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Citation for Study 10541

About Citation title: "Phylogeny and character evolution in the New Zealand endemic genus Plagianthus (Malveae, Malvaceae)".
About Study name: "Phylogeny and character evolution in the New Zealand endemic genus Plagianthus (Malveae, Malvaceae)".
About This study is part of submission 10531 (Status: Published).

Citation

Wagstaff S., & Tate J.A. 2011. Phylogeny and character evolution in the New Zealand endemic genus Plagianthus (Malveae, Malvaceae). Systematic Botany, 36(2): 405-418.

Authors

  • Wagstaff S.
  • Tate J.A. Phone +64-6-350-5515

Abstract

As presently circumscribed, the genus Plagianthus includes two morphologically distinct species that are endemic to New Zealand. Plagianthus divaricatus, a divaricate shrub, is a dominant in coastal wetland communities, whereas P. regius is a tree of lowland and montane forests. Results from independent analyses of ITS and 5′ trnK/matK sequences are congruent, and when combined provide a robust framework to study character evolution. Our findings suggest the ancestor of the genus originated in Australia where the sister genera Asterotrichion and Gynatrix are distributed. Divergence estimates obtained by maximum likelihood are older than those obtained from Bayesian analysis, with considerable uncertainty surrounding the mean values. The stem age of Plagianthus was estimated at 7.3 (4.0?14.0) million years ago (Ma) and the crown radiation at 3.9 (1.9?8.2) Ma. The Miocene epoch coincided with expanded aridity in Australia, whereas the onset of cooler climatic conditions in New Zealand caused extinction, which may have opened ecological niches for the newly established founders. Most of the functional characters that were optimized onto the molecular phylogeny are pleisomorphic as they were shared with the source lineages in Australia. Only the divaricate branching pattern characteristic of Plagianthus divaricatus was apomorphic, because it was acquired after the lineage became established in New Zealand. The initial Plagianthus founders were shrubs or small trees with deciduous leaves and small inconspicuous dioecious flowers. Juvenile vegetative morphology and sexual maturation are decoupled in Plagianthus; heteroblastic vegetative development is well documented in Plagianthus and its close relatives.

Keywords

Bayesian analysis, divergence estimates, long-distance dispersal, Malveae, New Zealand, Plagianthus

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  • Canonical resource URI: http://purl.org/phylo/treebase/phylows/study/TB2:S10541
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