Cascades in the Desert: Interactions between lizards and mammalian apex predators.

Abstract

Apex predators shape ecosystems through top down pressures which impact lower trophic levels through numerous interaction pathways. Lizard assemblages in arid Australia are driven by habitat structure, competition, and predation. The presence of mammalian predators in an ecosystem may influence the distribution of lizard species in Australian ecosystems. As lizards are ectotherms they are particularly sensitive to the changes in the thermal environment facilitated by climatic fluctuations, rainfall, herbivory and fire. The links between dingo control and lizard assemblages were explored using a natural experiment created by the Dingo Barrier Fence. Five years of data on predator activity and lizard assemblages from locations with a variety of management practices was used. The results showed that lizard assemblages reflected the differences in predator abundance and vegetation structure on either side of the Dingo Barrier Fence. Further investigation suggested a model where dingo control affects the abundances of lizard species via complex 4-link cascades. These findings suggest that there are winners and losers when dingoes are controlled: small lizards and geckoes benefit from dingo control while larger predatory lizards benefit from having dingoes in the ecosystem.