**IMA Complex Systems Seminar**

**2:30 Wednesday, October 15,
2003**

Department of Mathematics

Iowa State University

Ames, IA 50011

Abstract:
Suppose that a tree T has the set S of leaves and S' is a subset of
S. Then T|S' denotes the tree obtained
from T with the set S' of leaves, showing only the relationships among S'. Suppose that for i = 1, ..., k, T_i is a tree with the set S_i of leaves. A "supertree" is a single tree T
with the set S of leaves, where S is the union of the S_i, such that T|S_i =
T_i for each i. A major problem in
phylogeny is, given such a collection of trees T_i, to identify a supertree T
if one exists. A method for solving
this problem could be used to combine different phylogenetic trees from
different researchers into a larger tree.

The most common method currently used to find
supertrees is MRP (matrix representation with parsimony). It is computationally intensive, it often
leads to a great many possible solution trees, and it is not founded on theory.

This talk proposes a supertree method in
which additional input information is required. We require in addition that for each tree T_i there is given an
additive distance function d_i on S_i which estimates the amount of evolution
between any two taxa. We then try to
create a supertree T with additive distance function d which equals d_i when
restricted to S_i.

Some results of simulations will be
presented.