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Savanna ant species richness is maintained along a bioclimatic gradient of increasing latitude and decreasing rainfall in northern Australia

Andersen, Alan N., Del Toro, Israel and Parr, Catherine L. (2015). Savanna ant species richness is maintained along a bioclimatic gradient of increasing latitude and decreasing rainfall in northern Australia. Journal of Biogeography,42(12):2313-2322.

Document type: Journal Article
Citation counts: Altmetric Score Altmetric Score is 10
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IRMA ID 83393865xPUB242
Title Savanna ant species richness is maintained along a bioclimatic gradient of increasing latitude and decreasing rainfall in northern Australia
Author Andersen, Alan N.
Del Toro, Israel
Parr, Catherine L.
Journal Name Journal of Biogeography
Publication Date 2015
Volume Number 42
Issue Number 12
ISSN 0305-0270   (check CDU catalogue  open catalogue search in new window)
Scopus ID 2-s2.0-84955199241
Start Page 2313
End Page 2322
Total Pages 10
Place of Publication United Kingdom
Publisher Wiley-Blackwell Publishing Ltd.
Field of Research ENVIRONMENTAL SCIENCES
HERDC Category C1 - Journal Article (DIISR)
Abstract Aim
Using a standardized sampling protocol along a 600-km transect in northern Australia, we tested whether ant diversity within a single biome, tropical savanna, decreases with increasing latitude (as a surrogate of temperature) and decreasing rainfall, as is expected for biodiversity in general.

Location
Northern Australia.

Methods

Ants were sampled using pitfall traps on three occasions at 1-ha sand, loam and clay sites at each of five locations along the Northern Australian Tropical Transect (NATT), from 12°50′ S (1400 mm mean annual rainfall) to 17°21′ S (650 mm).

Results

We recorded a total of 246 species from 37 genera. Mean observed species richness pooled across sampling periods was similar at sand (85.4) and loam (82.2) sites, but was less than half this at clay sites (40.0). Ant communities were also compositionally distinct on clay soils compared with sands and loams. Individual genera showed variable diversity patterns, ranging from a linear increase to a linear decrease in species richness along the NATT. However, total species richness was relatively uniform along the gradient. Patterns of ant species turnover were consistent with previously recognized biogeographical boundaries, with a primary disjunction between the arid and monsoonal zones in the south, and a secondary disjunction between the semi-arid and mesic zones in the north.

Main conclusions

Patterns of ant diversity in Australian savannas do not conform to global patterns of biodiversity declines with increasing latitude and decreasing rainfall. We believe this is due to a lack of significant temperature change across the latitudinal gradient, and, in particular, to the fauna's evolutionary history in association with aridification, which makes it unusually resilient to increasing aridity. The diversity of other important faunal groups such as termites and lizards is also exceptionally high in arid Australia and is likewise not closely linked to rainfall in Australian savannas. We predict that these taxa are far more sensitive to increasing aridity in savannas elsewhere in the world, and especially in the Neotropics, where savannas have an evolutionary association with humid rain forest rather than desert.
DOI http://dx.doi.org/10.1111/jbi.12599   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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