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Leaf-Cutting Ants (Atta and Acromyrmex) Inhabiting Argentina: Patterns in Species Richness and Geographical Range Sizes
Alejandro Gustavo Farji Brener and Adriana Ruggiero
Journal of Biogeography
Vol. 21, No. 4 (Jul., 1994), pp. 391-399
Published by: Wiley
Stable URL: http://www.jstor.org/stable/2845757
Page Count: 9
You can always find the topics here!Topics: Species, Ants, Leaf cutting ants, Maps, Insect pests, Foraging, Social insects, Grasses, Insect ecology, Plant ecology
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Patterns in species richness of leaf-cutting ants inhabiting Argentina were analysed to identify the environmental factors that best determine the geographical trends. The size of geographical ranges was also studied and probable barriers limiting the expansion of the geographical ranges were identified. A grid composed of 311 cells of 10,000 km2 each was overlaid on a map of continental Argentina. Each quadrat was assigned values for topographic, climatic and vegetational variables, with species richness determined by counting the number of species present in each cell. It was observed that species richness decreased as latitude and longitude increase. The Patagonia, from 44⚬ S southward, and the Andean mountains, above 2500 m, lack leaf-cutters. Multiple regression analysis showed that annual precipitation, intra-annual temperature variation and the minimum mean winter temperature are the principal determinants of leaf-cutting ant richness. species havesting different types of vegetation showed differences in the size of their geographical ranges. Grass-dicot cutters are the most widespread species and no apparent barriers limit their southward expansion up to approximately 44⚬ S. Grass-cutters are restricted to the north of the Pampean grasslands and dicot cutters are profundly affected by the change from woody to grass vegetation. Both the size of the geographical ranges and patterns of species richness strongly depend on both climatic/vegetational features of the environment and the biological attributes of the different foraging group.
Journal of Biogeography © 1994 Wiley