Ungulates as dispersal vectors of non-native plants.

Abstract

Ungulates are present worldwide with 257 recorded species, including livestock. They cover different functional gradients, be it feeding regime, digestive strategy, body size, body mass, fur characteristics or sociality. All these specificities may intervene at different stages of animal-mediated plant dispersal. Ungulates move diaspores from both native and non-native plants, through endo- and epizoochory. Initially introduced by humans, non-native plants bearing specific traits can be carried over long distances and to new environments by ungulates. These vectors can further free local resources necessary for the germination and the subsequent growth of the released diaspores. We first looked at trait-based plant community changes at different timescales in the presence of different native ungulates. We then reviewed the literature on endozoochory, regurgitation and fur-epizoochory assisted by ungulates, focusing on the dispersal of non-native plants. We made an overall assessment of ungulate-mediated non-native plant dispersal by biogeographical zone and dispersal mode, and then provided additional information on plant growth form and taxonomy, vectors and associated modes of dispersal. Results are presented for four main ungulate families: Cervidae, Bovidae, Suidae and Equidae. For each family, we highlight our findings either by ungulate if sufficiently represented (e.g. <i>Odocoileus virginianus, Bison bison, Bos taurus</i>) or by group of species. According to their feeding regime, grazers dispersed solely forbs and graminoids whereas omnivores also dispersed plants from other growth forms (i.e. cactus, vine, shrub and tree). Numerous non-native plants are dispersed by ungulates around the world, but this is probably the visible part of the iceberg, as only 32 ungulates (i.e. 12%) have been studied as vectors so far, suggesting their overall contribution is certainly underrated.