Phylogenetic relationships in <i>Ribes</i> (Grossulariaceae) inferred from ITS sequence data

Abstract

Abstract Nuclear ITS sequence data were employed to assess phylogenetic relationships within Ribes , an angiosperm genus of approximately 200 species that is well­known for its taxonomic complexity. Our analyses revealed several major clades within Ribes , informally referred to here as the Berisia, Calobotrya, Coreosma , and Grossularia sensu lato clades. The clades recovered indicate that some of the subgenera recognized in previous taxonomic treatments are largely monophyletic, including Calobotrya, Grossularia , and Grossularioides . Our data suggest broader circumscriptions of Lobbia, Berisia , and Coreosma . Other subgenera, such as Heritiera and Ribesia are likely polyphyletic, with constituent taxa scattered throughout the topology. The gooseberries in the broad sense (subgenera Grossularia, Hesperia, Lobbia and Robsonia ), sometimes treated as a distinct genus Grossularia , are clearly embedded within Ribes and do not merit status as a separate genus. Comparison with a cpDNA topology reveals some similarities, such as the monophyly of subgenera Calobotrya and Grossularia and the inclusion of all gooseberries ( Grossularia s.l.) within Ribes . There are also noteworthy differences. In contrast to both ITS sequence data and morphological data, cpDNA restriction site data do not reveal a monophyletic Grossularia sensu lato clade comprising subgenera Grossularia, Hesperia, Lobbia , and Robsonia . However, few of the differences between the cpDNA and ITS trees are strongly supported. Our ITS topology suggests that dioecy may have evolved several times in the genus. We similarly explored floral form in light of our topology; highly reflexed sepals represent a morphological synapomorphy that unites the subgenera Grossularia, Hesperia, Lobbia and Robsonia , with a reversal in a single taxon.