Behavioral Ecology

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Chapter 51

• Behavioral Ecology

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Behavioral Ecology

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

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Behavioral Ecology

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

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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.

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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.

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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.

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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.

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Ultimate Questions

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

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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?

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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?

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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.

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Niko Tinbergen

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

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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.

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Niko Tinbergen

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

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Imprinting

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

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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.

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Imprinting

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

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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.

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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.

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Konrad Lorenz

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

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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).

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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.

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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.

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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.

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Taxis

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

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Studying Nature Vs. Nurture--Communication

• Behavior can be controlled by signals and
  responses.
• The transmission of, reception of, and response
  to signals constitute communication.

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The Types of Animal Signals

• There are two main types
• 1. Chemical signals
• 2. Auditory signals

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Chemical Signals

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

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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.

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Natural Selection

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

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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.

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Optimal Foraging

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

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Optimal Foraging

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

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Sexual Selection

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

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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.

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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

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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.

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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.

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Sexual Selection

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

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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.

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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.

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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.

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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.

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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.

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Preservation of Variation

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

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?, ?, 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.

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?, ?, 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.

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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.

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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.

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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

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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

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Game Theory

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

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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.

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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.

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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
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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.