Subclade
{{Other uses}}{{genetic genealogy}}{{Also|Cladistics}}
In genetics, a subclade is a subgroup of a haplogroup.{{cite book |last1=Caselli |first1=Giovanni |title=Etruria and the Origins of the Etruscans |date=21 July 2022 |publisher=Cambridge Scholars Publishing |isbn=978-1-5275-8475-4 |page=33 |url=https://books.google.com/books?id=BW1_EAAAQBAJ&pg=PA33 |language=en}}
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 (SNP) markers 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.{{cite web|title=Understanding Results: mtDNA: How are mitochondrial DNA (mtDNA) Haplogroups named?|url=http://www.familytreedna.com/faq/answers.aspx?id=10#476|publisher=Family Tree DNA|accessdate=3 April 2013}}{{cite web|title=About mtDNA Haplogroups (Maternal Ancient Ancestry)|url=http://www.dnahaplogroups.org/mtdnaHaplogroup.php?&l=n&__atoken=__NONE__|archive-url=https://archive.today/20130414162837/http://www.dnahaplogroups.org/mtdnaHaplogroup.php?&l=n&__atoken=__NONE__|url-status=dead|archive-date=April 14, 2013|publisher=DNA Ancestry Project|accessdate=1 April 2013}}{{cite web|title=Comparison of Y-DNA and mtDNA haplogroups|url=http://www.dnahaplogroups.org/introduction.php?type=start&page=2&l=n&__atoken=__NONE__|archive-url=https://archive.today/20130414163645/http://www.dnahaplogroups.org/introduction.php?type=start&page=2&l=n&__atoken=__NONE__|url-status=dead|archive-date=April 14, 2013|publisher=DNA Ancestry Project|accessdate=1 April 2013}}
=Y-DNA=
Y-DNA haplogroups are defined by the presence of a series of SNP markers on the Y chromosome. Subclades are defined by a terminal SNP, the SNP furthest down in the Y chromosome phylogenetic tree.{{cite web|title=myFTDNA 2.0 User Guide: Y-DNA: What is the Y-DNA - Matches page?|url=http://www.familytreedna.com/faq/answers.aspx?id=48#1990|publisher=Family Tree DNA|quote=A terminal SNP determines the terminal (final) subbranch on the Y-DNA Tree to which someone belongs.|accessdate=31 March 2013}}
=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). 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.{{cite web|title=Understanding Results: Y-DNA Single Nucleotide Polymorphism (SNP): How are haplogroups and their subclades named?|url=http://www.familytreedna.com/faq/answers.aspx?id=26#318|publisher=Family Tree DNA|accessdate=31 March 2013}} 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.{{cite web|title=Understanding Haplogroups: How are the haplogroups named?|url=http://www.familytreedna.com/understanding-haplogroups.aspx|publisher=Family Tree DNA|accessdate=31 March 2013|url-status=dead|archiveurl=https://web.archive.org/web/20120621052330/http://www.familytreedna.com/understanding-haplogroups.aspx|archivedate=21 June 2012}} This inconsistency, and increasingly cumbersome longhand nomenclature, has prompted a move towards using the simpler shorthand nomenclature.