Behaviour Flashcards
What is behavior and what does it encompass?
Actions with which organisms interact with the
external world, it encompasses manipulation of the environment, responses to stimuli, externally observable muscular activity and social behaviour
What 3 fields on science work together to make up the study on animal behaviour
Ethology, experimental psychology and behavioral ecology
What are Tinbergen’s 4 questions
1. Causation / Mechanism • How is the behaviour achieved? 2. Development • How does the behaviour develop in the individual’s lifetime? 3. Evolutionary history • What is the evolutionary history of the behaviour in the individual’s lineage? 4. Functional significance • What is the behaviour’s current adaptive value?
Which of Tinbergen’s questions are proximate causes?
Causation and development
Which of Tinbergen’s questions are ultimate causes (assume fitness maximising)
Evolutioary History ad Functional Significance
What do behavioural adaptations help an individual to do?
Helps them strive to maximize its inclusive fitness
(i.e. number of gene copies produced by itself,
in its offspring, and, if it is social, by its relatives,
in their offspring)
What is the selfish gene view?
Any gene is selected to influence its bearer
such that the organism acts as if striving to
maximize the spread of the gene (e.g. Dawkins
1976)
What are the reasons for expecting genetic
influences on behaviour?
Adaptation in behaviour presupposes (former) existence of genetic variation for behaviour
No a priori reason why behaviour should differ from morphology in being subject to genetic variation
What is the algebraic definition of an ESS
E (Ma, Ma) > E (Mu, Ma) where E (X,Y) = expected payoff when X plays Y
Define ESS
ESS defined as the strategy that, when in the majority,
cannot be invaded by a mutant strategy
What conclusions can be formed when game theory is applied to aggression in the case of the Hawk Dove game
The composition of a population will effect the best strategy (e.g Hawks do better in a pop of doves than with hawk).
A mixture of fighters and displayers can be stable with the proportions depending on the value of winning relative to the cost of injury. All-fight can be an ESS, but not all-display
How does the value of winning a contest relative to the cost of injury effect the proportions of a Hawk and Dove population
As cost of injury rises, proportion of fighters (or tendency to fight)
should fall
As value of winning rises, proportion of fighters (or tendency to
fight) should rise
What can we conclude is behaviour is adaptive
Behaviour is subject to genetic influences, including those underpinned by one or a few genes
What is one cause for behaviour variations within a population
Frequency dependent mechanisms
What is behaviour a product of
Gene-environment interactions
What is a social action
An action that affects the offspring output or survivorship of other individuals
What is the classification for actions where both the recipient and actor gain
mutual benefit (cooperation)
What is the classification for actions where both the recipient and actor lose
Spite
What is the classification for actions where the recipient loses and actor gains
Selfishness
What is the classification for actions where the recipient gains and actor loses
Altruism
What are the issue with cooperative behaviour
what conditions are required for such cooperation?
how it is kept stable – i.e. how is cheating controlled?
Why cooperation between non-relatives evolve
because actor gains offspring
What did W.D Hamilton (1971) reveal about the selfish herd
He showed that, starting with random positioning of individuals, assuming predators preferentially take
marginal individuals, an aggregation would form if each individual sought to minimize its predation risk
What is the dilution effect?
For any one predator attack, the larger the group of prey animals, the smaller is the chance that any particular individual will the victim
2 examples for dilution effect
Forest tent moth catepillars always forage in groups to reduce predation risk
Redshanks in widely spaced groupings are 35% more likely to be targeted by sparrowhawk predators. (Quinn and Cresswell, 2006)
What is needed for reciprocity to be stable
Requires partner fidelity otherwise A could donate to B, but to the delay B may defect before returning the favour. partner fidelity allows A to punish B, so by defecting B might damage itself.
What does reciprocity propose
It proposes that the basic condition for the evolution of
cooperation (mutual benefit) is that a benefit in one
direction must be returned in the other (reciprocated)
What is altruistic behaviour
behaviour that benefits another not closely related receiver while being apparently detrimental
to the organism actor in terms of inclusive fitness.
What do the benefits of reciprocity rely on
They depend on whether the benefit of the altruistic act to the recipient is greater than the cost of the act to
the performer
How does Triver’s define ‘cheating’
It is the failure to reciprocate
Example of reciprocal altruism in cleaning symbiosis
A cleaning organism such as the bluestreak cleaner wrasse, cleans another
organism e.g the Nassau grouper of ectoparasites,
sometimes entering into the gill chambers
and mouth of the “host” in order to do so
Give an argument as to why warning calls benefits the bird acting.
If the actor doesn’t call, the predator will likely eat a its neighbour, which will increase the chances of the actor being eaten because the predator will
be sustained by the meal,
(ii) be more likely to form a specific search
image of the prey species,
(iii) be more likely to learn the habits of
the prey species and perfect his predatory
techniques on it,
(iv) be more likely to frequent the area in
which the birds live, or
(v) be more likely to learn useful information
about the area in which the birds
live.
Explain a state the solution to a one shot game of the Prisoner’s Dilemma
If Player 1 cooperates, Player 2 does better by
defecting
If Player 1 defects, Player 2 does better by
defecting
Player 2 should always defect
Player 1 ‘reasons’ the same way
Both players always defect, even though both would benefit more from cooperating
In one-shot game, ESS is always to defect
What types of altruistic behaviour do human commit
(1) helping in times of danger (e.g. accidents,
predation, intraspecific aggression;
(2) sharing food;
(3) helping the sick, the wounded, or the
very young and old;
(4) sharing implements; and
(5) sharing knowledge.
What is gross cheating
In gross cheating the cheater fails to reciprocate at all, and the altruist suffers the costs of whatever altruism he has dispensed without any compensating benefit
What is subtle cheating
Subtle cheating involves reciprocating, but always attempting to give less than one was given, or more precisely, to give less than the partner would give if the situation were reversed
What is the tit for tat strategy
First cooperate, then do whatever other
player did on previous move
What are the results for the iterated Prisoner’s dilemma and who found them,
Axelrod and Hamilton (1981) created a computer tournament of several different behaviour strategies
and found that that always defect and tit for tat (if started positively) are ESSs
What does the prisoner dilemma reveal about cooperation in principle
cooperation can spread through reciprocity in a world of selfishness, provided it gets started (e.g. through kinship)
Why are the prisoner’s dilemma payoffs and assumptions probably not often all reflected in real world
The prisoners dilemma does not place communication in the model, in the real world negotiations happen
How is reciprocity kept stable
Through long-term association which allows prolonged series of interactions. This is helped by having a good memory for individuals/ advanced cognition and spatial proximity. Also rewarding cooperation and punishing defection
How can a gene for altruism spread through a population?
Such a gene can spread if the actor and recipient are related (kin selection theory) and if more copies of that gene are added to the population than are lost
Define relatedness (r)
the probability that a gene in one individual is present in another individual, due to the two individuals being related (i.e. being kin)
Define haplodiploidy
females are diploid and develop from fertilized eggs, males are haploid and develop from unfertilized eggs
What is the Hamilton’s rule equation(explain what the letters mean)
rb – c > 0 (relatedness times benefit minus cost must be greater than zero)
What, in words, is Hamilton’s rule
Hamilton’s rule states that a gene for altruism spreads if the loss the gene suffers in the sacrifice of the body it occupies is exceeded by the gain the gene experiences via the recipient’s increased reproduction
Why is altruism at the individual level is selfish at the genetic level
the gene spreads if care is directed at individuals
bearing copies of itself
How is Hamilton’s rule effected if r is 0
The equation becomes -C<0 which is impossible
Can Hamilton’s rule work if r is low
yes, because if the benefit is high rb-c can still be greater than 0
Why does kin conflict occur
If different parties in a group are unequally related to
progeny they have different Hamilton’s rules, hence different fitness optima, hence their inclusive fitnesses cannot simultaneously be maximised = Kin-selected conflict
Define potential conflict
kin structure dictates that conflict is potentially present (coexisting parties have different fitness optima
Define actual conflict
conflict is physically manifested, i.e. is expressed
Types of kin conflict
Between parents, offspring-parents and sliblings
Give an example of sibling competition
In sand tiger sharks, the first embryo to reach a certain size, referred to as “the hatchling,” will always consume the smaller, less-developed siblings in the womb. This interutrine cannibalism is also possibly a form of sexual selection as males compete post-fertilization for paternity
Define communication
Involves a sender, a signal and a receiver
– Transmits information or ‘meaning’
– Not necessarily ‘truthful’
– Alters behaviour or probability of behaviour of
receiver
– Occurs via many channels (visual, auditory, olfactory
etc.)
What does communication exclude
Excludes involuntary signals (‘body language’,
tics)
Cooperative communication
When sender and receiver share a coincidence of fitness interests (potential conflict is lacking or is minimized
When will cheating arise
It will arise in a cooperative communication system when the interests of the sender and receiver are not perfectly aligned (e.g. flowers and pollinators), or
when there is exploitation by third parties (e.g. Batesian mimicry)
Why is the success of cheating frequency-dependent
The phenotype for cheating is more effective in a population where there are few cheaters, since if cheaters start increasing in number, their deceptive communication would not be as effect and they would suffer
Why communicate in contests
To void harm to one’s own interests:
– via harm to kin
– via harm to self through escalated fighting
How is communication used in contests
signal conveys information about quality of
sender and that costliness of signal helps ensure its honesty. This benefits sender (signal is believed) and receiver (it receives honest information and doesn’t escalate to fight it cannot win)
How is communication in contests used to maintain an ESS
‘Lying’ is not easy because a truly low-quality individual
cannot sustain energetic, high-cost signalling
What is sexual selection
A subset of natural selection arising through preference by one sex for certain characteristics in individuals of the other sex.
How is intrasexual selection expressed
Competing (typically male-male) for access
to mates; adaptations for conspecific fighting / defence
How is intersexual selection expressed
Extravagant ornaments and displays, typically in males/ assessment and discrimination (mate choice), typically in females
Why does sexual selection occur
Reproductive success in sexually reproducing species
is dependent on acquiring a mate
Parental investment = investment in gamete +
investment in care of offspring
Potential asymmetry in sexes in parental investment -
differential potential reproductive rate (PRR)
When studying fruit flies, what did Bateman report
there was a stronger crrelation between Reproductive Success and Mating Success among males than females
What did Bateman conclude from is findings on fruitflies
Selection should universally favour ‘an undiscriminating eagerness in the males and a discriminating passivity in the females’ to obtain mates. (promiscuous males and choosy females)
What does selection high PRR sex (males) encourage
to maximise rate of mate finding and hence quantity of offspring, hence males competitive (to outcompete other males) and/or showy (to attract females)
What does selection on low PRR sex (females) encourage
to maximise quality of mates and hence quality of offspring, hence females choosy (to select best mates)
Describe the graphs that represent the Bateman Principle
In species without parental care male reproductive success (fitness) rises linearly with rising mate number whilst female reproductive success rises then flattens off with rising mate number
Hence, in these species, males are the high-PRR sex and females the low-PRR sex
What does parental investment (and hence PRR) depend on
relative gamete size and relative amount of parental care
How does parental care affect PRR
Female-only care: male has higher PRR still
Male-only care: female has higher PRR
What conditions does sexual monomorphorism evolve in
With lifetime monogamy with equal, biparental care
equalises PRRs, because male and female PRRs
now perfectly interdependent. Consquently there is less sexual conflict and relaxed sexual selection
What is PRR
Potential reproductive rate
Example monogamy
Black vultures pair both incubate, feed and care for their young and also show sexual monomorphism
Are females ever ornamented
Yes, in species in which there is mainly male parental care, hence females have higher PRR than males. Consequently females will compete with each other and for the male.
What are direct benefits of mate choice to females
Territory - Barn Swallows choose on territory quality
• Food - Common tern provides female with fish
• Nutrients
• Protection
– Predators
– Other potential mates
– Paternal (maternal)
8
Male sexual
What is a lek
aggregation of male animals gathered to engage in competitive displays, lekking, that may entice visiting females which are surveying prospective partners for copulation
What is the lek paradox
- Females receive no direct benefits from males;
they receive only genes. - Leks are characterized by high reproductive skew
– one male gets most of the matings. - After just a few generations of mating, genetic
variation at important fitness loci should be
limited; yet females remain very selective. - What benefit do females get from being choosy?
- What might maintain fitness genetic variability?
What indirect benefits are there to female choice
Attractive sons (Fisher's Principle) Good genes (Signals especially is extravagant and costly and Quality could include genetic resistance to parasites (Hamilton-Zuk hypothesis) Compatible genes
Elaborate on why choosines ensures compatible genes
Choose mate of correct species
– Choose mates that are unrelated to avoid inbreeding, e.g.
many mammals
– Choose mates with compatible immunity genes, e.g.
salmon
What is the Hamilton-Zuk hypothesis
Its the idea that sexual ornaments are indicators of parasite and disease resistance
Evidence for the Hamilton-Zuk hypothesis
Red jungle fowl males were infected with roundworm and their development was monitored. ffected the development and final appearance of ornamental traits and that females preferred males who were not infected.
In species which show no parental care, what does parental investment consist of
Just gamete size, microgametes in males, macro in female (Batemans principle)
What is percentage insurance
evolved mechanisms to increase one’s chances of being the parent of offspring
What is mate guarding?
when one sex (typically male) prevents same-sex competitors having access to its mate, i.e. in attempt to achieve reproductive monopoly of mate
Define pre-copulatory mate guarding
males guard females prior to copulation
Define post-copulatory mate guarding
males guard females after copulation
Why does pre-copulatory mate guarding evolve
when females have temporally restricted period of sexual receptivity. Male finding pre-receptive female benefits from guarding her, since he will be present
when she becomes receptive and so guarantee
that he fathers her offspring
What are the costs to male when mate guarding
cost of not feeding
cost of increased risk of predation
cost of lost opportunities to find other females closer to their receptive period
How can pre-copulatory mate guarding result in male choice for of females
Duration, frequency and costs can be so severe that encourgaes males to be selective of the female they commit to guarding e.g brine shrimp guarding larger females due to their increased fecundity
When does post-copulatory guarding evolve
• Females remain receptive post copulation
– hence mating with new male is possible
• Interval between copulation and egg-laying is short
– hence guarding male doesn’t have to guard too long
• Finding mates is easy
– hence risk of new male encountering female is high
• Last male to fertilize female gains most fertilizations of
eggs
– hence a new male would gain paternity of young at
expense of original male
Why are mating plugs advantageous
advantageous because it would allow a male to increase reproductive success by spending more time pursuing new female mates rather than active mate guarding
What is sperm competiton and what is it driven by?
competition for fertilizations by sperm from different males within a single female’s reproductive tract. Driven by selection on each male to maximize
his paternity
How did sperm competition effect sperm and testes directly
If two males mate with one female, male delivering most sperm likely to father most offspring which drove the evolution of numerous, small, motile sperm and
relatively large testes to produce them
What is some evidence for competition between
ejaculates
significant positive correlation between relative testis mass and level of extra-pair paternity in birds
How can sperm competition manifest
sperm scrapers, selection for numerous, small sperm, and within-ejaculate sperm cooperation
