Origin, diversification and classification of the Australasian genus Dracophyllum (Richeeae, Ericaceae)

S J Wagstaff; M I Dawson; S Venter; J Munzinger; D M Crayn; Dorothy A Steane; K L Lemson

doi:10.3417/2008130

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Origin, diversification and classification of the Australasian genus Dracophyllum (Richeeae, Ericaceae)

Journal article

Peer reviewed

Origin, diversification and classification of the Australasian genus Dracophyllum (Richeeae, Ericaceae)

S J Wagstaff, M I Dawson, S Venter, J Munzinger, D M Crayn, Dorothy A Steane and K L Lemson

Missouri Botanical Garden. Annals, Vol.97(2), pp.235-258

2010

DOI: https://doi.org/10.3417/2008130

Abstract

Plant Biology

adaptive radiation

angiosperm

biogeography

classification

dracophyllum

epacridaceae

ericaceae

matK

molecular phylogenetics

The genus Dracophyllum Labill. (Ericaceae) has a fragmented distribution in Australasia, but reaches the greatest level of species richness and morphological diversity in New Zealand. We investigated evolutionary processes that contribute to this disparity in species richness by comparing DNA sequences from members of Dracophyllum, its close relatives Richea Labill.and Sphenotoma R. Br. ex Sweet (together constituting tribe Richeeae Crayn & Quinn), along with more distant relatives in the Ericaceae. We created complementary data sets for the chloroplast-encoded genes matK and rbcL. Parsimony, Bayesian, and maximum likelihood analyses were conducted to assess the robustness of our phylogenetic inferences. The results were largelycongruent and, when analyzed in combination, provided greater resolution. In our analyses, tribe Richeeae formed amonophyletic group that diverged during the Eocene (at least 33.3 million years ago [Ma]) with a crown radiation during the Early Miocene (at least 16.5 Ma) that resulted in two disjunct lineages. This date corresponds roughly to the onset of aridification in central Australia. The southern Western Australian genus Sphenotoma formed an isolated evolutionary lineage, while Dracophyllum and Richea together formed a second lineage restricted to eastern Australia, Lord Howe Island, New Caledonia, and New Zealand. The relationships of the Tasmanian endemic, D. milliganii Hook. f., remain an enigma. It wasambiguously placed as sister to Sphenotoma or to the Dracophyllum-Richea clade. We recovered two distinct lineages, traditionally recognized as Richea sect. Cystanthe (R. Br.) Benth. and Richea sect. Dracophylloides Benth., which were nested within Dracophyllum. The Lord Howe Island endemic, D. fitzgeraldii F. Muell., emerged as sister to an eastern Australian clade of Dracophyllum. Our evidence suggests that the New Caledonian and New Zealand species of Dracophyllum dispersedfrom Australia; we document two independent episodes of long-distance dispersal in the Late Miocene to Early Pliocene. Low levels of sequence divergence suggest a rapid and recent species radiation in these two island archipelagos largely within the last three to six million years. This radiation accompanied Pliocene uplift of the New Zealand Southern Alps and episodes ofglaciation during the Pleistocene. Because Dracophyllum is paraphyletic and Richea is polyphyletic, the taxonomiccircumscription of these genera requires revision.

Details

Title: Origin, diversification and classification of the Australasian genus Dracophyllum (Richeeae, Ericaceae)
Authors: S J Wagstaff (Author) - Landcare Research, New Zealand
M I Dawson (Author) - Landcare Research, New Zealand
S Venter (Author)
J Munzinger (Author) - Laboratoire de Botanique et d’E´ cologie Ve´ge´tale Applique´es, New Calidonia
D M Crayn (Author) - James Cook University
Dorothy A Steane (Author) - University of Tasmania
K L Lemson (Author) - Edith Cowan University
Publication details: Missouri Botanical Garden. Annals, Vol.97(2), pp.235-258
Publisher: Missouri Botanical Garden
DOI: 10.3417/2008130
ISSN: 2162-4372
Organisation Unit: University of the Sunshine Coast, Queensland
Language: English
Record Identifier: 99450253402621
Output Type: Journal article