Title: Behavioral Ecology
1Chapter 51
2Behavioral Ecology
- The scientific observation of animal behavior,
what controls it, how it develops, evolves, and
contributes to the reproductive success of an
organism.
3Behavioral Ecology
- Understanding animal behavior is important to
conserving endangered species and controlling the
spread of infectious diseases.
4Animal 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.
5What 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.
6Proximate 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.
7Proximate 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.
8Ultimate Questions
- Address evolutionary significance of behavior.
- They are often questions that propose a
hypothesis about an observed behavior.
94 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?
104 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?
11Fixed 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.
12Niko Tinbergen
- A classic example of sign stimuli and FAPs
- 3-spined male stickleback fish.
13Niko 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.
14Niko Tinbergen
- The male sticklebacks will attack fake models,
unrealistic models, anything as long as some red
is present.
15Imprinting
- Imprinting is a type of behavior that involves
both learning and innate components which are
generally irreversible.
16Imprinting
- 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.
17Imprinting
- If bonding doesnt occur, death of the offspring
usually results. - How and on whom do the young know to imprint?
18Imprinting
- The tendency to respond is innate in the birds.
- The outside world provides an imprinting
stimulus, something to which the response will be
directed.
19Konrad 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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22Konrad 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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ng2.jpg
23Nature 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).
24Studying 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.
25Kinesis 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.
26Kinesis
- 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.
27Taxis
- Taxis is the movement toward or away from a
stimulus. - Positive-toward.
- Negative-away.
28Studying Nature Vs. Nurture--Communication
- Behavior can be controlled by signals and
responses. - The transmission of, reception of, and response
to signals constitute communication.
29The Types of Animal Signals
- There are two main types
- 1. Chemical signals
- 2. Auditory signals
30Chemical Signals
- Chemical signals and pheromones are genetically
controlled and elicit a behavior in other animals.
31Auditory 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.
32Natural Selection
- Natural selection favors behaviors that increase
survival and reproductive success. - This can be observed in nature.
33Optimal 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.
34Optimal Foraging
- According to this theory, natural selection
favors the individuals that utilize a foraging
behavior that minimizes energy costs while
maximizing energy output.
35Optimal Foraging
- Example
- The energy cost-benefit of dropping molluscs on
the coastal rocks by Northwestern crows.
36Sexual Selection
- Recall that it is basically natural selection for
mating success. Mates are chosen on the basis of
their characteristics.
37Sexual 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.
38Sexual 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
39Sexual 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.
40Sexual 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.
41Sexual Selection
- Females raised by non-adorned parents or females
with a headdress, had no preference between
ornamented or non-ornamented males.
42Sexual Selection
- Females raised in families with the male having
the red headdress preferred males with heads
having headdresses suggesting females imprint on
their fathers.
43Sexual Selection
- These results also suggest that the mate choice
selection by females plays a part in the
evolution of ornamentation in male zebra finches.
44Sexual 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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45Agonistic 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.
46Preservation 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.
47Preservation 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.
50Conclusions
- 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.
51Game 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.
52Game 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
53Game 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
54Game Theory
- Blue defeats yellow because they defend a smaller
number of females in a smaller area. - They cant defend against the aggressive orange.
55Game 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.
56Game 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.
57Altruism
- 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.
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s.jpg
58Inclusive 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.
59Reciprocal 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.
60Reciprocal 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.
61Social Learning
- This is a way many animals learn through
observation of others. - The transfer of information through social
learning influences the behavior of others.
62Mate 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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63Mate 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.
64Mate 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.
65Mate 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.
66Mate 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.