In the study of
molecular evolution, a haplogroup, from "ἁπλο-" (Greek "haplo-": simple or single) + "group", is a group of similar haplotypesthat 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. A SNP test confirms a haplogroup. Haplogroups are assigned letters of the alphabet, and refinements consist of additional number and letter combinations, Example: R1b1. Y-chromosome and mitochondrial DNA haplogroups have different haplogroup designations. Haplogroups pertain to deep ancestral origins dating back thousands of years. [The International Society of Genetic Genealogy see Haplogroup definition in DNA-NEWBIE GLOSSARY [http://www.isogg.org] ]
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 patrilinealline, while mtDNA is passed solely on the matrilinealline.
Classifications of human haplogroups of either sort based on
genetic markers, specifically by means of Unique event polymorphism(UEPs), have been rapidly evolving over the past several years as new markers are found.
Haplogroup population genetics
It is usually assumed that there is little
natural selectionfor or against a particular haplotype mutationwhich has survived to the present day, so apart from mutation rates (which may vary from one marker to another) the main driver of population geneticsaffecting 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 haplogroups
Y chromosomeDNA (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 [ [http://ycc.biosci.arizona.edu/ Y Chromosome Consortium] ] . Y-chromosomal Adamis 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 tothe recent European colonization), include:
International HapMap Project
Genealogical DNA test
List of genetic genealogy topics
* [http://www.worldfamilies.net/y-haplogroups.htm World Families Network]
* [http://www.springerlink.com/media/53f7mgywmp4qtqrgtav0/contributions/f/1/4/2/f142j25785572821_html/fulltext.html Indian maternal gene pool] , Journal of Human Genetics"
* [http://dienekes.blogspot.com/ Dienekes' Anthropology Blog] frequent highlights of new results.
all DNA haplogroups
Y chromosome DNA haplogroups
* [http://ycc.biosci.arizona.edu/ Y Chromosome Consortium]
* [http://www.isogg.org/tree/index.html ISOGG Y-DNA Haplogroup Tree 2006]
* [http://www.dnaheritage.com/ysnptree.asp DNA Heritage's Y-haplogroup map]
* [https://home.comcast.net/~whitathey/predictorinstr.htm Haplogroup Predictor]
*The Y Chromosome Consortium (2002), [http://www.genome.org/cgi/content/full/12/2/339 A Nomenclature System for the Tree of Human Y-Chromosomal Binary Haplogroups] , Genome Research, Vol. 12(2), 339-348, February 2002. (Detailed hierarchical [http://www.genome.org/cgi/content-nw/full/12/2/339/F1 chart] has conversions from previous naming schemes)
* [http://dnaconsultants.com/images/links/49-conversion.pdf DNA Consulting's Conversion Chart for Male Haplogroups] (PDF)
*Semino et al (2000), [http://hpgl.stanford.edu/publications/Science_2000_v290_p1155.pdf The Genetic Legacy of Paleolithic Homo sapiens sapiens in Extant Europeans] , Science, Vol 290 (paper which introduced the "Eu" haplogroups).
Mitochondrial DNA haplogroups
* [http://www.stats.gla.ac.uk/~vincent/images/skeleton07-08-02.jpggraphical mtDNA haplogroup skeleton]
* [http://www.ajhg.org/AJHG/fulltext/S0002-9297(07)60403-0 The Making of the African mtDNA Landscape]
* [http://www.ajhg.org/AJHG/fulltext/S0002-9297(07)61263-4 Do the Four Clades of the mtDNA Haplogroup L2 Evolve at Different Rates?]
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