special reading - cooperative breeding - 1 - helping effort in bell miners

Question 1

what is the aim of this paper?

Answer 1

distinguish between the only remaining hypotheses, kin selection and group augmentation, for the evolution of helping-at-the-nest in a cooperative bird
- predict an incremental increase in helping effort with genetic relatedness

Question 2

what are they exploring?

Answer 2

• explores in detail within- and between-individual variation in nest visit rates, load sizes and prey types delivered by parents and helpers according to sex and genetic relatedness in bell miners
• also examine visit-by-visit responses of breeders and helpers to nestling begging signals of brood need

Question 3

what were the results?

Answer 3

• proved kin selected helping – however no evidence that bell miners were more likely to help at the nests of relatives
• Bell miner helpers seemed to attend hungry broods located within their coterie as required, irrespective of helper sex or relatedness to the brood
• no sex differences were detectable in any aspect of helping, and even non-relatives provided substantial aid

Question 4

what do the results mean in relation to the hypotheses being tested?

Answer 4

• comprehensive test for both direct and indirect fitness effects on helping- showed no direct fitness benefits for some just that the visiting rates were strongly effected by the begging rates of the chick
• suggested within coterie relatedness could explain the apparent indirect effects

Question 5

what do the results mean in relation to the study of animal behaviour in general?

Answer 5

• Helping behaviour in bell miners appears consistent with adaptive cooperative investment in the brood, and kin-selected care by relatives

Question 6

methods

Answer 6

• studied two different bell minor populations in Australis
• molecular analyses of relatedness between individuals
• identified parent birds
• measured provisioning efforts between 6-12 days
• visual score of begging intensity