Gaphyl: A Genetic Algorithms Approach to Cladistics

This research investigates the use of genetic algorithms (GA's) to solve problems from cladistics | a technique used by biologists to hypothesize the evolutionary relationships between organisms. Since exhaustive search is not practical in this domain, typical cladis-tics software packages use heuristic search methods to navigate through the space of possible trees in an attempt to nd one or more \best" solutions. We have developed a system called Gaphyl, which uses the GA approach as a search technique for nd-ing cladograms, and a tree-evaluation metric from a common cladistics software package (Phylip). In initial results, Gaphyl is able to nd cladograms comparable to those found by Phylip on a nontrivial problem (23 species with 29 attributes). Furthermore, Gaphyl seems to be able to nd a wider variety of cladograms with the same \best" parsimony as the cladograms found by Phylip.