Chapter 51Chapter 51

Behavioral EcologyBehavioral Ecology

What is Behavior?What is Behavior?

Everything an animal does & how it does Everything an animal does & how it does it. it.

To study behavior you must observe To study behavior you must observe behaviors & study the mechanisms behaviors & study the mechanisms underlying the behavior.underlying the behavior.

When studying animal behavior, you When studying animal behavior, you should ask both should ask both proximateproximate and and ultimateultimate questions…questions…

Proximate QuestionsProximate Questions

These questions focus on the environmental These questions focus on the environmental stimuli that trigger a behavior and the stimuli that trigger a behavior and the genetic, physiological & anatomical genetic, physiological & anatomical mechanisms that power that behavior.mechanisms that power that behavior.

These are “how” questions…These are “how” questions…

Ultimate QuestionsUltimate Questions

These questions address the evolutionary These questions address the evolutionary significance of a behavior.significance of a behavior.

These questions typically suppose that a These questions typically suppose that a behavior increases fitness somehow.behavior increases fitness somehow.

These are “why” questions…These are “why” questions…

Ethology:Ethology: The scientific study of The scientific study of animal behavior.animal behavior.

Supposes that to understand any behavior, you must be Supposes that to understand any behavior, you must be able to answer the following questions:able to answer the following questions:1.) What is the mechanistic basis of the behavior 1.) What is the mechanistic basis of the behavior (chemical, anatomical,etc)?(chemical, anatomical,etc)?2.) How does the development of the animal influence 2.) How does the development of the animal influence the behavior?the behavior?3.) What is the evolutionary history of the behavior?3.) What is the evolutionary history of the behavior?4.) How does the behavior contribute to survival & 4.) How does the behavior contribute to survival & reproduction (fitness)?reproduction (fitness)?

2 types of behavior frequently studied are fixed action 2 types of behavior frequently studied are fixed action patterns and imprinting…patterns and imprinting…

Fixed Action PatternsFixed Action Patterns

Definition: a sequence of behavioral acts that once initiated Definition: a sequence of behavioral acts that once initiated are usually carried to completion (unlearned & are usually carried to completion (unlearned & essentially unchangeable).essentially unchangeable).

Sign stimulus: external stimulus that triggers the FAPSign stimulus: external stimulus that triggers the FAP

Example of FAPExample of FAP

Male 3-spined stickleback fish attacks other Male 3-spined stickleback fish attacks other males that invade its nesting territory.males that invade its nesting territory.

Sign stimulus: red underbelly of male Sign stimulus: red underbelly of male stickleback. stickleback.

Males will assume attack posture as long as Males will assume attack posture as long as some red is present – even with fake some red is present – even with fake models!models!

Causes of Behavior (FAP)Causes of Behavior (FAP)

Proximate cause: red belly of intruding male Proximate cause: red belly of intruding male acts as a stimulus that “releases acts as a stimulus that “releases aggression” in maleaggression” in male

Ultimate cause: Chasing away other males Ultimate cause: Chasing away other males decreases the chance that eggs laid in his decreases the chance that eggs laid in his nesting territory will be fertilized by another nesting territory will be fertilized by another male ---- increases his own fitness.male ---- increases his own fitness.

ImprintingImprinting

Definition: type of behavior that involves Definition: type of behavior that involves both innate & learning components & is both innate & learning components & is generally irreversible.generally irreversible.

Sensitive period: the limited period of time Sensitive period: the limited period of time during which imprinting is possible.during which imprinting is possible.

Example of ImprintingExample of Imprinting

Young geese follow their mother – they Young geese follow their mother – they “imprint” on her and learn her behaviors.“imprint” on her and learn her behaviors.

Sensitive (critical) period is the first few days Sensitive (critical) period is the first few days of life – young geese will imprint on the of life – young geese will imprint on the first object they see that moves toward & first object they see that moves toward & away from them – they then follow it as away from them – they then follow it as their “mother.”their “mother.”

Imprinting in Geese – why?Imprinting in Geese – why?

Proximate cause: During sensitive period, young Proximate cause: During sensitive period, young geese observe mother moving away from them geese observe mother moving away from them & calling (this is their imprinting stimulus and & calling (this is their imprinting stimulus and they will respond to anything – not just a geese – they will respond to anything – not just a geese – during that time).during that time).

Ultimate cause: geese that follow & imprint on Ultimate cause: geese that follow & imprint on their mother receive more care & learn more their mother receive more care & learn more skills & have a greater chance of surviving.skills & have a greater chance of surviving.

Genetic Components of BehaviorGenetic Components of Behavior

Innate Behavior: developmentally fixed & Innate Behavior: developmentally fixed & under strong genetic influence.under strong genetic influence.

Many animal movements are under genetic Many animal movements are under genetic influence…influence…

KinesisKinesis

Definition: change in Definition: change in activity rate in response activity rate in response to a stimulusto a stimulus

Sow bugs survive best in Sow bugs survive best in moist environments. moist environments. When exposed to dry When exposed to dry environments, they environments, they become more active – become more active – increases their chance of increases their chance of finding a moist area.finding a moist area.

TaxisTaxis

Definition: an automatic movement toward Definition: an automatic movement toward (positive taxis) or away (negative taxis) (positive taxis) or away (negative taxis) from a stimulus.from a stimulus.

Animal CommunicationAnimal Communication

Animals communicate by using visual, Animals communicate by using visual, auditory, chemical, tactile AND electrical auditory, chemical, tactile AND electrical signals – many of these are under genetic signals – many of these are under genetic control.control.

Chemical CommunicationChemical Communication

Pheromones: Pheromones: chemical chemical substances that are substances that are emitted by animals emitted by animals --- communication --- communication through odors.through odors.

– Production & Production & response is response is genetically genetically controlled.controlled.

Town ant workers following an artificial trail made by drawing a very dilute solution of the ant's trail pheromone methyl 4-methylpyrrole-2-carboxylate.   Only 0.33 mg of this pheromone would draw a detectable trail around the world.

Auditory CommunicationAuditory Communication

In most insects, mating songs are In most insects, mating songs are genetically controlled. genetically controlled.

Insects raised in isolation can sing their Insects raised in isolation can sing their species unique song. species unique song.

With birds, songs are usually learned (at With birds, songs are usually learned (at least in part).least in part).

Behavior is not all Genetically Behavior is not all Genetically controlled!controlled!

The environment interacting with The environment interacting with an organism’s genotype an organism’s genotype

influences the development of influences the development of behaviors.behaviors.

LearningLearning

Definition: the Definition: the modification of modification of behavior based on behavior based on specific experiences.specific experiences.

Examples of learning…Examples of learning…

HabituationHabituation

Definition: loss of responsiveness to stimuli Definition: loss of responsiveness to stimuli that convey little or no information.that convey little or no information.

If the stimulus doesn’t affect the survival of If the stimulus doesn’t affect the survival of the organism, they stop responding.the organism, they stop responding.

Ultimate cause: increase fitness by allowing Ultimate cause: increase fitness by allowing an animal’s nervous system to focus on an animal’s nervous system to focus on stimuli that ARE conveying info.stimuli that ARE conveying info.

Spatial Information Spatial Information

Definition: modification of behavior based Definition: modification of behavior based on experience with the spatial structure of on experience with the spatial structure of the environment (location of nests, the environment (location of nests, hazards, food, mates).hazards, food, mates).

Associative LearningAssociative Learning

Definition: ability of animals to associate Definition: ability of animals to associate one feature of the environment with one feature of the environment with another.another.

Examples: classical and operant Examples: classical and operant conditioningconditioning

Classical ConditioningClassical Conditioning

Definition: an arbitrary stimulus is Definition: an arbitrary stimulus is associated with a reward or punishmentassociated with a reward or punishment

Famous experiment: Pavlov’s dogs. Dogs Famous experiment: Pavlov’s dogs. Dogs associate ringing of bell with food (reward)associate ringing of bell with food (reward)…begin to salivate when they just hear a …begin to salivate when they just hear a bell.bell.

Operant ConditioningOperant Conditioning

An animal learns to associate one of its own An animal learns to associate one of its own behaviors with a reward or punishment behaviors with a reward or punishment and then tends to repeat or avoid that and then tends to repeat or avoid that behavior.behavior.

(Predators often learn to associate prey with (Predators often learn to associate prey with painful experiences or bad tastes)painful experiences or bad tastes)

B.F. Skinner did some work with this…B.F. Skinner did some work with this…

Concept CheckConcept Check

How might associative learning explain why How might associative learning explain why unrelated distasteful or stinging insects unrelated distasteful or stinging insects have similar colors? (Think why this would have similar colors? (Think why this would be an advantage for the insects in terms of be an advantage for the insects in terms of predators learning).predators learning).

Behavior can Evolve through Behavior can Evolve through Natural SelectionNatural Selection

1.) There is variation in behaviors (feeding 1.) There is variation in behaviors (feeding behaviors, attack behaviors, escape behaviors, behaviors, attack behaviors, escape behaviors, etc).etc).

2.) This variation depends on environment and 2.) This variation depends on environment and animals survival.animals survival.

3.) Some behavioral components are genetic - 3.) Some behavioral components are genetic - passed down from parent to offspring.passed down from parent to offspring.

*Read pages 1118-1121 on this topic. Discusses *Read pages 1118-1121 on this topic. Discusses experiments conducted on garter snake and experiments conducted on garter snake and spider behavior.spider behavior.

Natural Selection favors Natural Selection favors Behaviors that Increase FitnessBehaviors that Increase Fitness

Foraging (obtaining food) BehaviorForaging (obtaining food) Behavior

1.) 1.) Optimal foraging theory:Optimal foraging theory: foraging foraging behavior is a compromise b/w the benefits of behavior is a compromise b/w the benefits of nutrition and the costs of obtaining food.nutrition and the costs of obtaining food.

2.) According to this, natural selection should 2.) According to this, natural selection should favor behavior that minimizes the energy costs favor behavior that minimizes the energy costs of foraging and maximizes the food benefits.of foraging and maximizes the food benefits.

Example: Crow experiment (page 1122)Example: Crow experiment (page 1122)

Mating Behavior & Mate ChoiceMating Behavior & Mate Choice

1.) Mating behavior 1.) Mating behavior is the result of is the result of sexual selection.sexual selection.

2.) As other 2.) As other behaviors, must behaviors, must enhance enhance reproductive reproductive success (fitness).success (fitness).

Mating SystemsMating Systems

1.) In most species, mating is promiscuous – no 1.) In most species, mating is promiscuous – no strong pair bonds or relationships.strong pair bonds or relationships.

2.) Monogamous: one male mating with one 2.) Monogamous: one male mating with one femalefemale

3.) Polygamous: an individual of one sex mating 3.) Polygamous: an individual of one sex mating with several of the other.with several of the other.a.) Polygyny: one male w/ several femalesa.) Polygyny: one male w/ several femalesb.) Polyandry: one female w/ several malesb.) Polyandry: one female w/ several males

Influences on Mating systemsInfluences on Mating systems

1.) The needs of the young: if young require a lot 1.) The needs of the young: if young require a lot of care, male may increase fitness by helping a of care, male may increase fitness by helping a single mate than by seeking other mates.single mate than by seeking other mates.

2.) Certainty of paternity: is low in most species 2.) Certainty of paternity: is low in most species with internal fertilization (even monogamous with internal fertilization (even monogamous ones) b/c the acts of mating and birth are ones) b/c the acts of mating and birth are separated over time – this could be why separated over time – this could be why exclusively male parental care occurs in very exclusively male parental care occurs in very few species of birds & mammals.few species of birds & mammals.

Influences on Mating systems cont’d…Influences on Mating systems cont’d…

a.) Males of many species a.) Males of many species with internal fertilization with internal fertilization try to guard females, try to guard females, remove sperm from remove sperm from female reproductive tract female reproductive tract b/f mating, etc. b/f mating, etc.

b.) W/ external fertilization, if b.) W/ external fertilization, if parental care happens at parental care happens at all, just as likely to be all, just as likely to be male as female.male as female.

Sexual Selection & Mate ChoiceSexual Selection & Mate Choice

Intersexual selection: members of one sex Intersexual selection: members of one sex choose mates on the basis of particular choose mates on the basis of particular characteristics of the other sex.characteristics of the other sex.

Intrasexual selection: competition among Intrasexual selection: competition among members of one sex for mates.members of one sex for mates.

Agonistic behaviorAgonistic behaviorDefinition: ritualized contest Definition: ritualized contest

that determines which that determines which competitor gains access competitor gains access to a resource such as to a resource such as food or mates food or mates (intrasexual selection).(intrasexual selection).

The winner isn’t always the The winner isn’t always the only successful one! only successful one! Many species have Many species have multiple behaviors or multiple behaviors or morphologies that make morphologies that make them successful. them successful.

On to Altruism!On to Altruism!

What?What?

AltruismAltruism

Definition: altruistic behaviors are those that Definition: altruistic behaviors are those that reduce an organism’s individual fitness but reduce an organism’s individual fitness but increase the fitness of another individual in increase the fitness of another individual in the population (this is “selflessness”).the population (this is “selflessness”).

Examples: grounds squirrels give alarm Examples: grounds squirrels give alarm call, societies of honeybees or naked mole call, societies of honeybees or naked mole rats.rats.

Why would an organism be Why would an organism be altruistic???altruistic???

Inclusive FitnessInclusive Fitness

Definition: The total effect an individual has on Definition: The total effect an individual has on passing on its genes by producing its own passing on its genes by producing its own offspring AND by providing aid that enables offspring AND by providing aid that enables close relatives (who share may of those genes) close relatives (who share may of those genes) to produce offspring.to produce offspring.

So, being altruistic (helping out your relatives) So, being altruistic (helping out your relatives) increases your fitness.increases your fitness.

Natural selection that favors altruistic behaviors Natural selection that favors altruistic behaviors that enhance the reproductive success of that enhance the reproductive success of relatives is called relatives is called kin selection.kin selection.

Reciprocal AltruismReciprocal Altruism

Definition: the idea that if you help someone out, they will Definition: the idea that if you help someone out, they will return the favor. Used to explain altruistic behavior b/w return the favor. Used to explain altruistic behavior b/w unrelated individuals.unrelated individuals.

1.) Usually limited to organisms that live in stable social 1.) Usually limited to organisms that live in stable social groups.groups.2.) Occurs most often in groups where individuals are 2.) Occurs most often in groups where individuals are likely to meet again and where there would be negative likely to meet again and where there would be negative consequences for not returning a favor.consequences for not returning a favor.3.) Tit for tat behavioral strategy: an individual treat 3.) Tit for tat behavioral strategy: an individual treat another in the same way it was treated the last time they another in the same way it was treated the last time they met. If not met with cooperative/altruistic behavior, met. If not met with cooperative/altruistic behavior, individuals retaliate.individuals retaliate.

Evolution & Human CultureEvolution & Human Culture

Culture: a system of information transfer through Culture: a system of information transfer through social learning or teaching that influences the social learning or teaching that influences the behavior of individuals in a population. Humans behavior of individuals in a population. Humans aren’t the only ones with cultures!aren’t the only ones with cultures!

Sociobiology (relates human culture to Sociobiology (relates human culture to evolutionary theory): certain behavioral evolutionary theory): certain behavioral characteristics exist because they are characteristics exist because they are expressions of genes that have been expressions of genes that have been perpetuated by natural selection.perpetuated by natural selection.