Cooperative Breeding Flashcards
Why is cooperative breeding an evolutionary paradox?
Individuals help other individuals to reproduce, but at a cost to themselves, an example of altruistic behaviour. Contradicts the idea that individuals should maximise their own reproductive success.
How do helpers benefit dominants?
Increasing the reproductive success of breeders
Increase breeder survival
Is there a cost to helping?
In meerkats, helping is condition dependent:
- They only help when above threshold weight
- Short term cost = lose weight
- Stop helping when they drop below the threshold
- No reduction in survival.
However, in kingfishers and wrens, individuals that helped the most had a worse body condition at the end of the season and this lowered their survival.
Why do cooperative breeding systems evolve?
Kin selection - Individual can increase the number of copies of its genes in future generations by helping to increase the reproductive success of close relatives - Hamilton’s Rule.
Group Living - Ecological constraints force individuals to join groups as there are no good breeding opportunities available. Leads to increased survival, chance to inherit territory and safely look for breeding opportunities.
What are the direct and indirect benefits of helping?
Direct:
- Pay to stay
- Mate acquisition
- Group augmentation
- Gain breeding experience
- Direct breeding
Indirect:
- Young individuals delay dispersal and help parents raise subsequent offspring.
- Increased survival and production of kin/future helpers
What is the monogamy hypothesis?
When there is total monogamy, the benefits from independent breeding = the benefits from cooperative breeding.
Promiscuity reduces the relatedness between potential helper and dominant’s offspring.
During total monogamy, relatedness is always the same (full siblings, 0.5).
Therefore, cooperative breeding will be selected if there are additional direct benefits to it, or there are reduced benefits to independent breeding, such as ecological constraints, or inexperience.
Monogamy and kin benefits should therefore favour the transition to cooperative breeding.
