Award details

Optimal foraging for multiple nutrients: a comparison within and between feeding guilds

Reference	BB/C505483/1
Principal Investigator / Supervisor	Professor Stephen Simpson
Co-Investigators / Co-Supervisors	Professor Owen Lewis, Dr David Mayntz
Institution	University of Oxford
Department	Zoology
Funding type	Research
Value (£)	237,475
Status	Completed
Type	Research Grant
Start date	01/09/2004
End date	29/02/2008
Duration	42 months

Abstract

There is growing evidence that, rather than maximising energy intake subject to constraints, leaf-eating herbivores attempt to regulate intake of multiple nutrients independently. In the complex diets of herbivores, the consumption of nutritionally imbalanced foods is sometimes inevitable, forcing trade-offs between eating too much of nutrients present in the foods in relative excess against too little of those in deficit. Until recently, such situations have not been adequately represented in formulations of foraging theory. We have recently provided the necessary theory to fit this case, using an approach that combines our state-space models of nutrition (Simpson & Raubenheimer, 1993; Raubenheimer & Simpson, 1997) with Tilman¿s (1982) models of resource exploitation. We have shown how the needs for multiple nutrients can be assessed using direct measures of animal performance as the common currency, so that the nutritional strategies of animals can be mapped onto the fitness surface ¿ including the position of regulated points of intake and points of nutrient balance when fed sub-optimal foods. The current project aims to use this approach to study non-foliovorous feeding guilds, including seed feeders, omnivores and predators, as well as to compare two different predator feeding strategies, trap-building and active hunting. We will use four species of carabid beetles: a generalist and a specialist predator, a seed feeder and an omnivore. We will also compare a web-building spider with an actively hunting spider species. The protocol for all test species will comprise three parts. First, we will look for evidence of the ability to regulate and balance intake of the two major nutrient dimensions, protein and non-protein energy (digestible carbohydrate and lipid combined), using standard designs from our state-space Geometric Framework (Simpson & Raubenheimer 1993; Raubenheimer & Simpson, 1997). Second, we will construct performance landscapes across nutrient intakespace, based on multiple measures of performance, including reproduction, somatic growth, development time and survival. Third, we will collect and analyse the composition of real potential food items in the field and map these onto the performance landscapes in nutrient space, to establish how nutritional strategies have been shaped by the ecological environment. The ultimate aim is to unite and reconcile traditional energy-based models of optimal foraging theory with more physiologically realistic multi-nutrient models, and to explore the functional correlates of foraging and post-ingestive regulatory strategies.

Summary

unavailable

Committee	Closed Committee - Animal Sciences (AS)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

I accept the terms and conditions of use (opens in new window)

export PDF file

back to list new search