Isaac Towers is a PhD candidate at the University of Queensland under the supervision of Dr. John Dwyer and Prof. Margaret Mayfield. The main focus of his research is attempting to understand how biodiversity is maintained in hyperdiverse ecosystems such as the annual plant understorey of the York Gum – Jam woodlands in southwest Western Australia.
One of the persistent challenges in community ecology is attempting to understand how diversity is maintained in hyperdiverse ecosystems. Local-scale variation in the abiotic environment has been hypothesised as a possible means for species to coexist because the traits that confer a given species a fitness advantage in one microsite may be less favourable in another. Despite spatial variation in the environment being a common feature of many natural ecosystems, however, this hypothesis has been rarely tested. Using the diverse annual understorey of the York Gum – Jam woodlands in southwest Western Australia as a model system, Isaac aims to improve our understanding of how spatial variation in the environment promotes species diversity.
This will be conducted across three chapters:
- Isaac conducted a thinning experiment in natural assemblages of the wildflower understorey to test, firstly, whether species trade-off in their performance (i.e, their seed production) across spatial gradients in the environment and secondly, whether species tend to experience more intense competition in the microsites where they perform best. Together, these conditions provide evidence that species may coexist in this system due to a mechanism known as “the spatial storage effect”.
- Isaac conducted a germination assay in collaboration with the Botanic Gardens and Parks Authority, Western Australia to test a wide range of species’ light requirements for germination. Germination strategy has important consequences for species’ performance post-germination and can promote coexistence if it causes species to exhibit variable responses across heterogeneous landscapes.
- Isaac sowed focal species across a broad range of environmental conditions with the aim of testing species’ response to the abiotic environment not just for fecundity but across multiple life stages (i.e. survival in the seed bank, germination, post-germination survival and fecundity). In order to mechanistically explain how species’ respond to their local environment, he will use a trait-based approach to predict the magnitude and direction of species’ response curves with functional traits. The ESA Wiley – Blackwell Fundamental Ecology Award will allow him to conduct a wider range of trait assays which will more fully capture the diversity of species’ functional strategies in this system.