Potential hybridization among two species of California Salvia

Abstract

Hybridization among plants is fairly common, particularly in instances where closely related species are sympatric. One example of a group in which hybridization has been detected is the genus Salvia (Lamiaceae; mint family). Salvia is a diverse genus consisting of about 1,000 species and is defined primarily by having only two stamens, each with their anther sacs separated by elongated connective tissue. The genus has diversity centers around the world, including Southwest Asia and the Mediterranean region, Mexico/ Central America, northern and central South America, and temperate East Asia. The genus also has a smaller species radiation of 19 species in western North America, subgenus Audibertia centered in California, and there has been documented evidence of hybridization within the subgenus. For this study we investigated potential hybridization among Salvia columbariae and Salvia greatae, two species with a sympatric distribution in the Orocopia Mountains region of Southern California. These species are placed in different sections of subgenus Audibertia, and hybridization has not yet been documented between sections of this subgenus. To examine relationships between the species, we compared molecular phylogenies from nuclear ribosomal DNA and chloroplast DNA. The resulting phylogenies did not show evidence of hybridization between these species. Although no evidence of hybridization was found, it is possible that additional sampling could yield different results.