Walter Monroe Fitch (May 21, 1929 – March 10, 2011) was a pioneering American researcher in molecular evolution.
He was a member of the National Academy of Sciences, the American Philosophical Society,[2] and the American Association for the Advancement of Science, and was a Foreign Member of the London Linnean Society.
[3] Fitch is noted for his pioneering work on reconstruction of phylogenies (evolutionary trees) from protein and DNA sequences.
He also developed the Fitch maximum parsimony algorithm, which evaluates rapidly and exactly the minimum number of changes of state of a sequence on a given phylogeny.
His definition of orthologous sequences has been frequently cited and is used as a reference in many research publications.