4. Kin Selection Flashcards

1
Q

Natural selection selects for behaviours that increase whose chance of survival?

A

Our own, not other people’s

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2
Q

Why do we help others to survive, even when it may negatively affect our own chances of survival?

A

Inclusive fitness - we help those who share our genes

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3
Q

Kin selection is…

A

the propensity to be altruistic to our relatives, which increases our own inclusive fitness

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4
Q

What is kin selection based on?

A

inclusive fitness

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5
Q

Who devised the theory of kin selection?

A

William Hamilton (1964)

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6
Q

Kin selection correlation

A

Help given to relatives positively correlated with relatedness (i.e. how many genes on average are shared)

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7
Q

How did Hamilton express the relationship between helping relatives and relatedness?

A

Hamilton’s Rule

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8
Q

Formula for Hamilton’s Rule

A

rB>C
r = relatedness
B = benefit to recipient
C = cost actor incurs for performing act

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9
Q

Hamilton’s Rule: The bigger the value of r…

A

the greater the difference between the cost and benefit can be

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10
Q

Why are we more likely to rescue a sibling from a burning building than a cousin?

A

The value of r is less for the second cousin than it is for a sibling (we share fewer genes)

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11
Q

What is r in Hamilton’s Rule?

A

probability that 2 individuals share the same gene

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12
Q

Study testing Hamilton’s Rule in humans (Fieldman et al., 2001)

A

Tested Hamilton’s Rule in humans
Painful task for cash prizes (for different recipients each time)
Duration of task positively linked to prize
The greater the relatedness, the longer an individual would endure the painful task

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13
Q

Social behaviour of Hymenoptera:

A

e.g. ants, wasps, bees
individuals care for another’s offspring, defend and clean the nest
workers are sterile and devote lives to aiding survival and reproduction of the “queen” and her offspring

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14
Q

Eusociality in Hymenoptera

A

All members of the nest are related - ‘super sisters’ that share 75% of genes
By helping they enhance survival and reproductive chances of kin
In terms of inclusive fitness, better to help many other than reproduce themselves

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15
Q

Smith, Kish and Crawford (1987)

A

Analysed wealth inheritance in an American sample
Individuals more likely to bequeath (and more) to direct descendants (offspring) than relatives with a lower r value (e.g. spouses)

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16
Q

Females are more likely to care for a child of a relative than a non relative among…

A

Ye’kwana, Efe pygmies, black communities in the USA and Hungarian Gypsies

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17
Q

What is the r of an adopted offspring?

A

0

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18
Q

Adoption in Polynesia

A

as many as 1/4 of all children are adopted

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19
Q

Adoption: Sahlins (1976)

A

shows that evolutionary biology is irrelevant to human behaviour

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20
Q

Adoption: Joan Silk (1980)

A

adoption was mostly by post-reproductive or infertile couples of distant relatives

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21
Q

Kin recognition in mice

A

Mice can recognise offspring due to smells produced by their Major Histocompatibility Complex (MHC)

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22
Q

Study on recognition of twins (Roberts et al., 2005)

A

Individuals able to identify which 2 t shirts had been worn by twins by the smell

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23
Q

Importance of kin recognition

A

It is important to be able to identify who within a group is a relative

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24
Q

Kin recognition: study by DeBruine (2002) on trust

A

Evidence for humans recognising physical cues of kinship
Ps shown pictures of others - would they help them in a trust game?
Ps more likely to trust partners whose face had been manipulated to look like them
Not due to familiarity - no effect for famous people

25
Kin recognition: email study (Oates & Wilson, 2002)
Sent emails requesting help (from someone with either same or different surname to recipient) Individuals more likely to help others who shared their surname, especially if it's rare
26
Why can't helping other with the same surname be an adaptation?
Surnames are very recent in our history
27
Westermarck Effect
Animals receive negative imprinting - prevents them from finding people they grew up with sexually attractive Reduces likelihood of mating with close relatives and producing less viable offspring
28
Evidence for Westermarck Effect
Evidence in many animals, suggesting it is very early adaptation
29
Grandparental Investment
The presence of grandmothers positively affected the inclusive fitness of offspring among 18th/19th century Finnish communities
30
Grandparental Investment: Lahdenperä et al. (2004)
Individuals begin families earlier, had longer reproductive life, shorter gap between offspring & produce offspring more likely to survive into adulthood
31
Why do the closest relatives receive the most help?
They share the most genes
32
Helping relatives increases...
inclusive fitness
33
High reproductive value (RV)
individual of a specific age with high likelihood of producing future offspring
34
When is reproductive value (RV) the highest?
In individuals just passed through puberty and are ready to reproduce
35
Different relatives, different help: Essock-Vitale & McGuire (1985)
LA women were more likely to help kin that were younger than them (high RV)
36
Different relatives, different help: Burnstein et al. (1994)
Help in life-threatening situations decreased as age of kin member increased
37
Different relatives, different help: Smith et al. (1987)
Individuals leave more wealth to offspring than siblings even though both have r of 0.5
38
Trivers Willard effect
Parents invest more in offspring sex that give greatest evolutionary pay-off (i.e. greatest number of grandchildren)
39
How does differing values of r between relatives lead to parent-offspring conflict?
Offspring want maximum parental care (to maximise their inclusive fitness) but parents would rather share this between offspring
40
What causes conflict in the womb?
Mother has only 50% stake in foetus, whereas foetus has 100% stake in itself Also food supply
41
How do many spontaneous abortions and miscarriages occur without the mother knowing?
Due to an evolved mechanism that detects chromosomal abnormalities in foetuses
42
Haig (1993)
Foetuses can produce human chorionic gonadotropin (hCG)m which prevents the mother menstruating and allows the foetus to remain implanted in the uterus Is it he foetus' evolved mechanism to prevent being aborted
43
Conflict in the womb - food supply (Haig, 1993)
The foetus receives food from mother's blood supply Early stages of pregnancy - placental cells destroy arteriolar muscles that control blood flow to foetus When foetus wants nutrients - releases hormones to mother's bloodstream causing other arteries to constrict, but increases nutrients & blood to foetus Leads to increase in blood pressure in mother --> damage to kidneys (pre-eclampsia)
44
How does differing values of r between relatives lead to sibling rivalry?
In a family, siblings will compete for parental care | Each will seek more than their fair share
45
Example of siblicide
Chicks may throw siblings out of the nest in order to gain further resources
46
Why is paternity certainty important for males to avoid being cuckolded?
Investing care into a non-genetic offspring decreases inclusive fitness
47
Paternity certainty - Platek et al. (2002)
Genetic resemblance affects male investment - males invest more in 'offspring' when they saw pictures of them that had been morphed to look like them
48
TRUE OR FALSE: Babies look more like their fathers than their mothers.
False: They look more like their mothers
49
How can principles of paternity certainty be applied to grandparental investment?
Grandparents know that their daughter's offspring are genetically hers However due to paternity uncertainty the same can't be said for a son's offspring Also grandmothers have greater paternity certainty than grandfathers
50
Why is inbreeding linked to poor quality of offspring?
Due to the presence of dangerous alleles, of which everyone has around 2-3 However, only a problem if an individual has 2 recessive copies of that allele (not 1 dominant & 1 recessive) Inbreeding with genetically similar individuals increases chances that both parents have that allele and pass it on The closer the relative, the greater the chance of offspring inheriting both alleles
51
What is the likelihood and amount of investment a parent gives based on?
The r value they share with offspring
52
What leads to investment in non-genetic offspring in humans?
Moral, social norms
53
TRUE OR FALSE: There is evidence that non-genetic offspring receive the same amount of care than genetic relatives.
False
54
Infanticide & parenthood - study in Canada
Examined cases of 408 Canadian children killed by a parent figure Rates of death higher for step-parents Risk of infanticide greatest for children 2 years old or younger Independent of effects of socio-economic status & personality of abusers
55
Infanticide & parenthood - Cross cultural study
Cross-cultural | Ache of Paraguay, 43% of children of step-families died before age 15, compared to 19% raised by genetic parents
56
TRUE OR FALSE: On average a child raised in a step family will have lower reproductive success than those raised by genetic parents.
True
57
Infanticide & parenthood - study in Trinidad
Step-fathers in Trinidad interacted less (and also in a less friendly manner) with step-children than genetic offspring
58
What is the general rule of thumb for kin recognition?
identify those close to you during development as being kin (i.e. Lorenz's chicks)