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.

Expression of HIF-1α and Its Target Genes in the Nanorana parkeri Heart：Implications for High Altitude Adaptation

Hypoxia-inducible factor 1 alpha（HIF-1α） and its target genes vascular endothelial growth factor（VEGF） and transferrins（TF） play an important role in native endothermic animals＇ adaptation to the high altitude environments. For ectothermic animals – especially frogs – it remains undetermined whether HIF-1α and its target genes（VEGF and TF） play an important role in high altitude adaptation, too. In this study, we compared the gene sequences and expression of HIF-1α and its target genes（VEGF and TF） between three Nanorana parkeri populations from different altitudes（3008 m a.s.l., 3440 m a.s.l. and 4312 m a.s.l.）. We observed that the c DNA sequences of HIF-1A exhibited high sequence similarity（99.38%） among the three altitudinally separated populations; but with increasing altitude, the expression of HIF-1A and its target genes（VEGF and TF） increased significantly. These results indicate that HIF-1α plays an important role in N. parkeri adaptation to the high altitude, similar to its role in endothermic animals.

Amphibians Testing Negative for Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans on the Qinghai-Tibetan Plateau,China

A disease caused by the fungi Batrachochytrium dendrobatidis（Bd） and Batrachochytrium salamandrivorans（Bsal） is responsible for recent worldwide declines and extinctions of amphibian populations.The Qinghai-Tibetan Plateau（QTP） is aglobal biodiversity hotspot,yet little is known about the prevalence of Bd and Bsal in this region.In this study,we collected 336 non-invasive skin swabs from wild amphibians（including an exotic amphibian species） on the QTP.In addition,to assess the historical prevalence of Bd and Bsal on the QTP,we collected 117 non-invasive skin swabs from museum-archived amphibian samples（from 1964-1982） originating from the QTP.Our results showed all samples to be negative for Bd and Bsal.The government should ban the potentially harmful introduction of non-native amphibian species to the QTP and educate the public about the impacts of releasing exotic amphibians from chytridinfected areas into native environments of the QTP.

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.

The Expression Plasticity of Hypoxia Related Genes in High-Altitude and Plains Nanorana parkeri Populations

For species that have a broad geographic distribution, adaptive variation may be attributable to gene expression plasticity. Nanorana parkeri is an anuran endemic to the southern Tibetan Plateau where it has an extensive altitudinal range（2850 to 5100 m asl）. Low oxygen concentration is one of the main environmental characteristics of the Tibetan Plateau. Hypoxia-inducible factor α subunits（HIF-1α and HIF-2α, encoded by Endothelial PAS domain protein 1（EPAS1）） and associated genes（e.g., vascular endothelial growth factor（VEGF） and Erythropoietin（EPO）） play crucial roles in maintaining oxygen homeostasis. In this study, we compared the expression of HIF-1A, VEGF, EPAS1 and EPO mRNA between two populations of N. parkeri： one population inhabiting the native high altitudes, and the second living in, and being acclimated to, the lower plains（70 m asl）. The expression of HIF-1A, VEGF and EPAS1 mRNA in the high altitude population were significantly higher than in the acclimated population, whereas there was no significant difference for EPO between two groups. Our results indicated that gene expression plasticity may make significant contributions to local adaptation of species that have broad altitudinal distributions. In addition, we deepen our understanding of the adaptive potential of this species by evaluating the experiments in the scope of its evolutionary history.

The Influence of Oxygen on the Development of Nanorana parkeri Tadpoles

Ectothermic animals are tolerant of variable oxygen availability, whether low-oxygen levels constrain the fitness of ectotherms remains unclear. Nanorana parkeri, an anuran endemic to the southern Tibetan plateau, is an excellent model with which to answer this question. In this study, we raised tadpoles ofN. parkeri in oxygenated water （high-oxygen group） and deoxygenated unchlorinated tap water （low-oxygen group） and monitored their growth, mortality, and telomere length. The growth rate for body length and body weight was higher in the low-oxygen group than in the high-oxygen group. However, dissolved oxygen did not affect development time, mortality, and telomere length of the tadpoles. These results suggest that although the oxygen concentration influenced some phenotype traits of plateau tadpoles, but it didn＇t influence the telomere length and survival rate, potential explanations are the local adaptation and N. parkeri tadpoles＇ wide oxygen tolerance, and fluctuant toxic content that resulted in little oxidative stress on tadpoles. These results indicated that low oxygen was not a stress to N. parkeri tadpoles＇ fitness and survival. This study is helpful in understanding the adaptation mechanisms of Tibetan plateau amphibians.

Bergmann’s rule and Allen’s rule in two passerine birds in China

Background:Animals that live at higher latitudes/elevations would have a larger body size(Bergmann’s rule)and a smaller appendage size(Allen’s rule)for thermoregulatory reasons.According to the heat conservation hypoth-esis,large body size and small appendage size help animals retain heat in the cold,while small body size and large appendage size help them dissipate heat in the warm.For animals living in seasonal climates,the need for conserving heat in the winter may tradeoff with the need for dissipating heat in the summer.In this study,we tested Bergmann’s rule and Allen’s rule in two widely-distributed passerine birds,the Oriental Magpie(Pica serica)and the Oriental Tit(Parus minor),across geographic and climatic gradients in China.Methods:We measured body size(body mass and wing length)and appendage size(bill length and tarsus length)of 165 Oriental Magpie and 410 Oriental Tit individuals collected from Chinese mainland.We used linear mixed-effect models to assess variation patterns of body size and appendage size along geographic and climatic gradients.Results:Oriental Magpies have a larger appendage size and Oriental Tits have a smaller body size in warmer environ-ments.Appendage size in Oriental Magpies and body size in Oriental Tits of both sexes were more closely related to the climates in winter than in summer.Minimum temperature of coldest month is the most important factor related to bill length and tarsus length of male Oriental Magpies,and wing length of male and female Oriental Tits.Bill length and tarsus length in female Oriental Magpies were related to the annual mean temperature and mean temperature of coldest quarter,respectively.Conclusions:In this study,Oriental Magpies and Oriental Tits followed Allen’s rule and Bergmann’rule respectively.Temperatures in the winter,rather than temperatures in the summer,drove morphological measurements in Oriental Magpies and Oriental Tits in Chinese mainland,demonstrating that the morphological measurements reflect selec-tion for heat conservation rather than for heat dissipation.

The origin of invasion of an alien frog species in Tibet, China

Identifying the origins of alien species has important implications for effectively controlling the spread of alien species. The black-spotted frog Pelophylax nigromaculatus, originally from East Asia, has become an alien species on the Tibetan Plateau （TP）. In this study, we collected 300 individuals of P. nigromaculatus from 13 native regions and 2 invasive regions （including Nyingchi and Lhasa） on the TP. To identify the source region of the TP introductions, we sequenced portions of the mitochondrial cyt b gene. We sequenced a -600-bp portion of the mitochondrial cyt b gene to identify 69 haplotypes （124 polymorphic sites） in all sampled populations. According to the network results, we suggest that the P. nigromaculatus found on the TP was most likely originated from Chongqing by human introduction. Furthermore, we found that the genetic diversity was significantly lower for invasive than for native sites due to founder effects. Our study provides genetic evidence that this alien species invaded the cold environment of high elevations and expanded the distribution of P. nigromaculatus in China.

Comparative transcriptomic and metabolomic analysis reveals pectoralis highland adaptation across altitudinal songbirds

Pectoralis phenotypic variation plays a fundamental role in locomotion and thermogenesis in highland birds.How-ever,its regulatory and metabolic mechanisms remain enigmatic to date.Here,we integrated phenomic,tran-scriptomic,and metabolomic approaches to determine muscle variation and its underpinning mechanisms across altitudinal songbirds.Phenomics confirmed that all highland birds had considerable increases in muscle oxidative capacity,capillarity,and mitochondrial abundance in our study.Correspondingly,transcriptomic analyses found that differentially expressed genes in phenotype-associated modules enriched for blood vessel,muscle structure development,and mitochondrial organization.Despite similar traits and functional enrichments across highland birds,different mechanisms drove their occurrence in high-altitude tree sparrow and 2 snowfinches.Importantly,a metabolic feature shared by all the 3 highland birds is the improvement in insulin sensitivity and glucose utilization through activating insulin signaling pathway,which is vital to increase muscle oxidative capacity and maintain metabolic homeostasis.Nevertheless,fatty acid biosynthesis and oxidation are enhanced in only 2 snowfinches which had a long evolutionary history on the high plateau,also differing from ketone body metabolism in recently introduced colonizer of the tree sparrow of the high plateau.Our study represents a vital contribution to reveal the regulatory and metabolic basis of pectoralis variation across altitudinal songbirds.