title: Testing reticulate versus coalescent origins of Erica lusitanica using a species phylogeny of the northern heathers (Ericeae, Ericaceae).
abstract: Whilst most of the immense species richness of heathers (Calluna, Daboecia and Erica: Ericeae; Ericaceae) is endemic to Africa, particularly the Cape Floristic Region, the oldest lineages are found in the Northern Hemisphere. We present phylogenetic hypotheses for the major clades of Ericeae represented by multiple accessions of all northern Erica species and placeholder taxa for the large nested African/Madagascan clade. We identified consistent, strongly supported conflict between gene trees inferred from ITS and chloroplast DNA sequences with regard to the position of Erica lusitanica. We used coalescent simulations to test whether this conflict could be explained by coalescent stochasticity, as opposed to reticulation (e.g. hybridisation), given estimates of clade ages, generation time and effective population sizes (Ne). A standard approach, comparing overall differences between real and simulated trees, could not clearly reject coalescence. However, additional simulations showed that at the (higher) Ne necessary to explain conflict in E. lusitanica, further topological conflict would also be expected. Ancient hybridisation between ancestors of northern species is therefore a plausible scenario to explain the origin of E. lusitanica, and its morphological similarities to E. arborea. Assuming either process influences the results of species tree and further evolutionary inference. The coalescence scenario is equivocal with regard the standing hypothesis of stepping stone dispersal of Erica from Europe into Africa; whereas reticulate evolution in E. lusitanica would imply that the colonisation of Tropical East Africa by E. arborea instead occurred independently of dispersals within the rest of the African/Madagascan clade.
authors.affiliation: INRES Pflanzenzüchtung, Rheinische Friedrich-Wilhelms-Universität Bonn, Katzenburgweg 5, 53115 Bonn, Germany.
authors.forename: A L
authors.initials: AL
authors.lastname: Mugrabi de Kuppler
authors.affiliation: Department of Plant and Animal Biology and Ecology, University of A Coruña, Faculty of Science, 15001 A Coruña, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Fagúndez
authors.affiliation: Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
authors.forename: D U
authors.initials: DU
authors.lastname: Bellstedt
authors.affiliation: Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
authors.forename: E G H
authors.initials: EG
authors.lastname: Oliver
authors.affiliation: INRES Pflanzenzüchtung, Rheinische Friedrich-Wilhelms-Universität Bonn, Katzenburgweg 5, 53115 Bonn, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Léon
authors.affiliation: Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa; Institut für Spezielle Botanik und Botanischer Garten, Johannes Gutenberg-Universität, Anselm-Franz-von-Bentzelweg 9a, 55099 Mainz, Germany. Electronic address: pirie@uni-mainz.de.
authors.forename: M D
authors.initials: MD
authors.lastname: Pirie
mesh_terms: D000349:Africa; D000351:Africa, Eastern; D005075:Biological Evolution; D018742:DNA, Chloroplast / Q000737:chemistry; D029791:Ericaceae / Q000145:classification* / Q000235:genetics; D005060:Europe; D006824:Hybridization, Genetic; D010802:Phylogeny; D058974:Phylogeography; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast
keywords: Calluna; Coalescent stochasticity; Daboecia; Erica; Hybridisation; Reticulate evolution