XVI International Botanical Congess

A quantitative assessment of the role of plant structural and chemical defenses, plant cladogenesis, and plant biogeography in directing the evolution of host shifts was made. I used DNA sequences to reconstruct the evolutionary trees of the ancient and speciose Bursera (Burseraceae)-Blepharida (Chrysomelidae:Alticinae) system. Profiles of structural and chemical defenses, as well as maps of geographic distributions for the plant species were obtained to determine their relative importance in directing the evolution of shifts by these insects. This phylogenetic aproach also revealed interesting patterns of historical correlations between plant defenses and insect counterdefenses.