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Description

Understanding how variability shapes ecological dynamics requires disentangling the distinct roles of temporal forcing and spatial structure. In this talk, I present two complementary population modeling frameworks that separately investigate these effects in a complex food web.

First, I examine a temporally variable model in which empirical phytoplankton abundance is used as an external driver of variability. Fluctuations in this basal resource propagate through the trophic network, generating time-dependent responses across species. This approach reveals that temporal variability can expose species-specific vulnerabilities, identifying at-risk species whose persistence is sensitive to fluctuations in primary productivity.

Second, I introduce a spatially coupled model in which local food webs are linked through dispersal. Here, spatial structure is incorporated via connectivity among sites, allowing biomass exchange across the landscape. In contrast to the temporally forced system, dispersal acts as a stabilizing mechanism, enhancing species persistence and increasing overall community abundance by enabling spatial subsidy among locations.

Taken together, these results highlight fundamentally different roles for temporal and spatial variability: temporal forcing can amplify extinction risk, while spatial coupling can buffer against it. This work emphasizes the need to consider these processes both independently and in tandem when predicting community responses to environmental change.

*** This is Casey's GGAM PhD Exit Seminar. ***