Genealogical Tree


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Genealogical Tree

 

in biology, a treelike representation of phylogenetic relationships within any natural group of organisms or within the organic world as a whole. The concept of a genealogical tree and the method for depicting it are borrowed from human genealogy.

The idea of a chain of beings preceded the concept of a genealogical tree. In 1766 the Russian scientist P. S. Pallas was the first to prove that the linear arrangement of organisms does not reflect the true relationship between animal classes, and consequently he proposed representing organic systems in the form of genealogical tables. This idea was particularly developed after the publication of C. Darwin’s The Origin of the Species (1859), in which the phenomenon of divergence was illustrated by means of genealogical trees. In the 19th century the genealogical tables of the animal and plant kingdoms were depicted by E. Heckel and others in the form of actual trees (hence the name) with group names arranged on the branches.

Genealogical trees are drawn only on the basis of a mono-phyletic development of living nature and cannot be used to illustrate a polyphyletic origin of the organic world. A genealogical tree is constructed to show the phylogenetic relationships and the level of organization of equally ranking groups, including phyla, classes, and orders. The relative level of organization of each group corresponds with its position on a genealogical tree. The origin of each group and its relation to other groups is designated by the point at which a particular branch departs from the common trunk or from a larger branch. If a genealogical tree is supposed to illustrate both phylogenetic ties and subordinate relationships in a group, the large unifying taxons (phyla, classes, orders, and families) are arranged closer to the base of the trunk (or the main taxon is at the trunk’s base) or they are arranged according to their rank on the primary or secondary lateral branches.

The end-shoots of a genealogical tree designate the lowest ranking categories, which are genera and sometimes species. Genealogical trees based on only modern forms reflect purely systematic relationships. If paleontological material is also used, genealogical trees are plotted on diagrams representing the subdivisions of geologic time. The point of divergence of a particular branch indicates the time that the corresponding taxon emerged.

True phylogenetic relationships among different groups of organisms and within individual groups are very complex and can only be approximated on a plane. Therefore, the two-dimensional flat representation of a genealogical tree is frequently replaced by a three-dimensional representation.

V. G. GEPTNER

References in periodicals archive ?
The arrangement of branches of the new genealogical tree is reassuring, says Niels Kristensen of the University of Copenhagen, who was not involved in the study.
In contrast, despite previous evidence that China was the region containing the influenza source population for HPAI (H5N1) viruses (13-18), only 24% (95% CI 17%-31%) of the trunk of the genealogical tree is assigned to China.
The list goes on and on--Marc Quinn, Tim Noble and Sue Webster, Mariko Mori, John Currin, Yinka Shonibare--which is again a tribute to the way in which "Post Human" got right to the roots of a flourishing new genealogical tree for later-twentieth-century art.
These genealogies are fluid in that genealogies change as human conditions change; that is, as nations advance or decline, they move up or down the genealogical tree.
As the reader will see, the Indigenous drawings reflect a conception that, in many ways, is an addition, if not a contradiction, to the 'classic' anthropological mode for representing social relationships through the genealogical tree, and therefore questions the supposed supremacy of the genealogical concept in questions relating to the representation of socio-biological relationships.
Universal chronicles relating the history of the world since the Creation popularized the genealogical tree as a quick, legible device able to compress long stretches of time.
One very clear map and a useful genealogical tree appear just before the introduction (pp.
It thus conjures up the image of the genealogical tree, be it in its lay version or in the biblical one of Nebuchadnezzar (Daniel 4), or, as Paquet remarks (117), Jesse's tree (Isaiah 11).
The team attempted to infect 35 species picked from different branches of the amphibian genealogical tree.
His topics include discrete time Feynman-Kac models, the nonlinear evolution of intensity measures, a general class of mean field models, genealogical tree models, and backward particle Markov models.
Together, researchers of the University of Princeton in the US and the Max Planck Institute for Ornithology analyzed the genealogical tree of bats on the basis of their migratory behaviour.
RESPECTS Brian Cowen drops in on Ali MANIA Around 6,000 fans pack Ennis to see Ali GLOVE AND AFFECTION Boy turns out for hero HISTORIC Ali's genealogical tree is traced to Ennis man Abe Grady TOGETHER Star's daughter Hana Ali, right, and wife Yolanda PRIDE Ali unveils plaque in his honour in Ennis yesterday LIVING LEGEND Muhammad Ali waves to army of fans yesterday

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