Canadian Arctic food webs during the Eocene Epoch: how robust is the structure of range-shifted communities in response to latitudinal constraints?
Louis-Philippe Bateman, Alexandre Demers-Potvin, Gabrielle Bonin & Hans C.E. Larsson

Anthropogenic global warming is widely accepted to trigger poleward shifts in the geographical ranges of entire species and communities. However, less is known about the extent to which solar energy and photoperiod constrain those shifts at higher latitudes. We now propose that the fossil record of an enigmatic vertebrate fauna from Ellesmere Island in the Canadian High Arctic, which existed 50 to 54 million years ago during a global 'hothouse' phase termed the Early Eocene Climate Optimum, can provide a deep-time perspective to this question beyond more common extant biodiversity databases. This paleocommunity will be reconstructed as an ecological network accounting for feasible trophic links and body mass distributions. A preliminary examination of the Eocene Ellesmere Island fossil collections at the Canadian Museum of Nature proved crucial to make anatomical observations and measurements of different mammal, reptile, bird and fish elements, particularly jaws and teeth. These traits are key to estimating the body size and trophic interactions of each of the constituents of this community, and ultimately to assemble a food web. Ultimately, we hope to test whether the more extreme photoperiod of this polar community affected its network structure compared to coeval North American communities distributed along a paleolatitudinal gradient characterized by low paleoclimate variation from North to South relative to modern times.