Biogeography of the Malagasy Celastraceae: Multiple independent origins followed by widespread dispersal of genera from Madagascar

Abstract

Of the 97 currently recognized genera of Celastraceae, 19 are native to Madagascar, including six endemics. In this study we conducted the most thorough phylogenetic analysis of Celastraceae yet completed with respect to both character and taxon sampling, and include representatives of five new endemic genera. Fifty-one new accessions, together with 328 previously used accessions of Celastrales, were sampled for morphological characters, two rDNA gene regions, and two plastid gene regions. The endemic Malagasy genera are resolved in two separate lineages-Xenodrys by itself and all other endemic genera in a clade that also includes four lineages inferred to have dispersed from Madagascar: Brexia madagascariensis (Mascarene Islands, coastal Africa), Elaeodendron (West Indies, Africa to New Caledonia), and Pleurostylia (Africa to New Caledonia). Of the 12 extant Malagasy Celastraceae lineages identified, eight are clearly of African origin. The origins of the remaining four lineages are less clear, but reasonable possibilities include America, Eurasia, Africa, southern India, Malesia, and Australia. Based on 95% credible age intervals from fossil-calibrated molecular dating, all 12 extant Malagasy Celastraceae lineages appear to have arisen following dispersal after the separation of Madagascar from other landmasses within the last 70 million years.

Madagascar sheds new light on the molecular systematics and biogeography of grammitid ferns: New unexpected lineages and numerous long-distance dispersal events

“…In all other cases, the origin of dispersal within the region appeared to be either Madagascar or the other WIO islands. Therefore, Africa does not seem to be a source region for grammitid species in the WIO, contrary to what could be expected based on the Theory of Island Biogeography (MacArthur and Wilson, 1967) and empirical evidence for most of the angiosperms studied (Bacon et al, 2016;Buerki et al, 2013;Janssens et al, 2016;Yoder and Nowak, 2006). Actually, there is a growing body of evidence against the paradigm postulating that continents and islands respectively act as sources and sinks of species diversity (Heaney, 2007), and an increasing awareness of the importance of islands as cradles of diversity themselves: it has been documented for the WIO islands (Agnarsson and Kuntner, 2012;Krüger et al, 2012) and for the Macaronesian islands (Patiño et al, 2015).…”

“…15 Ma (Emerick and Duncan, 1982;Nougier et al, 1986) and 8 Ma (McDougall and Chamalaun, 1969). Whereas some studies underlined the impact of continental drift on the distribution of species occurring in Madagascar, others have more recently emphasized a greater role of LDD during the Cenozoic period (Agnarsson and Kuntner, 2012;Bacon et al, 2016;Buerki et al, 2013;Renner et al, 2010;Warren et al, 2010;Yoder and Nowak, 2006). At least, the role of dispersal is undisputable in the origin of lineages on the recent volcanic islands surrounding Madagascar.…”

Island hopping, long‐distance dispersal and species radiation in the Western Indian Ocean: historical biogeography of the Coffeeae alliance (Rubiaceae)

“…Micheneau et al ., ; Le Péchon et al ., ; Strijk et al ., ; Stride et al ., ). We also find evidence for back‐colonization from Madagascar to mainland Africa, a biogeographical pattern previously reported in plant families such as Gentianaceae (Yuan et al ., ) and Celastraceae (Bacon et al ., ). Specifically, at least three independent dispersal events to eastern Africa was inferred in Coptosperma (possibly also in Coffea and Tricalysia ).…”

Phylogeographic and phylogenetic analysis for Tripterygium species delimitation

“…Fossils of Tripterygium kabutoiwanum were collected from the Japanese island, which dates to 5.332–11.608 Ma (http://fossilworks.org/bridge.pl?a=taxonInfo&taxon_name=Tripterygium). To calibrate the cpDNA substitution rate, the 27 Ma (Bacon, Simmons, Archer, Zhao, & Andriantiana, ) for the split between Celastrus and Tripterygium is set to Normal, and the 5.46–11.6 Ma for the split within Tripterygium is set to Log Normal. The Yule speciation hypothesis and uncorrelated relaxed lognormal molecular clock model were tested in Beast.…”