Trophic Specialisation Levels of Geese, Lemmings, and Ruminants with Regard to the Transformation of Arctic Herbivore Communities

Abstract

Despite the availability of more and more data on Arctic biotic communities, even the principal course of their transformation remains unclear. Differences in the population dynamics of geese, lemmings, and ruminants covering more than 98% of the Arctic terrestrial ecosystem recycling and competing for common trophic resources on the basis of specialization are of great interest. Comparing 15 species of the taxa, we showed that grades of their morphophysiological adaptation to phytophagy are matched to empirical estimates of their food selectivity, thereby describing their trophic specialization distribution. Thus, in the Arctic herbivore communities, the selectivity distribution is just as stable as specialization. Populations of trophic specialists in these communities, the most glaring examples of which are the muskox and the snow goose, generally exceed in size and/or growth rate the populations of generalists, which include lemmings and the smallest black geese. The specialist populations have mainly higher size and/or growth rate than the generalist populations. It may be concluded that interspecific competition influences the contemporary transformation of the Arctic herbivore communities much more strongly than environmental factors such as global warming and human activity do.