title: Towards a synthesis of frameworks in nutritional ecology: interacting effects of protein, carbohydrate and phosphorus on field cricket fitness.
abstract: Phosphorus has been identified as an important determinant of nutrition-related biological variation. The macronutrients protein (P) and carbohydrates (C), both alone and interactively, are known to affect animal performance. No study, however, has investigated the importance of phosphorus relative to dietary protein or carbohydrates, or the interactive effects of phosphorus with these macronutrients, on fitness-related traits in animals. We used a nutritional geometry framework to address this question in adult field crickets (Gryllus veletis). Our results showed that lifespan, weight gain, acoustic mate signalling and egg production were maximized on diets with different P : C ratios, that phosphorus did not positively affect any of these fitness traits, and that males and females had different optimal macronutrient intake ratios for reproductive performance. When given a choice, crickets selected diets that maximized both lifespan and reproductive performance by preferentially eating diets with low P : C ratios, and females selected diets with a higher P : C ratio than males. Conversely, phosphorus intake was not regulated. Overall, our findings highlight the importance of disentangling the influences of different nutrients, and of quantifying both their individual and interactive effects, on animal fitness traits, so as to gain a more integrative understanding of their nutritional ecology.
authors.affiliation: Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6 sarah.harrison@carleton.ca.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Harrison
authors.affiliation: Charles Perkins Centre and School of Biological Sciences and Faculty of Veterinary Sciences, University of Sydney, Sydney, New South Wales 2006, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Raubenheimer
authors.affiliation: Charles Perkins Centre and School of Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Simpson
authors.affiliation: Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6.
authors.forename: Jean-Guy J
authors.initials: JG
authors.lastname: Godin
authors.affiliation: Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Bertram
mesh_terms: D000818:Animals; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism*; D005260:Female; D006135:Gryllidae / Q000254:growth & development / Q000378:metabolism*; D008136:Longevity; D008297:Male; D010058:Oviposition; D016226:Phosphorus, Dietary / Q000378:metabolism*; D012737:Sex Factors; D014828:Vocalization, Animal; D015430:Weight Gain
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D016226:Phosphorus, Dietary
keywords: carbohydrate; diet choice; field cricket; nutritional geometry; phosphorus; protein