Collaborative Research: LTREB Renewal: Large-scale removal of introduced ants as a test of community reassembly

University Of California-San Diego, La Jolla CA

Investigators

Abstract

Ecosystems are commonly disrupted by both natural and human forces. Species introductions are a costly and pervasive form of environmental change that cause impacts including degraded ecosystem services, agricultural damage, and species extinctions. Surprisingly little information exists, however, regarding the capacity of ecosystems to recover after introduced species are removed from ecosystems. This project examines the reassembly of native ant assemblages following the landscape-scale removal of the Argentine ant from Santa Cruz Island, California. A prominent urban and agricultural pest, the Argentine ant is also an ecologically disruptive invader. This species displaces other ant species, and its removal makes it possible to examine how native ants recover genetic diversity, species diversity, community structure, and ecological function. The insights gained from this relatively simple model ecosystem will provide general insights into how other ecosystems might recover from the impacts of invasive species, and perhaps other types of ecological disruptions. Multifaceted approaches, such as those employed in this long-term study, are needed to clarify the rate and extent to which ecosystems recover from different drivers of environmental change. Broader impacts related to this work include research support for PhD students from UC San Diego, research support for a postdoctoral researcher from UC Berkeley, and a Research Experience for Undergraduates (REU) program for students from local, four-year Hispanic Serving Institutions (California State University Channel Islands and University of California, Santa Barbara). We are also engaging in K12 outreach collaborations that focus on the importance of insects. The experimental removal of introduced species can provide unparalleled opportunities to examine community reassembly. Invader-removal experiments, for example, can clarify how recovery is influenced by processes acting within a given system or, alternatively, reflects processes acting at larger spatial scales. The core objectives of this research are to quantify the structural (genetic diversity, species diversity) and functional (trophic position, ecological function) components of the recovery of native ant assemblages following landscape-scale removal of the non-native Argentine ant from Santa Cruz Island, California. Despite the obvious value of such studies, surprisingly few examine recovery above the level of single-species populations. In particular, only a handful of studies on invasions couple long-term, pre-invasion data with invader-removal experiments over temporal scales long enough to capture the succesion of native species assemblages. Even fewer invader-removal experiments measure recovery in terms of functional components, such as energy flow or trophic position. This research will provide an unprecedented test of the recovery of native assemblages after invader removal and will yield novel information about the factors that control the richness, composition and functional properties of an important terrestrial animal assemblage. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.