4 research outputs found
Friedmannodendron rodriguesiana, a new segregate of Dombeya Cav. (Dombeyoideae, Malvaceae), endemic to Rodrigues
No full textDIVERSIFICATION OF DOMBEYOIDEAE (MALVACEAE) IN THE MASCARENES: OLD TAXA ON YOUNG ISLANDS?
No full textPremise of research.The patterns of diversification of Mascarene taxa remain largely unknown in comparison to other insular systems. Traditional interpretations of insular radiations often assume that endemic taxa radiated after the origin of the insular habitats on which they were established. The Dombeyoideae (Malvaceae) sublineage endemic to Mauritius and Reunion in the Mascarenes is an ideal model to test for the signature of insular diversification.Methodology.We combined molecular sequences for a dense sample of Mascarene dombeyoids together with African, Malagasy, and Asian outgroup species. We estimated divergence times based on two calibration schemes (including or excluding geological calibration). Comparative phylogenetic methods were used to study the diversification rates and the evolution of the floral disparity in the Mascarene clade.Pivotal results.Excluding geological constraints resulted in drastically older age estimates than when we included such calibrations. Diversification patterns suggest a decrease of diversification rates through time. The low morphological disparity indicates an early partitioning of floral characters.Conclusions.The lineage diversification and the morphological disparity are consistent with traditional scenarios of insular radiation. However, the Mascarene clade is older than Reunion and Mauritius, suggesting the onset of radiation before the formation of the archipelago. The diversification might have been driven by geographical opportunity rather than ecological opportunity
A global plastid phylogeny of the brake fern genus Pteris (Pteridaceae) and related genera in the Pteridoideae
No full textThe brake fern genus Pteris belongs to the Pteridaceae subfamily Pteridoideae. It contains 200-250 species distributed on all continents except Antarctica, with its highest species diversity in tropical and subtropical regions. The monophyly of Pteris has long been in question because of its great morphological diversity and because of the controversial relationships of the Australian endemic monospecific genus Platyzoma. The circumscription of the Pteridoideae has likewise been uncertain. Previous studies typically had sparse sampling of Pteris species and related genera and used limited DNA sequence data. In the present study, DNA sequences of six plastid loci of 146 accessions representing 119 species of Pteris (including the type of the genus) and 18 related genera were used to infer a phylogeny using maximum-likelihood, Bayesian-inference and maximum-parsimony methods. Our major results include: (i) the previous uncertain relationships of Platyzoma were due to long-branch attraction; (ii) Afropteris, Neurocallis, Ochropteris and Platyzoma are all embedded within a well-supported Pteris sensu lato; (iii) the traditionally circumscribed Jamesonia is paraphyletic in relation to a monophyletic Eriosorus; (iv) Pteridoideae contains 15 genera: Actiniopteris, Anogramma, Austrogramme, Cerosora, Cosentinia, Eriosorus, Jamesonia, Nephopteris (no molecular data), Onychium, Pityrogramma, Pteris, Pterozonium, Syngramma, Taenitis and Tryonia; and (v) 15 well-supported clades within Pteris are identified, which differ from one another on molecular, morphological and geographical grounds, and represent 15 major evolutionary lineages. (C) The Willi Hennig Society 2014
