Pollination, Mating System, Phenology and Characterisation of Medinilla multiflora Merr. (Melastomataceae) on Mt Makiling, Philippines

Abstract

An investigation into the reproductive biology of Medinilla multiflora Merr. (Melastomataceae) from Mt Makiling, Luzon, is presented. This includes a morphological and distributional examination of the population on the mountain, the documentation of reproductive phenological patterns, a study of the mating system and observations of biotic interactions. Measurements were made of trait variability, reproductive phenology was characterised from field and herbarium observations, stigmatic receptivity was tested by counting pollen germination, insect exclusion and hand-pollination experiments helped determine the mating system and field observations recorded the identity and behaviour of floral visitors. Significant reproductive morphological differences were found between described populations. This identified a need for the recognition of this diversity and further delimitation of the Medinilla multiflora species complex. Although Medinilla multiflora produced flowers and fruit year-round, the population also exhibited cycles of increased reproduction most likely initiated by seasonal low temperatures. Medinilla multiflora was found to require pollination but not cross-pollination. Two major peaks in stigmatic receptivity occurred throughout the day and the majority of pollen was found to be viable. Generalist bees proved to be the primary pollinators of the study population and were most active in the morning depending on weather conditions. Generalist pollinators and self-compatibility are advantageous traits for establishment and persistence in isolated mountain habitats; however, losses of this habitat due to climate change could have profound consequences for the future success of Medinilla multiflora.