Editing Lineage (evolution)

{{short description|Sequence of populations, organisms, cells, or genes that form a line of descent}}
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>

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" /> 

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" />

==Lineages with sexual reproduction==

Most species of multicellular [[plants]], [[animal]]s and [[fungus|fungi]] reproduce sexually as do many [[protist]]s. Therefore the evolution of the lineages of such species has likely been substantially influenced by sexual interactions.  In the fossil record, lineages with the capability for [[sexual reproduction]] first appeared about 2.0 billion years ago in the [[Proterozoic]] Eon,<ref>Otto, Sarah P. (2008). "Sexual Reproduction and the Evolution of Sex". Nature. Retrieved 1 October 2021</ref><ref>Zimmer, Carl (5 June 2009). "On The Origin Of Sexual Reproduction". Science. 324 (5932): 1254–1256. doi:10.1126/science.324_1254. PMID 19498143. S2CID 39987391. Retrieved 1 October 2021</ref> although a later date, 1.2 billion years ago has also been proposed.<ref>Butterfield, Nicholas J. (2000). "Bangiomorpha pubescens n. gen., n. sp.: implications for the evolution of sex, multicellularity, and the Mesoproterozoic/Neoproterozoic radiation of eukaryotes". Paleobiology. 26 (3): 386. Bibcode:2000Pbio...26..386B. doi:10.1666/0094-8373(2000)026<0386:BPNGNS>2.0.CO;2. S2CID 36648568. Retrieved 12 April 2021</ref><ref>Cumming, Vivian (4 July 2016). "The Real Reasons Why We Have Sex". BBC News. Retrieved 12 April 2021</ref>  Lineages of sexually reproducing [[eukaryote|eukaryotic organisms]] may have evolved from a single-celled common ancestor.<ref>Letunic, I; Bork, P (2006). "Interactive Tree of Life". Retrieved 23 July 2011</ref><ref>Bernstein H, Bernstein C (2010). "Evolutionary origin of recombination during meiosis". BioScience. 60 (7): 498–505. doi:10.1525/bio.2010.60.7.5. S2CID 86663600</ref><ref>Lodé, T (2011). "Sex is not a solution for reproduction: the libertine bubble theory". BioEssays. 33 (6): 419–422. doi:10.1002/bies.201000125. PMID 21472739</ref>

==See also==

* [[Clade]]
* [[Linnaean taxonomy]]

==References==
<references/>

==External links==

{{Phylogenetics}}

[[Category:Phylogenetics]]