Differing phylogeographic patterns within the Indo‐West Pacific mangrove genus Xylocarpus (Meliaceae)

Abstract

Aim The genus Xylocarpus contains two mangrove species, X. granatum and X. moluccensis, and a rare non‐mangrove, X. rumphii. The two mangrove species are ideal models to study the biogeography of coastal plants with a unique dispersal ability, that is via buoyant propagules. We constructed the phylogeny of Xylocarpus and its relatives and determined the population structures of the two mangrove species. We aimed to elucidate the roles of continental drift and long‐distance dispersal (LDD) in shaping the present‐day distribution of Xylocarpus and to determine the factors affecting the patterns of population differentiation. Location The Indo‐West Pacific (IWP) region. Methods Thirty populations of X. granatum, 15 of X. moluccensis and four of X. rumphii were sampled across the IWP region. Five chloroplast DNA intergenic spacers were sequenced for Xylocarpus and outgroup species to determine divergence times. The genetic diversity, divergence and structure of the two mangrove species were further analysed using five nuclear and two chloroplast DNA loci. Migrations between oceanic regions were estimated. Results The genus Xylocarpus diverged from its sister genus Carapa approximately 19.4 Ma. The populations of X. granatum differentiated into three groups, with genetic breaks present across the Malay Peninsula and Wallacea, whereas X. moluccensis populations differentiated into two groups, with a genetic break present only across the Malay Peninsula. Migration was also observed between populations of the Southeast Asian and Australasian regions in X. moluccensis but not in X. granatum. Main conclusion Since Xylocarpus originated after the breakup of Gondwana and subsequent plate motions, its current distribution range should have been facilitated by present‐day LDD instead of past continental drift. Despite the capacity of LDD, the presence of differing population structures across land barriers (the Sunda and Sahul Shelves) and ocean currents indicated differential limitations in the dispersal capabilities of X. granatum and X. moluccensis.

Biogeography and ecology in a pantropical family, the Meliaceae

“…The following seven genera form a clade (Koenen et al, 2015;Muellner-Riehl et al, 2016;Guo et al, 2018). The first three break off from the others in sequence: India -Madagascar -Africa, although the statistical support here was not strong.…”

“…Muellner-Riehl et al (2016) presented a phylogeny mainly similar to that of Koenen et al (2015), but with a clade: (Khaya of Africa + Swietenia of America) (Carapa + Xylocarpus). Guo et al (2018) proposed the arrangement used here: Khaya (Swietenia (Carapa + Xylocarpus)).…”

Contrasting colonization patterns of black mangrove (Avicennia germinans (L.) L.) gene pools along the Mexican coasts

“…Such post‐glacial recolonization resulted in genetic signatures that vary among taxa due to life history differences, local geography (Hewitt, ), and tolerance to the environmental conditions in the colonized areas (Davis & Shaw, ). Classic comparative phylogeographical studies address such differences by surveying patterns among co‐distributed taxa, although they often struggle to disentangle individual drivers of population structure (Carstens, Brunsfeld, Demboski, Good, & Sullivan, ; Carstens & Richards, ; Cerón‐Souza et al., ; Fouquet et al., ; Guo, Guo, et al., ; Maliouchenko, Palmé, Buonamici, Vendramin, & Lascoux, ; Marske, Leschen, & Buckley, ).…”

Testing Darwin's transoceanic dispersal hypothesis for the inland nettle family (Urticaceae)

“…; Guo et al . ), forcing the scientific community to accept other explanations for disjunctions, leading to increasing acceptance of the role of LDD in shaping the present distributions of organisms (Raxworthy et al . ; Pyron ; Rota et al .…”

“…The advent of molecular dating, however, repeatedly revealed cases of transoceanic disjunctions that were too young to result from tectonic vicariance (Popp et al 2011;Bourguignon et al 2018;Guo et al 2018), forcing the scientific community to accept other explanations for disjunctions, leading to increasing acceptance of the role of LDD in shaping the present distributions of organisms (Raxworthy et al 2002;Pyron 2014;Rota et al 2016;Carlton et al 2017;Luebert et al 2017).…”