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A simple cladogram showing the evolutionary relationships between four species: A, B, C, and D. Here, Species A is the outgroup, and Species B, C, and D form the ingroup. In cladistics or phylogenetics, an outgroup [1] is a more distantly related group of organisms that serves as a reference group when determining the evolutionary relationships of the ingroup, the set of organisms under study ...
The relative rate test is a genetic comparative test between two ingroups (somewhat closely related species) and an outgroup or “reference species” to compare mutation and evolutionary rates between the species. [1] Each ingroup species is compared independently to the outgroup to determine how closely related the two species are without ...
Willi Hennig 1972 Peter Chalmers Mitchell in 1920 Robert John Tillyard. The original methods used in cladistic analysis and the school of taxonomy derived from the work of the German entomologist Willi Hennig, who referred to it as phylogenetic systematics (also the title of his 1966 book); but the terms "cladistics" and "clade" were popularized by other researchers.
This is a popular form of phylogenetic bracketing first introduced by Witmer in 1995. [1] It works by comparing an extinct taxon to its nearest living relatives. [1] [2] [3] For example, Tyrannosaurus, a theropod dinosaur, is bracketed by birds and crocodiles.
A phylogenetic tree, phylogeny or evolutionary tree is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time. [ 1 ] [ 2 ] In other words, it is a branching diagram or a tree showing the evolutionary relationships among various biological species or other entities based upon ...
Categorization of people into social groups increases the perception that group members are similar to one another. An outcome of this is the out-group homogeneity effect. This refers to the perception of members of an out-group as being homogenous, while members of one's in-group are perceived as being diverse, e.g. "they are alike; we are ...
In biological phylogenetics, a clade (from Ancient Greek κλάδος (kládos) 'branch'), also known as a monophyletic group or natural group, [1] is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. [2]
Phylogenies showing the terminology used to describe different patterns of ancestral and derived trait states. [1] Imaginary cladogram. [2] The yellow mask is a plesiomorphy for each living masked species, because it is ancestral. [2] It is also a symplesiomorphy for them.