Comparative analysis of harvester ant assemblages of Argentinian and Chilean arid zones

In this paper we compare several attributes of a number of harvester ant assemblages of Argentinian Monte desert and Chilean arid zones, two South American arid regions separated by the Andes Mountain Range. Our data indicate that Monte desert assemblages have a higher species richness and diversity than Chilean assemblages. However, other attributes such as foraging distance, type of foraging, and community body size do not differ between the two regions. Argentinian ants presented a wider temporal activity breadth than Chilean ants, which may be due to the absence of species resistant to high temperatures in the Chilean myrmecofauna. Seed removal rate by harvester ants was markedly different in the two regions, being four times higher in the Argentinian biota than in the Chilean. Despite the geographical proximity of the two regions, biogeographical and historical processes such as the uplift of the Andes Mountain Range, the radiation of granivorous genera in Argentina, and the dispersal of granivorous species from the tropic toward the Monte must have contributed to the ant community dissimilarity between the two deserts. Judging by the genera participating in the seed removal, the species that compose the South American seed-eater myrmecofauna present a more generalized trophic behaviour than that observed in granivorous ant species of North American deserts.