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Fig. 1: A rooted tree: the phylogenetic "Tree of Life", c. 2003
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Fig. 2: Unrooted tree for myosin gene
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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 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.
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 treeš for myosin, a superfamily of proteins. Links to other pictures are given in the
Pictures on the web subsection below.
Caveats
- 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
- 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
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