Research Topics
 S J WillsonSummaryAffiliation: Iowa State University Country: USA Publications

Detail Information
Publications
 Constructing rooted supertrees using distancesStephen J Willson
Department of Mathematics, Iowa State University, Ames, IA 50011, USA
Bull Math Biol 66:175583. 2004..When no supertree exists because the input trees are incompatible, several variants of the method are described which still produce trees with provable properties...  Reconstruction of certain phylogenetic networks from their treeaverage distancesStephen J Willson
Department of Mathematics, Iowa State University, Ames, IA, 50011, USA
Bull Math Biol 75:184078. 2013..For a certain class of phylogenetic networks, a polynomialtime method is presented to reconstruct the network from the treeaverage distances. The method is proved to work if there is a single reticulation cycle. ..  CSD homomorphisms between phylogenetic networksStephen J Willson
Department of Mathematics, Iowa State University, Ames, IA 50011, USA
IEEE/ACM Trans Comput Biol Bioinform 9:112838. 2012..A CSD map from N to M puts strong constraints on N. In general, it may be useful to study classes of networks such that, for any N, there exists a CSD map from N to some standard member of that class...  Restricted trees: simplifying networks with bottlenecksStephen J Willson
Department of Mathematics, Iowa State University, Ames, IA 50011, USA
Bull Math Biol 73:232238. 2011..There is a restricted CSD map from N to the restricted tree. Many relationships in the tree can be proved to appear also in N...  Regular networks can be uniquely constructed from their treesStephen J Willson
Department of Mathematics, Iowa State University, Ames, IA 50011, USA
IEEE/ACM Trans Comput Biol Bioinform 8:78596. 2011..If D is a (usually very much smaller) collection of displayed trees that satisfies certain hypotheses, modifications of the procedure will still reconstruct N given D...  Properties of normal phylogenetic networksStephen J Willson
Department of Mathematics, Iowa State University, Ames, 50011, USA
Bull Math Biol 72:34058. 2010..These properties include that the number of vertices grows at most quadratically with the number of leaves and that the number of hybrid vertices grows at most linearly with the number of leaves...  Robustness of topological supertree methods for reconciling dense incompatible dataStephen J Willson
Department of Mathematics, Iowa State University, Ames, IA 50011, USA
IEEE/ACM Trans Comput Biol Bioinform 6:6275. 2009..A polynomialtime method Normalized Triplet Supertree (NTS) with the maximal possible R = 1/2 is defined. A geometric interpretation is given, and NTS is shown to solve an optimization problem. Additional properties of NTS are described...  Reconstruction of certain phylogenetic networks from the genomes at their leavesStephen J Willson
Department of Mathematics, Iowa State University, Ames, IA 50011, USA
J Theor Biol 252:33849. 2008..An explicit polynomialtime procedure is described for performing the reconstruction...  Reconstruction of some hybrid phylogenetic networks with homoplasies from distancesStephen J Willson
Department of Mathematics, Iowa State University, Ames, IA 50011, USA
Bull Math Biol 69:256190. 2007..Assume that the distances are known between all members of X. Sufficient conditions are given such that the graph G and all the originating and homoplasy weights can be reconstructed from the given distances...  Unique determination of some homoplasies at hybridization eventsStephen J Willson
Department of Mathematics, Iowa, State University, Ames, IA 50011, USA
Bull Math Biol 69:170925. 2007..Hence, for each character the vertex at which a homoplasy occurs in the character is uniquely determined. Without the assumption on regular paths, an example shows that the genomes and homoplasies need not be uniquely determined...  Unique reconstruction of treelike phylogenetic networks from distances between leavesStephen J Willson
Department of Mathematics, Iowa State University, Ames, IA 50011, USA
Bull Math Biol 68:91944. 2006..Thus, given exact distance information on the leaves and root, the phylogenetic network can be uniquely recovered, provided that it is a TOMnetwork. An outgroup can be used instead of a true root...  Minimum evolution using ordinary leastsquares is less robust than neighborjoiningStephen J Willson
Department of Mathematics, Iowa State University, Ames, IA 50011, USA
Bull Math Biol 67:26179. 2005..It follows that, for large n, minimum evolution with ordinary leastsquares can be only half as robust as neighborjoining...  An errorcorrecting map for quartets can improve the signals for phylogenetic treesS J Willson
Department of Mathematics and Laurence H Baker Center for Bioinformatics and Biological Statistics, Iowa State University, Ames 50011, USA
Mol Biol Evol 18:34451. 2001..Simulations show that if methods such as the Ctree or hypercleaning are applied to Ec(L), the resulting trees often have more resolution than when the methods are applied only to L...