Phylogenetics Phylogenetics Two structures in biology are said to be analogous if they perform the same or similar function by a similar mechanism. For example, the wings of insects and the wings of birds. These similar structures may have evolved through different pathways, a process known as convergent evolution, or may be homologous. ...more on Wikipedia about "Analogy (biology)"
In phylogenetics, basal members of a group are subgroups that diverged very early from the others (or vice versa). The term can be interpreted only in its context. ...more on Wikipedia about "Basal"
A clade is group of organisms which share a common ancestor and which includes all descendents of that ancestor. Taxonomy which requires all taxa to be clades is called cladistics. A clade may or may not conform to an existing taxon. A clade is thus a monophyletic group of organisms. The term evolutionary grade is sometimes used for groups of related organisms that don't include all decendents of their common ancestor. ...more on Wikipedia about "Clade"
Cladistics ( Greek: klados = branch) is a branch of biology that determines the evolutionary relationships between organisms based on derived similarities. It is the most prominent of several phylogenetic systematics, which study the evolutionary relationships between organisms. Cladistics is a method of rigorous analysis, using "shared derived properties" (synapomorphies: see below) of the organisms being studied. Cladistic analysis forms the basis for most modern systems of biological classification, which seek to group organisms by evolutionary relationships. In contrast, phenetics groups organisms based on their overall similarity, while approaches that are more traditional tend to rely on key characters. Willi Hennig (1913 - 1976) is widely regarded as the founder of cladistics. ...more on Wikipedia about "Cladistics"
Cladogenesis is an evolutionary splitting event in which each branch and its smaller branches is a "clade"; an evolutionary mechanism and a process of adaptive evolution that leads to the development of a greater variety of organisms. ...more on Wikipedia about "Cladogenesis"
Crown eukaryotes are a group of organisms found at the top of the phylogenetic tree of modern biology. They are multicellular and macroscopic lifeforms that have eukaryotic cells and represent the majority of the biomass of the planet while accounting for less than 1% of the genetic diversity. ...more on Wikipedia about "Crown eukaryotes"
A crown group is a living monophyletic group or clade, consisting of the last common ancestor of all living examples, plus all of its descendants. The name was given by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms relative to extinct ones. Extinct members of crown groups are possible. Because the Dodo, although extinct, is still descended from the last common ancestor of all living birds, for example, it is nevertheless included in the bird crown group. ...more on Wikipedia about "Crown group"
An Elvis taxon (plural taxa) is a term used in paleontology. It is similar to a Lazarus taxon and often confused with it. Where Lazarus taxa are those that have seemingly returned from the dead after extinction, Elvis taxa are the descendants of different groups that are known to have survived the extinction and have evolved to closely resemble the extinct group through convergent evolution. ...more on Wikipedia about "Elvis taxon"
Evolutionary taxonomy or evolutionary systematics seeks to classify organisms using a combination of phylogenetic relationship and overall similarity. It differs from strict cladism where all taxa in a classification always should include all descendants of a single ancestral node. It thus allows for paraphyletic taxa. As evolutionary systematicists define terms, paraphyletic taxa are monophyletic too, in the sense that they derive from a single common ancestor, just not holophyletic, meaning that all descendants are included (which is monophyletic according to the cladistic definition). ...more on Wikipedia about "Evolutionary taxonomy"
The evolutionary tree of living things is currently supposed to run something along the lines of that listed below. Most of the tree was based on ideas from cladistics; where more than two groups are shown in a single branch, there is disagreement about how they diverged. Hypothetically taxonomy would follow the tree whenever possible, but in many places it does not at present. ...more on Wikipedia about "Evolutionary tree"
A gene family is a set of genes defined by presumed homology, i.e. evidence that the genes evolved from a common ancestral gene. They generally share some biochemical activity. Genes are generally categorized into families based upon shared sequence motifs and similarities in structure. Phylogenetic techniques can be used as a more rigorous test. The positions of introns within the coding sequence can be used to infer common ancestry. Knowing the sequence of the protein encoded by a gene can allow researchers to apply methods that find similarities among protein sequences that provide more information than similarities or differences among DNA sequences. Furthermore, knowledge of the protein's secondary structure gives further information about ancestry, since the organization of secondary structural elements presumably would be conserved even if the amino acid sequence changes considerably. These methods often rely upon predictions based upon the DNA sequence. ...more on Wikipedia about "Gene family"
(Homology (biology)) In biology, two or more structures are said to be homologous if they are alike because of shared ancestry. This could be evolutionary ancestry, meaning that the structures evolved from some structure in a common ancestor (the wings of bats and the arms of humans are homologous in this sense), or developmental ancestry, meaning that the structures arose from the same tissue in embryonal development (the ovaries of female humans and the testicles of male humans are homologous in this sense). ...more on Wikipedia about "Homology (biology)"
Last universal ancestor (LUA), the hypothetical latest living organism from which all currently living organisms descend. As such, it is the most recent common ancestor of the set of all currently living organisms. Also LCA (last common ancestor) or LUCA (last universal common ancestor). It is estimated to have lived some 3.5 billion years ago. ...more on Wikipedia about "Last universal ancestor"
Maximum parsimony is a simple but popular technique used in cladistics to infer a phylogenetic tree for a set of taxa (commonly a set of species or reproductively-isolated populations of a single species) on the basis of some observed data on the similarities and differences among taxa. ...more on Wikipedia about "Maximum parsimony"
The molecular clock (based on the molecular clock hypothesis (MCH)) is a technique in genetics, which researchers use to date when two species diverged. It deduces elapsed time from the number of minor differences between their DNA sequences. It is sometimes called a gene clock. ...more on Wikipedia about "Molecular clock"
Molecular phylogeny 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 so-called phylogenetic tree. ...more on Wikipedia about "Molecular phylogeny"
Molecular systematics is a phrase that might be used to indicate that branch of the traditional field of systematics that utilizes data obtained by " molecular techniques". In order to resolve questions in systematics, i.e. about the evolutionary relationships of organisms, it analyzes data on the molecular structure of DNA, RNA and protein, by cladistic methods. Cladistics is older than molecular systematics and does not necessarily depend upon molecular data, but cladistics had been leaning heavily on specially developed software for its analyses and this software proved indispensible in dealing with molecular data. ...more on Wikipedia about "Molecular systematics"
(Monophyly) In phylogenetics, a group is monophyletic ( Greek: "of one race") if it consists of a common ancestor and all its descendants. A taxonomic group that contain organisms but not their common ancestor is called polyphyletic, and a group that contains some but not all descendants of the most recent common ancestor is called paraphyletic. ...more on Wikipedia about "Monophyly"
In bioinformatics, neighbor-joining is a bottom-up clustering method used for the creation of phylogenetic trees. Usually used for trees based on DNA or protein sequence data, the algorithm requires knowledge of the distance between each pair of taxa (e.g. species or sequences) in the tree. ...more on Wikipedia about "Neighbor-joining"
The term paleospecies refers to hypothetical species which are currently extinct. The separation of the remains of various animals into paleospecies, since it is impossible to determine whether extinct "species" could interbreed, is based entirely on differences in observed characteristics. ...more on Wikipedia about "Paleospecies"
(Paraphyly) In phylogenetics, a grouping of organisms is said to be paraphyletic ( Greek para = near and phyle = race) if the group contains the most recent common ancestor of its members, but the group does not include all the descendants of this common ancestor. ...more on Wikipedia about "Paraphyly"
In developmental biology, pedomorphosis or juvenification refers to a phylogenetic change in which the adults of a species retain traits previously seen only in juveniles. Peramorphosis is change in the reverse direction. ...more on Wikipedia about "Pedomorphosis"
Peramorphosis in developmental biology is a phylogenetic change in which individuals of a species mature past adulthood and take on hitherto unseen traits. It is the reverse of pedomorphosis. ...more on Wikipedia about "Peramorphosis"
PhyloCode is a draft for a formal set of rules governing phylogenetic nomenclature. Its current version is specifically designed to regulate the naming of clades, which do not have set ranks, unlike conventional Linnaean taxonomy. Later revisions will presumably also include new rules for the naming of species. Although some have argued that systems based on unranked clades should replace older systems, PhyloCode is designed so that it may be used alongside them. PhyloCode is still a contentious issue and there are many who feel that the system is without merit. The number of supporters for official adoption of phylocode is still small, and it is uncertain, as of 2005, whether the system will be adopted or forgotten. ...more on Wikipedia about "PhyloCode"
Phylogenetic System: This is a system of biological classification. It is based on evolutionary sequence and genetic relationships among the organisms. Darwin's book "On the Origin of Species by Means of Natural Selection" or "The Preservation of Races in the Struggle of Life" (1859) provided support for Taxonomy. The most important change was the change of the status of specied from fixity (ie static nature) to a dynamic or an everchanging one, which became dominant after Darwin. The classification of plants were on the basis of evolutionary development as well as morphological characters. ...more on Wikipedia about "Phylogenetic System" Visit again shortopedia
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