1 Chapter 32 Behavioral Ecology Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright.

1

Chapter 32Behavioral

EcologyLecture Outline

See PowerPoint Image Slidesfor all figures and tables pre-inserted into

PowerPoint without notes.

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32.1 Nature versus Nurture: Genetic Influences

• Behavior– Any action that can be observed and

described– Genes, to a degree, control behavior

32.1 Nature versus Nurture: Genetic Influences

• Experiments with Lovebirds, Snakes, and Snails– Lovebird Nesting Behavior

• Fischer lovebirds, Agapornis fischeri, cut strips from leaves and carry them to their nest site

• Peach-face lovebirds, Agapornis roseicollis, also cut strips but tuck them into their rump feather and carry them that way

• Hybrid lovebirds exhibit intermediate behavior. They cut strips and try to tuck them into feathers, but are unsuccessful

• These studies support the hypothesis that behavior has a genetic basis

Nest Building Behavior in Lovebirds

a. Fischer lovebird with nesting material in its beak

© Joe McDonald, Courtesy Jeff and Wendy Martin, Refuge for Saving the Wildlife, Inc.

b. Peach-faced lovebird with nesting material in its rump feathers.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

32.1 Nature versus Nurture: Genetic Influences

• Experiments with Lovebirds, Snakes, and Snails– Garter Snake Experiments

• Genetic role in food preference– Inland populations of garter snakes are aquatic and feed

in the water on fish and frogs– Coastal populations are terrestrial and feed on slugs– In the laboratory, inland snakes refused slugs, while

coastal snakes readily accepted them• Hybrid snakes exhibited intermediate acceptance of

slugs as food

• This study suggests a genetic basis for feeding preference

32.1 Nature versus Nurture: Genetic Influences

• Experiments with Lovebirds, Snakes, and Snails– Garter Snake Experiments

• Determined that sensory receptors are specific for prey – Researchers presented baby snakes with slug extract on

cotton swabs and then counted the number of tongue flicks

• Coastal snakes had a higher number of tongue flicks than inland snakes

• Apparently, coastal snakes have many receptors on their tongues for taste and smell of slugs, inland snakes do not

• A genetic difference between the two populations results in a physiological difference in nervous systems.

Feeding Behavior in Garter SnakesCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Inland garter snake does not eat slugs.

Coastal garter snake eats slugs. 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

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32.1 Nature versus Nurture: Genetic Influences

• Experiments with Lovebirds, Snakes, and Snails– Snail experiments

• Show role of endocrine system in behavior• ELH - egg-laying hormone was isolated in Aplysia

snails• ELH controls all aspects of egg laying behavior

– After mating, snail pulls egg string with mouth, winds it in a loose ball, and attaches it to an object

– When given ELH, snail exhibits all behaviors even without mating

32.1 Nature versus Nurture: Genetic Influences

• Experiments with Humans– Twin Studies

• Look at characteristics of twins raised apart• Many share common preferences in food, activity

patterns, and mate selection• Lend support to the hypothesis that at least certain

types of behavior are primarily influenced by nature (i.e., genes)

32.2 Nature versus Nurture: Environmental Influences

• Environmental influences (nutire) also affect behavior

• Fixed Action Patterns (FAP): specific behaviors elicited by a sign stimulus

• Learning: A durable change in behavior brought about by experience

32.2 Nature versus Nurture: Environmental Influences

• Learning in Birds– Appears to be a FAP but involves learning

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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a. Laughing gull adult and chick, Leucophaeus atricilla

Peckingaccuracyof newborn

Peckingaccuracy oftwo-day old

32.2 Nature versus Nurture: Environmental Influences

• Learning in Birds– Imprinting: a simple form of learning

• Young birds follow the first moving object they see– Sensitive period: time during which imprinting

may occur• Social interactions between parent and offspring

during the sensitive period are important– Young birds are sensitive to parents

vocalization even before hatching

32.2 Nature versus Nurture: Environmental Influences

• Learning in Birds– Song Learning

• White-crowned sparrows: species-specific song with different dialects; experiments show learning plays a role

• Birds that heard no songs: sang an undeveloped song as adults

• Birds that heard species song: sang in that dialect as long as tape was played during a sensitive period

• Birds that had adult tutor: sang the tutor’s song even if a different species and no matter when tutoring began

32.2 Nature versus Nurture: Environmental Influences

• Associative Learning– A change in behavior that involves an association

between two events– Classical Conditioning

• The presentation of two different types of stimuli at the same time causes an animal to form an association between them

– Operant Conditioning• A stimulus-response connection is strengthened• Training an animal by rewarding it

Classical ConditioningCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

saliva at sight of food

(unconditionedresponse)

saliva atsound of bell only

(conditioned response)

sound of bell(conditioned

stimulus)

apparatus tomeasure saliva

food(unconditioned

stimulus)

32.3 Animal Communication

• Communication– An action by a sender that influences the

behavior of the receiver– Chemical Communication: Pheromones

• Powerful chemical signals passed in low concentration

• May be released into the air or used in territory marking

– Auditory Communication• Very rapid and can be modified for specific situations

Use of a Pheromone(Chemical Communication)

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(main): © Arco Images/GmbH/Alamy; (inset): © Fritz Polking/Visuals Unlimited

32.3 Animal Communication

• Communication– Visual Communication

• Most used by diurnal species - must be able to be seen

• Plumage, courtship “dances”, aggressive displays, firefly flashes

– Tactile Communication• Occurs when one individual touches another

• Laughing gull chicks peck at the parent’s beak to induce the parent to feed them

• Waggle dance of honeybees

A Male Baboon Displaying Full Threat

Communication Among Bees(Tactile Communication)

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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

a: © OSF/Animals Animals

32.4 Behaviors that Affect Fitness

• Assume that most behavior is subject to natural selection

• Much of the behavior we observe must have adaptive value

• Territoriality– Defending a portion of the home range– More likely during reproductive time period– Cost – takes energy to sing and fight– Benefits outweigh the cost

32.4 Behaviors that Affect Fitness

• Foraging For Food– Animals need to ingest food that will provide

more energy than the effort expended acquiring the food

– Optimal foraging theory– Animals face trade-off of foraging for food or

avoiding predators

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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32.4 Behaviors that Affect Fitness

• Reproductive Strategies and Fitness– Usually, primates are polygamous

• Males monopolize multiple females• Females invest more in offspring

– Adaptive for females to be concerned with good food source – clump around food source

• Males are expected to compete with other males for the limited number of receptive females available

32.4 Behaviors that Affect Fitness

• Sexual Selection– Form of natural selection that favors features

that increase an animal’s chances of mating– Features are adaptive in the sense that they

lead to increased fitness– Often results in:

• Female choice – limited number of eggs to fertilize• Male competition – fertilize as many eggs as

possible

32.4 Behaviors that Affect Fitness

• Mating in Humans– Human Males Compete

• Women invest more time and energy in a child biologically– Nine month pregnancy and then lactation

• Men only need to contribute sperm during sex act• Result: men are more available for reproduction than

women– Because more men are available, they must compete

• Humans are dimorphic: men are larger and stronger perhaps as a result of past selection by females

– Males pay a price. The average life span is seven years less than females

32.4 Behaviors that Affect Fitness

• Mating in Humans– Females Choose

• In one study, the ability to achieve financial success was found to be the most preferred trait by females

• Other studies have shown that facial body symmetry is important

– Men Also Have a Choice• Men prefer youthfulness and attractiveness in females, signs

that their partner can provide them with children.• By choosing younger women, older men can increase their

fitness.

32.4 Behaviors that Affect Fitness

• Societies and Fitness– Sociobiologists hypothesize that societies

form when living in a society has a greater reproductive benefit than reproductive cost

– Group living does have its benefits• Avoid predators, rear offspring, find food

– Group living also has its disadvantages• Disputes, illness

32.4 Behaviors that Affect Fitness

• Sociobiology and Human Culture– Humans live in organized societies– The culture of a human society involves a wide

spectrum of customs– The earliest organized societies may have been the

“hunters-gatherers”– A predatory lifestyle likely encouraged the evolution of

intelligence and the development of language

32.4 Behaviors that Affect Fitness

• Altruisms versus Self-Interest– Self-sacrificing behavior for the good of another

member of the society– Kin selection

• Close relatives share many of your genes, it may make sense to self-sacrifice to save them

– Inclusive fitness• An individual’s personal reproductive success, as

well as that of his or her relatives, and thus to an individual’s total genetic contribution to the next generation

32.4 Behaviors that Affect Fitness

• Reciprocal Altruism– Minimal short-term reproductive sacrifice

made to maximize future reproductive potential

– Benefits• Helper contributes to survival of kin• Helper more likely to inherit territory

Inclusive Fitness

A meerkat acts as a babysitter for its siblings.