March 15 – Non-climate processes and ‘species on the move’

Evidence from the past several decades shows that species distributions are shifting in response to climate change. However, even the most robust studies attribute less than half of observed changes in species distributions to local climate factors. Foundational ecology considers climate as just one of many drivers that determine species distributions. I will review five prevalent mechanisms that may explain some of the high variance around the relationship between species range shifts and climate velocity, and describe how they might affect a species’ climate tracking: (1) biogeographic boundaries, (2) habitat gaps and fragmentation, (3) biotic interactions such as competition, predation, and mutualism, (4) other abiotic constraints including light and trace elements, and (5) life history traits that determine dispersal capacity. This work supports conservation initiatives for threatened species by highlighting several processes that may limit their potential redistribution, and can inform analyses of observational data and species distribution models that seek to incorporate multiple processes rather than climate alone.


Alexa Fredston-Hermann

Alexa is a third-year PhD student at the Bren School of Environmental Science & Management at UCSB. Her research focuses on biogeographic processes that may prevent species from tracking climate change, particularly in the oceans. She has also studied human impacts to coastal marine ecosystems, and participated in the Ridges to Reef Fisheries SNAPP Working Group. Before entering graduate school, she worked for the Environmental Defense Fund on management of the West Coast groundfish fishery, and graduated from Princeton University in 2012 with a B.A. in Ecology and Evolutionary Biology.

Species interactions as biotic filters of global change [Wed. Oct. 12]

The study of species interactions has greatly improved our appreciation of the importance of network structure for ecological community stability, sensitivity to invasion, and extinction. Because species interactions reflect past evolutionary constraints and niche partitioning within a particular local context, they constitute the underlying fabric of ecosystem dynamics, driving biomass and body size distributions, and ecosystem level processes. Here I propose that beyond being a simple witness of global change, species interactions can actually mediate their effects on population and ecosystem dynamics either locally via bottom-up or top-down mechanisms or regionally via spatial cascade processes. I will present case studies for each scenario and conclude with a discussion of future perspectives and challenges for the use of ecological networks in conservation biology.



Eric Harvey, PhD
Department of Evolutionary Biology and Environmental Studies
University of Zurich
Zurich, Switzerland