Cladistics

•  Clade

  In biological systematics, a clade (from ancient Greek κλάδος, klados, "branch") signifies a single "branch" on the "Tree of life", a group composed of a single ancestor and all its descendants.. The term was coined by English biologist Julian Huxley. The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological classification. In cladistics (which takes its name from the term), clades are the only acceptable units.

  

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•  Monophyly

  In common cladistic usage, a monophyletic group is a taxon (group of organisms) which forms a clade, meaning that it consists of an ancestor and all its descendants. The term is synonymous with the uncommon term holophyly. It is contrasted with the terms paraphyly, which is a taxon consisting of an ancestor and some of its descendants, and polyphyly, which is a taxon that does not share a common ancestor. Monophyletic groups are characterized by shared derived characteristics.

  

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•  Phylogenetics

  In biology, phylogenetics is the study of evolutionary relatedness among various groups of organisms (for example, species or populations), which is discovered through molecular sequencing data and morphological data matrices. The term phylogenetics is of Greek origin from the terms phyle/phylon (φυλή/φῦλον), meaning "tribe, race," and genetikos (γενετικός), meaning "relative to birth" from ' (γένεσις, "birth").

  

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•  Paraphyly

  A group of taxa is said to be paraphyletic if the group contains its last common ancestor but does not contain all the descendants of that ancestor. This term is used in both phylogenetics and linguistics.

  

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•  Mitochondrial Eve

  Mitochondrial Eve is defined as the woman who is the matrilineal most recent common ancestor for all living humans. Passed down from mother to offspring, all mitochondrial DNA (mtDNA) in every living person is directly descended from hers. Mitochondrial Eve is the female counterpart of Y-chromosomal Adam, the patrilineal most recent common ancestor, although they lived thousands of years apart.

  

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•  Homology (biology)

  In evolutionary biology, homology refers to any similarity between characteristics of organisms that is due to their shared ancestry. The word homologous derives from the ancient Greek ομολογειν, 'to agree'. There are examples in different branches of biology. Anatomical structures that perform the same function in different biological species and evolved from the same structure in some ancestor species are homologous. In genetics, homology refers to a similarity of DNA sequences.

  

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•  Phylogenetic tree

  A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics. The taxa joined together in the tree are implied to have descended from a common ancestor.

  

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•  Molecular phylogenetics

  Molecular phylogenetics, also known as molecular systematics, is the use of the structure of molecules to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree.

  

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•  Molecular clock

  The molecular clock (based on the molecular clock hypothesis) is a technique in molecular evolution which uses fossil constraints and rates of molecular change to deduce the time in geologic history when two species or other taxa diverged. It is used to estimate the time of occurrence of events called speciation or radiation. The molecular data used for such calculations is usually nucleotide sequences for DNA or amino acid sequences for proteins.

  

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•  Polyphyly

  A polyphyletic (Greek for "of many races") group is one whose members' last common ancestor is not a member of the group. For example, the group consisting of warm-blooded animals is polyphyletic, because it contains both mammals and birds, but the most recent common ancestor of mammals and birds was cold-blooded. Warm-bloodedness evolved separately in the ancestors of mammals and the ancestors of birds, so it is not a true phylogenetic grouping.

  

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•  Adhemar of Le Puy

  Adhemar (also known as Adémar, Aimar, or Aelarz) de Monteil (died 1 August 1098), one of the principal figures of the First Crusade, was bishop of Puy-en-Velay from before 1087. At the Council of Clermont in 1095, Adhemar showed great zeal for the crusade (there is evidence Urban II had conferred with Adhemar before the council) and having been named apostolic legate and appointed to lead the crusade by Pope Urban II, he accompanied Raymond IV, Count of Toulouse, to the east.

  

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•  British Rail Class 55

  The British Rail Class 55 is a successful class of diesel locomotive built between 1961 and 1962 by English Electric. They were designed for the high-speed express passenger services on the East Coast Main Line between London King's Cross and Edinburgh. They gained the name "Deltic" from the prototype locomotive, DP1 Deltic, which in turn was named for its Napier Deltic power units.

  

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•  Michael Martin Murphey

  Michael Martin Murphey (born March 14, 1945) is an American singer-songwriter. He is best known for writing and performing Western music as well as country and pop. Murphey has become a prominent musical voice for the Western horseman, rancher, and cowboy. A Western Music Association Hall of Fame inductee, Murphey has six gold albums, including Cowboy Songs, the first album of cowboy music to achieve gold status since the career of Marty Robbins.

  

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•  Jeroen

  Jeroen is a common Dutch male given name originating from the Greek Hieronymus, and is equivalent to the English name Jerome. People named Jeroen include: Jeroen Bleekemolen Jeroen Blijlevens Jeroen Delmee Jeroen Duyster Jeroen Groenendijk Jeroen Krabbé Jeroen Smits Jeroen Tel Jeroen van Aken (also Jeroen Bosch or Hieronymus Bosch) Jeroen van der Veer Jeroen Van Herzeele Jeroen van Veen Jeroen Wiedenhof

  

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•  Internet in Rwanda

  Telephones - main lines in use: 23,200 (2002) Telephones - mobile cellular: In January 2006, there is one provider, MTN Rwandacell with over 200,000 subscribers; Terracom/Rwandatel is poised to enter the market in early 2006. Government investment in the Rwandan telecommunication sector is growing and has been successful so far.

  

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