Behavioral Ecology

1
Behavioral Ecology

• Chapter 51

2
Behavior

• behavior everything an animal does and how it
  does it
• behaviors generate 2 types of questions
• proximate HOW?
• do environmental stimuli trigger the behavior?
• are there genetic, physiological, and anatomical
  mechanisms underlying the behavioral act ?
• ultimate WHY?
• does the behavior have evolutionary significance?

behavioral response to threat erect fins
3
Ethology

• ethology the scientific study of how animals
  behave, particularly in their natural
  environments
• questions at the core of ethology
• What is the mechanistic basis of the behavior,
  including chemical, anatomical, and physiological
  mechanisms?
• How does development of the animal, from zygote
  to mature individual, influence the behavior?
• What is the evolutionary history of the behavior?
• How does the behavior contribute to survival and
  reproduction (fitness)?

4
Fixed Action Pattern (FAP)

• a FAP is a sequence of unlearned behavioral acts
  that is essentially unchangeable and, once
  initiated, is usually carried to completion
• this type of behavior is studied extensively by
  the ethologists
• a FAP is triggered by an external sensory
  stimulus known as a sign stimulus
• (ex) the red underside of a male intruder
  triggers the male threespined stickleback fish
  to attack

5
FAP Example

• the red underside of a male intruder triggers the
  male threespined stickleback fish to attack

6
Imprinting

• imprinting is a type of behavior that includes
  both learning and innate components and is
  generally irreversible
• involves a sensitive period a limited phase in
  an animal's development that is the only time
  when certain behaviors can be learned
• this type of behavior is also studied by
  ethologists

7
Imprinting Example

• In species that provide parental care,
  parentoffspring bonding is a critical part of
  the life cycle. During the period of bonding, the
  young imprint on their parent and learn the basic
  behaviors of their species, while the parent
  learns to recognize its offspring

8
Nature vs. Nurture

• behavioral traits are the result of complex
  interactions between genetic and environmental
  factors
• thus, in biology, nature vs. nurture is not a
  debate
• biologists study how both genes and the
  environment influence the development of
  phenotypes, including behavioral phenotypes

9
Innate Behavior

• behavior that is developmentally fixed
• under strong genetic influence
• examples
• directed movements (kinesis, taxis, migration)
• animal signals communication
• mating parental behaviors

10
Directed Movements

• kinesis a simple change in activity or turning
  rate in response to a stimulus
• taxis an automatic, oriented movement toward
  () or away from () some stimulus
• bird migration

11
Signals Communication

• signal a behavior that causes a change in
  another animal's behavior (aka display)
• (ex) pheromones chemical substances in odors
• communication the transmission of, reception
  of, and response to signals
• reception can be visual, auditory, chemical
  (olfactory), tactile, or electrical

12
Mating Parental Behaviors

• prairie voles are monogamous
• male prairie voles form a strong pairbond with a
  single female after they mate
• male prairie voles also help their mates care for
  young
• they spend a great deal of time hovering over
  their young, licking them, and carrying them
  around

13
Environment Behavior

• environmental factors, such as the following, can
  influence the development of behaviors
• quality of the diet
• nature of social interactions
• opportunities for learning

14
Diet

• diet can influence mate choice
• (ex) mate choice by females in some Drosophila
  species is strongly influenced by the dietary
  environment in which larvae develop

15
Social Environment

• crossfostered California whitefooted mice
  adopt some of the behaviors of their foster
  parents
• this suggests that experience during development
  can lead to changes in parental and aggressive
  behaviors (in these rodents) that can be passed
  from one generation to the next

16
Learning

• learning the modification of behavior based on
  specific experiences
• types of learning include
• habituation the loss of responsiveness to
  stimuli that convey little or no information
• spatial learning the modification of behavior
  based on experience with the spatial structure of
  the environment
• cognitive mapping an internal representation of
  the spatial relationships between objects in an
  animal's surroundings
• associative learning - ability of many animals to
  associate one feature of the environment (a
  stimulus, such as color) with another (bad taste)
  
• classical conditioning an arbitrary stimulus is
  associated with a reward or punishment
• operant conditioning trial-and-error learning
• cognition the ability of an animal's nervous
  system to perceive, store, process, and use
  information gathered by sensory receptors
  (associated with problem solving)

17
Evolution of Behavioral Traits

• natural selection can result in the evolution of
  behavioral traits in populations
• one source of evidence behavioral variation
  between and within species
• (ex) prey selection aggressive behavior
• when behavioral variation within a species
  corresponds to variation in environmental
  conditions, it may be evidence of past evolution
• natural selection favors behaviors that increase
  survival and reproductive success
• (ex) foraging mate choice behaviors

18
Foraging Behavior

• foraging includes eating and any mechanisms an
  animal uses to recognize, search for, and capture
  food items
• natural selection should favor foraging behavior
  that minimizes the costs of foraging and
  maximizes the benefits

• this is based on the optimal foraging theory
  which views foraging behavior as a compromise
  between the benefits of nutrition and the costs
  of obtaining food

19
Mating Behavior

• includes seeking or attracting mates, choosing
  among potential mates, and competing for mates
• how mating behavior enhances reproductive success
  depends on the species' mating system
  (promiscuous, monogamous, polygamous)
• mate preferences by females may play a central
  role in the evolution of male behavior and
  anatomy
• male competition for mates can reduce variation
  among males
• competition for mates (or other resources like
  food) may involve agonistic behavior a
  ritualized contest that determines which
  competitor gains access to the resource

20
Game Theory

• a way of thinking about behavioral evolution in
  situations where the fitness of a particular
  behavioral phenotype is influenced by other
  behavioral phenotypes in the population
• (ex) side-blotched lizards
• the relative mating success of each male
  type is not fixed but changes with the
  relative abundance of the other
  male types in the populations

21
Altruism

• some animals behave in ways that reduce their
  individual fitness but increase the fitness of
  other individuals in the population
• inclusive fitness can account for most altruistic
  social behavior
• inclusive fitness the 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 those genes, to produce offspring
• natural selection that favors this enhancement of
  the reproductive success of relatives is called
  kin selection

22
Hamiltons Rule

• a quantitative measure for predicting when
  natural selection will favor altruistic acts
  among related individuals
• the three key variables in an act of altruism
  are
• B benefit to the recipient
• the average number of extra offspring that the
  beneficiary of an altruistic act produces
• C cost to the altruist
• how many fewer offspring the altruist produces
• r coefficient of relatedness
• the probability that if two individuals share a
  common parent or ancestor, a particular gene
  present in one individual will also be present in
  the second individual
• natural selection favors altruism when rB gt C

23
Reciprocal Altruism

• altruistic behavior between unrelated
  individuals, whereby the current altruistic
  individual benefits in the future when the
  current beneficiary reciprocates
• commonly invoked to explain altruism between
  unrelated humans rare in other animals
• limited largely to species (such as chimpanzees)
  with social groups stable enough that individuals
  have many chances to exchange aid

24
Social Learning

• social learning learning through observing
  others
• forms the roots of culture a system of
  information transfer through social learning or
  teaching that influences the behavior of
  individuals in a population
• cultural transfer of information has the
  potential to alter behavioral phenotypes and, in
  turn, to influence the fitness of individuals
• in many species, mate choice is strongly
  influenced by social learning (mate choice
  copying)

25
Sociobiology

• sociobiology the study of social behavior based
  on evolutionary theory
• main premise is that certain behavioral
  characteristics exist because they are
  expressions of genes that have been perpetuated
  by natural selection