry this mutation. The first man to carry mutation B was also a direct male line descendant of this man, but is also the direct male line ancestor of all men carrying mutation B. Series of mutations such as this form molecular lineages. Furthermore each mutation defines a set of specific Y chromosomes called a haplogroup. All men carrying mutation A form a single haplogroup, all men carrying mutation B are part of this haplogroup, but mutation B also defines a more recent haplogroup (which is a subgroup or subclade) of its own which men carrying only mutation A do not belong to. Both mtDNA and Y chromosomes are grouped into lineages and haplogroups; these are often presented as tree like diagrams.
It is usually assumed that there is little natural selection for or against a particular haplotype mutation which has survived to the present day, so apart from mutation rates (which may vary from one marker to another) the main driver of population genetics affecting the proportions of haplotypes in a population is genetic drift — random fluctuation caused by the sampling randomness of which members of the population happen to pass their DNA on to members of the next generation of the appropriate sex. This causes the prevalence of a particular marker in a population to continue to fluctuate, until it either hits 100%, or falls out of the population entirely. In a large population with efficient mixing the rate of genetic drift for common alleles is very low; however, in a very small interbreeding population the proportions can change much more quickly. The marked geographical variations and concentrations of particular haplotypes and groups of haplotypes therefore witness the distinctive effects of repeated population bottlenecks or founder events followed by population separations and increases. The lineages which can be traced back from the present will not reflect the full genetic variation of the older population: genetic drift means that some of the variants will have died out. The cost of full mtDNA sequence tests has limited the availability of data. Haplotype coalescence times and current geographical prevalences both carry considerable error uncertainties.
Human Y chromosome DNA (Y-DNA) haplogroups are lettered A through T, and are further subdivided using numbers and lower case letters. Y chromosome haplogroup designations are established by the Y Chromosome Consortium.[2]
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Human Y-chromosome DNA (Y-DNA) haplogroups (by ethnic groups · famous haplotypes) |
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| A | BT | ||||||||||||||||||||||||||||||
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| B | CT | ||||||||||||||||||||||||||||||
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| CF | DE | ||||||||||||||||||||||||||||||
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| C | F | D | E | ||||||||||||||||||||||||||||
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| G | H | IJK | |||||||||||||||||||||||||||||
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| IJ | K | ||||||||||||||||||||||||||||||
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| I | J | L | MNOPS | T | |||||||||||||||||||||||||||
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| M | NO | P | S | ||||||||||||||||||||||||||||
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| N | O | Q | R | ||||||||||||||||||||||||||||
Y-chromosomal Adam is the name given by researchers to the male who is the most recent common patrilineal (male-lineage) ancestor of all living humans.
Major Y-chromosome haplogroups, and their geographical regions of occurrence (prior to the recent European colonization), include:
Groups without mutation M168
Groups with mutation M168(mutation M168 occurred ~50,000 bp)
Groups with mutation M89(mutation M89 occurred ~45,000 bp)
Groups with mutations L15 & L16
Groups with mutation M9(mutation M9 occurred ~40,000 bp)
Groups with mutation M526
Groups with mutation M70
Human mitochondrial DNA haplogroupsMain article: Human mitochondrial DNA haplogroup
Human mtDNA haplogroups are lettered: A, B, C, CZ, D, E, F, G, H, pre-HV, HV, I, J, pre-JT, JT, K, L0, L1, L2, L3, L4, L5, L6, L7, M, N, P, Q, R, S, T, U, UK, V, W, X, Y, and Z.
Mitochondrial Eve is the name given by researchers to the woman who is the most recent common matrilineal (female-lineage) ancestor of all living humans. Defining populations
Haplogroups can be used to define genetic populations and are often geographically oriented. For example, the following are common divisions for mtDNA haplogroups:
The mitochondrial haplogroups are divided into 3 main groups, which are designated by the 3 sequential letters L, M, N. Humanity first split within the L group between L0 and L1. L1 gave rise to other L groups, one of which, L3, split into the M and N group. The M group comprises the first wave of human migration out of Africa, following an eastward route along southern coastal areas. Descendent populations belonging to haplogroup M are found throughout East Africa, Asia, the Americas, and Melanesia, though almost none have been found in Europe. The N group may represent another migration out of Africa, heading northward instead of eastward. Shortly after the migration, the large R group split off from the N. Haplogroup R consists of two subgroups defined on the basis of their geographical distributions, one found in southeastern Asia and Oceania and the other containing almost all of the modern European populations. Haplogroup N(xR), i.e. mtDNA that belongs to the N group but not to its R subgroup, is typical of Australian aboriginal populations, while also being present at low frequencies among many populations of Eurasia and the Americas. The L type consists of Africans, and especially Sub-Saharan Africans. The M type consists of: M1- Ethiopian, Somali and Indian populations. Likely due to much gene flow between the Horn of Africa and the Arabian Peninsula (Saudi Arabia, Yemen, Oman), separated only by a narrow strait between the Red Sea and the Gulf of Aden. CZ- Many Siberians; branch C- Some Amerindian; branch Z- Many Saami, some Korean, some North Chinese, some Central Asian populations. D- Some Amerindians, many Siberians and northern East Asians E- Malay, Borneo, Philippines, Taiwan aborigines, Papua New Guinea G- Many Northeast Siberians, northern East Asians, and Central Asians Q- Melanesian, Polynesian, New Guinean populations The N type consists of: A- Found in some Amerindians, Japanese, and Koreans I- 10% frequency in Northern, Eastern Europe S- Some Australian aborigines W- Some Eastern Europeans, South Asians, and southern East Asians X- Some Amerindians, Southern Siberians, Southwest Asians, and Southern Europeans Y- Ainus and Nivkhs; 1% in Southern Siberia R- Large group found within the N type.Populations contained therein can be divided geographically into West Eurasia and East Eurasia. Almost all European populations and a large number of Middle-Eastern population today are contained within this branch. A smaller percentage is contained in other N type groups (See above). Below are subclades of R: B- Some Chinese, Tibetans, Mongolians, Central Asians, Koreans, Amerindians, South Siberians, Japanese, Austronesians F- Mainly found in southeastern Asia, especially Vietnam; 8.3% in Hvar Island in Croatia.[5] R0- Found in Arabia and among Ethiopians and Somalis; branch HV (branch H; branch V)- Europe, Western Asia, North Africa; Pre-JT- Arose in the Levant (modern Lebanon area), found in 25% frequency in Bedouin poupulations; branch JT (branch J; branch T)- North, Eastern Europe, Indus, Mediterranean U- High frequency in Scandinavia, Baltic countries, Mediterranean Overlap between y-haplogroups and mt-haplogroupsThe ranges of specific y-haplogroups and specific mt-haplogroups overlap, indicating populations that have a specific combination of a y-haplogroup and an mt-haplogroup. Y mutations and mt mutations do not necessarily occur at a similar time, and differential rates of sexual selection between the two genders combined with founder effect and genetic drift can alter the haplogroup composition of a population, so the overlaps are only rough. The very rough overlaps between Y-DNA haplogroups and mtDNA haplogroups are as follows:
See also
References
External linksGeneralNews
all DNA haplogroupsY chromosome DNA haplogroups
Mitochondrial DNA haplogroups |
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The following is based on information in the gentree.com web site as well as Wikipedia articles including Human Y-chromosome DNA haplogroups. It provides a quick summary of the major haplogroups, as presently (2007) understood. While based on Genetree's presentation, some modifications have been made to reorganize the information more systematically to show a) timing of origin, b) place of origin, and c) center of modern occurrence. Some of this has required interpreting what Genetree said originally, and this may have introduced some ideas that they had not intended. Such passages are marked with an asterisk * Interested readers should examine the original GeneTree information.
| Haplogroup | Date of Origin | Place of Origin | Center of Modern Occurrence |
| A | Haplogroup A is the oldest, considered the group from which arose "Y-Chromosomal Adam." | most widespread Y-DNA haplogroup, | Found throughout Africa, A's descendants include Tanzania's Hadza peoples and eastern Africa's bushmen. |
| B | Like haplogroup A, B is among the oldest and most diverse of the Y-DNA haplogroups. | Africa | This group is best represented among African Pygmy populations (particularly among Baka and Mbuti peoples), in the sub-Sahara. |
| C | Originated before c4,0000 BC * | Asia * Scientists see this haplogroup as having migrated to the Americas circa 4,000-6,000 BC, settling in the Pacific Northwest. | With progeny spanning Asia and the South Pacific, haplogroup C is believed to have helped colonize Australia and New Guinea. C's traces are also to be found - although less commonly - among indigenous American peoples. |
| D | approximately 50,000 years ago | Africa; experienced a great Southern Asian coastal migration. | Its descendants populate Southeast Asia and the Pacific Rim, including Japan (especially subgroup D2). |
| E | This haplogroup represents a major segment of early mankind, with origins some 50,000 before our time. | Its progeny is most common to the Middle East and northern Africa. | |
| E3a | c4000 years ago | Northern Africa; | and is notable in its frequent representation among modern day black Americans. |
| E3b | appeared around 24,000 BC. E3b | Middle East | Thought to have emigrated from the Middle East into the Mediterranean region, westward during the agricultural expansion in the Neolithic era. Today's E3b descendants are said to be found in eastern and northern Africa, as well as southeastern Europe. |
| F | c45,000 years ago | It is sometimes believed to represent a "second-wave" of expansion out of Africa. However, the location of this lineage's first expansion and rise to dominance appears to have been in India or somewhere close to it within South Asia or the Middle East; | The extent of its distribution not yet known for certain, but its two clades (F1 and F2) seem to occur only at a very low frequency among modern human populations and primarily only among populations of India. Despite its rare occurrence, 90% of the modern male population belongs to Haplogroups derived from HG F. |
| G | It is thought to have its origins in circa 10,000-15,000 BC | India or Pakistan, | Migrated in a northwesterly direction; its descendants can be found in the eastern Mediterranean region, as well as the Middle East and western Asia. This haplogroup is widely distributed in Eastern Europe and Asia, despite a low overall representation in human populations. |
| H | H is believed to have been born approximately 30,000 years ago | Southern Asia. While scientists have traced H's roots to India itself, evidence also suggests a Middle Eastern/Iranian origin. | It is well represented in today's Indian and Pakistani populations. |
| I | A branch of haplogroup F, developed prior to about 20,000 years ago | Middle East | Believed to have migrated from the Middle East 20,000 to 25,000 years ago; it can be found in high concentrations in the Adriatic region (1/3 of modern day Croats), and is evidently also linked with Celtic populations. This haplogroup is thought to be linked with Scandinavia's Viking populations, ultimately spreading widely throughout modern-day Europe. |
| I1a | Its roots have been traced to as recently as the past 1,000 years, | Has been shown to be of non-Scandinavian origin, despite its nominal link with haplogroup I, a heavily Scandinavian segment. It is thought to be linked to Anglo-Saxon migrations from southern into northern Europe. | The group's modern-day seat is in central Europe. |
| I1b | Has been shown to be of non-Scandinavian origin, despite its nominal link with haplogroup I, a heavily Scandinavian segment. | I1b's progeny can be found in modern day Greece, and less frequently in other areas of southern Europe. | |
| J | This descendant of haplogroup F emerged roughly 10,000-15,000 years ago | Western Asia | It is traceable to current European, Middle Eastern and North African peoples, with progeny also represented in India and Pakistan. |
| J2 | Its 15,000-20,000 year old beginnings are said to have coincided with the spread of early agriculture, | J2's descendants include modern Jewish populations, with frequent representation also in Central Asia and the Mediterranean. with additional populations in India. J2 is also said to be represented in some Arab peoples. | |
| K | 40,000 years ago. | Central Asia some | This subgroup of F gave rise to every remaining haplogroup - namely L, M, N, O and P (which would spawn haplogroups Q and R). Haplogroup K descendants would fathered most of the current population of the northern hemisphere; almost all Asians are descendants of this group, many Indian peoples, and most Europeans are also descendants |
| L | Originating some 30,000 years ago, | L is said to have yielded the first significant influx of humans into India. Its descendants are still represented in the Indian nation, with further progeny extending throughout southern Asia and the Middle East. | |
| M | M made its first appearance circa 10,000 BC | in southeastern Asia, | and spawned populations in Indonesia and much of Southeast Asia. |
| N | This haplogroup's origins have been traced to northern Asia, where its peoples were divided between Siberia and a strong Eurasian migration. | Today's N populations are found throughout much of Europe, including Russia and Scandinavian nations. | |
| O | First appearing roughly 35,000 years ago, | O's membership is said to have left Siberia for the Pacific Rim region. | Virtually all Chinese, Korean and Japanese males are descendants of haplogroup O, with almost no representation among western Asian populations. |
| P | 30,000 to 40,000 years before the present day. | Scientists have traced P's roots to northern Asia, | This subgroup of K is ancestor to most Europeans, and has spawned nearly all Native American peoples. Today's P descendants are common to Asia and South America. |
| Q | Originated approximately 20,000 years ago, | in Siberia moving eastward across the Bering Strait into the American continent some c 15000 years ago | Today's Q progeny is found in nearly all Native American peoples, having spread from northeastern America throughout the entire continent.Q's lineage is common to members of both Asian and North American populations, |
| R | 30,000 years ago | This haplogroup arose in northwestern Asia | Central Asia, South Asia, Australia, Siberia, Native Americans, and Cameroon. |
| R1a | circa 10,000 BC, | likely originated in the Eurasian Steppes, and may be associated with the Kurgan culture and Proto-Indo-European expansion. | It is primarily found in Central and Western Asia, India, and the Slavic peoples of Eastern Europe, as well as among some populations of Mongolia and southern Siberia, where it might reflect Scythian influences of classical antiquity. |
| R1b | circa 10,000 BC, | Its progenitors are said to have descended from Cro-Magnon man, which immigrated into Europe some 35,000 years before our present day. | Most common of all haplogroups among European peoples. Generously exhibited in western European males, and thus within North American population groups, this haplogroup is represented most frequently in southern England, as well as among the Spanish and Portuguese. In fact, some western European regions (the Iberian peninsula and Ireland) contain R1b males at frequencies as high as 90%. |
   | Y Chromosome Consortium - The Y Chromosome Consortium |
| | DNA Heritage's Y-haplogroup map - Y-chromosome SNP testing at DNA Heritage |
| | chart - Genome Research -- Consortium 12 (2): 339 Figure 1 |
| | ISOGG Y-DNA Haplogroup Tree 2006 - ISOGG 2009 Y-DNA Haplogroup Tree |
| | Y Chromosome and mtDNA haplogroups - Y Chromosome and mtDNA haplogroups |
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