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Behavioral Ecology

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Title: Behavioral Ecology


1
Chapter 51
  • Behavioral Ecology

2
Behavioral Ecology
  • The scientific observation of animal behavior,
    what controls it, how it develops, evolves, and
    contributes to the reproductive success of an
    organism.

3
Behavioral Ecology
  • Understanding animal behavior is important to
    conserving endangered species and controlling the
    spread of infectious diseases.

4
Animal Behavior
  • There are two main classes of questions that can
    be asked about animal behavior
  • 1. Those that focus on immediate stimulus and
    mechanism of behavior.
  • 2. Those that explore how the behavior
    contributes to the survival and reproductive
    success.

5
What Is Behavior?
  • It is a phenotype--a product of our genes.
  • Behavior is everything an animal does, and how it
    does it.
  • Behavior can also be learned.

6
Proximate and Ultimate Questions
  • The observation of behavior involves proximate
    and ultimate questions.
  • Proximate questions focus on the stimulus and
    what triggers the behavior.
  • Ultimate questions address the evolutionary
    significance of a behavior.

7
Proximate Questions
  • Again, these focus on the stimulus and what
    triggers it.
  • Additionally, it seeks the genetic,
    physiological, and anatomical mechanisms
    underlying the behavior.
  • Most importantly these are mechanism and
    development questions.

8
Ultimate Questions
  • Address evolutionary significance of behavior.
  • They are often questions that propose a
    hypothesis about an observed behavior.

9
4 Questions For Understanding Behavior
  • Proximate Questions (mechanism and development)
  • 1. What is the mechanistic basis for behavior?
  • 2. How does the development of the animal from
    the zygote to the mature individual influence
    behavior?

10
4 Questions For Understanding Behavior
  • Ultimate Questions (evolutionary)
  • 3. What is the evolutionary history of the
    behavior?
  • 4. How does the behavior contribute to the
    survival and reproductive fitness?

11
Fixed Patterns and Imprinting
  • These are two behaviors frequently studied by
    ethologists.
  • Fixed Action Pattern (FAP) is a sequence of
    unlearned behaviors that are essentially
    unchangable.
  • Once initiated, they are carried to completion.
  • An FAP is triggered by an external sensory
    stimulus called a sign stimulus.

12
Niko Tinbergen
  • A classic example of sign stimuli and FAPs
  • 3-spined male stickleback fish.

13
Niko Tinbergen
  • These fish attack other males invading their
    nesting area.
  • The stimulus comes from the red underside of the
    intruder.
  • The stickleback wont attack any fish lacking a
    red-belly. Females dont have red bellies.

14
Niko Tinbergen
  • The male sticklebacks will attack fake models,
    unrealistic models, anything as long as some red
    is present.

15
Imprinting
  • Imprinting is a type of behavior that involves
    both learning and innate components which are
    generally irreversible.

16
Imprinting
  • The sensitive period of imprinting only lasts a
    limited time, and is the only time where certain
    behaviors can be learned.
  • During periods of bonding, young imprint on their
    parents and learn the basic behaviors of their
    species.
  • This is also the period of time where the parents
    learn the appearance of their offspring.

17
Imprinting
  • If bonding doesnt occur, death of the offspring
    usually results.
  • How and on whom do the young know to imprint?

18
Imprinting
  • The tendency to respond is innate in the birds.
  • The outside world provides an imprinting
    stimulus, something to which the response will be
    directed.

19
Konrad Lorenz
  • Lorenz experimented with geese.
  • Extensive research shows that behavioral traits
    are influenced by both genetic and environmental
    components. Just as much as are the anatomical
    and physiological traits.

20
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22
Konrad Lorenz
  • In fact, Lorenz showed that geese (and other
    nidifugous birds) imprint on the first moving
    stimulus they see shortly after their birth.

http//www.awakeningpotentials.com/images/imprinti
ng2.jpg
23
Nature Vs. Nurture
  • This is not a debate in biology. The question
    becomes How do both the genes and the
    environment influence the development of
    phenotypes?
  • Behavior that is developmentally fixed is called
    innate behavior (nature).
  • Behavior that is a result of the environment is
    called learned behavior (nurture).

24
Studying Nature Vs. Nurture--Movements
  • Many movements are under genetic influence and
    are called directed movements.
  • Kinesis is a simple change in activity or turning
    rate in response to a stimulus.

25
Kinesis Example
  • Sow (pill) bugs survive best in moist
    environments.
  • They exhibit kinesis in response to variations in
    humidity.
  • They become more active only in dry areas.
  • They are less active in moist areas.

26
Kinesis
  • The sow bugs dont move toward or away from
    specific conditions.
  • Their increased movement in response to a dry
    condition increases the likelihood they will end
    up under a moist area.
  • When they reach a moist area, they slow down, and
    this increases the likelihood they will stay
    there.

27
Taxis
  • Taxis is the movement toward or away from a
    stimulus.
  • Positive-toward.
  • Negative-away.

28
Studying Nature Vs. Nurture--Communication
  • Behavior can be controlled by signals and
    responses.
  • The transmission of, reception of, and response
    to signals constitute communication.

29
The Types of Animal Signals
  • There are two main types
  • 1. Chemical signals
  • 2. Auditory signals

30
Chemical Signals
  • Chemical signals and pheromones are genetically
    controlled and elicit a behavior in other animals.

31
Auditory Signals
  • Some animals such as birds and insects sing
    songs.
  • Others make noises with their body parts. These
    songs are related to courtship rituals and are
    under genetic control (nature), learned control
    (nurture), and/or both.

32
Natural Selection
  • Natural selection favors behaviors that increase
    survival and reproductive success.
  • This can be observed in nature.

33
Optimal Foraging
  • Optimal foraging behavior looks at the process of
    hunting for food as a compromise between the
    nutritional benefits of gathering food and the
    energy costs of obtaining food.

34
Optimal Foraging
  • According to this theory, natural selection
    favors the individuals that utilize a foraging
    behavior that minimizes energy costs while
    maximizing energy output.

35
Optimal Foraging
  • Example
  • The energy cost-benefit of dropping molluscs on
    the coastal rocks by Northwestern crows.

36
Sexual Selection
  • Recall that it is basically natural selection for
    mating success. Mates are chosen on the basis of
    their characteristics.

37
Sexual Selection
  • Determining the basis of sexual selection in
    female zebra finches.
  • Females imprinted on their fathers, and this was
    demonstrated by experimenting with the young
    finches.

38
Sexual Selection
  • Male zebra finches have a very ornate head
    compared to female finches.
  • On the heads of these birds were taped red
    feathers.
  • Different nests were examined.
  • Only males
  • Males and females
  • Just females

39
Sexual Selection
  • These feathers were taped on before the eyes of
    the young were opened to determine which sex
    played a role in mate preference.
  • The results were compared to control groups of
    offspring whose parents had no headdresses.

40
Sexual Selection
  • When the chicks matured, they were given a
    variety of mate choices.
  • Males had no preference at all toward ornamented
    or non-ornamented females.

41
Sexual Selection
  • Females raised by non-adorned parents or females
    with a headdress, had no preference between
    ornamented or non-ornamented males.

42
Sexual Selection
  • Females raised in families with the male having
    the red headdress preferred males with heads
    having headdresses suggesting females imprint on
    their fathers.

43
Sexual Selection
  • These results also suggest that the mate choice
    selection by females plays a part in the
    evolution of ornamentation in male zebra finches.

44
Sexual Selection
  • There are also forms of male competition for
    mates.
  • Male competition for mates is a source of
    intrasexual competition that can reduce variation.

http//image16.webshots.com/16/1/42/94/183414294zH
oflW_ph.jpg
45
Agonistic Behavior
  • Agonistic behavior, for example, is a ritualistic
    type of competition that determines which
    competitors gain access to a resource such as
    food or mates.
  • The outcome can be determined by strength, size,
    or in the form of horns, teeth, etc.
  • They can be psychological in appearance.

46
Preservation of Variation
  • Although the potential for reduced variation is
    there, there also exists a wide variety of
    individuals with a lot of behavioral and
    morphological adaptation.

47
Preservation of Variation
  • Despite cases of reduced variation, there are
    many species that maintain variation.
  • Isopods that live within sponges are an example.

48
?, ?, and ? Isopods
  • These genetically distinct males live within
    sponges.
  • ?-males defend sponges against other ?-males.
  • ?-males mimic the female morphology and behavior.
    They get no response from ?-males and have free
    access to the harem.
  • ?-males live within the harem.

49
?, ?, and ? Isopods Mating Success
  • The mating success is dependent on the densities
    of males and female living within the sponges.
  • When one female lives in the sponge, the ?-male
    fathers most of the offspring.
  • When there is more than one female, the ?-male
    fathers 60 of the offspring.
  • As the harem size increases, the ?-males
    reproductive rate increases.

50
Conclusions
  • The information demonstrates that the
    reproductive success among the three different
    males is equal.
  • To explain the situation where natural selection
    fails to exclude any one variation (such as the
    one with the ?,?, and ? isopods), scientists use
    what is known as game theory.

51
Game Theory
  • Game theory is used to explain the preservation
    of variation in the face of competition.
  • It evaluates the alternative strategies to a
    situation where the mating outcome depends on the
    strategies of all individuals involved in the
    process.

52
Game Theory An Example
  • The explanation of three different male
    phenotypes in populations of side blotched
    lizards in the inner coastal ranges of
    California.
  • There are 3 genetically controlled colors
  • Orange throats
  • Blue throats
  • Yellow throats

53
Game Theory
  • The frequencies of the individuals in the general
    population fluctuate between the 3 forms.
  • The relative mating success of these three morphs
    changes over time.
  • Its similar to rock, scissors, paper.
  • Blue defeats yellow
  • Orange defeats blue
  • Yellow defeats orange

54
Game Theory
  • Blue defeats yellow because they defend a smaller
    number of females in a smaller area.
  • They cant defend against the aggressive orange.

55
Game Theory
  • Orange moves in and defeats the less aggressive
    blue lizard and takes over a larger area with
    many females.
  • It now comes under attack from the sneaky yellow.

56
Game Theory
  • Due to the large number of females in the orange
    lizards territory, he cant defend against the
    sneaky yellow lizard who eventually takes over.
  • The cycle then repeats.

57
Altruism
  • The selfless behavior of some animals that
    reduces their fitness, but increases the overall
    fitness of the population.
  • Example
  • Beldings ground squirrels give a high pitched
    warning signal but draw attention to themselves.

http//www.sciencecases.org/kin_selection/squirrel
s.jpg
58
Inclusive Fitness
  • Inclusive fitness helps to explain altruism.
    Giving off the warning signal helps to preserve
    the genes of the individual or of its close
    relatives.
  • Protecting offspring in the face of death helps
    to increase their genetic complement in the next
    generation.

59
Reciprocal Altruism
  • This is a case where an animal will act
    altruistically toward another unrelated animal.
  • It is relatively rare, and is often observed in
    situations were the animals are likely to meet
    again where the favor can be returned.

60
Reciprocal Altruism
  • It is a tit-for-tat strategy.
  • Cooperation is key.
  • U of M professors have studied it in animals.
  • Non-cooperative animals bring on retaliation
    until cooperation is reached.

61
Social Learning
  • This is a way many animals learn through
    observation of others.
  • The transfer of information through social
    learning influences the behavior of others.

62
Mate Choice Copying--A Form of Social Learning
  • Individuals in a population copy the mate choice
    of others.
  • A classic example of this involves guppies.

http//www.aquariumschatzberger.com/images/lebendg
ebaerende/15392_guppy-maennchen-rote.JPG
63
Mate Choice Copying--Social Learning
  • Female guppies in the wild prefer to mate with
    males showing a high percentage of orange
    coloration.
  • They also copy the mate choice of other females.
  • That is, they mate with males that have been
    successful at attracting other females.

64
Mate Choice Copying--Social Learning
  • The experiment to demonstrate mate choice copying
    was as follows
  • Female guppies were given the choice of mating
    with males of varying degrees of orange
    coloration.
  • Females were also given the choice between males
    with or without other females present.

65
Mate Choice Copying--Social Learning
  • When the same degree of coloration in males was
    offered to females with another female present
    and engaging in a courtship ritual, the
    experimental females chose the males with little
    coloration.
  • They were copying the mate choice of the other
    females.
  • This demonstrated social learning.

66
Mate Choice Copying--Social Learning
  • What this demonstrates
  • Below a certain threshold of difference in male
    coloration, mate choice copying will mask the
    genetically controlled female preference for
    orange males.
  • A female that mates with males that are
    attractive to other females may increase the
    probability that her male offspring will also be
    attractive and have a high reproductive success.
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