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The Size-Grain Hypothesis and Interspecific Scaling in Ants
M. Kaspari and M. D. Weiser
Vol. 13, No. 4 (Aug., 1999), pp. 530-538
Published by: British Ecological Society
Stable URL: http://www.jstor.org/stable/2656560
Page Count: 9
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1. The size-grain hypothesis maintains that as terrestrial walking organisms decrease in size, their environment becomes less planar and more rugose. The benefits of long legs (efficient, speedy movement over a planar environment) may thus decrease with smaller body size, while the costs (larger cross-sectional area limiting access to the interstitial environment) are enhanced. 2. A prediction from this hypothesis - that leg size should increase proportionately with body mass - is examined. Ants are among the smallest walking animals and extend the size gradient five orders of magnitude beyond the traditional `mouse to elephant' curve. The mass of 135 species of worker ants spans 3.7 orders of magnitude (0.008-53 mg). Larger ants tended to be slimmer and longer legged. Ant subfamilies varied in their scaling relationships, but four out of five showed a positive allometry for hind leg length (b > 0.33). Mammals, in contrast, show isometry for leg length over six orders of magnitude. 3. It is suggested that ants make a transition from living in an interstitial environment when small to a planar environment when large, a habit continued by most terrestrial mammals. Head length and pronotum width are robust estimators of mass in ants.
Functional Ecology © 1999 British Ecological Society