The influence of interspecific interactions on species range expansion rates

Abstract

Ongoing and predicted global change makes understanding and predicting species’ range shifts an urgent scientific priority. Here, we provide a synthetic perspective on the so far poorly understood effects of interspecific interactions on range expansion rates. We present theoretical foundations for how interspecific interactions may modulate range expansion rates, consider examples from empirical studies of biological invasions and natural range expansions as well as process-based simulations, and discuss how interspecific interactions can be more broadly represented in process-based, spatiotemporally explicit range forecasts. Theory tells us that interspecific interactions affect expansion rates via alteration of local population growth rates and spatial displacement rates, but also via effects on other demographic parameters. The best empirical evidence for interspecific effects on expansion rates comes from studies of biological invasions. Notably, invasion studies indicate that competitive dominance and release from specialized enemies can enhance expansion rates. Studies of natural range expansions especially point to the potential for competition from resident species to reduce expansion rates. Overall, it is clear that interspecific interactions may have important consequences for range dynamics, but also that their effects have received too little attention to robustly generalize on their importance. We then discuss how interspecific interactions effects can be more widely incorporated in dynamic modeling of range expansions. Importantly, models must describe spatiotemporal variation in both local population dynamics and dispersal. Finally, we derive the following guidelines for when it is particularly important to explicitly represent interspecific interactions in dynamic range expansion forecasts: if most interacting species show correlated spatial or temporal trends in their effects on the target species, if the number of interacting species is low, and if the abundance of one or more strongly interacting species is not closely linked to the abundance of the target species.

Do community-weighted mean functional traits reflect optimal strategies?

“…R. Soc. B 283: 20152434 continuing to advance our understanding of the factors governing local functional diversity requires a stronger integration of local processes and community context with species population dynamics and geographical distributions [58]. Further development of a functional perspective in community ecology will help fill these gaps by providing mechanistic links between abiotic gradients and diversity patterns.…”

Mycorrhizal strategies of tree species correlate with trailing range edge responses to current and past climate change

“…Species ranges have shifted in response to past (Ordonez and Williams 2013) and contemporary (Parmesan and Yohe 2003, Angert et al 2011, Chen et al 2011, Buckley and Kingsolver 2012 climate change, expanding at the poleward (leading) edge and contracting at the equatorial (trailing) edge as climates warm. While species range shifts are typically predicted from abiotic variables, interactions among species may impact range dynamics by affecting dispersal and establishment (Svenning et al 2014) and/or a species' tolerance to novel climates (Jones et al 2008). Species interactions may affect range dynamics during climate warming through two main mechanisms: (1) by inhibiting or promoting range expansion into newly permissive areas beyond the leading range edge, and (2) by increasing or decreasing a species' ability to persist at its trailing range edge by broadening or narrowing its tolerance to novel climate conditions (Van der Putten et al 2010, Svenning and Sandel 2013, Svenning et al 2014.…”

“…While species range shifts are typically predicted from abiotic variables, interactions among species may impact range dynamics by affecting dispersal and establishment (Svenning et al 2014) and/or a species' tolerance to novel climates (Jones et al 2008). Species interactions may affect range dynamics during climate warming through two main mechanisms: (1) by inhibiting or promoting range expansion into newly permissive areas beyond the leading range edge, and (2) by increasing or decreasing a species' ability to persist at its trailing range edge by broadening or narrowing its tolerance to novel climate conditions (Van der Putten et al 2010, Svenning and Sandel 2013, Svenning et al 2014. At the leading edge, escape from specialized natural enemies may promote establishment, which has been frequently found for exotic species (Liu and Stiling 2006) and recently documented in response to warming climates (Engelkes et al 2008).…”

Global change and terrestrial plant community dynamics

“…The ecological and spatiotemporal scale gaps between landscape models and DGVMs are narrowing (137), but still represent a future challenge; their primary emphases on community vs. ecophysiological processes provide complementary abilities to fully address global change effects on vegetation dynamics. Improved models incorporating the effects of species interaction on population demography and vegetation response to global change are needed (138). Individual-based models of forest dynamics, validated using new remote sensing technology, have been proposed for forecasting climate change effects over large regions at a scale fine enough to capture key ecophysiological processes (73).…”