No abstract

Phylogenetic relationships within the tribe Gaultherieae (Chamaedaphne, Diplycosia, Eubotrys, Gaultheria, Leucothoë, and Tepuia) were examined with DNA sequence data from matK, ndhF, and nrITS. Parsimony analyses were performed in PAUP* for each gene region, combined chloroplast data, and total combined data. A Bayesian analysis was performed in MrBayes on the chloroplast and total combined data sets. The total combined parsimony and Bayesian analyses both strongly support the monophyly of the Gaultherieae and the wintergreen group (Diplycosia, Gaultheria, and Tepuia). Diplycosia is monophyletic and nested within part of Gaultheria. In the Bayesian total combined analysis, Tepuia is strongly supported as sister to a clade containing Gaultheria procumbens, Gaultheria hispidula, Gaultheria leucocarpa var. cumingiana, Gaultheria leucocarpa var. leucocarpa, and all sampled Diplycosia species. 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 sect. Pernettya members and Gaultheria species not exhibiting a berry fruit; and (3) the ancestral state for both the Gaultherieae and wintergreen group is a racemose inflorescence; solitary-flowered inflorescences have evolved at least eight times within the Gaultherieae, with several changes back to racemose or fascicular inflorescences.

Phylogenetic relationships within Gaultheria L. from Australia and New Zealand were examined by using DNA sequence data from matK, ndhF, nrITS, waxy and lfy. In the combined parsimony and maximum likelihood analyses, all Australia/New Zealand species form a clade that is sister to a clade of temperate South American species. Optimisation of morphological characters that have been emphasised in classifications of Gaultheria onto the molecular phylogeny revealed that, within the Australia/New Zealand clade, non-fleshy fruiting calyces, berries and solitary-flowered inflorescences each evolved twice, from fleshy fruiting calyces, capsules and multiple-flowered inflorescences, respectively. A historical biogeographical analysis that included the temperate southern hemisphere element in Gaultheria supports 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 our analysis.

The seed morphology of 90 samples from 83 species of tribe Gaultherieae (Chamaedaphne, Diplycosia, Eubotryoides, Eubotrys, Gaultheria and Leucothoe) and relatives in tribes Andromedeae (Andromeda and Zenobia) and Vaccinieae (Satyria) was investigated with stereoscopic and scanning electron microscopy. Seeds exhibit variation in shape, colour, size, wing, hilum region, primary ornamentation and epidermal cells. Non-metric multidimensional scaling (NMDS) analysis based on selected seed characters supports the affinities of some groups within Gaultherieae at various taxonomic levels. Seed characters corroborate the delimitation of Andromeda, Chamaedaphne, Leucothoe, Satyria and Zenobia and Gaultheria series Trichophyllae, series Hispidulae, section Amblyandra and section Brossaeopsis. Parsimony optimization of seed characters onto a previously published phylogenetic estimate of Gaultherieae reveals that small seeds have evolved from larger seeds and an areolate seed coat has evolved from a reticulate seed coat. Optimization also suggests that several seed character states are synapomorphies or potential synapomorphies for some major clades of Gaultherieae. Seeds of Gaultherieae from East Asia, temperate North America and the Pacific are more diverse than those from tropical America. Samples from the eastern Himalaya possess the highest variation in seed morphology. The wing and bulging edge cells observed in seeds of Leucothoe suggest dispersal by wind.

DNA sequence data from the low‐copy nuclear genes waxy (GBSSI) and leafy were compared with plastid and ITS sequence data from prior studies to reconstruct phylogenetic relationships in the Wintergreen Group of tribe Gaultherieae (Ericaceae). We conducted phylogenetic analysis with 102 species that includes representatives of all 15 major clades previously identified within the Wintergreen Group and that together span its circum‐Pacific distribution. Results yielded two distinct homeologous copies of waxy for two of the clades, each in widely separated parts of the tree. It also yielded two copies of leafy for one of the clades; only one copy of leafy was found for the other clade, but it was placed in the same major clade as its waxy counterpart and well away from its placement in a prior plastid analysis. A combined four‐locus (waxy, leafy, ITS and plastid data) phylogenetic analysis of all available relevant data placed the copies of each of the clades in two distinct positions in the phylogeny with strong overall statistical support. In combination with evidence from morphology, reproductive biology and cytology, the results suggest that these clades arose through allopolyploid hybridization between lineages deep in the phylogeny but relatively close geographically. This finding confirms previous assumptions that hybridization has played an important role in the evolution of the Gaultherieae.