摘要: Olfactory receptors(ORs),the largest vertebrate multigene family,exhibit wide copy number variation among taxa,ranging from ～100 to 4000.The ecological importance of smell has been suggested to positively correlate with OR gene number,though debate exists on whether the number of total ORs,functional ORs,or the percentage of pseudogenes matters most.While olfaction has been poorly studied in most birds,Turkey Vultures(Cathartes aura) demonstrate keen olfactory ability,capable of foraging using smell alone.In contrast,Black Vultures(Coragyps atratus) have been thought to primarily use vision to locate food.Comparison of the OR genes in these two New World vultures presents an opportunity to examine the dynamics of OR evolution in related avian species that may differ in olfactory abilities.Using a PCR and cloning approach with degenerate primers,we sampled the OR subgenome in Turkey and Black Vultures,as well as Red-tailed Hawks(Buteo jamaicensis) and the distantly related Chicken(Gallus gallus),neither of which are thought to use olfaction extensively.Our results indicate that Turkey Vultures have many more OR genes than Red-tailed Hawks or chickens.Surprisingly,Black Vultures had an intermediate number of OR genes.The number of OR genes we estimated in the Turkey Vulture was much greater than previously reported in studies that used short-read sequencing.Additionally,we found that OR genes from New World vultures and Red-tailed Hawks form clades that were distinct from the clade that included most chicken OR genes,indicating that chickens share few OR orthologs with New World vultures or hawks.As previously observed in other animal groups,pseudogenes appeared throughout all clades and their percentage varied among taxa.These findings suggest the OR gene family is highly dynamic,changing rapidly over evolutionary time,and that taxa may have distinct suites of ORs in their genomes.

摘要: The globin superfamily,central to oxygen（O₂） cascade dynamics,exemplifies how canalization—evolutionary stabilization of phenotypic traits—enables vertebrates to thrive in extreme environments.In birds,hemoglobins（Hbs） serve as a paradigm of this process,with structural and functional canalization underpinning their exceptional aerobic capacity and elevational diversification.Despite significant advances of globins in our understanding of avian aerobic adaptation,a comprehensive synthesis of functional diversity,molecular evolution,and structural innovation is essential to fully elucidate their canalized roles in O₂ homeostasis.Integrating perspectives on globin functional diversity and structural evolution,this review examines how chance（mutation/fixation biases） and contingency（historical genetic/epistatic constraints） shape Hb divergence and parallelism,thereby bridging molecular mechanisms with physiological adaptation in birds.We highlight how avian Hbs,canalized through compensatory substitutions and allosteric regulation,achieves a balance between evolutionary robustness and adaptive plasticity.However,critical gaps remain persist:the roles of understudied globins（e.g.,neuroglobin,globin E） and the mechanisms of genetic assimilation in migratory taxa.We propose an integrative framework that incorporates ecological divergence（elevation,flight endurance）,phylogenetic timescales,and systems biology to unravel how canalization directs adaptive compromise.By focusing on birds within the amniotes,this synthesis advances a cohesive model for vertebrate evolution,wherein canalized globins reconcile metabolic precision with ecological innovation.Ultimately,this review refines hypotheses of O2cascade evolution and calls for cross-disciplinary studies to decode the genetic and physiological architecture underlying adaptive canalization in extreme environments.

摘要: Investigating geographical variation and functional adaptation of gut microbiomes in endangered species is an emerging field in conservation biology.Here,we investigated the endangered waterbird,Scaly-sided Merganser(Mergus squamatus),that is endemic to East Asia.Using metagenomic sequencing,we characterized variations in gut microbiota composition and functional adaptation across Scaly-sided Merganser populations inhabiting the Fuer River,Manjiang River,and Lushui River basins in Northeast China.Furthermore,we investigated these variations at different developmental stages(adults and juveniles).Significant differences were observed in gut microbiota composition among the river populations,with the Fuer and Lushui groups exhibiting similar compositions that differed from the Manjiang group.However,no significant differences were found in the functional characteristics of gut microbiota among the three groups;these functions were primarily enriched in core pathways related to carbohydrate metabolism,amino acid metabolism,and translation.This finding suggests functional redundancy,where key metabolic functions remain stable despite differentiation in microbial community composition.The adult Scaly-sided Merganser gut microbiota exhibited higher alpha diversity and showed significant enrichment in pathways related to detoxification metabolism,environmental adaptation,and energy conversion efficiency,suggesting the capacity to adapt to complex habitats.In contrast,the gut microbiota of juveniles was enriched in metabolic pathways related to the essential and conditionally essential amino acids methionine and cysteine,supporting the high protein synthesis demand during the rapid growth and developmental stage.This study highlights the structural plasticity and functional adaptability of the gut microbiota in the Scaly-sided Merganser,providing an empirical basis for the species' conservation and habitat management from a gut microbiome perspective.

摘要: The rapid expansion of urbanization has led to widespread exposure of wild birds to intensive light at night(LAN).While previous studies have established LAN-induced cognitive impairment in birds,the underlying neurobiological mechanisms remain poorly understood.We hypothesized that LAN exposure impaired cognitive function of birds potentially through neurodegeneration,metabolic dysregulation and neuroinflammatory responses in the telencephalon.Using Zebra Finches(Taeniopygia guttata) as an avian model,under 16L:8D photoperiods,we compared associative learning and memory abilities and neurobiological parameters between experimental groups exposed to dim light at night(LAN) versus nocturnal darkness(CTR).Compared to the CTR birds,the LAN-exposed birds exhibited significantly lower learning and memory performances,reduced neuron density and simplified dendritic morphology in the telencephalons.The key energy metabolic substrates(cholic acid,CTP,D-mannose-6-phosphate) and neuroprotective agents(trehalose,menaquinone,L-gulono-1,4-lactone)in the telencephalons of LAN-exposed birds showed depletion,while oxidative stress markers(methionine sulfoxide) and inflammatory mediators(cis-gondoic acid) exhibited elevation.The neurotransmitter dopamine and histamine metabolic pathway were disrupted in the LAN-exposed birds.The microglias were activated with pro-inflammatory IL-1β and IL-6 levels increasing and anti-inflammatory IL-10 decreasing in the telencephalons of the LAN-exposed birds.These findings indicate a potential mechanistic pathway whereby dim light exposure at night can induce neuroinflammation through oxidative stress-mediated microglial activation,energy metabolism and neurotransmitter homeostasis disruption,ultimately leading to neurodegeneration in the telencephalons of birds.

摘要: Quantitative analysis of colouration is an essential tool for subspecies delimitation but has always posed a challenge in avian taxonomy.In this study on the Chestnut-winged Babbler(Cyanoderma erythropterum) species complex from tropical Southeast Asia,we made use of colour measurements taken with digital cameras and applied two methodologies—(1) the 75% subspecies rule on quantitative colourimetric variables,and(2) the CIEDE2000 colour distance method to generate phylograms,which has probably never been applied in taxonomy before.Given its large number of described subspecies,many of which have been synonymised in modern taxonomies,the species complex serves as an appropriate model to test subspecies validity.Our data indicate that one synonymised subspecies(C.e.apega),from the islands of Bangka and Belitung,requires re-instalment and recognition,whereas one widely recognised subspecies(C.e.fulviventre),from the Banyak Islands,should be synonymised.Our approach also allowed us to redraw geographic subspecies boundaries.Our work indicates that current subspecies taxonomies of many poorly known tropical species may remain error-ridden and highlights the importance and viability of large-scale taxonomic revisions targeting avian subspecies globally while incorporating quantitative colourimetric approaches.

摘要: This study investigates the genetic differentiation and gene flow within the Subalpine Warbler(Curruca cantillans) complex using mitochondrial DNA(mtDNA) analysis.We focused on three primary populations based on phylogenetic findings and geographical distributions.Popl:Includes C.c.albistriata(distributed in extreme northeast Italy(Trieste),southern Slovenia,and south along the north Adriatic coast to Albania,as well as east to southern Bulgaria,Greece,Crete,and western Turkey,with non-breeding grounds in the central and eastern Sahel from eastern Mali to northwest Sudan) and C.c.cantillans(occurring in Sicily,central and southern Italy,and locally in north-central Italy,with non-breeding grounds presumably in the western Sahel).Pop2:Represents C.iberiae,found in Spain and western France.Pop3:Comprises C.subalpina,distributed across the Balearic Islands,Corsica,Sardinia,some Tuscan islands,and north and central Italy,with non-breeding grounds extending into the western Sahel,reaching northern Nigeria and Niger.Our genetic analysis indicates that all three populations have expanded recently but maintain unique genetic structures.Despite this recent expansion,the populations exhibit limited genetic diversity.Using AMOVA,we found that most genetic variation is between populations rather than within them,indicating significant genetic differentiation.This study uniquely combines population genetic data with advanced analyses to provide detailed insights into the genetic structure and connectivity of the Subalpine Warbler complex,highlighting the distinct genetic lineages within the Mediterranean biodiversity hotspot.

摘要: The migratory nature of avian species is well known not only to researchers but also to the general public,becoming engrained in cultural traditions and even children's fairy tales.However,our understanding of these charismatic behaviors made great strides in the 1990s with the advent of small,light-weighted satellite transmitters capable of longterm tracking(Argos,2016).The emergence of this new technology made it possible to track a broader range of species at higher resolution than ever before.In turn,this data enabled detailed understanding of individual avian behavior and habitats,including transboundary migration routes.

摘要: Urban parks are essential habitats for birds in densely built environments.However,most studies focus only on horizontal features,overlooking the role of integrated vertical structures.Using bird records from the China Bird Report(CBR) collected between 2020 and 2024,this study focused on major urban parks in Harbin,a cold highlatitude city in Northeast China.Using interpretable machine learning models,we assessed the impact of threedimensional(3D) park features on bird species richness and identified key variables along with their nonlinear relationships.Subsequently,we grouped bird species by ecological traits and applied ordination analysis to assess their differential abundance responses to the 3D environmental characteristics of urban parks.Results showed that:(1) urban park 3D environmental features had a certain influence on bird richness,among which disturbance from built-up land and the coverage of commercial buildings were the most important factors;(2) different bird groups responded differently to the urban park 3D environmental features.Specifically,waterbirds and generalist birds preferred mixed habitats dominated by water,wetlands,and tall vegetation,and exhibited significant edge effects caused by built-up land disturbance.In contrast,forest birds were mainly affected by greenspace configuration.Although they showed tolerance to human disturbance,this trend may increase the risk of biotic homogenization.The study used a 3D environmental framework integrating horizontal and vertical dimensions to explore how bird diversity is shaped,providing detailed recommendations for biodiversitysensitive park planning in Harbin.

摘要: Nestedness is one of the important patterns in island biogeography,community ecology and conservation biology.However,most previous nestedness studies focus on the taxonomic dimension while neglecting the functional and phylogenetic processes in generating nestedness.Moreover,few studies have examined the seasonal change of the nestedness and underlying processes.Here,we examined the seasonal nestedness of bird assemblages in taxonomic,functional,and phylogenetic dimensions,and determined the underlying processes of nestedness patterns in the Zhoushan Archipelago,China.We surveyed the occurrence, abundance,and habitats of birds on 40 islands.We calculated taxonomic,functional,and phylogenetic nestedness using WNODF and treeNODF.We determined the processes underlying nestedness by relating nestedness ranks to island characteristics and species traits.The WNODF analyses showed that bird assemblages in winter and summer were both significantly nested.The habitat-by-site matrix was also significantly nested.The nestedness of bird assemblages was significantly correlated with island area,habitat diversity,habitat specificity,minimum area requirement,habitat specificity and hand-wing index(HWI) of birds in both seasons.While the distance to the nearest mainland(DTM) exerted the influence on nestedness in summer,the distance to the nearest larger island(DTNL)affected nestedness only in winter.However,the nestedness of bird assemblages was not caused by passive sampling or human disturbance.The results of treeNODF analyses illustrated that bird assemblages were functionally and phylogenetically nested in summer and winter,but the exact mechanisms were somewhat different in these two seasons.Overall,our results supported the habitat nestedness hypothesis,selective extinction hypothesis,and selective colonization hypothesis in both seasons.From a conservation viewpoint,we should protect islands with large area and diverse habitats,islands close to the mainland,and species with large area requirement and high habitat specificity to prevent local extinction.

摘要: The acceleration of global urbanization has caused habitat loss,fragmentation,and decrease of habitat quality,often leading to a decline in biodiversity.However,most previous urbanization studies focused on taxonomic diversity,with relatively less research on functional and phylogenetic diversity.In this study,we examined the phylogenetic and functional diversity and underlying influencing factors of bird communities in 37 urban parks in Nanjing,China.We conducted a systematic survey of bird communities in Nanjing urban parks and selected six park characteristics that are generally considered to affect bird diversity.Model selection based on corrected Akaike Information Criterion(AICc) and model averaging showed that park area,habitat diversity and building index(a proxy for the degree of urbanization) were significant factors affecting avian phylogenetic and functional diversity in Nanjing urban parks.Specifically,habitat diversity and park area were positively correlated with bird diversity,while the building index was negatively correlated with bird diversity.Moreover,the phylogenetic and functional structures of urban bird communities exhibited a clustered pattern,indicating that environmental filtering might play a role in shaping community composition.In addition,building index had certain impact on the construction of bird phylogenetic communities in urban parks.Our results suggest that expanding park areas,increasing habitat diversity and reducing building indexes may be effective measures to increase the avian phylogenetic and functional diversity in our system.