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Ericaceae: Systematics, Ecology and Evolution

Puente-Lelievre, Caroline [1], Crayn, Darren [2], Freyman, Will [3], Potter, Benjamin [4].

Historical Biogeography of the Australasian Ericaceae: Evaluating Competing Vicariance and Dispersal Scenarios.

The subfamily Epacridoideae, Ericaceae (commonly known as the epacrids) comprises 37 genera and ca. 640 species. This clade includes mostly perennial woody shrubs that occur in heathlands, sandplains, and tropical forests. Their distribution is mostly restricted to Gondwanan fragments (Australia, New Zealand, New Caledonia, and South America) with outliers in SE Asia and Hawaii. The epacrids are however most diverse in South-Western (WA) and South-Eastern Australia (EA). The Epacridoideae also typify many of the controversies in the historical biogeography of Australasia and the contributions of long distance dispersal versus Gondwanan vicariance. Such hypotheses can be tested with molecular dating and ancestral area reconstruction analyses. While a vicariance scenario predicts patterns of near-simultaneous divergences in multiple lineages, long-distance dispersal predicts independent, asynchronous divergences. We present the most densely sampled phylogeny to date that includes representatives from all genera and ca. 65% of the species in the Epacridoideae. Based on a 5-gene dataset (the nuclear ribosomal ITS region, and the chloroplast regions rbcL, matK, psbA-trnH, atpB-rbcL) we estimated the phylogenetic relationships and tempo of evolution within the subfamily with a focus on the relationships within the Australian clades, and their relationships with the New Zealand and New Caledonian clades. Furthermore, we used the resulting phylogeny to evaluate multiple calibration schemes, molecular clock models, and speciation priors, and estimated the ages of the disjunctions between these clades. We tested hypotheses of long distance dispersal versus Gondwanan vicariance using stochastic mapping of the dispersal-extinction-cladogensis (DEC) model of biogeographic range evolution. Our results under different schemes consistently suggest that the multiple disjunctions between the Australian, New Zealand, and New Caledonian clades are independent events and not older than ca. 10 Ma. They also indicate that the WA and EA clades diverged approximately over the same period of time during the Miocene (10 – 20 Ma), after the emergence of the Nullarbor Plain. We conclude that the current distributional patterns of the epacrids can be explained by both vicariance and long-distance dispersal events.


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1 - US Food and Drug Administration, 5001 Campus Drive, College Park, MD, 20740, USA
2 - Australian Tropical Herbarium, Sir Robert Norman (E2) Building, Po Box 6811, Cairns, QLD, QLD, 4870, Australia
3 - University of Minnesota, Department of Ecology, Evolution and Behaviour, 1479 Gortner Ave, Suite 140 , St Paul, MN, 55108, USA
4 - University of Auckland, School of Biological Sciences, 3a Symonds Street, Auckland, 1010, NZ

Keywords:
Ericaceae
Biogeography
Australasia
Epacridoideae.

Presentation Type: Colloquium Presentations
Session: C07b, Ericaceae: Systematics, Ecology, and Evolution Part 2
Location: 114/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 2:30 PM
Number: C07b005
Abstract ID:270
Candidate for Awards:None


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