Straddling the Mozambique Channel: molecular evidence for two major clades of Afro-Malagasy Schefflera (Araliaceae) co-occurring in Africa and Madagascar
Methods – Using sequence data from nuclear rDNA and chloroplast spacers derived from 33 of the 49 currently circumscribed species of Afro-Malagasy Schefflera, this study tested the group's monophyly and that of its two informal subgroups. We utilized alternative partitioning schemes to explore the combinability of datasets from the distinct genomic regions sampled.
Key results – Our results support the monophyly of Afro-Malagasy Schefflera and its two informal subgroups, 'Meiopanax' and 'Sciodaphyllum'. Each of these subgroups include species from both continental Africa and Madagascar, although species diversity in 'Meiopanax' is heavily based in Madagascar. In 'Sciodaphyllum', species diversity is much greater in continental Africa, despite evidence for more widespread dispersal events that have led to subsequent speciation in both Madagascar and the Seychelles Islands. Among several species that appear to be non-monophyletic, S. myriantha stands out as particularly problematic. This species, which shows very little morphological variation across its wide distribution in Africa and Madagascar, forms two subclades, one restricted to Africa, and another from Madagascar that also includes two additional, morphologically distinctive species.
Conclusions – This study makes an important contribution towards the circumscription of one of the five clades currently treated as Schefflera s. lat. and is the most inclusive systematic study of Afro-Malagasy Schefflera to date. Our results support the monophyly of both informal groups 'Meiopanax' and 'Sciodaphyllum', which we propose to recognize as two separate genera, Neocussonia and Astropanax, respectively.
Document Type: Regular Paper
Publication date: 2017-04-01
Plant Ecology and Evolution (a continuation of Belgian Journal of Botany, incorporating Systematics and Geography of Plants) is an international journal devoted to ecology, phylogenetics and systematics of all 'plant' groups in the traditional sense (including algae, cyanobacteria, fungi, myxomycetes), also covering related fields such as comparative and developmental morphology, conservation biology, ecophysiology, evolution, phytogeography, pollen and spores, population biology, and vegetation studies. It is published by the Royal Botanical Society of Belgium and the Botanic Garden Meise and contains original research papers, review articles, checklists, short communications and book reviews.
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