Efficient Quartet Systems: A New Systematic Approach to Supertree Reconstruction

Poster Number

28

Submitting Student(s)

MaLyn Lawhorn, Winthrop University

College

College of Arts and Sciences

Department

Mathematics

Faculty Mentor

Joseph Rusinko, Ph.D.

Abstract

A phylogenetic tree is described by quartets that show where a split in the tree should occur. The number of compatible quartets that define a tree is the number of taxa on the tree to the fourth power. Scientists often want to combine multiple phylogenetic trees, or input trees, to derive a “supertree.” This is typically done by giving a collection of all the quartets that define the input trees to tree reconstruction software such as MaxCut. However, the number of compatible quartets that define a supertree is often too large for MaxCut to handle and contains a lot of conflicting quartets. Therefore, it would be helpful to find a subset of quartets which would return a correct input tree so that, when the quartet systems defining the input trees are combined, there are not too many quartets for MaxCut to consider and a correct supertree is returned. An efficient quartet system is a collection of quartets which distinguish unique paths across a phylogenetic tree. An efficient quartet system is found by first distinguishing each internal vertex on a phylogenetic tree with pairs of taxa and then consistently using these vertex-distinguishing pairs to create quartets that distinguish the paths of the tree. An efficient quartet system reduces the number of quartets used to reconstruct a tree and, additionally, returns the correct tree for multiple different topologies of trees.

Start Date

24-4-2015 3:20 PM

End Date

24-4-2015 4:50 PM

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Apr 24th, 3:20 PM Apr 24th, 4:50 PM

Efficient Quartet Systems: A New Systematic Approach to Supertree Reconstruction

Richardson Ballroom

A phylogenetic tree is described by quartets that show where a split in the tree should occur. The number of compatible quartets that define a tree is the number of taxa on the tree to the fourth power. Scientists often want to combine multiple phylogenetic trees, or input trees, to derive a “supertree.” This is typically done by giving a collection of all the quartets that define the input trees to tree reconstruction software such as MaxCut. However, the number of compatible quartets that define a supertree is often too large for MaxCut to handle and contains a lot of conflicting quartets. Therefore, it would be helpful to find a subset of quartets which would return a correct input tree so that, when the quartet systems defining the input trees are combined, there are not too many quartets for MaxCut to consider and a correct supertree is returned. An efficient quartet system is a collection of quartets which distinguish unique paths across a phylogenetic tree. An efficient quartet system is found by first distinguishing each internal vertex on a phylogenetic tree with pairs of taxa and then consistently using these vertex-distinguishing pairs to create quartets that distinguish the paths of the tree. An efficient quartet system reduces the number of quartets used to reconstruct a tree and, additionally, returns the correct tree for multiple different topologies of trees.