The genus Acacia consists of shrubs and trees that are dominant in the arid vegetation of the tropical and subtropical world, including the Americas. Despite economic and ecological importance of acacias, the evolutionary relationships of the species (phylogenies) and morphological trends of evolution among the hundreds of described species (such as leaf, flower, and seed evolution) are poorly known. Collaborating researchers Dr. David Seigler at University of Illinois and Dr. Joseph Miller at University of Iowa will accumulate new DNA sequence data for plastid and nuclear genes from numerous species samples of acacias from the Americas, Africa, Asia, and Australia. Field work in Mexico and the Dominican Republic will complement samples supplied by colleagues from Old World species, to construct a phylogenetic framework for the largely American subgenus of acacias, and to explore relationships with those African species suspected to be close relatives, including some with symbiotic associations with ants remarkably similar to the American ant-acacia symbionts. In turn, the phylogenetic framework will help clarify issues concerning species delimitation, geographic distribution, and nomenclature in the group. Improved understanding of the systematics and phylogenetics of acacias will help agronomists, conservationists, ecologists, and rangeland managers in their work, and will sharpen questions to be addressed concerning pollination biology, rhizobial nitrogen fixation, and biogeography of these plants. Interactions will be strengthened with scientific colleagues in Latin America, Africa, Australia, and Europe. Students will be trained in field and laboratory (herbarium) studies, and will accompany the investigators on field collecting trips abroad. Interactive identification keys will be posted to a website maintained by Australian researchers for the study of acacia biology and evolution.
