RELATIONSHIPS BETWEEN DISPERSAL MODE AND GEOGRAPHIC RANGE IN THE ROSALES

Relationships between geographic range, diversity, and taxon survivorship have been demonstrated in paleontological studies as well as in extant populations, but the mechanisms that link the ecological traits of a species with its geographic range are still not well understood. The Rosales are a diverse group of flowering plants possessing a wide range of life history traits and dispersal modes, as well as a good fossil record. Here we quantify the relationships between different modes of dispersal, life history traits, and geographic range in rosalean genera using herbarium specimens and museum collection databases. We control for phylogenetic correlation using published phylogenies and gene sequence data from Genbank. Preliminary results from within the Rosaceae suggest a positive correlation between animal dispersal together with large propagules and increased geographic range and species diversity within genera, especially among woody taxa. There is also a positive correlation between number of continents occupied by a genus and the average proportion of those continents occupied. A positive correlation of geographic range size with animal dispersal is consistent with patterns seen in conifers. However, that the association is stronger in woody Rosalean genera suggests that life history traits may affect the relationship between between dispersal mode, biogeography, and biodiversity. Because long-lived woody plants would have fewer generations between Milankovitch or sub-Milankovitch scale climate events than short-lived herbs, we would predict that effective long-range animal-mediated dispersal would be more favored in woody taxa than in herbs. We plan to test this in two ways: first, by examining range-dispersal relationships in long-lived perennial herbs, and second, by examining changes in relative frequencies of animal-dispersed woody taxa in the past when glacial-interglacial climate cycles characteristic of the Quaternary were presumably less severe.