In renewed taxonomic studies of the large neotropical genus of sunflowers Viguiera, Dr. Edward Schilling of the University of Tennessee will conduct field work in Mexico and Argentina to amass samples for intensive morphological and molecular analyses of characters useful in delimiting species and in assessing relationships with other sunflower genera. Preliminary analysis of mutations in chloroplast DNA demonstrates that restriction- site mapping will be especially informative. The phylogenetic framework provided by the molecular data will then permit rigorous study of morphological and chromosomal changes in the several Mexican and Central-South American lineages of the group. Also, Dr. Schilling will be able to test whether a single migration from ancestral Mexican stock or multiple migrations best explains the diversity of related species in Andean South America.
