HOST USE BY A HEMIPARASITE MISTLETOEALONG TWO DIFFERENT BIOMES.

ATENCIO, N.O.; AMICO, G. C.; CHACOFF, N. P.; VIDAL RUSSELL, ROMINA

Congreso; XXXVII Jornadas Argentinas de Botánica; 2019

The complexity of natural communities is the result of the different species that coexist within them. Parasites are keystone species in natural systems, they represent an important component of the diversity and biomass and can alter the structure of the community. We describe host use by a South American mistletoe (Tristerix corymbosus, Loranthaceae) throughout its distribution range using bipartite network theory. This study was conducted in 22 localities covering the entire distribution range of the mistletoe in two biomes: the Chilean-matorral and the Temperate-forest. We recorded 1278 individuals parasitized by T. corymbosus. We found that parasitized a total of 27 host species in the two biomes, corresponding to 13 families and 24 genera. Ten of the 27 host species are non-native. In addition, host-use centrality was different between biomes. In Chilean matorral the mainhost used was Populus sp., while in Temperate forest was Aristorelia chilensis. We conclude that host-use by T. corymbosus show different patterns due to the relative availability of their host species through its distribution range, a big host range (generalist) on a large geographical scale and a restricted hostrange on smaller, local scale. This represents a characteristic to local adaptation the mistletoe. Seed dispersal vectors, host-availability, host-abundance, suitable niche can determine host specifi city-generality in mistletoes at different scales of analysis. If the different geographic host-use by the mistletoe could act as a selective force capable of originating races within the species is relevant to elucidate the pathways which lead to the process of differentiation within a phylogenetic unit.