South American exotic mammals as model organisms for ecological understanding

RICARDO A OJEDA, AGUSTINA NOVILLO AND FERNANDA CUEVAS

Lepzig, Alemania, September 15-19

Congreso; EURECO-GFOE 11th European Ecological Conference of the European Ecolgical Federation and 38th Annual Conference Ecological Society of Germany, Austria and Switzerland; 2008

UFZ Halle

South American exotic mammals as model organisms for ecological understanding   Ricardo A. Ojeda, Agustina Novillo & Fernanda Cuevas 1 Grupo de Investigaciones de la Biodiversidad, Institute for Aridlands Research (IADIZA) and Ntnl Council for Sci & Tech of Argentina (CONICET);Parque San Martín, 5500 Mendoza, Argentina;rojeda@lab.cricyt.edu.ar   Biological invasions, climate change, habitat fragmentation and wildlife commercialization are among the leading threats to global biodiversity. On the other hand, species invasions are like natural experiments that offer opportunities for research on several ecological and evolutionary aspects (1, 2, 3). The exotic mammals of South America represent about 20% of world mammal introductions. The aim of this presentation is to provide an overview of the mammal invaders of Argentina, their attributes as invasive species and potential role as model organisms for ecological understanding. Nineteen introduced mammal species (excluding domestics) are present in southern South America.  Among these, 18 species (the majority of them natural from Eurasia), represent 5% of the terrestrial native mammals of Argentina (4). The majority of introductions occurred between the 18th and 19th centuries. Their ports of entry were mainly located in the temperate eco-regions, between 34º and 55º SL, and mostly associated with human activitie s (e.g., sport hunting, food and fur industry purposes). Some of the ecological attributes suggested for their success are their wide geographic ranges, broad herbivorous and omnivorous diet, no ecological counterparts, generalists in habitat use and a predator- free environment (Table 1). High invasive potential corresponds to wild boar, red deer, goat, european hare, and old world rats, whereas low values were recorded for the red squirrel, antilope and axis deer. Exotic mammals occupy similar eco-regions as in their original distributions, but most of them have experienced a range expansion to novel habitats. The highest density of exotic mammals is found in the temperate eco-regions, and in some places species richness of exotics is higher than that of natives (5). Several interesting topics to be explored are their genetic diversity in relation to small founder populations, ecological role of keystone species/ecosystem engineers (e.g. wild boar, beaver), coexistence and interactions among potential ecological counterparts (e.g. native and exotic medium sized herbivores), rates of dispersal of recent invaders (e.g. squirrel), their role in plant and animal communities, seed dispersal and seed predation, among others. In conclusion, the exotic mammals of Argentina represents a rich diversity of macroniches and a good opportunity for research on ecological and evolutionary processes (Partially funded by ALARM project, EU, CONICET and Agencia- SECYT, Argentina).   Table 1 “Good” traits                                     Examples Broad diet (generalist) Old world rats; L. europaeus; O. cuniculus; C. hircus; S. scrofa; E. assinus; E. caballus. Larger than most relatives advantage ( advantage competition, dispersal) C. elaphus; R. tarandus; S. scrofa; E. assinus; E. caballus Associated with Homo sapiens (deliberate or not assistance) Old world rats; L. europaeus; O. cuniculus; C. hircus; S. scrofa; E. assinus; E. caballus. Generalist in habitat use – (Type of habitat is not a limiting factor) L. europaeus; O. cuniculus; A. axis; C. elaphus; D. dama; R. tarandus; C. hircus; A cervicapra; S. scrofa; E. assinus; E. caballus. Short generation time (high reproductive capacity) M. vison; C. canadensis; O. zibethicus Old world rats; L. europaeus; O. cuniculus; C. hircus; S. scrofa. Large native range M. vison; C. canadensis; O. zibethicus; R. norvegicus; L. europaeus; C. elaphus; R. tarandus; S. scrofa. No ecological counterpart (theory of vacant niche) C. canadensis; O. zibethicus; C. elaphus; R. tarandus; C. hircus; A. cervicapra; S. scrofa; E. assinus; E. caballus. Climatic matching (sets of species seem to be limited by climate)/range expansion L. europaeus; S. scrofa; O. cuniculus   References   1. Ehrlich P R (1989) Attributes of invaders and invading processes: Vertebrates. In Drake J, di Castri F, Groves R, Kruger R, Mooney H A, Rejmanek M and Williamson M (eds) Biological Invasions: A Global Perspective, John Wiley and Sons New York, pp 315-328 2.- Williamson M (1996) Biological Invasions. Chapman and Hall. USA 3.- Sax DF et al. 2007 Ecological and evolutionary insights from species invasions.TREE 22: 465-471 4.- Novillo, A. and  R.A. Ojeda. 2008. The exotic mammals of Argentina. Biological Invasions: 000-000 5.- Rozzi, R and Sherriffs M (2003) El visón (Mustela vison server, Carnivora: Mustelidae) un Nuevo mamífero exótico para la Isla Navarino. Anal Inst Patagonia 31: 97-104.   ORAL PRESENTATION