Chapter 51 2011 2012

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

PowerPoint Lectures for Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

Chapter 51Chapter 51

Behavioral Ecology


What You Must Know:

• The difference between kinesis and taxis

• Various forms of animal communication.

• The role of altruism and inclusive fitness in kin selection.


• Behavioral ecology extends observations of animal behavior by studying how such behavior is controlled and how it develops, evolves, and contributes to survival and reproductive success


Concept 51.1: Behavioral ecologists distinguish between proximate and ultimate causes of behavior

• Behavior is what an animal does and how it does it– It is the result of genetic and environmental

factors– It is essential for survival and reproduction– It is subject to natural selection over time

• Natural selection: those best adapted to their environment will survive, reproduce and pass on their traits to the next population..


Proximate and Ultimate Questions

• Ethology is the study of animal behavior. • There are two ways to analyze animal behavior: 1. Proximate, or “how,” questions focus on:

– Environmental stimuli that trigger a behavior– Genetic, physiological, and anatomical mechanisms

underlying a behavior– Example: a female bird chooses to mate with a male

bird who sings the best song2. Ultimate, or “why,” questions focus on evolutionary

significance of a behavior– Why is that behavior important to survival,

reproduction and passing on traits– Example: Females who select the best singing males,

have males who sing well


Innate Behaviors:

• Innate behaviors are developmentally fixed.– They are unlearned behaviors

• You do not have to learn them- you automatically do them without thinking

• Instincts• Reflexes

– Example:• Newly hatched sea turtles go into the ocean


Innate Behaviors/Instincts:

• Fixed Action Pattern

• Kinesis

• Taxis

• Migration

• Circadian rhythms

• Signals

• Waggle dance


Innate Behaviors:

• A fixed action pattern (FAP) is a sequence of unlearned, innate behaviors that is unchangeable

• Once initiated, it is usually carried to completion

• Unchangeable • A FAP is triggered by an external sensory

stimulus known as a sign stimulus• Example: Nicholas Tinbergen

– male stickleback fish, attack red objects.– Sign stimulus: red object– FAP: the attack


• It does not matter the shape of the fish or object.

• When male sticklebacks are presented with an object with RED, they attack.

• They do not attack the fish that looks like a stickleback, but does not have any red on it.

LE 51-4LE 51-4

BEHAVIOR: A male stickleback fish attacks other male sticklebacks that invade its nesting territory.

PROXIMATE CAUSE: The red belly of the intruding male acts as a sign stimulus that releases aggression in a male stickleback.

ULTIMATE CAUSE: By chasing away other male sticklebacks, a male decreases the chance that eggs laid in his nesting territory will be fertilized by another male.


Innate Behavior:

• Undirected Movement:– Kinesis is a simple change in activity in

response to a stimulus.– Examples:– Turn on a light and cockroaches randomly

scatter– **sow (pill) bugs become more active in dry

areas and less active in humid areas• End up spending more time in damp areas

LE 51-7a

Kinesis increases the chance that a sow bug will encounter and stayin a moist environment.

Dry openarea

Moist siteunder leaf

Kinesis


Innate Behavior:

• Directed Movement:– A taxis is an automatic movement toward or

away from a stimulus. • Positive taxis- movement towards the

stimulus• Negative taxis- movement away from the

stimulus• Phototaxis- movement in response to light• Chemotaxis- movement in response to

chemicals• Hydrotaxis• Thermo taxis, etc.


Taxis Example:

• Many stream fish exhibit positive rheotaxis

– In response to a current

– they automatically swim in an upstream direction

– prevents them from being swept away

– keeps them facing the direction from which food will come

LE 51-7b

Positive rheotaxis keeps trout facing into the current, the directionfrom which most food comes.

Directionof rivercurrent


Innate Behaviors:

• Migration: is a complex behavior seen in a wide variety of animals.

– Navigation may be by detection of the Earth’s magnetic field over visual cues


Migration- studies supporting it is innate

• Birds placed in funnel cages left marks indicating the direction they were trying to migrate

Blackcaps placed in a funnel cage left marks indicating the direction in which they were trying to migrate.


Innate Behaviors:

• Circadian rhythms: are those that occur on a daily cycle (24 hours)– Other rhythms that occur over longer periods

of time may be triggered by:• Variations in day lengths• Lunar cycles

– Examples:• Active/rest cycles


Innate Behaviors:

• A signal is a behavior that causes a change in the behavior of another individual and is the basis for animal communication.

• Examples:• Chemical signals:

– Pheromones: are chemical signals that are emitted by members of one species that affect other members of the species.

• Visual signals: such as warning flash- when a deer lifts its tail- white is seen to warn other deer of danger

• Auditory signals: bird singing, mating calls, etc.


Chemical Communication Example

• When a minnow or catfish is injured, an alarm substance in the fish’s skin disperses in the water, inducing a fright response among fish in the area

Minnows are widely dispersed in an aquarium before an alarm substance is introduced.

Within seconds of the alarm substance being introduced, minnows aggregate near the bottom of the aquarium and reduce their movement.


Innate Behaviors:

• The waggle dance of the honeybee as described by Karl von Frisch

– The behavior in which the location and distance of a food source is communicated to the members of a hive by a foraging worker.


51.2 Learning establishes specific links between experience and behavior

• Learning is the modification of behavior based on specific experiences.– Imprinting– Habituation– Spatial learning– Associative learning– Classical conditioning– Operant conditioning– Cognition


Imprinting

• Imprinting is a behavior that includes learning and innate components– Is generally irreversible– It is distinguished from other learning by a

sensitive period– A sensitive period is a limited developmental

phase that is the only time when certain behaviors can be learned


• Young geese following their mother

– Konrad Lorenz showed that when baby geese spent the first few hours of their life with him, they imprinted on him as their parent

Video: Ducklings

Imprinting Example

LE 51-5LE 51-5

BEHAVIOR: Young geese follow and imprint on their mother.

PROXIMATE CAUSE: During an early, critical developmental stage, the young geese observe their mother moving away from them and calling.

ULTIMATE CAUSE: On average, geese that follow and imprint on their mother receive more care and learn necessary skills, and thus have a greater chance of surviving than those that do not follow their mother.


Learned Behavior:

• Habituation: the loss of responsiveness to stimuli that convey little or no information.

– Simple form of learning

– Example: nagging sibling

– A hydra contracts when disturbed by a slight touch, but it stops responding if repeatedly disturbed without further consequences


Learned Behavior:

• A cognitive map is an internal representation of spatial relationships among objects in an animal’s surroundings.

– Spatial learning

NestNo nest

Nest


Learned Behaviors:

• Associative learning is the ability of many animals to associate one feature of their environment with another feature.

– Classical conditioning

– Operant conditioning


Learned Behaviors:

• Classical conditioning : a change in responding that occurs when two stimuli are regularly paired in close succession: the response originally given to the second stimulus comes to be given to the first – Pavlov– Pair an unconditioned stimulus (food) to cause a

response (salivation) to a conditioned stimulus (tuning fork) to create the same response (salivation)

– The conditioned stimulus (tuning fork) would not cause the response (salivation) on its own, it must be FIRST paired with the unconditioned stimulus (tuning fork) and then can be removed.

– This results in the dog salivating (response) to the tuning fork (conditioned response)


Classical Conditioning


Learned Behaviors:

• Operant conditioning occurs as an animals learns to associate one of its behaviors with a reward or punishment. – Rewards: increase the behavior– Punishments: decrease the behavior– Skinner– Trial-and-error learning


Learned Behaviors:

• Cognition is the ability of an animal’s nervous system to perceive, store, process and use information from sensory receptors. – Problem solving– Perception– Pattern recognition– Memory– Language– Art


Concept 51.3: Both Genetic makeup and environment contribute to the development of behaviors.

• Twin studies in humans indicate that both environment and genetics contribute significantly to behaviors.

– Personality, temperament, attitude, social behavior, etc.

• Behavior can be directed by genes.

– For example, a single gene appears to control courtship rituals in fruit flies.


Concept 51.4: Behavioral traits can evolve by natural selection

• Because genes influence behavior, natural selection can result in evolution of behavioral traits in populations

– Those best adapted to their environment, survive, reproduce and pass on their traits (genes).

• As generations continue, those traits will be more common among the population

• Fitness: refers to how well the organism is adapted to its environment


Foraging Behavior:

• Foraging behavior not only includes eating, but also mechanisms used in searching for, recognizing and capturing food.

• The optimal foraging model proposes that it is a compromise between the benefits of nutrition and the cost of obtaining food.


Mating systems

• Vary between species.

• The needs of the young are important in the development of this behavior:

– Promiscuous- no strong pair-bonds

– Monogamous- one male/one female

– Polygamous- one individual mating with several others.

• Ornamental males

LE 51-25b

Among polygynous species, such as elk, the male (left) is often highly ornamented.


Agonistic Behavior

• Are often ritualized contents that determine which competitor gains access to a resource, such as food or mates.


Concept 51.5: Inclusive fitness can account for the evolution of altruistic behavior

• Altruism occurs when animals behave in ways that reduce their individual fitness, but increase the fitness of other individuals in the population.

– selflessness

• Example: a blue jay giving an alarm call attracts attention to its location.

• Example: In naked mole rat populations, nonreproductive individuals may sacrifice their lives protecting the reproductive individuals from predators



• Inclusive fitness: is the total effect an individual has on proliferating (passing on) its genes by producing its own offspring and by providing aid that enables other close relative to produce offspring.

– The natural selection that favors this kind of altruistic behavior by enhancing reproductive success of relatives is called kin selection.

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Chapter 51 2011 2012

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