COS 27-4 - Warming and Dispersal Rate in Marine Food Webs Lead to Heterogeneous Biodiversity Effects

Abstract: Biological theories often predict that warming will lead to biodiversity decline, and maintaining spatial connectivity is essential in halting or minimizing this decline by facilitating dispersal and adaptive range shift. However, it is unclear how dispersal in complex communities with trophic interactions organized by body size mediate marine biodiversity changes. Using a simulation model containing a spatial temperature gradient and parameterized by allometric and metabolic relationships, we show that dispersal and warming lead to heterogeneous biodiversity outcomes. A decrease in dispersal rate among heterotrophs (eg. fish) through lost connectivity increases global richness, dissimilarity across space, and mean body size in a constant environment. However, under warming, lost connectivity leads to a higher loss in global richness and higher decrease in body size and trophic level. Net biodiversity outcomes depend on the relative magnitudes of these contrasting effects. These result reconcile opposing predictions from spatial coexistence theory and single-species dynamics, with the former focussing on a static environment and the latter focussing on a changing environment. Additionally, food web dynamics produce predictions consequential to ecosystem services beyond simple biodiversity metrics.