An optimum body size for mammals? Comparative evidence from bats |
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Authors: | K E JONES & A PURVIS |
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Institution: | School of Life Sciences, Roehampton Institute London, West Hill, London SW15 3SN and ,;Department of Biology, Imperial College at Silwood Park, Silwood, Ascot, Berkshire SL5 7PY, UK |
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Abstract: | 1. The distribution of body sizes among mammalian species has been modelled by Brown, Marquet & Taper (1993), who suggest that reproductive power (the rate at which energy from the environment is channelled into offspring production) is maximized at a size of 100 g, and the observed size distribution among species reflects the way reproductive power depends on size. The model makes a testable prediction about life-history allometries: namely, that components of reproductive power should not scale linearly with body size but should change sign at the optimum size. 2. A large set of life-history data from a single clade of small mammals, the bats (Order: Chiroptera), was analysed to test this key prediction. The analyses in this study offer no support for the idea that allometries of reproductive power change sign in bats, either at 100 g or at any other size. Furthermore the life-history allometries of bats, which are mostly below the 100 g optimum, were broadly the same as in mammalian taxa larger than the optimum size. 3. These findings together contradict a key prediction of Brown et al. 's (1993) model to explain the skewed body size distribution across mammalian species. |
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Keywords: | Body size distribution Chiroptera independent contrasts life history reproductive power |
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