Galls of the Temperate Forest of Southern South America: Argentina and Chile

Abstract

South American temperate forests are of special conservation concern due to their highly endemic flora and fauna, and the occurrence of unique plant-animal interactions. Yet, knowledge regarding gall inducers diversity is limited although increasing rapidly in the last two decades. Here, we performed a review of the literature, supplemented with field collected data by the authors, in order to provide the most up to date knowledge of gall inducers’ diversity associated with native woody species of the temperate forest of Chile and Argentina. We present data for 90 morphospecies of galls associated with 39 host-plant species (21 genera, 15 families), spanning insects and arachnids of at least 6 orders and nematodes. Most of this richness is associated to the best surveyed host-plant genus, Nothofagus, with up to 43 morphospecies of galls in just 8 dominant tree species. Moreover, we provide evidence that gall species richness across all woody host-plant species decreases with elevation, probably driven by decreased temperature and number of available host-plant species. However, this overall trend vary among host plant species and scales of observation. Overall, the study of gall diversity and the biotic and abiotic factors that shape their distribution in these austral forests offer an exciting and fertile field for future research. Besides emphasizing the need for more in depth taxonomic and diversity studies of the gall fauna of these forests, we propose several future lines of research that promise to further elucidate our understanding of the evolution of plant-gall interactions in these forests.