Other conflicts: caste/ worker reproduction

Question 1

Different types of conflict in social insects

Answer 1

Sex allocation conflict: workers want 3:1 and queens want 1:1

Reproduction conflict: who gets to reproduce (workers/ queens) and who gets to become queen?

Question 2

What is reproductive conflict and conflict resolution?

Answer 2

• Potential conflict: any difference in reproductive optima of individuals
• Actual conflict: overt conflict among individuals with different optima
• Conflict resolution: an outcome that reduces to a low level the proportion of the colony’s resources that are wasted in the conflict.

Example: Policing/ coercion
- A response to selfish behavior of others that helps to reduce reproductive conflit (e.g. Stopping worker larvae developement, limiting which larvae become queen)

Example: relatedness
- Kinship is also a mechanism for conflict resolution
- The more related individuals are the less selfishness and conflict there is
Reproductive optima are more aligned

Question 3

Reproductive conflict: Caste conflict

Answer 3

A totipotent larve can either become a queen or a larvae

Queen: Fitness is passed directly to offspring
Workers: Fitness generated by queen reproducing

What effects probality of becoming queen:

The probaility of becoming queen is a function of how many times the queen mates (level of paternity and relatedness in colony).

• If the colony is monogamous then the workers will be more related to their queen so get a greater fitness pay off when queen reproduces so larvae are less likely to become queen.
• If the colony is monogamous, the workers are more related to eachother so there will be a greater cost to the colony due to conflict as more workers try to become queen.

Question 3

Types of policing to control number of queens

Answer 3

Killing queens once they emerge

Example: Stingless Bee
- Monogamous colony
- Honey pots contain food and larvae so no extrinsic control of larvae fait
- 20% become queens -> good example of predicting number of queens based of paternity -> graph
- Once they emerge, the queens are decapitated by workers

Controlling which larvae become queens

Example: Swarming species
- Swarming colonies want v few queen
- old queen swarms off and new queen raised in old nest
- They feed larvae royal jelly which allows them to become queen
- First queen that emerges kills the others
- Conflict resolution: reduce the number fo queens produced (if they were produced they would have to be killed)

The level of conflict resolution varies between colonies depending on the the level of kinship and the amount of coercion that is possible.
- The less kinship the more coercion.

Question 4

Reproductive conflict: male reproduction

Answer 4

As males are haploid, workers can produce males without fetilisation

Polygamous:
- Workers are more related to the queens sons (0.5) than to their nephews (0.25)
- Policing as workers want to stop their sister’s reproducing and promote production of queens sons (Conflict resolution as production of worker sons would lead to conflict)

Monogamous:
- Workers are more related to their nephews (0.5) than to the queens sons
- Excess of worker sons are produced and conflict against the queens sons

Example: Honeybee
- Worker laid eggs and queen laid eggs place in a test comb
- Within 7 hours all worker laid eggs were removed

Example: The common wasp
- Workers also removed worker eggs

As with eusocilaity, worker policing has evolved convergently many times

Question 5

Policing and worker self restraint

Answer 5

• Over time in societies with very good policing, the incentive to lay eggs declines and the ovaries become to under-developed to lay eggs
• This shows conflict resolution due to policing

Question 6

What happens when there is no policing to stop worker reproduction?

Answer 6

• The lack of policing can lead to queen loss, especially when effective paternity is low and workers are closely related (monogamous)
• Optimum solution with no policing: kill your mother and reproduce as much as possible

eg. in annual species at end of year once queen has made next year’s queens and fecundity is reduced. workers kill her and make males themselves which then overwinter + survive to next year

E.g. Temnothorax crassispinus (ant) attack and kill the only queen present. Study questioned if adaptive strategy -> large increase in worker reproduction increasing direct fitness. Sex bias compensated by other colonies becoming female biased. Eventually negative as females started to die and left with just males.

Question 7

Escape from worker policing by worker to produce queens

Answer 7

• There is a strain of honey bee in SA where the workers lay diploid eggs asexually and avoid policing as eggs have same hydrocarbon smell as queens egg
• ## This has evolved once and spread (societal cancer
• These workers completely destroy honeybee societies as the eusocial system breaks down.

Question 8

Overview

Answer 8

Type key types of conflicts

1) Caste developement
- Polygamous: larvae want to become queen
- monogamous: larvae less likely to become queen

Workers want larvae to become workers
- Kill Queens once they emerge
- Control the developement of the larvae

2) Male reproduction
- Polygamous: more related to the queens son so policing to stop worker reproduction
- Monogamous: more related to their nephews so workers reproduce
- > Can lead to killing the queen

Escape from policing
- Asexual reproduction of queens by workers that have the same scent as queens of the colony
- leads to collapse of society

Enforcement is a common feature of cooperative evolution
- “An action that evolves to reduce selfish behaviour within a cooperative alliance”
- Conflict resolution/ kinship and enformemce reduces selfish behavior