User:Alvinyuuu/sandbox

Outgroup (cladistics) From Wikipedia, the free encyclopedia In cladistics or phylogenetics, an outgroup is a group of organisms that serve as a reference group when determining the evolutionary relationship among three or more monophyletic groups of organisms. The outgroup is used as a point of comparison for the ingroup, the set of organisms under study that specifically allows the phylogeny to be rooted. Because the polarity (direction) of character change can be determined only on a rooted phylogeny[1], the choice of outgroup is essential for understanding the evolution of traits along a phylogeny. The chosen outgroup is hypothesized to be closely related to the other groups but less closely related than any single one of the other groups is to each other. [MOD] An outgroup is a taxonomic group chosen such that its members are hypothesized to share some characteristics with the ingroup, but as a whole, the outgroup is still less closely related to other groups in the phylogenetic tree. (Cited from) http://scholarcommons.sc.edu/cgi/viewcontent.cgi?article=1102&context=jscas)

The evolutionary conclusion from these relationships is that the outgroup species has a common ancestor with the ingroup that is older than the common ancestor of the ingroup. An outgroup may be a sister group to the ingroup or may be more distantly related.[2] Choice of outgroup[edit] The best outgroups satisfy two characteristics: They must not be members of the ingroup They must be related to the ingroup, close enough for meaningful comparisons to the ingroup.

Therefore, an appropriate outgroup must be unambiguously outside the clade of interest in the phylogenetic study. An outgroup that is actually nested within the ingroup will, when it is used to root the phylogeny, result in incorrect conclusions about phylogenetic relationships and trait evolution. In molecular phylogenetics, satisfying the second requirement typically means that DNA or protein sequences from the outgroup can be successfully aligned to sequences from the ingroup. [NEW] This one? Although there are algorithmic approaches to identify the outgroups with maximum global parsimony, they are often limited by failing to reflect the continuous, quantitative nature of certain character states. (Cited:    This is the one I put in my sandboxhttp://www.jstor.org/stable/pdf/2419343.pdf) Character states are traits, either primitive or derived, that affect the construction of branching patterns in a phylogenetic tree. (Cited: http://scholarcommons.sc.edu/cgi/viewcontent.cgi?article=1102&context=jscas) [MOD:] Technology & Cladistics[edit] Computerization of Cladistic Determinatory PHD language algorithms designing to maximize efficiency of cladsisicatal development-=-. Used  machine learning and reinforcement learning to design cladsisicatal phylogeny. Examples[edit]

Ingroup Outgroup Great Apes New world monkeys Placental mammals Marsupials Chordates Echinoderms Angiosperms Gymnosperms Character states are traits, either primitive or derived, that affect the construction of branching patterns in a phylogenetic tree. In each of the above examples, organisms are categorized into their respective ingroups based on having similar character states with each other in comparison to the outgroup. See also[edit] Sister group, a group that may be closely related to an outgroup Plesiomorphy, an ancestral trait of an organism Primitive (phylogenetics), a term for ancestral traits References[edit] Jump up ^ Farris, J. S. (1982). "Outgroups and Parsimony". Systematic Biology. 31 (3): 328–334. ISSN 1063-5157. doi:10.1093/sysbio/31.3.328. Jump up ^ David A. Baum; Stacey D. Smith (2013). Tree Thinking: An Introduction to Phylogenetic Biology. Roberts. p. 175. ISBN 978-1-936221-16-5.