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Citation for Study 22660

About Citation title: "Australasian orchid biogeography at continental scale: molecular phylogenetic insights from the sun orchids (Thelymitra, Orchidaceae)".
About Study name: "Australasian orchid biogeography at continental scale: molecular phylogenetic insights from the sun orchids (Thelymitra, Orchidaceae)".
About This study is part of submission 22660 (Status: Published).

Citation

Nauheimer L., Schley R., Clements M., Micheneau C., & Nargar K. 2018. Australasian orchid biogeography at continental scale: molecular phylogenetic insights from the sun orchids (Thelymitra, Orchidaceae). Molecular Phylogenetics and Evolution, .

Authors

  • Nauheimer L. (submitter) Phone 089 17861251
  • Schley R.
  • Clements M.
  • Micheneau C.
  • Nargar K.

Abstract

Australia harbours a rich and highly endemic orchid flora, with c. 90 % of species endemic to the country, but so far the biogeographic history of Australasian orchid lineages is only poorly understood. Here we examined evolutionary relationships and the spatio-temporal evolution of the sun orchids (Thelymitra, 119 species), which display disjunct distribution patterns frequently found in Australasian orchid lineages. Phylogenetic analyses were conducted based on one nuclear (ITS) and three plastid markers (matK, psbJ-petA, ycf1) using Maximum Likelihood and Bayesian inference. Divergence time estimations were carried out with a relaxed molecular clock in a Bayesian framework. Ancestral ranges were estimated using the dispersal-extinction-cladogenesis model and an area coding based on major disjunctions. The phylogenetic analyses clarified intergeneric relationships within Thelymitrinae, with Epiblema being sister group to Thelymitra plus Calochilus, which were both well supported clades. Within Thelymitra, eight major and several minor clades were retrieved in the nuclear and plastid phylogenetic reconstructions. Five major clades corresponded to species complexes previously recognized based on morphological characters, whereas other previously recognized species groups were found to be paraphyletic. Conflicting signals between the nuclear and plastid phylogenetic reconstructions provided support for hybridization and plastid capture events both in the deeper evolutionary history of the genus and more recently. Divergence time estimation placed the origin of Thelymitra in the late Miocene (c. 10.8 Ma) and the origin of the majority of the main clades within Thelymitra during the late Pliocene and early Pleistocene, with the majority of extant species arising during the Pleistocene. Ancestral range reconstruction revealed that the early diversification of the genus in the late Miocene and Pliocene took place predominantly in southwest Australia, where most species with highly restricted distributional ranges occur. Several long-distance dispersal events eastwards across the Nullarbor Plain were inferred, recurrently resulting in lineage divergence within the genus. The predominant eastwards direction of long-distance dispersal events in Thelymitra highlights the importance of the West Wind Drift for the present-day distribution of the genus, giving rise to the Thelymitra floras of Tasmania, New Zealand and New Caledonia, which were inferred to be of comparatively recent origin.

Keywords

Plant Evolution, Plant Systematics, Biogeography, Vascular Plants, Botany, Molecular Phylogenetics

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  • Canonical resource URI: http://purl.org/phylo/treebase/phylows/study/TB2:S22660
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