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 ?
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.
In addition, most (93%) of the trunk of the genealogical tree is in the tropics and China (including Hong Kong), and the remaining regions, such as Siberia, play major roles in migration and genetic reassortment and are less responsible for emergence of variants with novel hemagglutinin proteins.
The influenza A(H5N1) virus genealogical tree notably contains long side branches; some lineages (mostly comprising hemagglutinin sequences from Southeast Asia, Africa, and southern Asia) persist for years.
So far, Famillion's servers have received the genealogical tree of 70,000.
We needed to each write down our genealogical tree and list various pathological disorders among our parents and relatives," he recalls.
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.
She is not, after all, a branch on the great "Fairfacian oak," but a sprig of mistletoe with only a tenuous connection to the genealogical tree.
Printed on high-quality glossy paper, several essays include brilliant plate reproductions of documents, paintings, and several genealogical trees.
1) And yet they are of major concern to the researcher, especially if his or her main topic is kinship and hence the tracing of genealogical trees.
The main object was to collect data for a thesis on Western Desert kinship and the construction of genealogical trees of the population.
He includes an etymology of Semitic and Afrasian terms of an intellectual/spiritual nature, notes on the importance of this etymology for interpreting the Bible, and genealogical trees of world and Afrasian languages.

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