Title
On Computing the Maximum Parsimony Score of a Phylogenetic Network.
Abstract
Phylogenetic networks are used to display the relationship among different species whose evolution is not treelike, which is the case, for instance, in the presence of hybridization events or horizontal gene transfers. Tree inference methods such as maximum parsimony need to be modified in order to be applicable to networks. In this paper, we discuss two different definitions of maximum parsimony on networks, "hardwired" and "softwired," and examine the complexity of computing them given a network topology and a character. By exploiting a link with the problem MULTITERMINAL CUT, we show that computing the hardwired parsimony score for 2-state characters is polynomial-time solvable, while for characters with more states this problem becomes NP-hard but is still approximable and fixed parameter tractable in the parsimony score. On the other hand we show that, for the softwired definition, obtaining even weak approximation guarantees is already difficult for binary characters and restricted network topologies, and fixed-parameter tractable algorithms in the parsimony score are unlikely. On the positive side we show that computing the softwired parsimony score is fixed-parameter tractable in the level of the network, a natural parameter describing how tangled reticulate activity is in the network. Finally, we show that both the hardwired and the softwired parsimony scores can be computed efficiently using integer linear programming. The software has been made freely available.
Year
DOI
Venue
2015
10.1137/140959948
SIAM JOURNAL ON DISCRETE MATHEMATICS
Keywords
Field
DocType
phylogenetic trees,phylogenetic networks,parsimony,complexity,approximability,fixed-parameter tractability,software
Discrete mathematics,Maximum parsimony,Combinatorics,Phylogenetic tree,Tree rearrangement,Inference,Algorithm,Network topology,Integer programming,Mathematics,Phylogenetic network,Binary number
Journal
Volume
Issue
ISSN
29
1
0895-4801
Citations 
PageRank 
References 
2
0.37
0
Authors
4
Name
Order
Citations
PageRank
Mareike Fischer121.05
Leo van Iersel221524.58
Steven Kelk319325.60
Celine Scornavacca421618.80