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Testing competing measures of profitability for mobile resources.

Barrette, Maryse; Wu, Gi-Mick; Brodeur, Jacques; Giraldeau, Luc-Alain; Boivin, Guy (2009). Testing competing measures of profitability for mobile resources. Oecologia , vol. 158 , nº 4. p. 757-764. DOI: 10.1007/s00442-008-1175-y.

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Résumé

Optimal diet theory often fails to predict a forager’s diet choice when prey are mobile. Because they escape or defend themselves, mobile prey are likely to increase the forager’s handling time, thereby decreasing its fitness gain rate. Many animals have been shown to select their prey so as to maximize either their fitness gain or their fitness gain rate. However, no study has yet compared directly these two measures of profitability by generating testable predictions about the choice of the forager. Under laboratory conditions, we compared these two measures of profitability, using the aphid parasitoid Aphidius colemani and its host, Myzus persicae. Fitness gain was calculated for parasitoids developing in each host instar by measuring life-history traits such as developmental time, sex ratio and fecundity. Fitness gain rate was estimated by dividing fitness gain by handling time, the time required to subdue the host. Fourth instar aphids provided the best fitness gain to parasitoids, whereas second instar aphids were the most profitable in terms of fitness gain rate. Host choice tests showed that A. colemani females preferred second instar hosts, suggesting that their decision maximizes fitness gain rate over fitness gain. Our results indicate that fitness gain rate is a reliable predictor of animal’s choice for foragers exploiting resources that impose additional time cost due to their mobility.

Type de document: Article
Mots-clés libres: fitness; handling time; parasitoids; optimal diet
Centre: Institut national de la recherche scientifique
Date de dépôt: 02 mai 2018 18:19
Dernière modification: 02 mai 2018 18:19
URI: http://espace.inrs.ca/id/eprint/6966

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