Ecological cascades following trophic rewilding: A case of study with dung beetles in the Iberá wetlands of Argentina

In the context of the biodiversity crisis, trophic rewilding became an important (but controversial) management practice to restore biological interactions and ecological processes. The success of this practice relies on the richness and abundance of other organisms, mainly invertebrates. In the Ibera wetlands of Argentina, a rewilding project reintroduced large herbivores locally extinct (the Tapir and Pampas deer, among others). Taking advantage of this project, we explored taxonomic and functional changes in dung beetle assemblages associated with replacing domestic livestock with native mammals. In five replicates, we sampled dung beetles with seven different baits, estimated temperature and grass eight and described landscape composition (forest and grassland cover). Through lineal and mixed models, NMDS and ANOSIM, we compared the taxonomic and functional dung beetle structure in both areas and explored the role of environmental variables. Trophic rewilding did not change dung beetle richness and the trophic structure of assemblages; however, it strongly modified the composition of species and their functional structure. Both areas shared 40 % of species. Species associated with cow dung (such as the exotic. D. gazella) became rare or disappeared in rewilded areas. Roller species dominated rewilded areas, whereas livestock areas exhibited a large abundance of burying species. The trophic rewilding changed dung beetle assemblages in the Iberá partially due to changes in the diversity of available dung but also on environmental conditions. Rewilding should include the medium and long-term evaluation of other taxa and ecological processes to quantify the conservation and functional value of species reintroduction.