Chapter 51 Population Ecology

Chapter 35 Behavioral Ecology
Define behavior.
 Behavior encompasses a wide range of
 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
 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
 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
• 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
• 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
• Sensitive period
• Ex. Young geese follow mother
Explain how genes and
environment contribute to
• 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
• Kinesis – simple change in activity/turning rate
in response to a stimulus
▫ Sow bugs more active in dry, less active in humid
• Taxis – automatic, oriented movement toward
(positive) or away from (negative) some
▫ 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
• 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
• Ex. Naked mole rat.
Define the concept of kin
• Natural selection that favors altruistic behavior
by enhancing reproductive success of relatives
▫ Weakens with hereditary distance
▫ Quantifiable