A Theoretical Investigation into the Direct and Indirect Effects of State on the Risk of Predation

✍ Scribed by NICKY J. WELTON; ALASDAIR I. HOUSTON

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 487 KB
• Volume: 213
• Category: Article
• ISSN: 0022-5193
• DOI: 10.1006/jtbi.2001.2419

✦ Synopsis

As well as there being a direct physical e!ect of the state (for example fat reserves, or size) of an animal on the risk of being caught by a predator, state also has an e!ect on predation risk indirectly through changes in behaviour. We present a mathematical model which looks at these two components of the e!ect of state on predation risk. We focus on two di!erent models, (i) where the animal must achieve a "xed state and its "tness depends on the time at which this state is reached and (ii) where the animal must survive until a "xed time and its "tness depends on its "nal state. We investigate conditions under which the indirect e!ect of increased state is to increase or decrease predation risk, and give some numerical illustrations. Under certain conditions in the "xed-state model, the indirect e!ect of state is to increase predation risk, whereas under certain conditions in the "xed-time model the indirect e!ect of state is to decrease predation risk. We discuss the implications of our results for empirical investigations into the e!ect of state on predation risk.