What factors may facilitate or inhibit species range changes due to climate change and what are the consequences of altered composition?
Factors influencing large-scale species distributions are of particular interest currently, as global climate change is altering abiotic controls on species ranges. However, predicting shifts in species ranges will depend not only on an understanding of changes in climatic factors, but also insight into species interactions that may facilitate or inhibit range expansion. Further, as some habitat forming species extend their ranges and others contract, the gain and loss of species may influence community processes.
Seagrass composition and trophic interactions
The abundance and species composition of marine foundation species is changing, with potential for ecosystem-level consequences. Warmer water in Chesapeake Bay due to climate change is likely to favor the more heat and stress-tolerant Ruppia maritima (widgeongrass) over Zostera marina (eelgrass). We addressed how trophic control differs between communities associated with the 2 seagrass species in a mesocosm experiment. Overall, predation was higher in Ruppia than in Zostera, although mesograzer species individually differed in their susceptibility to predation and response to seagrass species. Differences in grazer composition and predation between seagrass species could have consequences for higher trophic levels that rely on fauna in seagrass beds. However, given the considerable effects of manipulated seagrass and mesograzer density on trophic interactions and the fouling community, it may be most important to consider the overall density and distribution of seagrass present, rather than seagrass species identity. Our results highlight the importance of testing redundancy in ecological functions among habitat-forming species. See: Moore & Duffy, 2016.
Collaborator: J.E. Duffy
At what spatial scales can below-ground enemy release facilitate range expansion?
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Natural enemies can determine species distributions at scales ranging from local to intercontinental as escaping co-evolved enemies can allow species to establish successfully in a new range. While species expanding just beyond the edge of their current range may encounter habitats and interactions similar to those in their current range, there is mounting evidence that range-expanding plants can also benefit from enemy release. We are examining the scales at which below-ground enemy release may benefit range expanding black mangroves, using a laboratory experiment manipulating the origin of soil and seedlings across a marsh-mangrove ecotone. We are analyzing soil microbial communities to determine how their composition may influence seedling success.
Collaborators: R. Hughes, Alex Forde, Jen Bowen
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