New Research Illuminates Ecology of Desert Small Mammals of the Southern Hemisphere

Newswise — Our knowledge of desert small mammals, such as prairie dogs, kangaroo rats, and gerbils, is based primarily on pioneering North American studies. In the past decade data obtained from studies conducted in arid regions of the Southern Hemisphere have shown that different dynamics are at work in these animal communities. The assumption that all desert mammals share the same ecological history is no longer valid; new research has revealed that they have developed and evolved in many unique directions.

A special feature in the current issue of the Journal of Mammalogy presents similarities in and differences between small mammals in arid lands of the Northern and Southern Hemispheres. Specific regional studies from Australia and South America permit intercontinental comparisons of the influences on small mammal diversity, history, climate, and evolution in different parts of the world.

A global review of literature on the ecology of desert small mammals is among the articles in this special feature. It emphasizes four patterns: the importance of competition as compared to predation in the development of foraging strategies and selection of habitat, biotic and abiotic influences on the ecology of species, the structure of small mammal communities, and how these animals affect vegetation and habitat. Another study focuses on food habits relative to resource availability in small mammal assemblages on five continents. A single dietary category provides half or more of the food sources on four of the continents, but sources differ among the continents.

Dramatic fluctuations among the small mammals in arid lands of Australia are addressed. Animals at eight widely separated sites were studied. Researchers found that rainfall-driven resources can cause a switch from bottom-up to top-down control in the food chain. Another study considers the importance of climate change to resource availability and, thereby, the structure of small mammal species assemblages.

South American contributions include a long-term study from Chile uncovering major trends in semiarid zones, with pulses of rainfall triggering remarkable increases in many small mammal populations due to increases in primary productivity. A study from the Argentine Monte Desert highlights the unique features of small mammals in this region. Species turnover is high here, although a central area exists where the composition of these animal communities remains constant.

Overall, fire and climatic events have greatly influenced small mammal populations in the arid lands of the Southern Hemisphere. These abiotic factors often have more impact than competition and predation (biotic factors), which have been principal in fashioning these animal communities in other parts of the world.

Full text of “Small Mammal Community Structure and Dynamics in Arid Lands: Overall Patterns and Contrasts with Southern Hemispheric Systems”, Comparative ecology of desert small mammals: a selective review of the past 30 years, and other articles in this special feature of the Journal of Mammalogy, Vol. 92, No. 6, December 2011, are available at: http://www.asmjournals.org/toc/mamm/92/6

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About the Journal of MammalogyThe Journal of Mammalogy, the flagship publication of the American Society of Mammalogists, is produced six times per year. A highly respected scientific journal, it details the latest research in the science of mammalogy and was recently named one of the top 100 most influential journals of biology and medicine in the last century by the Special Libraries Association. For more information, visit http://www.mammalogy.org/.