Correlation of personality with individual reproductive success in shrub-nesting birds depends on their life history style

Two questions in the research of animal personality—whether there is a correlation between a personality trait and individual reproductive success,and what is the genetic basis underlying a personality trait—remain unresolved.We addressed these two questions in three shrub-nesting birds,the Azure-winged Magpie(Cyanopica cyanus,AM),White-collared Blackbird(Turdus albocinctus,WB),and Brown-cheeked Laughingthrush(Trochalopteron henrici,BL).The personality type of an individual was first identified according to its response to a territorial intruder.Then,we compared the fleeing distance,breeding parameters,and differential expressed genes(DEGs) in the brain transcriptome between bold and shy breeders.In the three species,bold breeders exhibited more aggressiveness towards an intruder of their territory than did shy breeders.The reproductive success of bold breeders was significantly higher than that of shy breeders in AM but not in WB and BL.The three species shared one DEG,crabp1,which was up-regulated in bold relative to in shy individuals.By regulating the expression of corticotropin-releasing hormone,higher crabp1 gene expression can decrease cellular response to retinoic acid.Therefore,bold individuals are insensitive to external stresses and able to exhibit more aggressiveness to intruders than their shier counterparts.Aggressiveness is beneficial to bold individuals in AM but not in WB and BL because the former could evoke neighbors to make the same response of defending against intruders but the latter could not.Although a personality trait may have the same genetic basis across species,its correlation with reproductive success depends largely on the life history style of a species.

The Grey-backed Shrike parents adopt brood survival strategy in both the egg and nestling phases

Background:Great diversity exists in the parenting pattern of altricial birds,which has long been considered as an adaptive response to specific environmental conditions but not to their life-history style.Methods:We examined the egg-laying and nestling-raising pattern of the Grey-backed Shrike(Lanius tephronotus)that breeds only once a year on the Tibetan Plateau.We compared the dietary composition to that of its sympatric competitor,the Brown-cheeked Laughing Thrush(Trochalopteron henrici)that breeds twice a year.Results:Female Grey-backed Shrikes produced a fixed clutch size of five,with increasing egg size by their laying sequence.The last offspring in the brood is disadvantageous in the size hierarchy because it hatches later.However,they had the largest fledgling body mass.These findings indicate that Grey-backed Shrikes adopt the brood survival strategy in both the egg and nestling phases.Moreover,males and females exhibit no sexual division in providing parental care as they made an equal contribution to the total amount of food delivered to their brood.This parenting pattern of Grey-backed Shrikes,as well as their dietary items,differ significantly from those of the Brown-cheeked Laughing Thrush.Conclusions:We suggest that the differentiation in life-history style between sympatric competitors,rather than a behavioral response to specific environmental conditions,plays a decisive role in driving avian parenting strategy diversification.

Responses of a resident group to an outsider in the blue-breasted quail: A paradigm for studying social resettlement of dispersers

Dispersal is an individual life-history trait that can influence the ecological and evolutionary dynamics of both the source and recipient populations.Current studies of animal dispersal have paid little attention to how the responses of residents in a recipient population affect the social resettlement of dispersers into a new habitat.We addressed this question in the blue-breasted quail Synoicus chinensis by designing an outsider introduction experiment to simulate a scenario of interaction between residents and dispersers.In the experiment,we introduced an unfamiliar quail into a group of 3 differently ranked residents and then examined their behavioral responses to the arrival of the outsider.We found that all residents made negative responses by pecking at the outsider to maintain their pecking order,in which high-ranked residents displayed significantly greater intensity than those of lower ranks.This result highlighted that adverse behavioral responses of residents would prevent outsiders from obtaining hierarchical dominance in the recipient group.Moreover,the residents’sex ratio,their relative ages to the outsiders,and whether outsiders counter-pecked at the residents all influenced the probability of outsiders prevailing against the residents.Those outsiders that displayed counter-peck courage were more likely to gain higher dominance and hence resettle into the recipient group successfully.Our findings suggest that resident groups may impose a selection among dispersers via adverse behavioral responses.Therefore,social factors that can influence the resettlement step of dispersers in a new habitat should be accounted for in future studies of animal dispersal.