Molecular phylogeny and biogeography of Ribes (Grossulariaceae), with an emphasis on gooseberries (subg. Grossularia)

Gooseberries are often distinguished from currants as a distinct genus (Grossularia) or subgenus (Ribes subg. Grossularia), but recent molecular phylogenetic analyses of chloroplast and nuclear data disagree as to the monophyly of this group. We report new sequence data from the 18-26S nuclear rDNA ITS and ETS regions and from the chloroplast psbA-trnH intergenic spacer that, in combination with previously reported data, suggest subg. Grossularia is monophyletic and nested within Ribes. Two main lineages are evident within subg. Grossularia, corresponding to the true gooseberries (subg. Grossularia sect. Grossularia) and a clade of glabrous-styled western North American gooseberries (subg. Grossularia sect. Robsonia, subg. Hesperia, Lobbia). Biogeographic analyses based on DIVA optimizations suggest a western North American origin for subg. Grossularia, with subsequent dispersal to east Asia giving rise to a well-supported clade of Asian gooseberry species in sect. Grossularia. This example contrasts with the well-documented pattern of dispersal from Asia to North America, and highlights the need to investigate additional groups distributed widely through the Northern Hemisphere.