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Latebreaking Poster

Session: Mutualism And Facilitation (Latebreaking)

LB 29-248 - Generalists Increase the Resilience of Host-Mutualist Systems to Habitat Destruction

Thursday, August 10, 2023
5:00 PM – 6:30 PM PDT
Location: ESA Exhibit Hall
Habitat destruction is one of the leading causes of biodiversity loss and ecosystem collapse. Habitat destruction, like the clear-cutting of forested ecosystems, impacts both the focal species and any species that rely on these host organisms, including mutualist partners. We developed a multispecies mutualism metapopulation model to better understand the impacts of habitat destruction on host and mutualist systems. Our model considers a variety of patches inhabited by combinations of mutualists and hosts, including two mutualist species, two specialist tree hosts and one generalist tree host. The specialist hosts can only grow on patches currently occupied by their corresponding specialist mutualist, while generalist hosts can partner with either mutualist type. The proportions of each patch type shift over time due to the reproductive dynamics and colonization rules of both hosts and mutualists. We modeled habitat destruction by rendering a proportion of patches uninhabitable. We tested the impact of the proportion of uninhabitable patches on the community composition given different host-mutualist scenarios. Our model demonstrates the importance of complex habitat in supporting higher species diversity. The generalist host can only persist in the presence of both mutualists. Furthermore, when both mutualists and all hosts are present, increasing the amount of uninhabitable patches promotes the generalist, and eventually leads to the extinction of the specialist hosts before the generalist host. As uninhabitable patches increase further, the model demonstrates complete, abrupt ecosystem collapse from 40% occupation to 0%. This result has significant implications for conservation, as such catastrophic collapses may be hard to predict in host-mutualist systems. Furthermore, the model results reveal the importance of generalists in supporting resilience to habitat destruction in a host-mutualist ecosystem. The complete system, with both specialist hosts and a generalist host, can withstand more than double the habitat loss of a system without a generalist host prior to collapse. Thus generalists, though they may not be the focal species of conservation goals, may support other specialist species by sustaining a mutualist network and preventing or delaying ecosystem collapse.