Chapter 35 Behavioral Ecology

Chapter 35 Behavioral Ecology

Define behavior. Behavior encompasses a wide range of

activities. A behavior is an action carried out by muscles

or glands under the control of the nervous system in response to an environmental cue.

Collectively, behavior is the sum of an animal’s responses to internal and external environmental cues.

The questions investigated by behavioral ecologists fall into two broad categories.1. Proximate questions concern the immediate

reason for the behavior. How is it triggered by stimuli (environmental cues

that cause a response)? What physiological or anatomical mechanisms play a

role? What underlying genetic factors are at work? Proximate causes are the answers to such

questions about the immediate mechanism for behavior.

2. Ultimate questions address why a particular behavior occurs. Ultimate causes are the evolutionary explanations for behavior.

Explain what is unique about innate behavior.•Developmentally fixed, despite differences

in development•Under strong genetic influence

Define fixed action patterns and give an example.•Sequence of unlearned behavioral acts

that is essentially unchangeable and, once initiated, usually carried to completion

•Triggered by an external sensory stimulus (sign stimulus)

•Ex. Three-spined stickleback fish attacks other males that invade nesting territory

•Sign stimulus = red underside of intruder

Define imprinting.•Type of behavior that

includes both learning and innate components; generally irreversible

•Sensitive period •Ex. Young geese follow

mother

Explain how genes and environment contribute to behavior.

•Genes and environment interact (not nature VS. nurture, but nature AND nurture)

•Observe the “norm of reaction”▫Vary based on environment?▫Similar, despite environmental differences?

•Developmentally fixed behavior is innate

Distinguish between kinesis and taxis. •Kinesis – simple change in activity/turning

rate in response to a stimulus▫Sow bugs more active in dry, less active in

humid areas•Taxis – automatic, oriented movement

toward (positive) or away from (negative) some stimulus▫Trout swim into current

Explain optimal foraging theory. •Compromise between the benefits of

nutrition and the costs of obtaining food▫Energy expenditure▫Risks of being eaten by predator while

foraging•Natural selection should favor behavior

that minimizes costs and maximizes benefits.

Explain how predation risk may affect the foraging behavior of a prey species.

•A “successful” forager will avoid areas of high risk, even though food availability might be higher in high-risk areas.

Define inclusive fitness and reciprocal altruism. Discuss conditions that would favor the evolution of altruistic behavior. •Inclusive fitness – total effect an

individual has on proliferating its genes by producing its own offspring AND by providing aid that enables other close relatives, who share many of the same genes, to produce offspring.

•Ex. Sterile worker bees labor on behalf of fertile queen

•Ex. Naked mole rat.

Define the concept of kin selection.

•Natural selection that favors altruistic behavior by enhancing reproductive success of relatives▫Weakens with hereditary distance▫Quantifiable