The Offspring Recognition Mechanisms Of The Azure-Winged Magpie

The kinship theory that is founded on the concept of inclusive fitness is one of the most important theories widely used in the researches of animal behaviors.Although it has been considered as a powerful tool to explain the evolution of animal social behaviors,such as the altruism,group-living,and parent-offspring conflicts,et al.,it remains being challenged by two unresolved questions.One is that whether animals really have the ability of distinguishing their relatives from unrelated individuals;and the other is what type of cues has been used by animals in their kin recognition.To address these two questions will be helpful to broaden the usage of kinship theory in the studies of animal behaviors.In this study,I addressed the above two questions by investigating how did parents of the azure-winged magpie(Cyanopica cyanus)recognize their offspring.Two kinds of investigations were carried out in a population that bred on the Tibetan Plateau.First,a series of experiments were designed in the field,including the nest position change experiment,cross-fostering experiment,nest duplication experiment and the experiment of re-selection between cross-fostered nestlings.These experimental investigations aimed to determine the types of cues that were used by parents to find their offspring,as well as how did parental dependence on different cues change with the growth of offspring.Second,comparative analysis of the brain transcriptome of different-aged nestlings were carried out to examine which gene might play an important role in the offspring recognition by the azure-winged magpie.The major findings of this study are listed below.1)In the nest position change experiment,a focus nest was first removed to a new position,by different directions and different distances.Then,parents were monitored to determine whether they returned to the manipulated nest and restore their interrupted behaviors,by which it can be verified whether parents could locate their own offspring.This experiment was carried out at the stages of incubation and nestlings,respectively.Finally,it was uncovered that the cues that parents of the azure-winged magpie used in offspring recognition changed with the growth of nestlings.At incubation,they relied largely on the nest position to locate their offspring;whereas during the nestling period,particularly at the later stage,they began to rely on the phenotypic traits,such as nestling's begging call,to locate their own offspring.2)In the cross-fostering experiment,the nest content of two paired nests were exchanged,one contained only eggs and the other contained only nestlings.By monitoring whether parents changed their parental behaviors according to the cues of nest content,it can be determined whether they are capable of recognizing their own offspring.The findings in this experiment indicated that parents cannot recognize their own offspring at the stage of incubation;however,they began to gain such an ability during the nestling period.At the nestling age of 11 days or so,parents can almost recognize their own offspring.3)In the nest duplication experiment,a new nest was fixed nearby the position of a focus nest.By placing their own offspring and unrelated young into the focus nest or the duplicated nest,parents were monitored to determine whether they provisioned their offspring in priority.The findings of this experiment further proved that parents of the azure-winged magpie began to gain the ability of offspring at the nestling age of 11 days or so.4)By comparative analyzing the brain transcriptome of different-aged nestlings,this study identified that the Foxp2 gene may play a key role in the offspring recognition of the azure-winged magpies.As the variation of m RNA expression of the FOXP2 gene changed with the nestling age,it is fitting curve accorded with the process of parents gained the ability of offspring recognition.It seems that the acoustic characteristics of nestling begging call are almost fixed near the nestling age of 11 days,which in turn drove parents of the azure-winged magpie to transform their offspring recognition from relying on nest position cue to relying on nestling phenotypic cues.In conclusion,by experimentally investigating how did parents of the azurewinged magpie recognize their own offspring from a manipulated nest or from a mixed brood,this study found that azure-winged magpie parents might have gradually obtained the ability of offspring recognition,which is tightly linked with the development of nestling's phenotypic traits.Based on the comparative analysis of brain transcriptome of different-aged nestlings,it suggests that nestlings' begging call,in addition to the Foxp2 gene that has been considered to link with animal acoustic traits,may play a key role in the transformation of offspring recognition mechanisms by the azure-winged magpie.