Prunus (plant family Rosaceae) is a large diverse genus of the temperate northern hemisphere with about 200 species and includes such economically important species as plums /prunes, peaches, apricots, cherries, and almonds. The North American plum group includes about 13-17 species that are so closely related that they have not established reproductive barriers and frequently hybridize. Because they hybridize so readily, species boundaries cannot easily be delimited and therefore differentiation and classification of North American plum species has long been difficult. The North American plums serve as an interesting model for systematic studies (the study of the kinds and diversity of organisms and the relationships among them) because they are at the interface of phylogenetics (studies of evolutionary relationships among species) and population genetics (studies of patterns of genetic variation among populations of species). This study will therefore not only help to resolve the relationships within a closely related group of species but it will also test the limits of phylogenetic resolution in a closely related group of species. Evolutionarily closely related groups of species that are difficult to distinguish morphologically are amenable to analysis with genetic data. The goals of this research are to resolve the evolutionary relationships among the North American plums using DNA sequence data. By comparing the DNA sequences of multiple accessions of each putative species from throughout their ranges, we can infer how much genetic variation exists within each species and how much genetic differentiation exists between putative species. This research will be important to the academic community as it will serve as a baseline investigation of a very closely related group of species.
Many species within the genus Prunus are economically important as ornamentals or food crops (e.g., plums /prunes, peaches, apricots, cherries, and almonds). The Eurasian plums of are those most often used in agriculture but are difficult to grow in many parts of North America because they are not well adapted to environmental conditions or diseases. Native North American plums, the focus of this research, are not cultivated on a large scale, although some species are currently under investigation as potential food crops. Most plum crop species are of hybrid origin from a small number of native Eurasian plums. Because there are more native North American plum species, the potential for improved cultivars through hybridization is greater. In addition to their potential economic importance, several species of North American plums are of conservation concern at the state level. Further, the scrub plum (P. geniculata) is Federally Endangered and restricted to only four counties in central Florida where habitat loss through development is critically endangering its habitat. Thus, understanding the classification and evolutionary history the native North American plums is of economic importance as well as conservation and biological interest. Lastly, this work will be of utility to the agricultural and horticultural communities as Prunus is used extensively in horticulture and there appears to be great potential for native North American plums to become a valuable North American food crop.
