L'espansione di specie invasive di Litoria in Nuova Zelanda: conosci il passato per prevedere il futuro

Frogs from the genus Litoria (L. aurea, L. raniformis, L. ewingìi) have been introduced to New Zealand in the late eighteenth century a sbiological control agents and for the acclimatisation of European settlers. In this period, various introductions and translocations have resulted in the establishment of new populations scattered across NewZealand. During the following century their distribution ranges gradually expanded and in more recent years their spread has been accelerated by intense trading activities by private collectors. the aim of this study is to assess whether the range expansion of L. aurea, L. raniformis and L. ewingìi is currently on-going and to predict its future dynamics. For this purpose, we modelled: i) the habitat suitability for all three species based on their current distribution; ii) the frogs dispersal capabilities based on historical data. We then integrated these models in an automated algorithm to simulate their future range expansion. In order to validate our method, we simulated their current; distribution based on sighting locations recorded before1980 and compared the results with empirical data. Finally, we projected our model for the next decades based on their current distribution. Our models are coherent with the observed distributions and predict a possible further range expansion for all the study species. They also highlight the magnitude of the anthropogenic component of this process. Although there is no evidence of direct competition between Litoria and New Zealand native wildlife, the more abundant and mobile introduced species can act as a carrier for Batracochytrium dendrobatidis. Our model can be also used to predict the diffusion of B. dendrobatidis.