A phylogenetic network is any graph used to visualize evolutionary relationships between sequences, genes, chromosomes, genomes, or species. It is employed when reticulate events such as hybridization, horizontal gene transfer, recombination, or gene duplication and loss are believed to be involved. They differ from phylogenetic trees by the explicit modeling, by means of the addition of hybrid nodes (nodes with two parents) instead of only tree nodes (nodes with only one parent).^[1] Phylogenetic trees are a subset of phylogenetic networks. Phylogenetic networks can be inferred and visualised with software such as SplitsTree. A standard format for representing phylogenetic networks is a variant of Newick format which is extended to support networks as well as trees.^[2]

Many kinds and subclasses of phylogenetic networks have been defined based on the biological phenomenon they represent or which data they are built from (hybridization networks, usually built from rooted trees, recombination networks from binary sequences, median networks from a set of splits, optimal realizations and reticulograms from a distance matrix), or restrictions to get computationally tractable problems (galled trees, and their generalizations level-k phylogenetic networks, tree-child or tree-sibling phylogenetic networks).

Contents 1 Microevolution 2 See also 3 References 4 Software to compute phylogenetic networks 5 External links

[edit] Microevolution

Phylogenetic trees also have trouble depicting microevolutionary events, for example the geographical distribution of muskrat or fish populations of a given species among river networks, because there is no species boundary to prevent gene flow between populations. Therefore, a more general phylogenetic network better depicts these situations.^[3]

[edit] See also

• Phylogenetics
• Median graph

[edit] References

1. ^ "Characterization of Reticulate Networks Based on the Coalescent with Recombination". Mol Biol Evol 25 (12): 2517–2520. 2008-10-15. OCLC doi: 10.1093/molbev/msn219. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2582979. 
2. ^ "Extended Newick: it is time for a standard representation of phylogenetic networks". BMC Bioinformatics 9 (532). 2008-12-15. OCLC doi: 10.1186/1471-2105-9-532.. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=19077301. 
3. ^ Legendre, P; Makarenkov, V (Apr 2002), "Reconstruction of biogeographic and evolutionary networks using reticulograms", Systematic biology 51 (2): 199–216, doi:10.1080/10635150252899725, ISSN 1063-5157, PMID 12028728 

• D. H. Huson and D. Bryant, Application of Phylogenetic Networks in Evolutionary Studies, Mol. Biol. Evol., 23(2):254-267, 2006.|

• Makarenkov, V., Kevorkov, D. and Legendre, P. (2006),Phylogenetic Network Reconstruction Approaches, Applied Mycology and Biotechnology, International Elsevier Series, vol. 6. Bioinformatics, 61-97.

• D. H. Huson and R. Rupp, Phylogenetic Networks, Cambridge University Press, in preparation.

[edit] Software to compute phylogenetic networks

• Network, Free Phylogenetic Network Software. Network generates evolutionary trees and networks from genetic, linguistic, and other data.
• Phylogeny programs, some of which compute phylogenetic networks
• List of programs for phylogenetic network reconstruction, evaluation, visualization, etc.
• SplitsTree
• Dendroscope
• Network inferring on the T-REX server
• TCS, Phylogenetic networks from DNA sequences or nucleotide distances using statistical parsimony.

[edit] External links

• A tutorial that reviews the terminology used for phylogenetic networks and covers both split networks and reticulate networks, their definition and interpretation.

v • d • e Topics in phylogenetics Relevant fields Computational phylogenetics · Molecular phylogeny · Cladistics Basic concepts Synapomorphy · Phylogenetic tree · Phylogenetic network · Long branch attraction · Clade · Ghost lineage Inference methods Maximum parsimony · Maximum likelihood · Neighbor-joining · UPGMA · Bayesian inference · Least squares Current topics PhyloCode · DNA barcoding -morphy Symplesiomorphy · Apomorphy · Plesiomorphy · Synapomorphy · Autapomorphy -phyly Monophyly/Holophyly · Paraphyly · Polyphyly List of evolutionary biology topics

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