A polyphyletic group is a set of organisms, or other evolving elements, that have been grouped together but do not share an immediate common ancestor. The term is applied to groups that share characteristics that appear to be similar but have not been inherited from common ancestors; the arrangement of the members of a polyphyletic group is called a polyphyly. Alternatively, polyphyletic is used to describe a group whose members come from multiple ancestral sources, regardless of similarity of characteristics. For example, the biological characteristic of warm-bloodedness evolved separately in the ancestors of mammals and the ancestors of birds. Other polyphyletic groups are for example algae, C4 photosynthetic plants, edentates. Many biologists aim to avoid homoplasies in grouping taxa together and therefore it is a goal to eliminate groups that are found to be polyphyletic; this is the stimulus for major revisions of the classification schemes. Researchers concerned more with ecology than with systematics may take polyphyletic groups as legitimate subject matter.
In recent research, the concepts of monophyly and polyphyly have been used in deducing key genes for barcoding of diverse group of species. The term polyphyly, or polyphyletic, derives from the two ancient greek words πολύς, meaning "many, a lot of", φῦλον, meaning "genus, species", refers to the fact that a polyphyletic group includes organisms arising from multiple ancestral sources. Conversely, the term monophyly, or monophyletic, builds on the ancient greek prefix μόνος, meaning "alone, unique", refers to the fact that a monophyletic group includes organisms consisting of all the descendants of a unique common ancestor. By comparison, the term paraphyly, or paraphyletic, uses the ancient greek prefix παρά, meaning "beside, near", refers to the situation in which one or several monophyletic subgroups are left apart from all other descendants of a unique common ancestor. In many schools of taxonomy, the existence of polyphyletic groups in a classification is discouraged. Monophyletic groups are considered by these schools of thought to be the most important grouping of organisms.
One reason for this view is that some clades are simple to define in purely phylogenetic terms without reference to clades introduced: a node-based clade definition, for example, could be "All descendants of the last common ancestor of species X and Y". On the other hand, polyphyletic groups can be delimited in terms of clades, for example "the flying vertebrates consist of the bat and pterosaur clades"; because polyphyletic groups can be defined as a sum of clades, they are considered less fundamental than monophyletic clades. A stronger reason is that grouping species monophyletically facilitates prediction far more than does polyphyletic grouping. For example, classifying a newly discovered grass in the monophyletic family Poaceae, the true grasses results in numerous predictions about its structure and its developmental and reproductive characteristics, inherited from the common ancestor of this family. In contrast, Linnaeus' assignment of plants with two stamens to the polyphyletic class Diandria, while practical for identification, turns out to be useless for prediction, since the presence of two stamens has developed convergently in many groups.
Predictive success is the touchstone. Species have a special status in systematics as being an observable feature of nature itself and as the basic unit of classification, it is implicitly assumed that species are monophyletic. However hybrid speciation arguably leads to polyphyletic species. Hybrid species are a common phenomenon in nature in plants where polyploidy allows for rapid speciation. Convergent evolution Tudge, Colin; the Variety of Life. Oxford University Press. ISBN 0198604262. "Evolution - A-Z - Polyphyletic group". Www.blackwellpublishing.com. Retrieved 2018-02-24. Funk, D. J. and Omland, K. E.. "Species-level paraphyly and polyphyly: Frequency and consequences, with insights from animal mitochondrial DNA" Annu. Rev. Ecol. Evol. Syst. 34: 397–423. At ftp://184.108.40.206/users/bhhanser/Subspecies%20general%20literature/FunkEtal2003AnnuRevEcolEvolV34pp397-423.pdf
Pterocaulon is a genus of flowering plants in the sunflower family, native to North and South America and to Australasia. Blackroot is a common name for species native to North America; the plants are perennial herbs densely covered with woolly hairs. The generic name means "winged stem," referring to the decurrent leaf bases that give the appearance of wings running down the sides of the stems. SpeciesPterocaulon alopecuroides - South America, Puerto Rico, Virgin Islands Pterocaulon angustifolium - Brazil, Paraguay, Uruguay Pterocaulon balansae - Brazil, Paraguay, Uruguay Pterocaulon cordobense - Brazil, Paraguay, Uruguay Pterocaulon globuliflorus - Western Australia, Northern Territory Pterocaulon lanatum - Brazil, Paraguay, Salta Pterocaulon lorentzii - Brazil, Paraguay, Bolivia Pterocaulon niveum - Western Australia, Northern Territory Pterocaulon polypterum - Brazil, Uruguay Pterocaulon polystachyum - Brazil, Paraguay, Uruguay Pterocaulon purpurascens - Mato Grosso, Paraguay, Bolivia Pterocaulon pycnostachyum - United States Pterocaulon redolens - Indochina, Orissa, Maluku, New Guinea, eastern Australia Pterocaulon rugosum - Brazil, Paraguay Pterocaulon serrulatum - Western Australia, Northern Territory, South Australia Pterocaulon sphacelatum - Australia Pterocaulon sphaeranthoides - Western Australia, Northern Territory, Queensland Pterocaulon spicatum - South America Pterocaulon verbascifolium - Western Australia, Northern Territory, Queensland Pterocaulon virgatum - Central + South America, West Indies, United States
Alexander Vasilievich Soloviev was a historian of Serbia and Serbian law. He published research on the Bogumils, Serbian heraldry and archeology, translations from Russian and French, he was a professor at the University of Belgrade Faculty of Law, first Dean of the Sarajevo Law School and professor of Slavic studies at the University of Geneva. Alexandr Vasilievich Soloviev was born in Poland in 1890 at Kalisz, his father, Vasili Feodorovich Soloviev, was a judge at the Appellate Court in Warsaw, it was in Warsaw University that Alexandr studied and graduated, in law and literature. In 1917 he became a lecturer in Slavic law in the university of Rostov on Don. Soloviev moved to Serbia from Russia in the 1920s, with tens of thousands of other White Russian immigrants. From 1920 to 1936 he was a professor at Belgrade university, where he received his doctorate in 1928 for his thesis on the 14th-century king and legislator Stefan Uroš IV Dušan of Serbia. After the second World War he was dean of the law faculty at Sarajevo university from 1948 to 1949.
Soloviev became professor of Slavic studies at the University of Geneva. Subsequently, he continued his career in Washington, D. C, he died on 15 January 1971 in Geneva. For a short time, he lectured at the University of Lvov, where he published his research on Dušan's Code in Polish, his son Alexander worked at the Library of Congress in Washington D. C. Selected Monuments of Serbian Law from the 12th to 15th centuries Legislation of Stefan Dušan, emperor of Serbs and Greeks Dušan's Code in - 1349 and 1354 Greek Charters of Serbian Rulers Lectures from the History of Serbian Law History of Serbian Coat of Arms Соловьев Александр Васильевич // РЕЛИГИОЗНЫЕ ДЕЯТЕЛИ РУССКОГО ЗАРУБЕЖЬЯ