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When does a reproducing female viper (Vipera aspis) ‘decide’ on her litter size?

Published online by Cambridge University Press:  17 February 2003

Olivier Lourdais
Affiliation:
Centre d'Etudes Biologiques de Chizé, CNRS, 79360, Villiers en Bois, France University of Poitiers, 40 avenue du recteur Pineau, 86022 Poitiers, France
Xavier Bonnet
Affiliation:
Conseil Général des Deux Sèvres, rue de l'abreuvoir, 79000 Niort, France
Richard Shine
Affiliation:
Biological Sciences, University of Sydney, Sydney, NSW 2006, Australia
Emily N. Taylor
Affiliation:
Department of Biology, Arizona State University, Tempe, AZ 85287-1501, U.S.A.
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Abstract

Some organisms rely on stored energy to fuel reproductive expenditure (capital breeders) whereas others use energy gained during the reproductive bout itself (income breeders). Most species occupy intermediate positions on this continuum, but few experimental data are available on the timescale over which food intake can affect fecundity. Mark–recapture studies of free-ranging female aspic vipers Vipera aspis have suggested that reproductive output relies not only on the energy in fat bodies accumulated in previous years, but also on food intake immediately before ovulation. A simple experiment was conducted to test this hypothesis, maintaining female snakes in captivity throughout the vitellogenic period and controlling their food intake. The energy input of a female strongly influenced the amount of mass that she gained and the number of ova that she ovulated. Multiple regression showed that litter size in these snakes was affected both by maternal body condition in early spring (an indicator of foraging success over previous years) and by food intake in the spring before ovulation. Our experimental data thus reinforce the results of descriptive studies on free-ranging snakes, and emphasize the flexibility of energy allocation patterns among vipers. Reproducing female vipers may combine energy from ‘capital’ and ‘income’ to maximize their litter sizes in the face of fluctuating levels of prey abundance.

Type
Research Article
Copyright
2003 The Zoological Society of London

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