Navigation Links
Phylogenetic tree


Fig. 1: A rooted tree for rRNA genes
Fig. 2: Unrooted tree for myosin gene

A phylogenetic tree is a tree showing the evolutionary interrelationships among various species or other entities that are believed to have a common ancestor. A phylogenetic tree is a form of a cladogram. In a phylogenetic tree, each node with descendants represents the most recent common ancestor of the descendants, and edge lengths correspond to time estimates. Each node in a phylogenetic tree is called a taxonomic unit. Internal nodes are generally referred to as Hypothetical Taxonomic Units (HTUs) as they cannot be directly observed.

A rooted phylogenetic tree is a directed tree with a unique node corresponding to the (usually imputed) most recent common ancestor of all the entities at the leaves of the tree. Figure 1 depicts a rooted phylogenetic tree, which has been colored according to the three-domain system (Woese 1998).

An unrooted phylogenetic tree is, loosely speaking, a tree derived from a rooted phylogenetic tree by omitting the root. More precisely, it is a forest of rooted phylogenetic trees depicted so that the roots are all linked. Figure 2 depicts an unrooted phylogenetic tree¹ for myosin, a superfamily of proteins. Links to other pictures are given in the Pictures on the Web subsection below.

There are three main methods of constructing phylogenetic trees: Distance based methods such as Neighbour Joining, Parsimony based methods such as Maximum Parsimony , and character based methods such as Maximum Likelihood or Bayesian inference.

Caveats

  • By their very nature, phylogenetic trees hide any hybridization and lateral gene transfer (Woese 2002) that may have taken place. For these reasons, the proposed PhyloCode (see External Link below) does not assume a tree structure.
  • The phylogenetic tree of a single gene or protein taken from a group of species often differs from similar trees for the same group of species, and therefore great care is needed in inferring phylogenetic relationships amongst species.
  • Trees that do not include extinct species must also be interpreted with care.

See also

Footnote

  1. T. Hodge, M.J.T.V. Cope (2000) A Myosin Family Tree. Journal of Cell Science 113, 3353-3354. See also the Myosin external link below.

References

External links

Pictures on the web

General


'"/>


(Date:7/9/2015)... 9, 2015  Synaptics Inc. (NASDAQ: SYNA ), a ... it will report financial results for the fourth quarter ... after the close of market. The company will host ... 2:00 p.m. PT (5:00 p.m. ET), during which management ... on the live call, analysts and investors should dial ...
(Date:7/9/2015)... 9, 2015  Unchained Labs just can,t get ... of Avid Nano. Avid Nano designs, develops and ... Also today, Unchained Labs UNcaged ... to use protein sizing system. The pUNk is ... hydrodynamic size, size distribution, aggregation population and molecular ...
(Date:7/8/2015)... YORK , July 8, 2015 Summary ... globally, and the fourth most fatal, with a mortality ... The poor prognosis of pancreatic cancer patients has highlighted ... treatment, which is not being met by the current ... an array of products with varying molecule types and ...
Breaking Biology News(10 mins):Synaptics to Report Fourth Quarter, Fiscal Year 2015 Results on July 30 2Unchained Labs just can't get enough, acquires Avid Nano, rocks out the new pUNk! 2Frontier Pharma: Pancreatic Cancer - Identifying and Commercializing First-in-Class Innovation 2Frontier Pharma: Pancreatic Cancer - Identifying and Commercializing First-in-Class Innovation 3
... 2008 American Society for Microbiology (ASM) Siemens ... presented to Adrian M. Zelazny, Staff Scientist, ... Institutes of Health (NIH). This award recognizes ... antimicrobial therapy. Dr. Zelazny is honored ...
... of supercomputers have hardware set up not just for ... seemingly random data. And now, a multi-institutional group of ... for these supercomputers. Applications include anywhere complex webs of ... grid stability to complex biological networks. The ...
... from infecting other cells and triggering their destruction by ... HIV-infected individuals but eventually peters out. To find out ... Infectious Diseases examined the cells that make the antibodies, ... that HIV gradually depletes the numbers of healthy, functional ...
Cached Biology News:Multithreaded supercomputer seeks software for data-intensive computing 2Multithreaded supercomputer seeks software for data-intensive computing 3
Other biology definitionOther Tags