In
genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar worki ...
, a subclade is a subgroup of a
haplogroup.
Naming convention
Although
human mitochondrial DNA (mtDNA) and
Y chromosome DNA (Y-DNA) haplogroups and subclades are named in a similar manner, their names belong to completely separate systems.
[
]
mtDNA
mtDNA haplogroups are defined by the presence of a series of single-nucleotide polymorphism
In genetics, a single-nucleotide polymorphism (SNP ; plural SNPs ) is a germline substitution of a single nucleotide at a specific position in the genome. Although certain definitions require the substitution to be present in a sufficiently lar ...
(SNP) marker
The term Marker may refer to:
Common uses
* Marker (linguistics), a morpheme that indicates some grammatical function
* Marker (telecommunications), a special-purpose computer
* Boundary marker, an object that identifies a land boundary
* Marke ...
s in the hypervariable regions and the coding region of mitochondrial DNA. They are named with the capital letters A through Z, with further subclades named using numbers and lower case letters.
Y-DNA
Y-DNA haplogroups are defined by the presence of a series of SNP markers on the Y chromosome
The Y chromosome is one of two sex chromosomes ( allosomes) in therian mammals, including humans, and many other animals. The other is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or a ...
. Subclades are defined by a ''terminal SNP'', the SNP furthest down in the Y chromosome phylogenetic tree.
Human Y-DNA
The Y Chromosome Consortium (YCC) developed a system of naming major human Y-DNA haplogroups with the capital letters A through T, with further subclades named using numbers and lower case letters (YCC longhand nomenclature
Nomenclature (, ) is a system of names or terms, or the rules for forming these terms in a particular field of arts or sciences. The principles of naming vary from the relatively informal conventions of everyday speech to the internationally agre ...
). YCC shorthand nomenclature names Y-DNA haplogroups and their subclades with the first letter of the major Y-DNA haplogroup followed by a dash and the name of the defining terminal SNP. Y-DNA haplogroup nomenclature is changing over time to accommodate the increasing number of SNPs being discovered and tested, and the resulting expansion of the Y chromosome phylogenetic tree. This change in nomenclature has resulted in inconsistent nomenclature being used in different sources.
See also
* Clade
*Cladistics
Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived ch ...
* Haplotype
References
{{Reflist
Genetics
Genetic genealogy