Predicting the current distribution and potential spread of the exotic grass Eragrostis plana Nees in South America and identifying a bioclimatic niche shift during invasion FABIANA G. BARBOSA, 1 * VALÉRIO D. PILLAR, 2 ANTHONY R. PALMER 4 AND ADRIANO S. MELO 3 1 Programa de Pós-Graduação em Ecologia, Instituto de Biociências, 2 Departamento de Ecologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, 3 Departamento de Ecologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, GO, Brazil; and 4 Agricultural Research Council, Animal Production Institute, Grahamstown, South Africa Abstract Eragrostis plana (Poaceae) is a perennial grass introduced from South Africa to the state of Rio Grande do Sul in southern Brazil. Currently, it is considered an invasive grass in several regions of the world, including South America, where it has caused negative ecological and socio-economic impacts. Ecological niche models, using bioclimatic variables, are often used to predict the potential distribution of invasive species. In this study we prepared two bioclimatic models for E. plana using the Genetic Algorithm for Rule-set Production, the first based on data from its native region (South Africa) and the second on data from both the native and invaded (South America) regions.We then projected each model onto South America to identify regions vulnerable to invasion by the species, and compared our results with available records of the species in South America. Finally, we explored the model’s predictions for the existence of a bioclimatic niche shift during the invasion process of E. plana in South America, using multivariate statistical analysis. The model created with native distribution data was only able to predict (with highly suitable habitat) the region of introduction of E. plana in South America. However, the current distribution, as well as the region of introduction of the species, was reliably predicted by the model created with data from both native and invaded regions. Our multivariate analysis supports a hypothesis of bioclimatic niche shift during the invasion process of E. plana in South America. Key words: bioclimatic variable, ecological niche model, GARP, invasive grass, native pasture. INTRODUCTION Biological invasions by exotic grasses are a threat to the maintenance of biodiversity (D’Antonio & Vitousek 1992; Pivello et al. 1999). They can nega- tively affect the native community structure (Brewer 2008; Hoffmann & Haridasan 2008; Yoshioka et al. 2010) and ecosystem properties and processes (Will- iams & Baruch 2000; Holly et al. 2009), as well as cause many negative impacts on human economic activities (Pimentel et al. 2001). Species of African grasses have been introduced acci- dentally or intentionally in different parts of the world (D’Antonio & Vitousek 1992; Pivello et al. 1999; Will- iams & Baruch 2000). In many instances, these grasses spread successfully and displaced native plants (Lenz et al. 2008) and caused problems for native herbivores (Yoshioka et al. 2010). South America harbours several invasive grasses native to South Africa, including Digi- taria decumbens Stent., Eragrostis ciliaris (L.) R. Brown, Eragrostis plana Nees, Hyparrhenia rufa (Nees) Stapf., Panicum coloratum L., Panicum maximum Jacq., and Rhynchelytrum repens (Willd.) C.E. Hubb. (Filgueiras 1990; Williams & Baruch 2000). Eragrostis plana, known as fan lovegrass (or capim- annoni in Brazil), is a perennial grass (Kissmann 1991) native to South Africa (Reis & Coelho 2000; Medeiros et al. 2004). It was introduced into the state of Rio Grande do Sul in southern Brazil in 1957 (Reis & Coelho 2000), as a contaminant of forage seed (Chloris gayana Kunth and Eragrostis curvula Schrader) imported from South Africa (Ferreira et al. 2008a,b). In 1971, the species was identified as a high-potential forage species and was propagated and marketed as seed in several regions of Rio Grande do Sul and other states of Brazil (Paraná, Mato Grosso and Santa Cata- rina States) (Medeiros et al. 2009). Eragrostis plana has low forage quality compared with native species that are abundant in natural *Corresponding author. Present address: Laboratório de Estatística Ambiental, Instituto de Matemática, Estatística e Física, Universidade Federal do Rio Grande. CP 474, Rio Grande, RS 96201900, Brazil (Email: fabibarbos@gmail.com) Accepted for publication March 2012. Austral Ecology (2013) 38, 260–267 © 2012 The Authors doi:10.1111/j.1442-9993.2012.02399.x Austral Ecology © 2012 Ecological Society of Australia