Origin matters? Comparing impacts of native and introduced ungulates in European protected areas

The prevailing theory in invasion biology has been that introduced species have ecological and life-history characteristics that predispose them to do more damage than native species. However, this principle has been challenged and the last decade has become involved in controversy around the hypothesis of whether origin matters. The objectives of this study were 1) to compare the intensity and types of environmental impacts of native European ungulates and their introduced counterparts using EICAT and 2) to discuss whether the results support the hypotheses on the importance of the origin of species. We relied on two previously published lists of literature on ungulate impacts. We conducted four types of comparisons: 1) same species, different locations, 2) different species, same location, 3) all species, all locations and 4) between impact mechanisms. All data comparisons between native European and introduced ungulate species indicated non-significant differences in their levels and types of impacts. In conclusion, this study found that the negative impact of native European ungulates is like that produced by introduced species. Nevertheless, the mechanisms that determined high levels of damages in native and introduced ungulates may not be the same; thus, further research using the methodological tools provided by invasion biology is required.