IEAB group living and animal behaviour

Define altruism

increasing the fitness of another individual at a cost to yourself

Hamilton’s rule

rB > C

the coefficient of relatedness-r-multiplied by the benefits gained by the recipient outweigh the cost to the individual performing the act

What is r within hamilton’s rule?

the percentage of genes shared by common descent between two individuals, from 100 to 0

How do we achieve inclusive fitness?

Helping your own offspring

Helping relatives to raise their offspring

How do animals end up in groups?

1. Increased direct fitness: leads to more fluid groups of non-related individuals

2. increased direct fitness: offspring remain to help parents raise next generations, sometimes due to ecological constraints

3. delayed individual breeding success: help raise non kin to increase your experience and resources, wit until right conditions to breed yourself

what are some advantages of group living?

1. the transmission of information

2. breeding

3. foraging

4. anti-parasite defence

5. anti-predation

6. energy saving

what are some disadvantages of group living?

1. exploitation

2. in-breeding

3. predation

4. competition

5. disease transmission

6. risks to young

what are the different mating systems?

1. polyandry

2. monogamy

3. polygynandry

4. polygyny

outline polyandry

multiple males, one female

the female ensures reproductive success

marmosets

theories behind polyandry

Genetic advantages:

fertility insurance hypothesis

good genes hypothesis

genetic compatability hypothesis

Material advantages:

more resources hypothesis

better protection hypothesis

reduced infanticide hypothesis

what is the fertility insurance hypothesis?

more males reduces the risk that some eggs will remain unfertilised

what is the good genes hypothesis?

social partner has lower genetic quality than other potential donors

what is the genetic compatibility hypothesis?

more mates means more available sperm means more chance of a good DNA match

what is the increased resources hypothesis?

more males means more resources of parental care

what is the better protection hypothesis?

more time with mates (aka protectors) stops other males from harassing them

what is the reduced infanticide hypothesis?

confusion over paternity reduces the likelihood that the father will kill offspring

outline monogamy

1 male 1 female

both parents contribute to parental care

most commonly used strategy in birds - swans

advantages and disadvantages of monogamy

+:

shared care, territory maintenance and resources

-:

lower genetic variation in offspring, can lead to the breaking of monogamy

outline polygynandry

multiple males and multiple females

looser bonds between the mates, rarely pair bonded but may have preferences

males may care for broods of females

strategy more likely to be employed when environment is unpredictable

chimpanzees

outline polygyny

multiple females, one male

often used by males to increase their reproductive fitness

more commonly seen in mammals

3 types

outline the three types of polygyny

1. resource defence polygyny:

2. harems

3. leks

what is resource defence polygyny?

females attracted to a resource, males compete to control it, successful males gain access to the females. occurs in species where resources are patchy

yellow headed blackbird

what are harems?

defended group of females associate with 1 male. females may be related and males compete to gain access to a group. females within the group often have dominance hierarchy. the bigger the harem, the lower the offspring mortality

elephant seals

what are leks?

temporary aggregation of males looking to attract a mate. do not form in relation to resources- occur when males cannot monopolise resources or females. males display and compete with each other. the closer to the centre of the learning arena a male is, the more the male is to be chosen by the females.

greater sage-grouse

define parental care

behaviour directed towards a reproductively immature individual that increases their chance of surviving to become reproductively mature

what are the types of parental care?

1. maternal care: most animals

2. paternal care: short inter-birth interval, females still invest more in reproduction

3. biparental care: male care increases the survival of the offspring. common in birds

4. alloparental care: individuals other than the mum and dad raise young

what are the advantages and disadvantages of providing parental care?

the parent has reduced longevity and immune function, as well as an increase in physical activity

however, there is an increase in long-term direct fitness

what are the types of fertilisation?

internal: riskier for female

external: riskier for male

Outline the role of association in parental care

a close association with the embryo increases the likelihood of parental care

outline the role of paternity certainty in parental care

paternal and biparental care is more likely to occur if the male knows it is the father

define animal behaviour

explain the mechanisms and function of a behaviour and the evolution of biological diversity

define behavioural ecology

how the physical environment impacts on an animal’s behaviour and its evolution

define sociobiology

how an animal’s social environment affects their behaviour and its evolution

what is innate behaviour?

genetically programmed response to an external stimuli

subject to change through mutation, recombination and natural selection

heritable, intrinsic (present in isolation), stereotypical (occurs the same way every time), inflexible and consummate (fully expressed straight away)

example: baby gripping things

what is learned behaviour

relatively persistent change in behaviour that occurs as a result of experience. can be individual and social, but occurs within the lifetime of an individual

non-heritable

extrinsic (absent in isolation

permutable (can change)

adaptable

progressive (can be improved)

imprinting or habituation

what are the two types of behaviour?

innate and learned- exist along a spectrum

what are fixed action patterns

sequences of unlearned behavioural acts

triggered by unique stimulus

unchanging

once initiated, carried out to completion

behavioural cascades can occur

the graylag goose will roll an egg back into its nest with its beak (or anything resembling an egg)

what is habituation?

learning to ignore something. repetition until something fades into the background

prairie dogs have learned to stop responding (with an alarm call) to human footsteps

what is conditional learning?

postitive or negative stimuli, rewarding good behaviour or punishing bad

what is insight learning?

tends to be reserved for animals with higher cognitive capacities- learning from experience

what is imprinting?

programmed learning: innate behaviours are released in response to a learnt stimulus:

critical sensitive period, establishes a preference or avoidance, may be irreversible, stress increases the strength of imprinting

ducks on their mothers

define culture

the transfer of information from individual to individual through social learning within and between generations

individual learning disappears when that individual dies

cultural transmission faster than natural selection changing the frequency of genes that code for a behaviour

why has learning evolved?

we assume there is some cost to learning

we assume the ability to learn is a trait with an underlying genetic basis

the ability to learn will be favoured in environments that change relatively often

no change: fixed genetic rule

constant change: fixed genetic rule

what are the two types of sexual selection?

intrasexual selection: members of one sex compete with each other for access to the other sex (male-male or female-female competition)

intersexual selection: individuals of one sex choose which members of the other sex to mate with

rarely exclusive