Will prey availability limit northward expansion of Canadian vertebrates?

Background/Question/Methods

Contrary to global trends, northern ecosystems are expected to have a net influx of species with climate change (aka the northern biodiversity paradox). Aside from documented cases of northward expansion, this expectation is largely built upon the predictions of climate-based species distribution models. In these models, species typically track their climate niche to a greater or lesser degree based on their dispersal capacity. However, these models very rarely take into account the effect of prey. How likely is it that prey will limit northward expansion of predators?

Results/Conclusions

We ask this question for terrestrial canadian vertebrates by combining a large predicted meta food web with a range of present and future climate projections. For each predator, we compare the average number of prey in each pixel currently compared to areas of potential future colonization (new climatically-suitable areas) using a probabilistic framework. We find that, on average, the number of prey species in the potentially colonized areas is about half that available in the current distribution. If prey species are allowed to track their climate niches, then there is still a ~30% reduction in prey diversity compared to the current distributions. Results suggest that prey might indeed limit northward migration of predators.