West to east dispersal and subsequent rapid diversification of the mega‐diverse genus Begonia (Begoniaceae) in the Malesian archipelago
Aim The complex palaeogeography of the Malesian archipelago, characterized by the evolution of an ever‐changing mosaic of terrestrial and marine areas throughout the Cenozoic, provides the geographic backdrop for
the remarkable diversification of Malesian Begonia (> 450 species). This study aimed to investigate the origin of Malesian Begonia, the directionality of dispersal events within the Malesian archipelago and the impact of ancient water gaps on colonization patterns, and
to identify drivers of diversification.
Location Asia, Southeast Asia, Malesia.
Methods Plastid DNA sequence data of representatives of all families of the Cucurbitales and Fagales (matK, rbcL, trnL intron, trnL–F spacer, 4076
aligned positions, 92 taxa) and a sample of all major Asian Begonia sections (ndhA intron, ndhF–rpl32 spacer, rpl32–trnL spacer, 4059 aligned positions, 112 taxa) were analysed under an uncorrelated‐rates relaxed molecular clock
model to estimate the age of the Begonia crown group divergence and divergence ages within Asian Begonia. Ancestral areas were reconstructed using a likelihood approach implementing a dispersal–extinction–cladogenesis model, and with a Bayesian approach to dispersal–vicariance
Results The results indicated an initial diversification of Asian Begonia in continental Asia in the Miocene, and subsequent colonization of Malesia by multiple lineages. There was support for at least six independent dispersal events from continental Asia
and western Malesia to Wallacea dating from the late Miocene to the Pleistocene. Begonia section Petermannia (> 270 species) originated in Western Malesia, and subsequently dispersed to Wallacea, New Guinea and the Philippines. Lineages within this section diversified
rapidly since the Pliocene, coinciding with rapid orogenesis on Sulawesi and New Guinea.
Main conclusions The predominant trend of Begonia dispersals between continental Asia and Malesia, and also within Malesia, has been from west to east. The water bodies separating
the Sunda Shelf region from Wallacea have been porous barriers to dispersal in Begonia following the emergence of substantial land in eastern Malesia from the late Miocene onwards. We hypothesize two major drivers of the diversification of Malesian Begonia: (1) the formation
of topographical heterogeneity and the promotion of microallopatry by orogenesis in the Pliocene and Pleistocene; and (2) cyclic vicariance by frequent habitat fragmentations and amalgamations due to climate and sea‐level fluctuations during the Pleistocene.
Document Type: Research Article
Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, UK
Herbarium, Princess Maha Chakri Sirindhorn Natural History Museum & Centre for Biodiversity of Peninsular Thailand (CBiPT), Department of Biology, Prince of Songkla University, Hat Yai, Songkhla, Thailand 90112
Bogor Botanic Gardens, Jl. Ir. H. Juanda No. 13, Bogor 16003, Indonesia
Central Department of Botany, Tribhuvan University, Kirtipur, Kathmandu, Nepal
Department of Biology, College of Arts and Sciences, University of the Philippines Manila, Padre Faura, Manila, Philippines
Publication date: January 1, 2012