SR11: Green+ Hatchwell 2016- helper effort variation in cooperatively breeding birds Flashcards
what does the inclusive fitness theory predict cooperative investment should positively correlate with?
relatedness of helpers to recipients of their care
what was the comparative analysis of?
helper investment in 36 cooperatively breeding bird species
what increases as mean relatedness between helpers and recipients increases
species specific helper contributions
what fact did the study support?
that variation in helping behaviour in cooperatively breeding birds is consistent with hamilton’s rule
in vertebrate cooperative systems what are social groups mainly comprised of?
close relatives
what is more likely to evolve in species with low promiscuity?
caring for others offspring
what does hamilton’s rule predict?
conditions under which kin selected cooperation should evolve with investment in cooperation greater as relatedness between actor and recipient increases
when are potential helpers more likely to help?
when recipients close kin
when caring for young what is the trade off?
between fitness gained from current investment against costs of investment for future fitness gain
what does comparing helper effort across species show?
that helper investment increases with kinship to the brood
what was the mean provisioning rate of helpers expressed as a proportion of?
provisioning rate of parents
when should helper investment be high?
when probability of future independent breeding is low
if most individuals in a population can breed then what does this mean?
low constraints on reproduction and few pairs have helpers
what should carers adjust their care according to
the number of carers at a nest
typically what sex are the helpers?
male due to females dispersing and reproducing outside their natal group so the sex ratio is often male biased
how many species in how many families was data collected from?
36 species in 23 families
in all species what did care provided by helper increase with?
kinship to the brood
what % did helper effort approach when r was close to 0.5? and what does this support?
100%
supports inclusive fitness theory
when should kin discrimination only be selected for?
when risk to caring for non kin
what may happen if costs are low and indirect benefits are high?
lots of helpers may care for non kin
when did helper effort decrease?
with proportion of male helpers
when do both sexes work harder relative to parental effort?
when more female biased helper sex ratios?
if females remain in their natal territory what does it mean?
higher relatedness in groups which may select for more provisioning effort by helpers
what does helper contributions to brood care increase with?
relatedness of helpers to recipients
what is a direct fitness benefit that may arise?
inheritance of the breeding territory
what does the optimal strategy for investment depend on?
investment of others in the same brood
how does it provide evidence for hamiltons rule?
close relatives provide more care
in cooperatively breeding species in some cases what do helpers assume most?
the responsibility for brood care
what was it testing?
if variation in helper contribution is predicted by inclusive fitness theory
what will happen when constraints on successful independent reproduction are high and an example
most pairs will have helpers such as the white winged chough
what is the result for the females when helpers are typically male
higher probability of dispersing and of independent reproduction outside the natal group
what findings from other studies does it support?
that there is consistent discrimination in favour of kin by helpers
