R19 Evolutionary conflict and cooperation

Question 1

What are the types of conflicts ?

Answer 1

Parent-offspring conflict, sibling conflicts and mate conflicts, genetic conflict

Question 2

How do family conflicts arise?

Answer 2

investment in gametes, and offspring success vs investment in offspring (more investment increases the chance of their success)

Conflicts in families are the result of unequal investment from parents, and/or differential investment that maximises individual fitness at the expense of others (e.g., mating partner, offspring, or siblings)

Question 3

In most cases, what does a male want to achieve ?

Answer 3

Multiple mating increases offspring quantity, they go for the quantity of mates

Question 4

In most cases, what does a female want to achieve ?

Answer 4

increase mates doesn’t increase offspring quantity, they go for the quality of mates

Question 5

What is the relatedness coefficient ?

Answer 5

r is the relatedness coefficient, so r=1 for offspring but r=0.5 to offspring from parents. Sibling conflicts have a r of 0.5, one sibling will get a better proportion of both parents.

larger value = more relation

Question 6

Why do females want to conserve resources ?

Answer 6

Females want to conserve as many resources to have as many children as possible, this causes sex conflicts.

Question 7

Males benefit most when females … ?

Answer 7

• Invest in his offspring (instead of another male’s)
• Invest in current reproduction (instead of future reproduction)

Question 8

Females benefit most when … ?

Answer 8

• They produce offspring with the best quality of males
• Get the greatest investment from a male in their offspring

Question 9

Why would a male want to damage a female ?

Answer 9

Males may want to damage females to stop them re-mating until the damage is healed, limits the loss of paternity
- Females lay more eggs so the male does not need to mate again

Question 10

What is inter-loci sexual conflict ?

Answer 10

o Inter-loci sexual conflict (different loci): males develop a morphology that increases their reproductive success, this creates a selective pressure for the females to gain resistance which is on a different locus. This causes a “arms race” where a cycle of constant evolution is created, referred to as “chase away” sexual selection.
 This could lead to speciation, as different male morphology and different female resistance can form

Question 11

What is intra-loci sexual conflict ?

Answer 11

o Intra-locus sexual conflict (same loci): an allele that increases showiness will benefit the male but harm the female, sexual antagonism (SA) can be expressed as females could carry phenotype of the males’ bright colours but have no advantage and costs the organism

Question 12

What is altruism and what are the different types ?

Answer 12

• Collective self-interest: an apparently ‘altruistic’ act benefits the individual; they can get more prey when they cooperate
• Mutual benefits: an altruistic act can be repaid later (reciprocity or ‘reciprocal altruism), like grooming behaviour or alarm calls in birds
• Group selection
  o Doing good things for the group, the population is being selected not the individual
  o Carrying capacity limits the group, dominant females may evict other mating females (meerkats)
  o Requires a thought experiment: a mutation may occur so that the lineage of the ‘only mating female’ is disrupted. The offspring mate despite the rules
  o Group selection is not an evolutionarily stable strategy (ESS)
• Kin selection
  o r – wright’s coefficient of relatedness – the probability that an allele present in an individual is also present, by common descent, in its relatives.

Question 13

What is the value of r between you and:
siblings
parents
half siblings
aunt/uncle/niece/nephew
grandparent
first cousins by two grandparents

Answer 13

1
0.5
0.5
0.25
0.25
0.25
0.125

Question 14

What is inclusive fitness?

Answer 14

the number of offspring equivalents that an individual rears, rescues or otherwise supports through its behaviour

Question 15

How do we work out the inclusive fitness ?

Answer 15

Wi = ai - ci + rij+bij

wi = inclusive fitness of donor
i = individual
ai = direct fitness of donor
ci = effect of altruistic act on donor’s own direct fitness
rij = coefficient of relatedness between donor and recipient
j = recipient
bij = increase in fitness of recipient due to the action of donor

Question 16

What happens in wi is 0?

Answer 16

no mate is present

Question 17

What is Hamiliton’s rule ?

Answer 17

altruism will evolve if:
 Relatedness x benefit to recipient > cost to donor
 r x b > c
 r x b – c > 0

Question 18

what is direct and indirect fitness ?

Answer 18

Direct fitness is the number of offspring the individual procreates, whereas indirect fitness is defined by the number of offspring begotten by the genetic relatives of the individual.

Question 19

Usually, What is the female and male seeking ?

Answer 19

• the females seek quality mates, the males seek multiple mates
• males produce more offspring with more mates, so they seek multiple mates for more offspring

Question 20

How can we tell which sex is investing less ?

Answer 20

The parental investment is unequal

they mate with multiple mates

Question 21

What is polyandry?

Answer 21

Females mate with multiple males
(other way around to the normal)

Question 22

If females have less investment than males what should happen?

Answer 22

Males should be choosy and have a greater opportunity cost to investing in a female’s offspring.

Question 23

How would mutations spread if they affect sexual selection?

Answer 23

• Mutations that confer a mating advantage will spread in males in this example.

Question 24

How can we remove sexual conflicts ?

Answer 24

remove differential investment, one sex wants lots of partners, and another wants to work on the offspring.
- Ensure paternity (that the female invests in his offspring)
- Enforce monogamy (so there is no loss in mating opportunities)

Question 25

What was the holland and rice experiment ?

Answer 25

• One population of fruit flies with sexual conflict and one with monogamy

Question 26

What are the expected outcomes to a population that has the sexual conflict removed ?

Answer 26

No protein compound (that harm the female in fruit fly sex conflict) needed as the female wants to invest in his offspring and only his, Courtship decreases in monogamy, female survival is higher as they aren’t damaged by sexual conflict, females can put more investment into the offspring as less is needed in costly defence to the conflict leading to increase in overall reproduction.

Question 27

How does sexual conflict arise?

Answer 27

Sexual conflict is caused by unequal investment in reproduction and differential costs to missed reproductive opportunities, and can lead to an arms race if the traits in conflict is at different loci or a tug-of-war if the trait is at the same locus. It can lower overall reproduction, but persists because it has advantages to the individuals that engage in the conflict.

Question 28

Why would altruistic behaviour occur in unrelated individuals ?

Answer 28

Apparently altruistic behaviour in unrelated individuals can be due to self-interest or reciprocity and altruism can evolve in related individuals if the cost of the behaviour is low, the benefits are high, and/or they are more closely related.