Pollination ecology and evolution of Epacrids

Relationships between plants and their pollinators are thought to have played a major role in the morphological diversification of angiosperms. The epacrids (subfamily Styphelioideae) comprise more than 550 species of woody plants ranging from small prostrate shrubs to temperate rainforest emergents. Their range extends from SE Asia through Oceania to Tierra del Fuego with their highest diversity in Australia. The overall aim of the thesis is to determine the relationships between epacrid floral features and potential pollinators, and assess the evolutionary status of any pollination syndromes. The main hypotheses were that flower characteristics relate to pollinators in predictable ways; and that there is convergent evolution in the development of pollination syndromes. Four case-studies obtained information on specific epacrid-pollinator relationships using a combination of field observation, breeding systems experiments, and comparative phylogenetics. A further study develops a molecular phylogeny for the 38 recognised genera of the epacrids, and the final study places the ecological pollination research into this evolutionary context. Epacrid floral traits were related to bird, bee, and fly pollination systems. Bird pollination occurs in the most basal tribe, but insect pollination is also predicted for this tribe. Fly and bee pollination are widely supported by epacrid flowers, while red flowers and long floral tubes are the most important predictors for those visited by birds. Insect pollination is widespread across the evolutionary tree, but bird pollination coincides largely with the convergent evolution of red flowers. Purple, green, yellow, and nectarless flowers are distributed across the tree, also consistent with a hypothesis of convergent evolution. Nectarless flowers tend to be associated with wind or buzz pollination. Nocturnal mammals and lizards forage on epacrids but their role in pollination remains uncertain. Overall, the data suggest that pollinators have played a major role in the morphological diversification of the epacrids.