SR11: Wright 2009- helping effort increases with relatedness in bell minors Flashcards
helping by non relatives requires what?
direct fitness benefits such as group augmentation
what were the 3 main things observed?
- visit rates
- load sizes
- prey types by breeding pairs and helpers
what is the positive effect?
of kinship as helpers assist at multiple nests
how did helpers and breeders regulate provisioning effort
by responding visit by visit to changes in nestling begging
what is helping behaviour consistent with?
adaptive cooperative investment in the brood and kin selected care by relatives
in cooperatively breeding birds what is explained by kin selection?
altruism of helping raise others offspring
what does the group augmentation principle state about if helpers help raise reproductive success?
the benefits of living in a larger group will favour the evolution of altruistic helping behavior
non relatives often help and what could it be that they gain?
future increases in survivorship/reproduction
what do the male and female helpers vary in?
relatedness, indirect fitness benefits, direct fitness benefits
what type of breeders are the bell miners known as?
obligate cooperative breeders
what does female dispersal result in?
male biased colony sex ratios
what do the coteries usually contain?
a few young females that have not dispersed and many males helping whilst waiting to breed
what does the fact there is a rapid turnover of breeding females mean about the helpers?
they aren’t direct descendents of adults they aid
what did they test for ?
direct and indirect fitness effects of helping from related and unrelated individuals
when does the number of bell miners per nest and provisioning effort reach its max?
when nestlings are 5-6 days old
how many helpers and how many nests were observed?
217 helpers
27 nests
how many helpers attended the average nest?
8.63
what was the sex ratio found for non breeding individuals?
7:1
how many nests did helper males and helper females visit on average?
M: 2.26
F: 1.19
what did individuals change their visit rates at different nests according to?
variation in their genetic relatedness
when feeding more related broods what did helpers increase and how?
provisioning effort by increasing visit rates
where was there a positive linear effect?
brood begging on load size delivered
if helpers hear a hungry brood what do they return with on their next visit?
larger load sizes
in response to genetic relatedness of the broods they were provisioning what did helpers of both sexes show?
increase in visit rates, biomass delivered and increase helping effort
what may allow for preferential care of relatives
distinct mew calls given by breeders and helpers containing information
which sex visited the nest more than expected by relatedness?
females
what do male breeders trade off and why?
move and feed at multiple nests so trade off visits to their own nest with cooperative provisioning, mobbing and colony defence
why were there fewer female helpers?
early dispersal
what % of total food delivery did helpers provide?
60%
at what % of the rate of parents did the related and unrelated helpers work at?
related: 50%
unrelated: 25%
what is an example of an active benefit from group augmentation?
offspring assisted may later become helpers and enhance reproductive success of helper that raised them
what is a passive benefit from group augmentation?
improved chance of survival, especially of non dispersing males
what did some use as an indirect measure of brood demand?
changes in others nest visit rates
in the system what is there that is extreme?
sex biased dispersal
what does the system offer an opportunity to distinguish between?
kin selection or group augmentation for evolution of helping at the nest in a cooperative bird
how was pairwise relatedness assessed?
by calculating likeliness birds are related or not
what was highly correlated?
visual and acoustic measures of begging intensity
what did members of the breeding pair differ in and how did this compare to the male and female helpers
provisioning investment
didn’t differ in helpers
where is the main effect of relatedness on load size?
between breeders and helpers
what did breeding females deliver and experience and a potential reason for why?
delivered larger loads and experienced louder begging perhaps because they visited the nests more often
why did it appear that females visited more nests?
males move and feed at multiple nests
what does the adjustment of bell miner helping effort according to kin represent?
kin selection for inclusive fitness benefits
what may result from kin selection between social groups
help by non relatives
