Submitted to: Systematic Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/1996
Publication Date: N/A
Citation: Interpretive Summary: The cultivated potato has about 220 wild species relatives that grow from the southwestern United States to southern Chile. There are many unanswered questions about what a species is in this group and how these species are related. Because all 220 species are too large for any one study, we tried to study what was thought to be a natural group of wild potatoes, those with elongated fruits, containing only 40 species, technically known as the Conicibaccata group. We studied their species boundaries by their overall form (morphology), and their genetic material (DNA from the chloroplasts, those structures that contain chlorophyll that make the plants green). Our results indicated two things: 1) there are many less than the 40 species previously thought to occur in this conical-fruited group, and 2) they are not all related to each other. Because species are a major factor in organizing and predicting traits of our wild potato collections, these new findings will greatly improve the organization and use of the world's collections of this group of wild potatoes.
Technical Abstract: Solanum sect. Petota series Conicibaccata is a group of 40 wild potato species, composed of diploids, tetraploids, and hexaploids, widely distributed from central Mexico to central Bolivia. This study examined their species boundaries and interrelationships by phenetic analyses of morphological data and cladistic analyses of chloroplast DNA restriction enzyme site data. Most results were concordant in showing three main groups of species: 1) tetraploids and hexaploids from central Mexico to southern Ecuador, 2) diploids from northern Peru to Bolivia, included in a cpDNA clade of diploids and hexaploids assigned to ser. Demissa and ser. Tuberosa, 3) diploids and tetraploids from southern Colombia to Peru, cladistically related to members of ser. Piurana. Some species boundaries, and even series boundaries of ser. Conicibaccata and ser. Piurana, are supported morphologically only by a combination of widely overlapping character states, none of which is constant for a species. Other species have no support, and it is likely that too many species are recognized in the group. The cladistic analysis of cpDNA data suggested that some species represent a combination of apospecies and plesiospecies, and some populations are of possible hybrid origin. Species first reported here for chromosome counts are S. garcia-barrigae, S. orocense, and S sucubunense.