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The term sister group is used in phylogenetic analysis, however, only groups identified in the analysis are labeled as "sister groups".. An example is birds, whose commonly cited living sister group is the crocodiles, but that is true only when discussing extant organisms; [3] [4] when other, extinct groups are considered, the relationship between birds and crocodiles appears distant.
An alternative definition does not require any members of a crown group to be extant, only to have resulted from a "major cladogenesis event". [6] The first definition forms the basis of this article. Often, the crown group is given the designation "crown-", to separate it from the group as commonly defined.
In evolutionary biology, all life on Earth is theoretically part of a single phylogenetic tree, indicating common ancestry. Phylogenetics is the study of phylogenetic trees. The main challenge is to find a phylogenetic tree representing optimal evolutionary ancestry between a set of species or taxa.
In biology, phylogenetics (/ ˌ f aɪ l oʊ dʒ ə ˈ n ɛ t ɪ k s,-l ə-/) [1] [2] [3] is the study of the evolutionary history of life using genetics, which is known as phylogenetic inference. It establishes the relationship between organisms with the empirical data and observed heritable traits of DNA sequences, protein amino acid sequences ...
Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional method , by which taxon names are defined by a type , which can be a specimen or a taxon of lower rank , and a description in words. [ 1 ]
The varied definitions either place taxonomy as a sub-area of systematics (definition 2), invert that relationship (definition 6), or appear to consider the two terms synonymous. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy (definitions 1 and 2), or a part of systematics outside taxonomy.
Taxonomic databases digitize scientific biodiversity data and provide access to taxonomic data for research. [1] Taxonomic databases vary in breadth of the groups of taxa and geographical space they seek to include, for example: beetles in a defined region, mammals globally, or all described taxa in the tree of life. [2]
Lazarus taxon; node-based taxon; ootaxon (oospecies, etc.): a taxon known from fossil eggs; parataxon; sciotaxon a taxon known from partial evidence but believed to be identical to an orthotaxon; sister taxon; zombie taxon; polyphyletic taxon; monophyletic taxon: a taxon consisting of a common ancestor and all its lineal descendants; a clade ...