Eusociality Flashcards
What are the 3 key features of eusociality?
- Cooperative brood care
- Sterile castes
- Overlapping generations
Describe the ‘staying at home hypothesis’ for eusociality
Genetic predisposition:
- For daughters raising full siblings ( r = 0.5) is the same as raising own offspring ( r = 0.5)
- For queen producing offspring ( r = 0.5) is better than grand-offspring (r = 0.25)
- Queen should prefer daughters to stay as workers
Describe the ‘sharing a nest’ hypothesis for eusociality
Genetic predisposition:
- For sisters that cooperate, there’s benefit from raising dominants offspring
- May outweigh the benefit of breeding alone if that is a high risk activity
Give evidence for the ‘staying at home’ hypothesis for eusociality
(subsocial)
Behaviour found in Halictine bees
Give evidence for the ‘Sharing a nest’ hypothesis for eusociality
(parasocial)
- Found in Polistes and Stenogastrine wasps
Describe the haplodiploid system
- Males develop from unfertilised eggs (haploid)
- Females develop from fertilised eggs (diploid)
What order uses the haplodiploid sex determination system?
Hymenoptera (ants, bees, wasps)
What does the haplodiploid system mean for sibling relatedness?
- Sister-sister r = 0.75
- Sister-brother r = 0.25
- Brother-sister r = 0.5
What does the haplodiploid system mean for offspring-parent relatedness?
- Mother-daughter r = 0.5
- Mother-son r = 0.5
Describe the difference between the preferred sex ratios of the queen and the workers in an ant colony.
Queen: 1F:1M
Worker: 3F:1M
Describe Trivers annd Hare’s (1976) study into sex ratios in ant spp.
- Q: Who controls the sex ratio, the queen or ther workers?
- P: If queen controls should be 1F:1M ratio, if workers should be 3F:1M
- R: Found a 3:1 ratio, so the workers control the colony’s sex ratio
Describe local mate competition in a eusocial species
- Brothers may compete to mate
- E.g Fig wasps: females may want to produce daughters to avoid conflict
