PHYLOGENETIC APPROACHES IN COEVOLUTION AND BIOGEOGRAPHY

I review phylogenetic approaches to problems in coevolution and biogeo graphy, illustrating with case studies. In coevolution, genealogical t rees are essential in differentiating between ancient and recent assoc iations, in identifying cospeciation events, and in studying host-swit ching patterns. Cospeciating associations are of particular interest b ecause they allow powerful tests of molecular clocks and accurate comp arison of evolutionary rates across groups of organisms. In biogeograp hy, phylogenies can help reconstruct the distribution history of indiv idual groups and identify past geological events that have affected th e evolution of entire communities. Parsimony analysis in coevolution a nd biogeography should be based on identification of different types o f events, each of which is associated with a specific cost. Similar ev ent-based methods are applicable to coevolutionary and biogeographic i nference, as well as in the mapping of gene trees onto organism trees. The discussed examples span a variety of organisms and spatiotemporal scales: primate pin worms, HIV, pocket gophers and their lice, aphids and their bacterial symbionts, gall wasps and their host plants, the root of the tree of life, the historical biogeography of the Holarctic , and the geographical origin of our own species. (C) 1998 The Norwegi an Academy of Science and Letters.