Taxonomic variation among North and South American subspecies of Fragaria virginiana Miller and Fragaria chiloensis (L.) Miller

Abstract

A morphometric comparison was done in the greenhouse of 220 genotypes representing all the American taxa of octoploid strawberries. Only two groups of Fragaria virginiana Miller (Staudt) and Fragaria chiloensis (L.) Miller were well separated in both principle component and cluster analyses: a group composed primarily of F. chiloensis subspecies plus some F. virginiana ssp. glauca (Wats.) Staudt and F. virginiana ssp. platypetala (Rydberg) Staudt and another group composed primarily of F. virginiana ssp. virginiana Duchesne; and F. virginiana ssp. grayana (E. Vilmorin ex Gay) with some F. virginiana ssp. glauca and F. virginiana ssp. platypetala. Among the individual traits examined, only hair orientation reliably distinguished F. chiloensis ssp. lucida (E. Vilmorin ex Gay) from F. chiloensis ssp. pacifica Staudt, and F. virginiana ssp. grayana from F. virginiana ssp. virginiana. Little separation was observed between North and South American F. chiloensis in our principle component and cluster analyses, although these groups did show significant individual discontinuities for a number of traits. Individuals representing the cultivated race of F. chiloensis were in a relatively tight cluster within the scatter of native F. chiloensis. Taken together, these data indicate that F. virginiana and F. chiloensis may be extreme forms of the same biological species and that many of the subspecies designations currently employed in F. virginiana and F. chiloensis should not be recognized. We suggest, however, that there is sufficient morphological and geographical separation to warrant the species designations F. chiloensis and F. virginiana. Fragaria chiloensis ssp. pacifica and Fragaria chiloensis ssp. lucida do not appear to deserve distinct subspecies rank, nor do F. virginiana ssp. virginiana and F. virginiana ssp. grayana. North and South American F. chiloensis are morphologically quite similar, but probably deserve subspecies rank, based on their isolation from each other and the fact that they are evolving separately. Fragaria virginiana ssp. glauca and F. virginiana ssp. platypetala should probably be joined as a single subspecies and retained within F. virginiana until further investigations more definitively determine affinity to other F. virginiana and F. chiloensis subspecies.Key words: Rosaceae, interspecies hybridization, polyploidy.