Top-down effects of a large mammalian carnivore in arid Australia extend to epigeic arthropod assemblages. (June 2019) - Contos, Peter
Abstract: We compared abundances of terrestrial vertebrate insectivores, the rate of insectivory and composition of epigeic arthropod assemblages where an apex predator the dingo was common and rare on either side of the Dingo Barrier Fence (DBF) in Australia's Strzelecki Desert. Previous research in the region shows that suppression of dingoes initiates trophic cascades between dingoes-red foxes-small mammals and woody shrubs and between dingoes-kangaroos and grasses. Results show that terrestrial insectivores were more abundant and the rate of insectivory indexed as the rate of consumption of experimentally provisioned meal-worms was greater where dingoes were common. Overall abundance, diversity and taxon richness of arthropods was unaffected by dingo status. However, there were distinct differences in the composition of arthropod assemblages across the DBF. Scolopendridae, Acrididae and Lepismatidae were more abundant where dingoes were rare, while Tenebrionidae and Blattidae were more abundant where dingoes were common. Our results lend support to the idea that suppression of dingo populations can trigger ≥4 link trophic cascades that extend to arthropod assemblages. We hypothesize that dingo suppression engenders shifts in arthropod assemblages due to a decrease in the intensity of insectivory, changes in habitat structure and alteration of the predatory and competitive interactions between arthropod taxa. Highlights: We found evidence for a ≥4 level trophic cascade initiated by the dingo. Arthropod assemblages were distinctly different in the presence or absence of the dingo. We hypothesize that the dingo extirpation has shifted arthropod assemblages by altering rates of insectivory and changing habitat structure.