| The definition of parent-offspring conflict is that there is a conflict between parents supply and offspring demand caused by the deference of predicted benefit between them.In other words,parents always intend to control the parental investment in order to maximum their own fitness;offspring intend to gain more parental investment in order to maximum their own fitness,as well.In altricial birds,patent-offspring conflict is a universal.However,in the different species and even different individuals of the same species,the variety and the intensity of parent-offspring conflict are various.Because the capacity of controlling parental investment are different between parent and offspring,the way of how parent or offspring trade-off to get what they want remain a key point of ethology.We studied the azure-winged magpie(Cyanopica cyana),in order to make clear some question related to parent-offspring conflict: 1)the honesty of nestlings' begging;2)factors that related with parental provisioning;3)the effect of nestlings' demand on parental supply.During 2014-2017,in Gansu province Luqu county,collected life history date of azure-winged magpie,including reproductive cycle,laying date,clutch size,brood size,hatching period,hatching rate,brood period,fledging number,newborn weight,fledging weight.According to hatching rate,the nests were divided into two groups.According to video and video replay,all the behaviors in regard to parental supply and offspring bagging were recorded.The behavior about parent supply includes the brood provisioning rate,parental feeding efficiency,feeds number,time interval of feeding,hatching duration,courtship rate.The behavior about nestling begging includes the maximum proportion of begging nestling,the last proportion of begging nestling.Using SPSS(version 22.0),all the date of life history,parent supply,nestling begging were analyzed.Thought constructing generalized linear mixed model,GLMM,we analyzed factors which may have effect on the maximum proportion of begging nestling,parents food efficiency,hatching duration,the courtship feeds' number,Clutch size in next reproductive attempt.We show that:1)There is a significantly relationship between Nestlings maximum begging intensity of current feeding visits and nestling age,brood size,time interval of feeding.In other words,the bigger brood size,age,and time interval of feeding,the more proportion of the maximum proportion of begging nestling.2)There is a significantly relationship between male food efficiency and nestlings age,and the elder the nestlings,the higher males food efficiency.Males' food efficiency in the total hatched nests is higher than the partial hatched nests.There is not a significantly relationship between male food efficiency and the maximum number of beggars,the final number of beggars in last nest visit,group,whether there were helpers-at-nest,the feeds' number in last feeding visit of a particular bird.3)There is a significantly relationship between female food efficiency and the maximum number of beggars,and the more begging nestlings,the higher male food efficiency.There is not a significantly relationship between female food efficiency and nestling age,brood size,the final number of beggars in last nest visit,group,whether there were helpers-at-nest,the feeds' number in last feeding visit of a particular bird.4)Hatching duration increase with the less brood size and less environmental temperature.There is not a significantly relationship between hatching duration and nestling age.5)Courtship feeds number increase with the less brood size and younger nestling.There is not a significantly relationship between courtship feeds number and environmental temperature,maximum number of beggars,the intensity of females' begging.6)There is not a significantly relationship between fledging weight and group.7)There is a significantly relationship between clutch size and clutch size in next reproductive attempt,and the more clutch size in current reproductive attempt,the more clutch size in next reproductive attempt.We suggest that:1)The behavior of nestlings' begging is honest,which can reflect their nutritional need.2)Male parents play the dominant role of deciding the amount of food supplied by male parents.Because they do not adjust the total amount of food according to nestlings' begging(nestlings begging intensity when the parents give the last feed of last feeding visits and nestlings maximum begging intensity of last feeding visits).In contrast nestlings' need can be expected by their fathers during the early phase of brooding or the incubation period or even earlier.So how much the level of care(food providing)provided by male parents can be decided by their expectation.If the virtual need is not match the expectation any more,the male parents will provide according to the expectation but virtual need.3)However,nestlings play the dominant role of deciding the amount of food coming from female parents,because how much the level of care(food providing)provided by female parents is decided by nestlings' begging(nestlings begging intensity when the parents give the last feed of last feeding visits and nestlings maximum begging intensity of last feeding visits).Besides,females parent do not expect nestlings' need during the early phase of brooding or the incubation period,because even if the virtual need is not match the expectation any more,the female parents will provide according to virtual nestlings' need but the expectation.4)Male parent can affect females' behavior,like offspring attendance.Therefore,they affect the level of females' food providing.With the lager clutch size and elder nestlings,comes the less nest attentiveness of females.Although,the number of female's feeds of a nest visit divided by off-bout duration do not change significantly,females' nest visit must be increased.Therefore,the total amount of females' provisioning increases.But the course may not happen spontaneously,since the total amount of females' providing is directly affected by males' courtship feeding and not directly affected by brood size and females' age,and the females' nest visit are affected by males' courtship feeding directly.We conclude that1)The evolutional outcome of parent-offspring conflict of azure-winged magpie are different between sexes: males do not interact with offspring,;females interact directly with offspring.2)At the further study of parent-offspring conflict,the model of parent offspring co-adaptation as a parameter may be added into parent-offspring conflict model. |
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