Abstract:

Connectivity plays a vital role in many ecosystems through its effects on fundamental ecological and evolutionary processes. Its consequences for populations and metapopulations have been well-documented, but the influence of connectivity on animal communities is less well understood. Landscape ecology has recently seen the revival of a long-standing debate about the importance of habitat amount (composition) vs arrangement (configuration) for community composition. One of the central challenges in resolving this debate is that of selecting and measuring a scale of analysis, given that different species may move over a wide range of different scales.
After introducing some core ideas about connectivity and network analysis, I will propose a new measure of patch connectivity, cross-scale centrality, which identifies the patches that most consistently contribute to landscape connectivity across multiple different scales. Results from a metapopulation simulation model support my claims of ecological relevance. I then turn to a real-world case study of the fish communities using coral reefs in the Great Barrier Reef Marine Park. Cross-scale connectivity and other regional influences can explain a significant amount of the variance in fish community composition across the AIMS long-term sampling sites. The analysis also supports the hypothesis that the GBRMPA management zones make a difference to fish communities. The findings suggest a potentially important role for management of the GBR to facilitate connectivity between reefs, and highlight the need to carefully prioritise the spatial location of ongoing restoration efforts if they are to be successful.

Bio:

Graeme grew up in Harare, Zimbabwe, and studied in South Africa and England. Following a postdoc in Madison, Wisconsin, he held a position at the University of Florida before returning to South Africa in 2006 to take up the position of Pola Pasvolsky Chair in Conservation Biology at the University of Cape Town. He started at the CoE in 2015 and has been the Director since mid-2020. Graeme is a landscape ecologist and conservation theorist with a wide range of research interests that revolve around understanding spatial pattern-process-structure dynamics in natural resource management.