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Encyclopedia > Lineage (evolution)

An evolutionary lineage (also called a clade) is composed of species, taxa, or individuals that are related by descent from a common ancestor. Lineages are subsets of the evolutionary 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. This cladogram shows the relationship among various insect groups. ... In biology, a species is the basic unit of biodiversity. ... A taxon (plural taxa) is an element of a taxonomy, e. ... The evolutionary tree of living things is currently supposed to run something along the lines of that listed below. ... This cladogram shows the relationship among various insect groups. ... Molecular systematics is a product of the traditional field of systematics and the growing field of bioinformatics. ...


Phylogenetic representation of lineages

Fig. 1: A rooted tree for rRNA genes
Fig. 1: A rooted tree for rRNA genes

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 cluster individuals by similarity. Download high resolution version (1874x1240, 210 KB)A phylogenetic tree of living things, based on rRNA data, showing the separation of bacteria, archaea, and eukaryotes. ... Download high resolution version (1874x1240, 210 KB)A phylogenetic tree of living things, based on rRNA data, showing the separation of bacteria, archaea, and eukaryotes. ... A phylogenetic tree is a tree showing the evolutionary interrelationships among various species or other entities that are believed to have a common ancestor. ... Subgroups Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular: bacterium) are a major group of living organisms. ... Phyla / Classes Phylum Crenarchaeota Phylum Euryarchaeota     Halobacteria     Methanobacteria     Methanococci     Methanopyri     Archaeoglobi     Thermoplasmata     Thermococci Phylum Korarchaeota Phylum Nanoarchaeota The Archaea (pronounced /ɑːˌkiːə/), also called Archaebacteria (pronounced /ˈɑːkɪbakËŒtɪərɪə/), are a major division of living organisms. ... Kingdoms Eukaryotes are organisms with complex cells, in which the genetic material is organized into membrane-bound nuclei. ... A phylogeny (or phylogenesis) is the origin and evolution of a set of organisms, usually of a species. ... The general structure of a section of DNA Deoxyribonucleic acid (DNA) is a nucleic acid —usually in the form of a double helix— that contains the genetic instructions specifying the biological development of all cellular forms of life, and most viruses. ... Data clustering is a common technique for statistical data analysis, which is used in many fields, including machine learning, data mining, pattern recognition, image analysis and bioinformatics. ...


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. This article is about biological evolution. ... The general structure of a section of DNA Deoxyribonucleic acid (DNA) is a nucleic acid —usually in the form of a double helix— that contains the genetic instructions specifying the biological development of all cellular forms of life, and most viruses. ...


The "lineage" definition of human races

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. This article is 100 KB or more in size. ...

Fig. 2: An example of the lineage concept of human races in the context of higher levels of categorization. This rendering is a simplification.
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Fig. 2: An example of the lineage concept of human races in the context of higher levels of categorization. This rendering is a simplification.

A primary motivation for categorizing human genetic variation in this way comes from biomedical research. In this context, human races represent different genetic backgrounds that may influence the association of diseases with their causes (genetic or environmental). Download high resolution version (1229x245, 18 KB) File links The following pages link to this file: Race Talk:Race (Archive 14) Lineage (evolution) Categories: GFDL images ... Download high resolution version (1229x245, 18 KB) File links The following pages link to this file: Race Talk:Race (Archive 14) Lineage (evolution) Categories: GFDL images ... Race in Biomedicine refers to an active debate among biomedical researchers about the meaning and importance of race to their research. ...


The concept of racial lineage is very similar to the concept of familial lineages in genealogy. This has led some commentators to describe races as extended families. Kinship and descent is one of the major concepts of cultural anthropology. ... Genealogy is the study and tracing of family pedigrees. ...


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 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).

Fig. 3: Triangle plot shows average admixture of five North American ethnic groups.
Fig. 3: Triangle plot shows average admixture of five North American ethnic groups.
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.
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.

Download high resolution version (1781x1753, 51 KB)adapted from Keita et al (2004) Nat Genet. ... Download high resolution version (1781x1753, 51 KB)adapted from Keita et al (2004) Nat Genet. ... Image File history File links Download high resolution version (2390x1956, 64 KB)i drew it, so it should be free; Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File links Download high resolution version (2390x1956, 64 KB)i drew it, so it should be free; Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ...

References

  • Sarich, Vincent, and Frank Miele. Race: The Reality of Human Differences. Westview Press, 2004.

  Results from FactBites:
 
Lineage (evolution) - Wikipedia, the free encyclopedia (504 words)
Lineages are subsets of the evolutionary tree of life.
Lineages are often determined by the techniques of molecular systematics.
Lineages are typically visualized as subsets of a phylogenetic tree.
  More results at FactBites »

 
 

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