The phylogeny, morphological evolution and biogeography of the Gaultherieae (Ericaceae)

The tribe Gaultherieae (Ericaceae: subfamily Vaccinioideae) comprises Chamaedaphne Moench, Diplycosia Blume, Eubotrys Nutt., Eubotryoides (Nakai) Hara, Gaultheria Kalm ex L., Leucothoe D. Don, and Tepuia Camp., with a total of approximately 250 species. The tribe is defined by its four-appendaged anthers and a base chromosome number of 11, although both of these characters also occur in a closely related genus, Zenobia D. Don (tribe Andromedeae; Kron et al. 2002). The group exhibits an amphi-Pacific distribution, that is, temperate and tropical regions of the Americas, eastern Asia, Southeast Asia, and New Guinea, Australia, and New Zealand. The informally named wintergreen group (Diplycosia, Gaultheria and Tepuia) is thought to be diagnosable by the presence of methyl salicylate, although this compound has apparently been lost in many species (or has not been detected).;Phylogenetic analyses using DNA sequence data have shown that the Gaultherieae and the wintergreen group are monophyletic. Optimization of morphological characters emphasized in classifications of the Gaultherieae onto the molecular phylogeny revealed that (1) fleshy calyces evolved either early in the lineage leading to the wintergreen group or later in two separate clades; (2) capsular fruits are plesiomorphic and berry fruits have evolved independently in Diplycosia and Tepuia and once or twice within a large clade containing all sampled Gaultheria sect. Pernettya members and Gaultheria species not exhibiting a berry fruit; and (3) A racemose inflorescence is the ancestral state for both the Gaultherieae and wintergreen group. Solitary-flowered inflorescences have evolved at least eight times within the Gaultherieae, with several changes back to racemose or fascicular inflorescences.;The genus Leucothoe s.l. has been split into as many as three genera in current taxonomic work involving morphological data. Based on phylogenetic data, Leucothoe s.l. is divided into three genera: Eubotryoides (E. grayana), Eubotrys (E. racemosa and E. recurva), and Leucothoe s.s. (L. axillaris, L. davisiae, L. fontanesiana, L. grithiana, and L. keiskei).;Several strongly supported clades within the wintergreen group (i.e., Gaultheria s.s.) include members from a particular geographic region. Phylogenetic relationships within Gaultheria L. from Australia and New Zealand were examined by using DNA sequence data and it was found that all Australia/New Zealand species form a clade that is sister to a clade of temperate South American species. A historical biogeographical analysis that included the temperate southern hemisphere element in Gaultheria suggests a South American origin of the Australia/New Zealand clade, followed by three dispersal events from New Zealand to Australia. Whether the origin is from temperate or tropical South America is ambiguous in the analysis. The species of Gaultheria from Australia and New Zealand were analyzed using morphological data and the species number for this region was reduced from fifteen to ten; the results were corroborated by the molecular phylogeny.;Finally, the disjunct Brazilian species of Gaultheria were analyzed in a molecular phylogeny. Six species of Gaultheria are endemic to the Mata Atlantica (Atlantic rainforest) in Brazil, several of which exhibit unique morphological characters within Gaultheria. A strongly supported clade of five Brazilian endemics was recovered (corresponding to the currently recognized G. ser. Myrtilloideae clade) and is sister to a clade of Gaultheria from temperate South America. Gaultheria serrata, another endemic Gaultheria species and two other Gaultheria that exhibit distributions in Brazil and the Andes are closely related to each other and other species from the Andes/Mexico. These results support the hypothesis that some Brazilian species of Gaultheria are derived from Andean ancestors. However, the G. ser. Myrtilloideae clade is imbedded within a clade containing species from temperate South America, indicating that the Andes may not have served as the only source area for the species in the Mata Atlantica of Brazil.