prey protein content influence

prey protein content influence - Ecological Entomology...

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© 2009 The Authors Journal compilation © 2009 The Royal Entomological Society Introduction As foraging influences fitness, animals regularly assess the prof- itability of their foraging strategy. Recent models suggest that animals that ingest the most food do not necessarily reap the greatest fitness benefits, rather the quality and balance of nutri- ents ingested is a better determinant of foraging profitability ( Simpson & Raubenheimer, 1993; Bowen et al. ± ,±1995;±Mayntz± et al. , 2005 ). Protein intake, for instance, has been strongly tied to growth in fish, insects, and spiders ( Bowen et al. ± ,± 1995;± Mayntz et al. , 2003; Lee, 2007 ), suggesting that selectively for- aging for high protein food could result in substantial fitness benefits ( Simpson & Raubenheimer, 1993; Bowen et al. ± ,±1995;± Lee, 2007 ). Web building (araneomorph) spiders make excellent study organisms for testing foraging models, as their principal forag- ing cost; silk manufacture and web construction, can be readily observed and quantified ( Sherman, 1994 ). Also, building different webs has differential effects on fitness ( Sherman, 1994; Li, 2005; Venner & Casas, 2005 ). Since they make their webs from biomaterials, araneomorph spiders are potentially subject to a nutritional deficiency and face the dilemma of whether to invest limited nutrients into growth and bodily functions or into web building ( Craig et al. , 1999 , 2000; Higgins & Rankin, 1999 ). Silk is a protein polymer with amino acid sequences and ratios that differ from other biomaterials ( Craig et al. , 1999, 2000 ). As such, the availability of amino acids and protein, place limits on silk synthesis ( Higgins & Rankin, 1999; Craig et al. ± ,±2000±).± Many araneomorphs can partially overcome this limitation by re-ingesting their webs ( Crews & Opell, 2006 ). Nonetheless, the type, quantity, and quality of silks produced vary according to diet ( Higgins & Rankin, 1999; Craig et al. , 2000; Mayntz et al. ± 2003 ). Since fitness parameters such as growth and survivorship are correlated with diet quality ( Bilde & Toft, 1998; Mayntz et al. , 2003 ), silk synthesis may be additionally traded off with fitness parameters. We performed laboratory experiments in which we manipu- lated the dietary protein availability for the orb web building spi- der Argiope keyserlingi . Our aims were to: (1) determine whether dietary protein or energy influences growth and silk investment, Correspondence: Michael B. Thompson, School of Biological Sciences, Heydon-Laurence Building (AO8), University of Sydney, NSW±2006,±Australia.±E-mail:±±mike.Thompson@bio.usyd.edu.au± Prey protein infl uences growth and decoration building in the orb web spider Argiope keyserlingi SEAN J. BLAMIRES , DIETER F. HOCHULI and± ±MICHAEL B. THOMPSON School of Biological Science, University of Sydney, Sydney, Australia Abstract . 1. Protein is important for a foraging animal to consume, as it promotes growth and enhances survival, particularly in web-building spiders, which need to invest considerable protein into web building and may trade-off growth for web investment.
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prey protein content influence - Ecological Entomology...

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