special reading - cooperative breeding 2 - helper effort in birds

Question 1

what are the hypotheses?

Answer 1

cooperative investment should correlate positively with the relatedness of helpers to the recipients of their care as predicted by inclusive fitness

Question 2

what was the methods?

Answer 2

• tested 36 cooperatively breeding bird species
• developed a measure of helper effort
• excluded species with extra pair paternity from the study - because they were testing relatedness
• determined kinship of broods from published resources
• also reported the sex ratio of helpers
• identified the proportion of breeding pairs helped
• recorded group size

Question 3

what were the results?

Answer 3

• species-specific helper contributions to cooperative brood care increase as the mean relatedness between helpers and recipients increases

Question 4

relation of results to hypotheses?

Answer 4

• findings support hypothesis that variation in helping behaviour among cooperatively breeding birds is consistent with Hamilton’s rule

Question 5

relation of results to general animal behaviour?

Answer 5

• kin selection has a key role in the evolution of cooperative investment in social birds
• gives an explanation for the considerable inter-specific variation in the amount of effort that helpers contribute towards cooperative brood care

Question 6

what was the aim of the experiment?

Answer 6

comparative analysis to test variation in brood care among species predicted by inclusive fitness theory

Question 7

problems with the experiment?

Answer 7

didn’t investigate direct fitness benefits which could have contributed