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Predation shapes invertebrate diversity in tropical but not temperate seagrass communities

Citation

Freestone, Amy et al. (2019), Predation shapes invertebrate diversity in tropical but not temperate seagrass communities, Dryad, Dataset, https://doi.org/10.5061/dryad.kh189321p

Abstract

1. The hypothesis that biotic interactions are stronger at lower relative to higher latitudes has a rich history, drawing from ecological and evolutionary theory. While this hypothesis suggests that stronger interactions at lower latitudes may contribute to the maintenance of contemporary patterns of diversity, there remain few standardized biogeographic comparisons of community effects of species interactions. 2. Using marine seagrasses as a focal ecosystem of conservation importance and sessile marine invertebrates as model prey, we tested the hypothesis that predation is stronger at lower latitudes and can shape contemporary patterns of prey diversity. To further advance understanding beyond prior studies, we also explored mechanisms that likely underlie a change in interaction outcomes with latitude. 3. Multiple observational and experimental approaches were employed to test for effects of predators, and the mechanisms that may underlie these effects, in seagrass ecosystems of the western Atlantic Ocean spanning 30 degrees of latitude from the temperate zone to the tropics. 4. In predator exclusion experiments conducted in a temperate and a tropical region, predation decreased sessile invertebrate abundance, richness, and diversity on both natural and standardized artificial seagrass at tropical but not temperate sites. Further, predation reduced invertebrate richness at both local and regional scales in the tropics. Additional experiments demonstrated that predation reduced invertebrate recruitment in the tropics but not the temperate zone. Finally, direct observations of predators showed higher but variable consumption rates on invertebrates at subtropical and tropical relative to temperate latitudes. 5. Together, these results demonstrate that strong predation in the tropics can have consequential impacts on prey communities through discrete effects on early life stages as well as longer-term cumulative effects on community structure and diversity. Our detailed experiments also provide some of the first data linking large-scale biogeographic patterns, community-scale interaction outcomes, and direct observation of predators in the temperate zone and tropics. Therefore, our results support the hypothesis that predation is stronger in the tropics, but also elucidate some of the causes and consequences of this variation in shaping contemporary patterns of diversity. 16-Sep-2019

Funding

National Science Foundation, Award: OCE 1225583 to AF, OCE 1434528 to AF, GR and MT, and DEB 1257916 to BS and AF

National Science Foundation

National Science Foundation, Award: OCE 1434528 to AF, GR and MT

National Science Foundation

National Science Foundation, Award: DEB 1257916 to BS and AF