Landscape connectivity and keystone frugivores: implications for the population genetics and life-history of the rare rainforest tree species Ryparosa kurrangii - PhD Completion Seminar
Tropical rainforests, the most structurally complex and bio-diverse terrestrial biome, are overwhelmingly reliant upon frugivorous animals as seed-dispersal vectors. The largest frugivores in tropical forests play a disproportionately important role as dispersers, being able to process large quantities of seed, transport them over long distances, and swallow the largest seed sizes. Unfortunately, large animal species are also often the most sensitive to anthropogenic disturbances. The impact of changes in large frugivore abundance on tropical plant communities remains understudied. My thesis explored the population dynamics of a rare tropical tree, Ryparosa kurrangii B. L. Webber. A large seeded species, R. kurrangii is inferred to be sensitive to disperser limitation due to its need for large frugivores to ingest and distribute its seed. The only extant candidate long-distance disperser in North Queensland is the threatened Southern Cassowary. My research investigated the drivers of life-history processes in R. kurrangii populations across a gradient of human induced disturbance; with an objective to pull apart anthropogenic signals from the natural background processes that drive tropical plant community structure. To do this, I surveyed three R. kurrangii populations to calculate growth-rates, maximum lifespan, and demographic dynamics for the species. I conducted spatial analyses on the distributions of trees across their ontogenetic phases, identifying the spatial drivers to variation in reproductive activity, mortality and growth. I conducted a PIR camera-trapping program, finding stark contrasts in faunal visitation rates between rainforest catchments. Finally, I conducted population genetic studies; discovering evidence of historical inbreeding and fine-scale genetic structuring in all three study populations. The findings of my work highlight the importance of maintaining viable community processes in the conservation of tropical forests.
Supervised by Ian Woodrow and Bruce Webber