Giant taro and its relatives: A phylogeny of the large genus Alocasia (Araceae) sheds light on Miocene floristic exchange in the Malesian region

Abstract

Alocasia comprises over 113 species of rainforest understorey plants in Southeast Asia, the Malesian region, and Australia. Several species, including giant taro, Alocasia macrorrhizos, and Chinese taro, Alocasia cucullata, are important food plants or ornamentals. We investigated the biogeography of this genus using plastid and nuclear DNA sequences (5200 nucleotides) from 78 accessions representing 71 species, plus 25 species representing 16 genera of the Pistia clade to which Alocasia belongs. Divergence times were inferred under strict and relaxed clock models, and ancestral areas with Bayesian and maximum likelihood approaches. Alocasia is monophyletic and sister to Colocasiagigantea from the SE Asian mainland, whereas the type species of Colocasia groups with Steudnera and Remusatia, requiring taxonomic realignments. Nuclear and plastid trees show topological conflict, with the nuclear tree reflecting morphological similarities, the plastid tree species' geographic proximity, suggesting chloroplast capture. The ancestor of Alocasia diverged from its mainland sister group c. 24 million years ago, and Borneo then played a central role in the expansion of Alocasia: 11-13 of 18-19 inferred dispersal events originated on Borneo. The Philippines were reached from Borneo 4-5 times in the Late Miocene and Early Pliocene, and the Asian mainland 6-7 times in the Pliocene. Domesticated giant taro originated on the Philippines, Chinese taro on the Asian mainland.

Morphological and molecular data reveal a new species of Alocasia (Araceae) from Vietnam

“…In both analyses, the order of the genera and species are in agreement with those in the previous studies [12][13][14][15][16].…”

“…very numerous) found in those of Colocasia [3-5, 9, 11]. Due to the morphological divergence of A. rivularis, we have used molecular data to ascertain its phylogenetic relationship to known species of Alocasia, especially those of the Cuprea Group, and other genera of the tribe Colocasieae, applying the methods employed similarly in previous phylogenetic studies of the Araceae [12][13][14][15][16].…”

Out of Borneo: biogeography, phylogeny and divergence date estimates ofArtocarpus(Moraceae)

“…While the barrier to crossing Wallace's line has proved to be a hindrance for the dispersal in many faunal groups, it is less so among plants (Van Welzen et al, 2011). Other examples of an inferred origin of flora in Borneo and subsequent dispersal across Wallace's line during the Miocene include Rhododendronsection Vireya (Ericaceae) (Brown et al, 2006;Webb and Ree, 2012), Alocasia (Araceae) (Nauheimer et al, 2012) and Begonia (Thomas et al, 2012). Finally, the dispersal of two taxa native to the Western Ghats of India may be the result of overland or overwater dispersal.…”

“…Within Southeast Asia, certain regions may have higher rates of endemism and diversification. For example, de Bruyn et al (2014) recently identified Borneo and Indochina as 'evolutionary hotspots' in a phylogenetic meta-analysis of both flora and fauna, and several studies cite Borneo as the centre of diversification for multiple taxa (Nauheimer et al, 2012;Webb and Ree, 2012).…”

Andean Mountain Building Did not Preclude Dispersal of Lowland Epiphytic Orchids in the Neotropics

“…The potential of dust-like seeds for rare longer distance dispersals by wind might be greater compared with other plants with propagules locally dispersed by animals (e.g. Araceae 39 ). Indeed, detailed studies on epiphyte orchid seed dispersal and gene flow provide evidence for the rarely long distance exchange of orchid propagules between geographical areas 40–42 .…”