Animal Behavior exam 1

13 on communication

Hypothesis

are assumptions that make a testable prediction – they are explanations

alternative hypothesis

Multiple hypotheses that compete to explain an observation

Null Hypothesis

s a statistical explanation that observations result from chance.

predictions

are expectations of results and each hypothesis could have multiple predicted outcomes

the hypothesis is

The amount of food in a yard determines the number of robins feeding there.

the prediction is

yards with more food will have more robins

probability

is a measure of how likely something is to occur. If you’ve had statistics, you’ve seen a p-value

p= 0.50

means 50% of the time, random chance would show our results. We then accept the null
hypothesis and say there is no association in the data.

p = 0.05

means 5% of the time, random chance would show our results. This is the accepted value of
significance, and we say that we reject the null hypothesis. There is an association in the data.

scientific theory

is made after a large amount of testable hypotheses support an explanation that
is agreed upon by a majority of experts. It is not a speculative, unsupported statement

evolution by means of natural selection

1. Individuals in a population have variation
2. Variation in a population is heritable
3. Individuals have differential reproduction based on that specific variation

stabilizing selection

directional selection

disruptive selection

research Question: how does territory size in cichlids affect fitness

Hypothesis: an intermediate territory size with optimistic growth.

conclusion: selection will favor individuals that defend intermediate-sized territories, because they will have the highest growth rate.

Directional selection in tree lizards:Prediction: faster individuals should be able to evade predators and capture mobile prey more efficiently.

conclusion: there is strong directional selection on limb length in juveniles that enhances survivorship

Disruptive selection in spadefoot tadpoles Hypothesis: Disruptive selection is acting on tadpole morphology and feeding behavior

conclusion” individuals with specialized morphology have higher fitness than individuals with intermediate morphology.

4 questions of behavior

1. What is the mechanism that causes the behavior?
2. How does the behavior develop?
3. How does the behavior affect survival and reproduction?
4. How did the behavior evolve?

proximate causes

are those that explain what is responsible for the building and operation of an
animal that enable it to exhibit a behavior. (HOW)

They can happen within a single individual

ultimate causes

are those that occur through long-term processes that gradually shape the
history of the species. (WHY)

They can happen over evolutionary time

Approaches to studying behavior

observational, experimental, comparative

observational

no interference, correlational

experimental

manipulative with controls

Comparative

evaluating closely-related groups
 Ancestral (plesiomorphic) trait - Found in commonancestor of two or more species
 Derived (apomorphic) trait - Found in more recentlyevolved species and not present in common ancestor

convergent evolution

distinct ancestry shared mobbing behavior

divergent evolution

shared ancestry divergent behavior

Parent-offspring regression analysis

Examines the similarity between parents and their offspring in terms of the traits they possess
• If a trait has a genetic basis, then the trait values of offspring should be similar to the trait values of their parents: there should be a positive relationship between offspring and parent trait values

2. Selection experiment method:

• Different groups of individuals are subjected to differential selection on the trait in question
• If artificial selection acting on a trait results in changes in that trait value in subsequent generations, then the trait has a genetic basis

why do individuals in population vary?

due to differences in genetic composition, environmental conditions, learning and learning ability.

variation in traits may lead to similiar fitness but

variation doesnt always impact fitness

frequency dependent selection can maintain different

traits in a population, where the fitness of a trait depends on its frequency in a population

Positive frequency-dependent selection,

fitness increases as trait becomes more common

 Negative frequency-dependent selection,

fitness decreases as trait becomes more common

adaptations are traits that result from

natural selection and have been selected for theri current function

direct measure of fitness

number of progeny that go on to reproduce

indirect measures of fitness include

survivorship, number of mates, body size and growth, feeding efficiency

fitness benefit

are those positive effects of a trait on the number of surviving offspring

fitness costs

are damaging effects of a trait on an individuals success of passing on genes to the next generation.

game theory is a cost/benefit approach used

when the behavior that maximizes fitness
depends on the behavior of others

Game theory predicts the evolutionary stable strategy

– the strategy that yields the highest fitness; it can predict the frequency
of different behaviors in a population that all result in equal fitness

How to explain cooperative behavior where individuals help others survive and reproduce?

One explanation was group selection acting on groups
 Problematic explanation due to
faulty logic and existence of “cheaters”

in kin selection, individuals can

increase their fitness by helping kin

Behaviors vary in

their heritability

interactive theory development

All behaviors are associated with both genes and the environment

its not Nature vs nurture so much as it is

Nature with Nurture

innate behaviors can be shaped by

environmental experiences as much as earned behaviors are influence by genetic traits

Many organisms respond to predators with a fixed action pattern

behavior that displays almost no variation and, once started, cannot be stopped until completed

Developmental and behavioral responses to stimuli are controlled by

the nervous system – made up of neurons and neural circuit networks

Behaviors that are part of a FAP are due to the response of

a neural network to the sign stimulus (innate releasing mechanism).

Arginine vasopressin (AVP) is a

peptide hormone and can affect behavior under stressful conditions such as being in the open and light for a nocturnal animal

Environmental exposure to conspecific song

is a critical factor for proper song development in birds

Closed-ended learners must hear a tutor sing its
conspecific song

shortly after hatching in order to
learn the song correctly

Open-ended learners can

acquire new song elements throughout life

Reaction norm represents

the same genotype raised across different environmental conditions resulting in range of behavioral phenotypes

polyphenism

multiple alternative phenotypes

canalization

during development, certain mechanisms are activated to steer development down a particular pathway

cannibals develop with population density, when individuals have

size differences, and when there are more non-siblings

Sensory systems allow

animals to interact and respond to their environment

different sensory receptors can detect

chemicals, light, vibrations, electric fields, or magnetic fields

Sensory receptors are nerve endings that respond

to
environmental stimuli and transmit information via neurons

Types of systems:

Chemoreception
 Photoreception
 Mechanoreception
 Electroreception
 Magnetoreception

Neurons are composed of:

Dendrites that detect a stimulus
 Cell body where information is integrated
 Axon which conducts an electrical signal to the axon terminal where it
can be transmitted to another neuron, organ or muscle

Chemoreception includes:

Gustation: detection of dissolved chemicals, often
within the mouth
 Olfaction: detection of airborne chemical stimuli
 Odorants are general and not species- specific
 Pheromones are species-specific

Photoreception:

Visual sensory systems detect electromagnetic radiation

Mechanoreception

detect mechanical waves or vibration in air, water, or substrates

electroreception

electroreception is most common in sharks and rays, but can be found in some fish, amphibians, and mammals

Magnetoreception

Earth’s magnetic field provides directional information

To determine whether individuals use the earth’s magnetic field for
orientation

, researchers manipulate their experienced magnetic field and observe whether behavior changes

coevolution is a receptor arms race

A back-and-forth process of adaptation in one species favoring counteradaptation in another.

Nueral networks trigger behaviors by:

1. Detecting sensory information

2. relaying messages

3. Controlling motor commands

Stimulus filtering

Nueral networks an also ignore sensory info focus on biologically important ones

Communication

The transfer of information from sender to receiver that affects current/future behavior
and the fitness of one or both individuals.

Signals are not cues

(consistent aspects of environment that can guide behavior)

Example of cue

Group of vultures on ground can be a cue to other scavengers

preexisting trait hypothesis

ritualization

Preexisting bias hypothesis

exploitation

Novel attribute hypothesis

randomization

Chemical signals are relatively

long lasting and can travel great distances, but cannot be modified once transmitted

Visual signals can move rapidly through the environment,

but require adequate light levels and can be blocked by objects

Auditory signals can

travel around objects and can be turned on and off quickly, but attenuate (diminish) as they travel through the environment

Selection should favor

visual signals that contrast with their environment

honest signaling

mating displays, territorial displays

Share Information

Group foraging, territoriality, mating readiness, alarm signaling, social status

deception

deceitful signalling, eavesdropping

honest signaling is conditions that favor

the evolution of signals as accurate or “honest” indicators:

honest signaling facts

1. Fitness interests of signaler and receiver are similar
2. Signals will be accurate when they cannot be faked
3. Signals will be accurate indicators when they are costly to produce or maintain

Courtship displays are

honest

Signaling as cooperation

Alarm calls are unique vocalizations produced when a predator is nearby. Some
species produce different alarm calls for different predators. Interspecies
communication also exists!

deceitful signaling

Using deceptive signals to reduce the fitness of the receiver
 This produces a coevolutionary arms race where signalers are selected to produce signals that affect the behavior of receivers, and receivers are selected for better discrimination
abilities

novel environment hypothesis

response of the receiver
is caused by a mechanism that is no longer adaptive

Net Benefit hypothesis

response of the receiver is caused by a mechanism that reduces fitness, but less than
the net fitness gain of responding