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{{short description|Sequence of populations, organisms, cells, or genes that form a line of descent}}
An evolutionary '''lineage''' is a series of organisms, populations, cells, or genes connected by a continuous line of descent from ancestor to descendent.<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/descendent 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."[http://www.askoxford.com/concise_oed/lineage?view=uk OED definition of lineage]</ref> Lineages are subsets of the evolutionary [[Evolutionary tree|tree of life]]. Lineages are often determined by the techniques of [[molecular systematics]].
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 ==
== 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:Phylogenetic_tree.svg|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]]. Thus a lineage is a single branch of the tree. [[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.


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 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.
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" />
==References==
<references/>


==See also==
==See also==
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* [[Clade]]
* [[Clade]]
* [[Linnaean taxonomy]]
* [[Linnaean taxonomy]]

==References==
<references/>


==External links==
==External links==


{{Phylogenetics}}
{{Phylogenetics}}

[[Category:Phylogenetics]]
[[Category:Phylogenetics]]

Latest revision as of 05:14, 26 July 2024

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

[edit]
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.[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]

See also

[edit]

References

[edit]
  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.
  4. ^ a b c d Kliman, R. M., ed. (2016). "Phylogenetic Tree". Encyclopedia of Evolutionary Biology. Academic Press. ISBN 9780128004265.
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