Altruism Flashcards
What is altruism?
A behaviour that has a fitness cost to the individual and a fitness benefit to the recipient.
-organism behave altruistically only when it increases their inclusive fitness.
Ex: an individual meerkat will sound an alarm if a predator is spotted. This is risky for them, but beneficial to other meerkats.
What are two types of selfish altruism?
-Cooperation: interactions between individuals where both parties benefit from the interaction.
Ex: African wild dogs work together to hunt prey, so that their fitness increases when they cooperate with each other.
-Mutualism: a form of cooperation between two different species.
Ex: cleaner wrasse fish eat dead skins from a client fish. The cleanser wrasse has a reliable food source and the client fish is healthier.
EXTRA: All alleles are selfish when they cause an individual to behave altruistically.
What is reciprocal altruism?
It is a behaviour between a pair of individuals at different times. (When an individual returns the favour later).
Ex:
- vervet monkeys are more likely to groom individuals who have helped them in the past.
- vampire bats donate blood meals to other bats who have previously shared food with them.
1) What is Kin selection altruism?
2) what is direct, indirect and inclusive fitness?
1) It is a form of natural selection that favours traits that increase the survival or reproduction of an individual’s Kin at the expense of the individual.
2)
- direct fitness: the number of offspring an individual produces themselves.
- indirect fitness: the offspring produced by relatives because of the help an individual provides.
- inclusive fitness: the production of offspring via the combination of direct and indirect fitness.
Ex: making alarm calls increases a meerkats’s indirect fitness, since it increases the fitness of relatives.
Though the alarm will decrease direct fitness, meerkats will have a high inclusive fitness and this behaviour is selected.
What is Hamilton’s rule?
It is a formula ( Br > C) explaining under what conditions altruistic behaviours will be favoured by natural selection.
- (B) Benefit to recipient: altruistic behaviours is more likely if the fitness benefit to the recipient is high (high B).
Ex: meerkat alarm calls prevents relative from dying, increasing the # of offspring from that relative.
- (C) Cost to altruist: altruistic behaviour is more likely if the fitness cost to the altruist is low (low c).
Ex: meerkats calls only slightly increase the chance of the caller being killed by the predator.
- (r) Relatedness: altruistic behaviour is more likely if the altruist and recipient are closely related (high r).
Ex: meerkat alarm calls alert family members to danger.
1) What does the Coefficient of relatedness (r) describe?
2) describe parents & offspring
3) describe half siblings
4) describe full siblings
1) It is a measure of how closely related two individuals are, by calculating the probability that an allele in two individuals is inherited from a shared ancestor. ( 0 -> 1) 0 being unrelated and 1 being genetically identical.
2) parents & offspring: 50% chance of sharing an allele with each other so r = 0.5
3) half siblings 50% chance each siblings will inherit a shared allele from their parent so r = 0.5 x 0.5 = 0.25
4) 50% chance each sibling will inherit a shared allele from each parent. So r = 0.25 + 0.25 ( if shared alleles are inherited from both parents you add set of probabilities)
How does inclusive fitness and Hamiltonian rule explain the sexy son hypothesis? (Use description below)
Description:
monogamous male starlings provide resources to their mates, but polygamous males don’t. Females will still mate with polygamous males if they are attractive enough.
Inclusive fitness:
mating with attractive males could increase the female’s inclusive fitness
Hamiltons’s rule:
- B: sons are more attractive to mates and have more offspring
- C: Females forego resources and help with offspring, so they have fewer offspring
- r: females are highly related to their sons ( r = 0.5)
Explain the relationship between a male turkey and it’s brother:
Brothers coordinate their mating displays to attract more females and then chosen between the two. The non-mating male will have a higher inclusive fitness by helping the brother out.
How does plant help neighbouring relatives? (2)
1) Warning of danger: when a plant is attacked they release chemicals to warn neighbours to prepare for defences. (Close relatives benefit more from warnings, and have fewer damages)
2) Sharing resources : plants compete with neighbours for light by allocating energy to growing leaves, so they can capture light before neighbours. (Plants will reduce their leaf growth if they are growing near relative, So they can share resources better)
What is greenbeard effect?
It is when individuals help others that they share recognizable traits with, as they are a signal of similar genetics.
Ex: blue male lizards recognize each other and they cooperate to defend their territories from males of other colours.
