Haplogroup

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A haplogroup is a group of haplotypes that have specific positions on a chromosome.

In human genetics , for example, the

examined. Y-DNA is routed exclusively along the paternal line and mtDNA is routed primarily along the maternal line .

One can use haplogroups to define genetically related groups of people within populations. The different haplogroups are assigned to different regions of origin. For example, some groups are only found among Europeans, others only or predominantly in Africa.

The haplogroups are designated with letters (or letter-number combinations) to distinguish them, whereby the same designations can occur for Y-groups and mt-groups - the correct assignment must therefore be observed when searching for certain groups.

Assumed migration of mitochondrial haplogroups (maternal line). In Central Europe the mt haplogroup “U” and the now dominant mt haplogroup “H” are widespread.
Assumed migration of the Y chromosome haplogroups (paternal line). Significant shares for Europe: the haplogroup "I" (with up to 30% today) and the most common group "R" (with "R1a" and "R1b") with shares of 50% and more.

From haplotype to haplogroup

Haplotype (from the Greek haplús or haplóos "simple" and typos "image, pattern") are variants of a nucleotide sequence on one and the same chromosome in the genome of a living being. A certain haplotype can be typical for individuals, populations or even species.

When comparing the alleles of haplotypes , individual combinations of SNPs are identified that can be used as genetic markers . If some of the individuals have the same haplotype due to common ancestry at a certain gene locus , they are combined to form a haplogroup.

Genetics and SNP markers

In molecular biology, markers are e.g. B. uniquely identifiable, short DNA sections whose location in the genome is known, e.g. B. SNP (Single Nucleotide Polymorphisms).

While the human genetics as an interdisciplinary science , the medical diagnostics with molecular biology related research and methodology, it is a special field of paleogenetics , based on haplogroups (and the derived SNP markers) prove

  • How the age and relationship of species and subspecies are represented, from whose fossils ancient DNA could be extracted,
  • The millennia-old hiking trails over which species / subspecies (and their haplogroups) migrated from their areas of origin to their current distribution areas,
  • What proportions of haplogroups occur today in certain areas of the world.

A spectrum of certain haplogroups can be assigned priority in terms of frequency to a certain region or a certain area of ​​origin. In areas with many adjoining or co-living ethnic groups and their ancestors (as in Eurasia) one can only speak of a typical haplogroup belonging to a certain “people” to a limited extent, since in most peoples several haplogroups occur in different proportions.

Mitochondrial haplogroup distribution in Europe in modern times. The haplogroups H and U are particularly dominant.
Y-chromosome haplogroup distribution in Europe in modern times. The haplogroup R (east with R1a and west with R1b) and group I.

Haplogroups in Europe

The distribution of haplogroups today and in the past is the result of mixing :

  • Europeans, Africans and Asians are so genetically similar that they cannot be meaningfully divided into clearly defined large groups.
  • The (pre-) history has constantly mixed up the ethnic groups of Europe, so that all Europeans have many common genetic ancestors, some of which lived in the more recent past: In Europe, to a certain extent, there is an extended family with close cousins ​​on all continents.
  • Only a few gene variants are "European". These determine external features such as hair and skin color or the tolerance of certain foods, such as milk or lactose .
  • Gene analysis techniques that take into account as many different genome communities as possible can still identify age-old substructures in the European population. They provide clues to the millennia-old history of settlement and mixing.

In Europe, for example, two specific mutations in the mitochondrial genome, which first appeared around 25,000 to 30,000 years ago and have since been passed on through the maternal line, define the “mt haplogroup H” most common among Europeans today. The probably much older "mt-haplogroup U" is also common in Europe.

Another European haplogroup characterized in the paternal line by mutations in the Y chromosome is called: I ; it is found in a fifth of all Europeans today, but was probably more widespread in the Paleolithic. The Y-chromosomal haplogroup R , which is most common in Europe today , is divided into two differently old subgroups based on additional SNP markers: "R1a and R1b", which can be used to trace the history of colonization in Europe after the Paleolithic.

When tracing back within a haplogroup, at some point in the distant past one will come across the hypothetical mitochondrial Eve and the hypothetical Adam of the Y chromosome . In 2013, a study was published in Science , according to which “mitochondrial Eve” lived 99,000 to 148,000 years ago and the so-called “Adam of the Y chromosome” 120,000 to 156,000 years ago.

Evolution trees

Evolution Tree Haplogroup Mitochondrial DNA (mtDNA)
mtDNA Eva
L0 L1 L2 L3   L4 L5 L6
  M. N  
CZ D. E. G Q   A. S.   R.   I. W. X Y
C. Z B. F. R0   pre-JT P  U
HV JT K
H V J T
Evolution tree haplogroups Y-chromosomal DNA (Y-DNA)
Adam of the Y chromosome
A00 A0'1'2'3'4
A0 A1'2'3'4
A1 A2'3'4
A2'3 A4 = BCDEF
A2 A3 B. CT 
|
DE CF
D. E. C. F.
|
G IJK H  
| |
G1 G2  IJ K 
| |
I. J L. K (xLT) T
| | |
I1 I2 J1 J2 M. NO P S.
| |
| |
N O Q R.
|
R1 R2
|
R1a R1b

Groups (selection / mtDNA and Y-DNA)

Haplogroup A.

Haplogroup B.

Haplogroup C

Haplogroup D.

Haplogroup E.

Haplogroup F.

Haplogroup G.

Haplogroup H.

Haplogroup I.

Haplogroup J.

Haplogroup K

Haplogroup L.

Haplogroup M.

Haplogroup N.

Haplogroup O

Haplogroup P

Haplogroup Q

Haplogroup R.

Haplogroup S.

Haplogroup T

Haplogroup U

Haplogroup V

Haplogroup W

Haplogroup X

Individual evidence

  1. ^ University of Illinois: World Haplogroups by JD McDonald. PDF
  2. ^ The International HapMap Consortium: The International HapMap Project. In: Nature. Volume 426, 2003, pp. 789-796 PDF
  3. ↑ National Genome Research Network , dump of August 28, 2012: When the world pulls together: The Human Genome Project (HGP).
  4. ↑ Spectrum of Science Compact: The Origins of Man. May 2013 edition (with selected articles from natur magazine ), page 44
  5. ↑ Jan Osterkamp in: Spectrum of Science Compact: "Neolithic Revolution - DNA analyzes from different millennia", April 2014 edition, page 48
  6. ↑ Spectrum of Science in Brief: “The Origins of Man”, May 2013 edition (with selected articles from the magazine natur ), p. 37.
  7. ↑ Spectrum of Science in Brief: "The Origins of Humans - Sorted by SNP Differences", May 2013 edition (with selected articles from the magazine natur ), p. 45.
  8. ↑ Spectrum of Science Compact: "The Origins of Man - Sorting According to SNP Differences", May 2013 issue (with selected articles from the magazine natur ), p. 45.
    Jan Osterkamp in: Spectrum of Science Compact: "Neolithic Revolution - DNA- Analyzes from different millennia ", April 2014 edition, p. 48.
  9. ↑ G. David Poznik et al: Sequencing Y Chromosomes Resolves Discrepancy in Time to Common Ancestor of Males Versus Females. In: Science . Volume 341, No. 6145, 2013, pp. 562-565, doi: 10.1126 / science.1237619
    C.F. Aquadro, BD Greenberg: Human mitochondrial DNA variation and evolution, analysis of nucleotide sequences from seven individuals. (PDF; 1.7 MB) In: Genetics. Vol. 103, Bethesda 1983, pp. 287-312. PMID 6299878 ISSN  0016-6731

See also

Web links

Commons : haplogroups  - collection of images, videos and audio files