Biological invasions have become so widespread as to constitute a significant component of the global environmental change (Vtousek et al. 1996) and are viewed as one of the most important determinants of change in biodiversity at a global scale (Sala et al. 2000). The redistribution of the earth's species, a progressive homogenisation of biota in heavily human-influenced zones, is usually ecologicallt and economically damagning. The growing urbanisation process, international transport fluxes, explosive growth of agriculture in developing countries and the abandonment of rural areas in industrialised countries, are among the principal factors that lead to the introduction of non-native species in habitats that we initially far apart. In this project we focus on two invasive ant species (Lasius neglectus, Linepithema humile)and plan to obtain quantitative evidence of the direct effects of their presence on the biodiversity of arthropods. The evaluation of indirect effects, by interfering on natural processes, as seed dispersal by ants, is also planned, as is thestudy of the behavioural mechanisms that allow for their numerical prevalence in the invaded areas. For one species (L.neglectus) we will obtain basic biological data (nest foundation, queen numbe, egg-laying rate, survival, food andfeeding habits, biological cycle), behavior (recognition and aggression between members of different colonies, recruitment processes)and response to human perturbations. For L. neglectus and L. humile their effects on the ants and other arthropods assemblages in the infested habitats ill be evaluated. For the last species, its indirect effects on local processes of seed dispersal and predation by ants and pollination by insects. For both ant species we will document the rate of colonial expansion rang and the behavioural mechanisms that are at the base of their abundance and dominance in the occupied areas.
|Effective start/end date||28/12/00 → 28/12/03|