​The Marginal Value Theorem describes the behavior of an animal foraging in a habitat where resources occur in patches. A major prediction of the theorem is how long an animal must stay in a patch to optimize the energy extracted, depending on its travel time to reach the patch, which is depicted in the figure below.​

​Based on this information, choose the option that correctly describes what both P and Q represent.​

Correct option is D

Sol.

• Point P represents the optimum patch residence time, i.e., the time an animal should stay in the patch to maximize net energy gain. Staying beyond this point reduces efficiency.

• Point Q represents the time taken to travel between patches, which influences the optimal residence time (longer travel time → longer stay in patch).

• The slope of the tangent at P corresponds to the average rate of energy gain, balancing time spent traveling and foraging.

Information Booster:

• The Marginal Value Theorem (Charnov, 1976) predicts that animals should leave a resource patch when the instantaneous rate of resource gain falls below the average rate for the environment.

• Travel time between patches affects how long an animal should stay in a patch; longer travel means longer stays to maximize energy efficiency.

• This theory is fundamental in behavioral ecology and optimal foraging theory.