Phylogenetic invariants and geometry.

The method of invariants is an important approach in biology for determining phylogenetic information which avoids the problems involving long branch lengths that plague some other methods. In this paper, we present a geometric framework underlying the method of invariants. This perspective sheds new lights on problems in the field. It has recently enabled the solution of questions on the number and structure of phylogenetic invariants and suggests possible avenues for future empirical and theoretical research.