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An evolutionary lineage is a temporal series of populations, organisms, cells, or genes connected by a continuous line of descent from ancestor to descendant.^[1]^[2] Lineages are subsets of the evolutionary tree of life. Lineages are often determined by the techniques of molecular systematics.

Phylogenetic representation of lineages

Lineages are typically visualized as subsets of a phylogenetic tree. A lineage is a single line of descent or linear chain within the tree, while a clade is a (usually branched) monophyletic group, containing a single ancestor and all its descendants.^[3] Phylogenetic trees are typically created from DNA, RNA or protein sequence data. Apart from this, morphological differences and similarities have been, and still are used to create phylogenetic trees. Sequences from different individuals are collected and their similarity is quantified. Mathematical procedures are used to cluster individuals by similarity.^[4]

Members of a species are considered to evolve as a single unit (or lineage) when they repeatedly share the same genes. The nodes would represent a split in lineage due to a breaking of genetic connections: when a single lineage is divided into two subsets, with the individuals not exchanging genes, they will accumulate differences in genes. If they do not fuse back again, it will create a new distinct descendant clade.^[4]

Just as a map is a scaled approximation of true geography, a phylogenetic tree is an approximation of the true complete evolutionary relationships. For example, in a full tree of life, the entire clade of animals can be collapsed to a single branch of the tree. However, this is merely a limitation of rendering space. In theory, a true and complete tree for all living organisms or for any DNA sequence could be generated.^[4]

Nevertheless, phylogenies can sometimes appear in a non-treelike form. Branches on the tree of life may grow together, a phenomenon called reticulation, which occurs due to different biological processes. Another process, introgression, occurs when hybrids between distinct lineages transfer novel genetic material through subsequent crossing. In other cases, hybrid speciation takes place when lineages hybridize to form a new, distinct lineage. Horizontal gene transfer, involving the introgression of very few genes, usually appears as a treelike population history with some genes having a discordant history. Thus, the tree-like representation would be proper as long as introgression and hybrid speciation are rare or limited to closely related tips (of lineages). In some cases, evolutionary relantionships should be depicted better in the form of a network.^[4]

References

^ The University of California, Berkeley resource on understanding evolution defines a lineage as "A continuous line of descent; a series of organisms, populations, cells, or genes connected by ancestor/descendant relationships." Understanding Evolution, Glossary of Terms
^ The Oxford English Dictionary defines biological lineage as "a sequence of species each of which is considered to have evolved from its predecessor."OED definition of lineage
^ "Blood Cell Lineage | SEER Training". training.seer.cancer.gov. Retrieved 2024-07-26.
^ ^a ^b ^c ^d Kliman, R. M., ed. (2016). "Phylogenetic Tree". Encyclopedia of Evolutionary Biology. Academic Press. ISBN 9780128004265.

External links

[1] The University of California, Berkeley resource on understanding evolution defines a lineage as "A continuous line of descent; a series of organisms, populations, cells, or genes connected by ancestor/descendant relationships." Understanding Evolution, Glossary of Terms

[2] The Oxford English Dictionary defines biological lineage as "a sequence of species each of which is considered to have evolved from its predecessor."OED definition of lineage

[3] "Blood Cell Lineage | SEER Training". training.seer.cancer.gov. Retrieved 2024-07-26.

[:0-4] Kliman, R. M., ed. (2016). "Phylogenetic Tree". Encyclopedia of Evolutionary Biology. Academic Press. ISBN 9780128004265.

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+{{short description|Sequence of populations, organisms, cells, or genes that form a line of descent}}
-An evolutionary '''lineage''' (also called a [[cladistics|clade]]) is composed of [[species]], [[taxa]], or individuals that are related by descent from a common ancestor. Lineages are subsets of the evolutionary [[Evolutionary tree|tree of life]]. The concept of an evolutionary lineage is grounded in the science of [[cladistics]]. Lineages are often determined by the techniques of [[molecular systematics]]. A lineage can be distinguished from a mere collection of species by the fact that it contains only and all individuals that share a common ancestor.
+An evolutionary '''lineage''' is a temporal series of populations, organisms, cells, or genes connected by a continuous line of descent from ancestor to descendant.<ref>The [[University of California, Berkeley]] resource on understanding evolution defines a lineage as "A continuous line of descent; a series of [[organism]]s, populations, cells, or genes connected by ancestor/descendant relationships." [http://evolution.berkeley.edu/evolibrary/glossary/glossary.php?start=g&end=m Understanding Evolution, Glossary of Terms]</ref><ref>The [[Oxford English Dictionary]] defines biological lineage as "a sequence of species each of which is considered to have evolved from its predecessor."[https://web.archive.org/web/20070930004858/http://www.askoxford.com/concise_oed/lineage?view=uk OED definition of lineage]</ref> Lineages are subsets of the evolutionary [[Tree of life (biology)|tree of life]]. Lineages are often determined by the techniques of [[molecular systematics]].
 == Phylogenetic representation of lineages ==
+{{unreferenced section|date=November 2016}}
+[[image:Phylogenetic_tree.svg|thumb|upright=1.4|A rooted tree of life into three ancient monophyletic lineages: [[bacteria]], [[archaea]], and [[eukaryotes]] based on [[rRNA]] genes]]
+Lineages are typically visualized as subsets of a [[phylogenetic tree]]. A lineage is a single line of descent or linear chain within the tree, while a [[clade]] is a (usually branched) [[monophyletic]] group, containing a single ancestor and all its descendants.<ref>{{Cite web |title=Blood Cell Lineage {{!}} SEER Training |url=https://training.seer.cancer.gov/leukemia/anatomy/lineage.html |access-date=2024-07-26 |website=training.seer.cancer.gov}}</ref> [[Phylogenetic]] trees are typically created from [[DNA]], RNA or [[protein]] sequence data. Apart from this, morphological differences and similarities have been, and still are used to create phylogenetic trees. Sequences from different individuals are collected and their similarity is quantified. Mathematical procedures are used to [[data clustering|cluster]] individuals by similarity.<ref name=":0">{{Cite book |title=Encyclopedia of Evolutionary Biology |publisher=Academic Press |year=2016 |isbn=9780128004265 |editor-last=Kliman |editor-first=R. M. |chapter=Phylogenetic Tree}}</ref>
-[[image:PhylogeneticTree.jpg|thumb|right|220px|Fig. 1: A rooted tree for rRNA genes]]
+Members of a species are considered to evolve as a single unit (or lineage) when they repeatedly share the same genes. The nodes would represent a split in lineage due to a breaking of genetic connections: when a single lineage is divided into two subsets, with the individuals not exchanging genes, they will accumulate differences in genes. If they do not fuse back again, it will create a new distinct descendant clade.<ref name=":0" />
-Lineages are typically visualized as subsets of a [[phylogenetic tree]]. For example, the tree in Figure 1 shows the separation of life into three ancient lineages: [[bacteria]], [[archaea]], and [[eukaryotes]]. [[Phylogenetic]] trees are typically created from [[DNA]] or protein sequence data. Sequences from different individuals are collected and their similarity is quantified. Mathematical procedures are used to [[data clustering|cluster]] individuals by similarity.
-Just as a map is a scaled approximation of true [[geography]], a phylogenetic tree is an approximation of the true complete [[evolutionary]] relationships. For example, in Figure 1, the entire lineage of animals has been collapsed to a single "leaf" in the tree. However, this is merely a limitation of rendering space. In theory, a true and complete tree for all living organisms or for any [[DNA]] sequence could be generated.
+Just as a map is a scaled approximation of true [[geography]], a phylogenetic tree is an approximation of the true complete [[evolutionary]] relationships. For example, in a full tree of life, the entire clade of animals can be collapsed to a single branch of the tree. However, this is merely a limitation of rendering space. In theory, a true and complete tree for all living organisms or for any [[DNA]] sequence could be generated.<ref name=":0" />
+Nevertheless, phylogenies can sometimes appear in a non-treelike form. Branches on the [[Tree of life (biology)|tree of life]] may grow together, a phenomenon called [[Reticulation (single-access key)|reticulation]], which occurs due to different biological processes. Another process, [[introgression]], occurs when hybrids between distinct lineages transfer novel genetic material through subsequent crossing. In other cases, [[hybrid speciation]] takes place when lineages hybridize to form a new, distinct lineage. Horizontal gene transfer, involving the introgression of very few genes, usually appears as a treelike population history with some genes having a discordant history. Thus, the tree-like representation would be proper as long as introgression and hybrid speciation are rare or limited to closely related tips (of lineages). In some cases, evolutionary relantionships should be depicted better in the form of a network.<ref name=":0" />
-== The "lineage" definition of human races ==
+==See also==
-Many contemporary biological definitions of [[race]] conceptualize races as evolutionary lineages within the human species. Genetic data can be used to infer population structure and assign individuals to groups that often correspond with their self-identified geographical ancestry. An example of this concept is represented in Figure 2.
+* [[Clade]]
-[[Image:Human-phylo-tree.png|thumb|center|610px|Fig. 2: An example of the lineage concept of human races in the context of higher levels of categorization. This rendering is a simplification.]]
+* [[Linnaean taxonomy]]
+==References==
-A primary motivation for categorizing human genetic variation in this way comes from [[race in biomedicine|biomedical research]]. In this context, human races represent different [[genetic background]]s that may influence the association of diseases with their causes (genetic or environmental).
+<references/>
+==External links==
-The concept of racial lineage is very similar to the concept of familial [[kinship and descent|lineages]] in [[genealogy]]. This has led some commentators to describe races as extended families.
-A major objection to the view that contemporary humans can be categorized into lineages is the existence of individuals with ancestry from multiple lineages. To accommodate [[Wiktionary:admixture|admixture]], the definition of races is expanded beyond straightforward lineages to include the possibility of fractional lineage membership. This is often represented graphically as a triangle plot (see Figure 3). The fuzziness of racial lineages has led to the description of races as fuzzy sets (Sarich & Miele 2004).
-[[Image:Admixture triangle plot.png|thumb|right|200px|Fig. 3: Triangle plot shows average admixture of five North American ethnic groups.]]
-[[Image:Four race triangle graph.png|thumb|right|200px|Fig. 4: 3D triangle plots (in 2D projection) are used to describe ancestry relative to four groups. The plot is meant to be folded out of the plane such that the three East Asian points meet, forming a four-sided solid.]]
-==References==
+{{Phylogenetics}}
-* Sarich, Vincent, and Frank Miele. ''Race: The Reality of Human Differences''. Westview Press, 2004.
+[[Category:Phylogenetics]]
-{{evolution-stub}}

v t e Phylogenetics
Relevant fields	Computational phylogenetics Molecular phylogenetics Cladistics Taxonomy Evolutionary taxonomy Systematics	Evolutionary biology portal
Basic concepts	Phylogenesis Cladogenesis Phylogenetic tree Cladogram Phylogenetic network Long branch attraction Clade vs Grade Lineage Ghost lineage Ghost population
Inference methods	Maximum parsimony Phylogenetic reconciliation Probabilistic methods Maximum likelihood Bayesian inference Distance-matrix methods Neighbor-joining UPGMA Least squares Three-taxon analysis
Current topics	PhyloCode DNA barcoding Molecular phylogenetics Phylogenetic comparative methods Phylogenetic niche conservatism Phylogenetic signal Phylogenetics software Phylogenomics Phylogeography
Group traits	Primitive Plesiomorphy Symplesiomorphy Derived Apomorphy Synapomorphy Autapomorphy
Group types	Monophyly Paraphyly Polyphyly
Nomenclature	Phylogenetic nomenclature Crown group Sister group Basal Supertree
Category Commons