Appendix E. Geographic variation in stable isotope ratios of snowshoe hare and red squirrel hair samples collected across Canada and the northern United States.
|FIG. E1. For each species (207 hares and 187 squirrels) we fit separate models relating δ15N and δ13C to longitude, latitude and their interaction. Open symbols are model output from western North America (120oW longitude), and closed symbols are model output from eastern North America (70oW longitude). The three-way interaction between species, longitude and latitude was significant for both carbon (F1,386 = 5.35, P = 0.021) and nitrogen (F1,386 = 6.25, P = 0.022). In western North America, differences between squirrels and hares in both δ15N and δ13C decreased with latitude, while in the east, differences between the species increased with latitude.|