Molecular confirmation of natural hybridisation between Melastoma sanguineum and M. malabathricum (Melastomataceae)

Abstract

The genus Melastoma (Melastomataceae) is known to have undergone rapid species radiation, and natural hybridisation has been observed to happen whenever two or more species co-occur. Many cases of natural hybridisation have been confirmed between Melastoma species in China, but only a few cases have been confirmed in Southeast Asia, which is where the majority of the diversity of the genus occurs, although hybrids have been suspected based on morphological intermediacy. Recently in Peninsular Malaysia, we observed co-occurring populations of Melastoma sanguineum Sims and M. malabathricum L., two of the most widely distributed species of Melastoma L. Many individuals with intermediate morphologies were also at the site. In this study, we used DNA sequence data of three partial nuclear genes and one chloroplast locus to determine the identity of the intermediate individuals. We found that the chloroplast haplotypes could be grouped by similarity to clusters corresponding to the two species, and the same individuals shared nuclear alleles from both clusters. Our findings revealed that, (1) the morphologically intermediate individuals are indeed hybrids of Melastoma sanguineum and M. malabathricum; (2) both F1 hybrids and further hybrid generations are present; (3) both species can act as pollen donor.