Australia's recently established predators restore complexity to food webs simplified by extinction

• Published in: Current biology
• Main Authors: Wooster, Eamonn I.F., Middleton, Owen S., Wallach, Arian D., Ramp, Daniel, Sanisidro, Oscar, Harris, Valerie K., Rowan, John, Schowanek, Simon D., Gordon, Chris E., Svenning, Jens-Christian, Davis, Matt, Scharlemann, Jörn P.W., Nimmo, Dale G., Lundgren, Erick J., Sandom, Christopher J.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 07.10.2024
• Subjects: functional ecology; metaweb; network ecology; novel ecosystems; predator-prey interactions; trophic cascades; network ecology; trophic cascades; predator-prey interactions; metaweb; novel ecosystems; functional ecology
• ISSN: 0960-9822; 1879-0445; 1879-0445
• DOI: 10.1016/j.cub.2024.09.049

Since prehistory, humans have altered the composition of ecosystems by causing extinctions and introducing species. However, our understanding of how waves of species extinctions and introductions influence the structure and function of ecological networks through time remains piecemeal. Here, focusing on Australia, which has experienced many extinctions and introductions since the Late Pleistocene, we compared the functional trait composition of Late Pleistocene (130,00–115,000 years before present [ybp]), Holocene (11,700–3,000 ybp), and current Australian mammalian predator assemblages (≥70% vertebrate meat consumption; ≥1 kg adult body mass). We then constructed food webs for each period based on estimated prey body mass preferences. We found that introduced predators are functionally distinct from extinct Australian predators, but they rewire food webs toward a state that closely resembles the Late Pleistocene, prior to the megafauna extinctions. Both Late Pleistocene and current-day food webs consist of an apex predator and three smaller predators. This leads to food web networks with a similar total number of links, link densities, and compartmentalizations. However, this similarity depends on the presence of dingoes: in their absence, food webs become simplified and reminiscent of those following the Late Pleistocene extinctions. Our results suggest that recently established predators, even those implicated in species extinctions and declines, can restore complexity to food webs simplified by extinction. •Australia’s fauna has been radically reorganized since the Late Pleistocene•New predators share little functional overlap with extinct predators•Yet, current-day food webs have been rewired in resemblance to the Late Pleistocene•Prehistory provides important perspectives to current-day conservation Investigating how the biotic reorganization of Australia’s predator community has shaped the form and function of food webs, Wooster et al. unveil that, despite having distinct traits, recently established predators rewire food webs in the image of the Late Pleistocene. However, food web similarities are dependent on apex predator protection.