TItle: [PhD Thesis Public Presentation_Zoom] - Yuka Suzuki - The effects of dispersal network structure on biodiversity pattern and stability in metacommunities.
Presenter: Yuka Suzuki
Supervisor: Professor Evan P Economo
Unit: Biodiversity and Biocomplexity Unit
Title: The effects of dispersal network structure on biodiversity pattern and stability in metacommunities.
Biodiversity patterns in nature are often heterogeneous across space. Individual organisms can be influenced by spatial constraints via dispersal processes and interactions with the environment, and thus connectivity among patches is a key aspect of spatial structure that can influence the community processes controlling biodiversity patterns. Although the connectivity concept has fostered a large body of theory, many theoretical results are derived assuming simplified spatial structures, which are often not capturing the complexity of natural systems. Network metacommunity models, where patches are connected in potentially heterogeneous ways, can be used to build a theoretical basis for how different landscape and seascape structures may affect metacommunity dynamics. Likewise, recent technical advances permit a better estimation of connectivity in natural systems, such as networks of coral reefs or hydrothermal vents. To fill the knowledge gap about the role of space in ecology, this thesis investigates how the spatial structure drives metacommunity dynamics and biodiversity patterns and stability of metacommunities by utilizing computer simulations and marine connectivity data. In particular, I analyze the two aspects of metacommunity systems: biodiversity assembly and stability, both of which can contribute to biodiversity patterns. First, I examine the role of spatial topology (i.e. the pattern of dispersal linkages among patches) in the interplay between different metacommunity processes, including species sorting and mass effects. I find that network topology strongly mediates the balance of different dynamics in ways that are not captured by simplified spatial models that form the basis of metacommunity theory. Second, I examine the contribution of different aspects of spatial structure to metacommunity stability and find that the size of the network, rather than topology, is the dominant factor driving stability on the metacommunity level. Third, I combine these two simulation analyses with empirical marine connectivity networks and provide a better understanding of spatial processes applicable to natural systems. Overall, these analyses dissect the complexity in connectivity and reveal key aspects of connectivity in regulating biodiversity and stability. This study provides a better understanding of spatial processes and specifically reveals how and which spatial features control biodiversity patterns and metacommunity stability, contributing to a metacommunity theory that can ultimately inform conservation planning.