PRIMARY RESEARCH ARTICLE From endogenous to exogenous pattern formation: Invasive plant species changes the spatial distribution of a native ant Kevin Li 1 * | Yifan He 2 * | Susanna K. Campbell 3 | A. Shawn Colborn 3 | Eliot L. Jackson 2 | Austin Martin 2 | Ivan V. Monagan Jr. 3 | Theresa Wei Ying Ong 3 | Ivette Perfecto 2 1 Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, NC, USA 2 School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI, USA 3 Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA Correspondence Ivette Perfecto, School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI, USA. Email: perfecto@umich.edu Abstract Invasive species are a significant threat to global biodiversity, but our under- standing of how invasive species impact native communities across space and time remains limited. Based on observations in an old field in Southeast Michigan spanning 35 years, our study documents significant impacts of habitat change, likely driven by the invasion of the shrub, Elaeagnus umbellata, on the nest distri- bution patterns and population demographics of a native ant species, Formica obscuripes. Landcover change in aerial photographs indicates that E. umbellata expanded aggressively, transforming a large proportion of the original open field into dense shrubland. By comparing the ant’s landcover preferences before and after the invasion, we demonstrate that this species experienced a significant unfavorable change in its foraging areas. We also find that shrub landcover sig- nificantly moderates aggression between nests, suggesting nests are more related where there is more E. umbellata. This may represent a shift in reproductive strategy from queen flights, reported in the past, to asexual nest budding. Our results suggest that E. umbellata may affect the spatial distribution of F. obscuripes by shifting the drivers of nest pattern formation from an endoge- nous process (queen flights), which led to a uniform pattern, to a process that is both endogenous (nest budding) and exogenous (loss of preferred habitat), resulting in a significantly different clustered pattern. The number and sizes of F. obscuripes nests in our study site are projected to decrease in the next 40 years, although further study of this population’s colony structures is needed to understand the extent of this decrease. Elaeagnus umbellata is a common inva- sive shrub, and similar impacts on native species might occur in its invasive range, or in areas with similar shrub invasions. KEYWORDS autumn olive, Elaeagnus umbellata, Formica obscuripes, invasive species, landcover change, pattern formation, spatial distribution, thatching ant *These authors are co-first authors. Received: 7 August 2016 | Revised: 20 November 2016 | Accepted: 27 January 2017 DOI: 10.1111/gcb.13671 Glob Change Biol. 2017;1–12. wileyonlinelibrary.com/journal/gcb © 2017 John Wiley & Sons Ltd | 1