The Species Interaction - Abiotic Stress Hypothesis (SIASH) posits that, where abiotic conditions are stressful, species interactions become less important in determining distributions. Species distribution models are common tools ecologists use to make predictions about where a species is likely to occur. Heikkinen et al. (2007) tested the effect of inclusion of biotic and land-cover variables on distribution model performance for high-latitude owl species. While the express purpose of this study was not to test SIASH, it is an interesting case study which presents a potential counter-example to the position of SIASH.
In their study, Heikkinen et al. made a baseline distribution model for four owl species which contained only climatic predictor variables.. As treatments, the authors also created models where land-cover and biotic interaction predictor variables were included in addition to climatic variables. It was found that when land-cover and biotic interactions were included in models, performance of said models improved significantly. These results imply that biotic interactions were taking place amongst the boreal bird species modeled.
While the purpose of this paper was to demonstrate the general utility of including land-cover and biotic variables in models, there are also interesting implications from a SIASH perspective. Each of the bird species tested exist in the extremely high latitudes of Scandinavia. SIASH would predict that minimal important biotic interactions should occur at high latitudes, however the improvement of model predictions resulting from the inclusion of biotic interaction variables suggests otherwise. This study therefore demonstrates that there may be limits to generalizing SIASH across species. At the same time, caution must be applied when interpreting species distribution model outcomes in the context of SIASH, as the methods used provide a purely correlational assessment of the relationships between the boreal owls and their environments.
Paper reference:
Heikkinen R., Luoto M., Virkkala R., Pearson R., Korber J.H. (2007). Biotic interactions improve prediction of boreal bird distributions at macro-scales. Global Ecology and Biogeography. 16(6): 754-763.