Chloroplast evidence for geographic stasis of the Australian bird-dispersed shrub Tasmannia lanceolata (Winteraceae).

Few chloroplast-based genetic studies have been undertaken for plants of mesic temperate forests in the southern hemisphere and fossil-based models have provided evidence of vegetation history only at the broadest scales in this region. This study investigates the chloroplast DNA phylogeography of Tasmannia lanceolata (Winteraceae), a fleshy-fruited, bird-dispersed shrub that is widespread in the mountains of southeastern Australia and Tasmania. Thirty haplotypes were identified after sequencing 3206 bp of chloroplast DNA in each of 244 individuals collected across the species' range. These haplotypes showed unexpectedly strong phylogeographic structuring, including a phylogeographic break within a continuous part of the species' range, with the distribution of four major clades mostly not overlapping, and geographic structuring of haplotypes within these clades. This strong geographic patterning of chloroplast DNA provided evidence for the survival of T. lanceolata in multiple putative wet forest refugia as well as evidence for additional wet forest species refugia in southeastern Australia. In western Tasmania lower haplotype diversity below the LGM tree line compared to above the LGM tree line suggests that glacial refugia at high altitudes may have been important for T. lanceolata. The level of geographic structuring in T. lanceolata is similar to gravity dispersed southern hemisphere plants such as Nothofagus and Eucalyptus. Behavioural traits of the birds transporting seed may have had a strong bearing on the limited transport of T. lanceolata seed, although factors limiting establishment, possibly including selection, may also have been important.

Generic relationships and dating of lineages in Winteraceae based on nuclear (ITS) and plastid (rpS16 and psbA-trnH) sequence data.

Phylogenetic analyses of representative species from the five genera of Winteraceae (Drimys, Pseudowintera, Takhtajania, Tasmannia, and Zygogynum s.l.) were performed using ITS nuclear sequences and a combined data-set of ITS+psbA-trnH+rpS16 sequences (sampling of 30 and 15 species, respectively). Indel informativity using simple gap coding or gaps as a fifth character was examined in both data-sets. Parsimony and Bayesian analyses support the monophyly of Drimys, Tasmannia, and Zygogynum s.l., but do not support the monophyly of Belliolum, Zygogynum s.s., and Bubbia. Within Drimys, the combined data-set recovers two subclades. Divergence time estimates suggest that the splitting between Drimys and its sister clade (Pseudowintera+Zygogynum s.l.) occurred around the end of the Cretaceous; in contrast, the divergence between the two subclades within Drimys is more recent (15.5-18.5MY) and coincides in time with the Andean uplift. Estimates suggest that the earliest divergences within Winteraceae could have predated the first events of Gondwana fragmentation.