Gene expression plasticity followed by genetic change during colonization in a high-elevation environment.

Phenotypic plasticity facilitates organismal invasion of novel environments, and the resultant phenotypic change may later be modified by genetic change, so called 'plasticity first.' Herein, we quantify gene expression plasticity and regulatory adaptation in a wild bird (Eurasian Tree Sparrow) from its original lowland (ancestral stage), experimentally implemented hypoxia acclimation (plastic stage), and colonized highland (colonized stage). Using a group of co-expressed genes from the cardiac and flight muscles, respectively, we demonstrate that gene expression plasticity to hypoxia tolerance is more often reversed than reinforced at the colonized stage. By correlating gene expression change with muscle phenotypes, we show that colonized tree sparrows reduce maladaptive plasticity that largely associated with decreased hypoxia tolerance. Conversely, adaptive plasticity that is congruent with increased hypoxia tolerance is often reinforced in the colonized tree sparrows. Genes displaying large levels of reinforcement or reversion plasticity (i.e. 200% of original level) show greater genetic divergence between ancestral and colonized populations. Overall, our work demonstrates that gene expression plasticity at the initial stage of high-elevation colonization can be reversed or reinforced through selection-driven adaptive modification.

Gene flow and an anomaly zone complicate phylogenomic inference in a rapidly radiated avian family (Prunellidae).

BACKGROUND: Resolving the phylogeny of rapidly radiating lineages presents a challenge when building the Tree of Life. An Old World avian family Prunellidae (Accentors) comprises twelve species that rapidly diversified at the Pliocene-Pleistocene boundary. RESULTS: Here we investigate the phylogenetic relationships of all species of Prunellidae using a chromosome-level de novo assembly of Prunella strophiata and 36 high-coverage resequenced genomes. We use homologous alignments of thousands of exonic and intronic loci to build the coalescent and concatenated phylogenies and recover four different species trees. Topology tests show a large degree of gene tree-species tree discordance but only 40-54% of intronic gene trees and 36-75% of exonic genic trees can be explained by incomplete lineage sorting and gene tree estimation errors. Estimated branch lengths for three successive internal branches in the inferred species trees suggest the existence of an empirical anomaly zone. The most common topology recovered for species in this anomaly zone was not similar to any coalescent or concatenated inference phylogenies, suggesting presence of anomalous gene trees. However, this interpretation is complicated by the presence of gene flow because extensive introgression was detected among these species. When exploring tree topology distributions, introgression, and regional variation in recombination rate, we find that many autosomal regions contain signatures of introgression and thus may mislead phylogenetic inference. Conversely, the phylogenetic signal is concentrated to regions with low-recombination rate, such as the Z chromosome, which are also more resistant to interspecific introgression. CONCLUSIONS: Collectively, our results suggest that phylogenomic inference should consider the underlying genomic architecture to maximize the consistency of phylogenomic signal.

Genomes, fossils, and the concurrent rise of modern birds and flowering plants in the Late Cretaceous.

The phylogeny and divergence timing of the Neoavian radiation remain controversial despite recent progress. We analyzed the genomes of 124 species across all Neoavian orders, using data from 25,460 loci spanning four DNA classes, including 5,756 coding sequences, 12,449 conserved nonexonic elements, 4,871 introns, and 2,384 intergenic segments. We conducted a comprehensive sensitivity analysis to account for the heterogeneity across different DNA classes, leading to an optimal tree of Neoaves with high resolution. This phylogeny features a novel Neoavian dichotomy comprising two monophyletic clades: a previously recognized Telluraves (land birds) and a newly circumscribed Aquaterraves (waterbirds and relatives). Molecular dating analyses with 20 fossil calibrations indicate that the diversification of modern birds began in the Late Cretaceous and underwent a constant and steady radiation across the KPg boundary, concurrent with the rise of angiosperms as well as other major Cenozoic animal groups including placental and multituberculate mammals. The KPg catastrophe had a limited impact on avian evolution compared to the Paleocene-Eocene Thermal Maximum, which triggered a rapid diversification of seabirds. Our findings suggest that the evolution of modern birds followed a slow process of gradualism rather than a rapid process of punctuated equilibrium, with limited interruption by the KPg catastrophe. This study places bird evolution into a new context within vertebrates, with ramifications for the evolution of the Earth's biota.

Climate match is key to predict range expansion of the world's worst invasive terrestrial vertebrates.

Understanding the determinants of the range expansion of invasive alien species is crucial for developing effective prevention and control strategies. Nevertheless, we still lack a global picture of the potential factors influencing the invaded range expansion across taxonomic groups, especially for the world's worst invaders with high ecological and economic impacts. Here, by extensively collecting data on 363 distributional ranges of 19 of world's worst invasive terrestrial vertebrates across 135 invaded administrative jurisdictions, we observed remarkable variations in the range expansion across species and taxonomic groups. After controlling for taxonomic and geographic pseudoreplicates, model averaging analyses based on generalized additive mixed-effect models showed that species in invaded regions having climates more similar to those of their native ranges tended to undergo a larger range expansion. In addition, as proxies of propagule pressure and human-assisted transportation, the number of introduction events and the road network density were also important predictors facilitating the range expansion. Further variance partitioning analyses validated the predominant role of climate match in explaining the range expansion. Our study demonstrated that regions with similar climates to their native ranges could still be prioritized to prevent the spread of invasive species under the sustained global change.

Cryptic diversity begets challenges and opportunities in biodiversity research.

How many species of life are there on Earth? This is a question that we want to know but cannot yet answer. Some scholars speculate that the number of species may reach 2.2 billion when considering cryptic diversity and that each morphology-based insect species may contain an average of 3.1 cryptic species. With nearly two million described species, such high estimates of cryptic diversity would suggest that cryptic species are widespread. The development of molecular species delimitation has led to the discovery of a large number of cryptic species, and cryptic biodiversity has gradually entered our field of vision and attracted more attention. This paper introduces the concept of cryptic species, how they evolve, and methods by which they may be discovered and confirmed, and provides theoretical and methodological guidance for the study of hidden species. A workflow of how to confirm cryptic species is provided. In addition, the importance and reliability of multi-evidence-based integrated taxonomy are reaffirmed as a way to better standardize decision-making processes. Special focus on cryptic diversity and increased funding for taxonomy is needed to ensure that cryptic species in hyperdiverse groups are discoverable and described. An increased focus on cryptic species in the future will naturally arise as more difficult groups are studied, and thereby, we may finally better understand the rules governing the evolution and maintenance of cryptic biodiversity.

Phylogenetic conflict between species tree and maternally inherited gene trees in a clade of Emberiza buntings (Aves: Emberizidae).

Different genomic regions may reflect conflicting phylogenetic topologies primarily due to incomplete lineage sorting and/or gene flow. Genomic data are necessary to reconstruct the true species tree and explore potential causes of phylogenetic conflict. Here, we investigate the phylogenetic relationships of four Emberiza species (Aves: Emberizidae) and discuss the potential causes of the observed mitochondrial non-monophyly of Emberiza godlewskii (Godlewski's bunting) using phylogenomic analyses based on whole genome resequencing data from 41 birds. Analyses based on both the whole mitochondrial genome and ~39 kilobases from the non-recombining W chromosome reveal sister relationships between each the northern and southern populations of E. godlewskii with E. cioides and E. cia, respectively. In contrast, the monophyly of E. godlewskii is reflected by the phylogenetic signal of autosomal and Z chromosomal sequence data as well as demographic inference analyses, which - in combination - support the following tree topology: (((E. godlewskii, E. cia), E. cioides), E. jankowskii). Using D-statistics, we detected multiple gene flow events among different lineages, indicating pervasive introgressive hybridization within this clade. Introgression from an unsampled lineage that is sister to E. cioides or introgression from an unsampled mitochondrial + W chromosomal lineage of E. cioides into northern E. godlewskii may explain the phylogenetic conflict between the species tree estimated from genome-wide data versus mtDNA/W tree topologies. These results underscore the importance of using genomic data for phylogenetic reconstruction and species delimitation.

Comparative genomics of widespread and narrow-range white-bellied rats in the Niviventer niviventer species complex sheds light on invasive rodent success.

Widespread species that inhabit diverse environments possess large population sizes and exhibit a high capacity for environmental adaptation, thus enabling range expansion. In contrast, narrow-range species are confined to restricted geographical areas and are ecologically adapted to narrow environmental conditions, thus limiting their ability to expand into novel environments. However, the genomic mechanisms underlying the differentiation between closely related species with varying distribution ranges remain poorly understood. The Niviventer niviventer species complex (NNSC), consisting of highly abundant wild rats in Southeast Asia and China, offers an excellent opportunity to investigate these questions due to the presence of both widespread and narrow-range species that are phylogenetically closely related. In the present study, we combined ecological niche modeling with phylogenetic analysis, which suggested that sister species cannot be both widespread and dominant within the same geographical region. Moreover, by assessing heterozygosity, linkage disequilibrium decay, and Tajima's D analysis, we found that widespread species exhibited higher genetic diversity than narrow-range species. In addition, by exploring the "genomic islands of speciation", we identified 13 genes in highly divergent regions that were shared by the two widespread species, distinguishing them from their narrow-range counterparts. Functional annotation analysis indicated that these genes are involved in nervous system development and regulation. The adaptive evolution of these genes likely played an important role in the speciation of these widespread species.

Global prevalence of self-harm during the COVID-19 pandemic: a systematic review and meta-analysis.

BACKGROUND: COVID-19 and its transmission mitigation measures have caused widespread mental health problems. Previous studies have suggested that psychological, economic, behavioral, and psychosocial problems associated with the COVID-19 pandemic may lead to a rise in self-harm. However, little is known about the prevalence of self-harm worldwide during COVID-19. Therefore, a quantitative synthesis is needed to reach an overall conclusion regarding the prevalence of self-harm during the pandemic. METHODS: By using permutations of COVID-19, self-harm or relevant search terms, we searched the following electronic databases from November 2019 to January 2022: Web of Science, PubMed, MEDLINE, Embase, PsycINFO, Cochrane Database of Systematic Reviews, China National Knowledge Infrastructure (CNKI), Wanfang Database and systematically reviewed the evidence according to MOOSE guidelines. We employed Cochran's chi-squared test (Cochran's Q), I2test and subgroup analysis to assess and address the heterogeneity. Sensitivity analysis was conducted by eliminating each included study individually and then combining the effects. RESULTS: Sixteen studies that met the inclusion and exclusion criteria were identified, with sample sizes ranging from 228 to 49,227. The methodological quality of the included studies was mostly at the medium level. By using a random effect model, the pooled prevalence of self-harm was 15.8% (95% CI 13.3-18.3). Based on subgroup analysis, the following characteristics of the included studies were more likely to have a higher prevalence of self-harm: studies conducted in Asia or prior to July 2020, cross-sectional studies, samples recruited in hospitals or schools, adolescents, females, the purpose of self-harm (NSSI), mental symptoms and restriction experiences. CONCLUSIONS: We provided the first meta-analytic estimated prevalence of self-harm based on a large sample from different countries and populations. The prevalence of self-harm during COVID-19 was not encouraging and requires attention and intervention. Further high-quality and prospective research are needed in order to determine the prevalence of self-harm with greater accuracy because to the clear heterogeneity across the included studies. In addition, this study also provides new directions for future research, including the identification of high-risk groups for self-harm, the formulation and implementation of prevention and intervention programs, and the long-term impact of COVID-19 on self-harm.

Recurrent selection and reduction in recombination shape the genomic landscape of divergence across multiple population pairs of Green-backed Tit.

Speciation is fundamental for building and maintaining biodiversity. The formation of the highly differentiated genomic regions between diverging taxa has been interpreted as a result of divergence with gene flow, linked selection, and reduction in recombination. It is challenging to unravel these nonexclusive processes in shaping genomic divergence. Here, we investigate the relative roles of these processes in shaping genomic differentiation in a montane bird, the Green-backed Tit (Parus monticolus). Our genetic structure and demographic analyses identify that four genetic lineages diverge between 838 and 113 thousand years ago and there is evidence of secondary gene flow. The highly divergent genomic regions do not increase with the divergence time, as we found that the old lineages show relatively fewer numbers and smaller sizes of highly differentiated regions than the young divergent lineages (numbers, 118-138 vs. 156-289; sizes, 5.9-6.9 vs. 7.8-14.5 megabase). Across the genome, the outlier windows show a reduction in nucleotide diversity, absolute genetic divergence, and recombination rate, suggesting recurrent selection in regions with low recombination being the major driver of genomic divergence. Finally, we show that secondary gene flow tends to affect the highly differentiated genomic regions if these regions are less likely to be the targets of selection. Altogether, our study shows how common ancestry, recurrent selection, low recombination rate, and gene flow have contributed to the emergence of genomic islands at different stages of speciation.

Divergent contributions of coding and noncoding sequences to initial high-altitude adaptation in passerine birds endemic to the Qinghai-Tibet Plateau.

Early events in the evolution of an ancestral lineage can shape the adaptive patterns of descendant species, but the evolutionary mechanisms driving initial adaptation from an ancestor remain largely unexplored. High-altitude adaptations have been extensively explored from the viewpoint of protein-coding genes; however, the contribution of noncoding regions remains relatively neglected. Here, we integrate genomic and transcriptomic data to investigate adaptive evolution in the ancestor of three high-altitude snowfinch species endemic to the Qinghai-Tibet Plateau. Our genome-wide scan for adaptation in the snowfinch ancestor identifies strong adaptation signals in functions of development and metabolism for the coding genes, but in functions of the nervous system development for noncoding regions. This pattern is exclusive to the snowfinch ancestor compared to a control ancestral lineage subject to weak selection. Changes in noncoding regions in the snowfinch ancestor, especially those nearest to coding genes, may be disproportionately associated with the differential expression of genes in the brain tissue compared to other tissues. Extensive gene expression in the brain tissue can be further altered via genetic regulatory networks of transcription factors harbouring potential accelerated regulatory regions (e.g., the development-related transcription factor YEATS4). Altogether, our study provides new evidence concerning how coding and noncoding sequences work through decoupled pathways in initial adaptation to the selective pressure of high-altitude environments. The analysis highlights the idea that noncoding sequences may be promising elements in facilitating the rapid evolution and adaptation to high altitudes.

Effects of climate change and anthropogenic activity on ranges of vertebrate species endemic to the Qinghai-Tibet Plateau over 40 years.

Over the past 40 years, the climate has been changing and human disturbance has increased in the vast Qinghai-Tibet Plateau (QTP). These 2 factors are expected to affect the distribution of a large number of endemic vertebrate species. However, quantitative relationships between range shifts and climate change and human disturbance of these species in the QTP have rarely been evaluated. We used occurrence records of 19 terrestrial vertebrate species (birds, mammals, amphibians, and reptiles) occurring in the QTP from 1980 to 2020 to quantify the effects of climate change and anthropogenic impacts on the distribution of these 4 taxonomic groups and estimated species range changes in each species. The trend in distribution changes differed among the taxonomic groups, although, generally, ranges shifted to central QTP. Climate change contributed more to range variation than human disturbance (the sum of the 4 climatic variables contributed more than the sum of the 4 human disturbance variables for all 4 taxonomic groups). Suitable geographic range increased for most mammals, amphibians, and reptiles (+27.6%, +18.4%, and +27.8% on average, respectively), whereas for birds range decreased on average by 0.9%. Quantitative evidence for climate change and human disturbance associations with range changes for endemic vertebrate species in the QTP can provide useful insights into biodiversity conservation under changing environments.

En los últimos 40 años, el clima ha cambiado y las perturbaciones humanas han aumentado en la vasta meseta Qinghai-Tíbet (MQT). Se espera que estos dos factores afecten la distribución de un gran número de especies de vertebrados endémicos. Sin embargo, las relaciones cuantitativas entre los cambios del área de distribución y el cambio climático y las perturbaciones humanas en estas especies de la MQT han sido poco evaluadas. Utilizamos los registros de presencia de 19 especies de vertebrados terrestres (aves, mamíferos, anfibios y reptiles) de la MQT tomados entre 1980 y 2020 para cuantificar los efectos del cambio climático y los impactos antropogénicos sobre la distribución de estos cuatro grupos taxonómicos y estimar los cambios en el área de distribución de cada especie. La tendencia en los cambios de distribución difirió entre los grupos taxonómicos, aunque, en general, las áreas de distribución se desplazaron hacia el centro de la MQT. El cambio climático contribuyó más a la variación del área de distribución que las perturbaciones humanas (la suma de las cuatro variables climáticas contribuyó más que la suma de las cuatro variables de perturbaciones humanas para los cuatro grupos taxonómicos). El área de distribución geográfica adecuada aumentó para la mayoría de los mamíferos, anfibios y reptiles (+27.6%, +18.4% y +27.8% en promedio, respectivamente), mientras que para las aves disminuyó en promedio un 0.9%. Las pruebas cuantitativas de la asociación del cambio climático y las perturbaciones humanas con los cambios en el área de distribución de las especies vertebradas endémicas de la MQT pueden aportar información útil para la conservación de la biodiversidad en entornos cambiantes.

Genomic Consequences of and Demographic Response to Pervasive Hybridization Over Time in Climate-Sensitive Pikas.

Rare and geographically restricted species may be vulnerable to genetic effects from inbreeding depression in small populations or from genetic swamping through hybridization with common species, but a third possibility is that selective gene flow can restore fitness (genetic rescue). Climate-sensitive pikas (Ochotona spp.) of the Qinghai-Tibetan Plateau (QHTP) and its vicinity have been reduced to residual populations through the movement of climatic zones during the Pleistocene and recent anthropogenic disturbance, whereas the plateau pika (O. curzoniae) remains common. Population-level whole-genome sequencing (n = 142) of six closely related species in the subgenus Ochotona revealed several phases of ancient introgression, lineage replacement, and bidirectional introgression. The strength of gene flow was the greatest from the dominant O. curzoniae to ecologically distinct species in areas peripheral to the QHTP. Genetic analyses were consistent with environmental reconstructions of past population movements. Recurrent periods of introgression throughout the Pleistocene revealed an increase in genetic variation at first but subsequent loss of genetic variation in later phases. Enhanced dispersion of introgressed genomic regions apparently contributed to demographic recovery in three peripheral species that underwent range shifts following climate oscillations on the QHTP, although it failed to drive recovery of northeastern O. dauurica and geographically isolated O. sikimaria. Our findings highlight differences in timescale and environmental background to determine the consequence of hybridization and the unique role of the QHTP in conserving key evolutionary processes of sky island species.

Genomic and phenotypic changes associated with alterations of migratory behaviour in a songbird.

The seasonal migration of birds is a fascinating natural wonder. Avian migratory behaviour changes are common and are probably a polygenic process as avian migration is governed by multiple correlated components with a variable genetic basis. However, the genetic and phenotypic changes involving migration changes are poorly studied. Using one annotated near-chromosomal level de novo genome assembly, 50 resequenced genomes, hundreds of morphometric data and species distribution information, we investigated population structure and genomic and phenotypic differences associated with differences in migratory behaviour in a songbird species, Yellow-throated Bunting Emberiza elegans (Aves: Emberizidae). Population genomic analyses reveal extensive gene flow between the southern resident and the northern migratory populations of this species. The hand-wing index is significantly lower in the resident populations than in the migratory populations, indicating reduced flight efficiency of the resident populations. Here, we discuss the possibility that nonmigratory populations may have originated from migratory populations though migration loss. We further infer that the alterations of genes related to energy metabolism, nervous system and circadian rhythm may have played major roles in regulating migration change. Our study sheds light on phenotypic and polygenic changes involving migration change.

Pathways from self-disclosure to medical coping strategy among adolescents with moderate and major depression during the COVID-19 pandemic: A mediation of self-efficacy.

Background: The prevalence of adolescent depression in China during the COVID-19 pandemic is increasing. Self-disclosing depressive emotions could help release stress. Self-disclosure, which is a prerequisite for self-efficacy, can directly contribute to people's psychological health, and depression and the choice of coping strategy are determined by the level of self-efficacy perceived. Purpose: We aimed to discuss the relationship between self-efficacy, self-disclosure, and medical coping strategy. Further, we explore the mediation effect of self-efficacy on the influence of self-disclosure on medical coping strategies in adolescents with depression. Methods: A total of 585 patients aged 11-24 years with moderate and major depression were recruited. All the assessments were completed on the second day after admission, including the General Self-Efficacy Scale (GSE), Distress Disclosure Index (DDI), and Medical Coping Modes Questionnaire (MCMQ). Pearson correlation was performed to explore the relationships of these variables. The bootstrap analysis was used to conduct to assess the mediation effects. Results: Both direct and indirect effects of self-disclosure on medical coping strategy were found. As predicted, self-efficacy partially mediated the relationship between self-disclosure and medical coping strategy (b = 0.0385, 95% CI: 0.0244-0.0538 for Confrontation; b = -0.0466, 95%CI: -0.0651 to -0.0296 for Resignation), respectively. The effect size for Confrontation and Resignation was 0.2659 and 0.2485, respectively. Conclusion: Self-efficacy played a partial mediating role in the effect of self-disclosure on medical coping strategies for adolescent depression during the COVID-19 pandemic, and the use of a positive self-disclosure mechanism may be anticipated to promote improved self-efficacy and the use of active coping strategies.

Orthologous microsatellites, transposable elements, and DNA deletions correlate with generation time and body mass in neoavian birds.

The rate of mutation accumulation in germline cells can be affected by cell replication and/or DNA damage, which are further related to life history traits such as generation time and body mass. Leveraging the existing datasets of 233 neoavian bird species, here, we investigated whether generation time and body mass contribute to the interspecific variation of orthologous microsatellite length, transposable element (TE) length, and deletion length and how these genomic attributes affect genome sizes. In nonpasserines, we found that generation time is correlated to both orthologous microsatellite length and TE length, and body mass is negatively correlated to DNA deletions. These patterns are less pronounced in passerines. In all species, we found that DNA deletions relate to genome size similarly as TE length, suggesting a role of body mass dynamics in genome evolution. Our results indicate that generation time and body mass shape the evolution of genomic attributes in neoavian birds.

A 14,000-year-old genome sheds light on the evolution and extinction of a Pleistocene vulture.

The New World Vulture [Coragyps] occidentalis (L. Miller, 1909) is one of many species that were extinct by the end of the Pleistocene. To understand its evolutionary history we sequenced the genome of a 14,000 year old [Coragyps] occidentalis found associated with megaherbivores in the Peruvian Andes. occidentalis has been viewed as the ancestor, or possibly sister, to the extant Black Vulture Coragyps atratus, but genomic data shows occidentalis to be deeply nested within the South American clade of atratus. Coragyps atratus inhabits lowlands, but the fossil record indicates that occidentalis mostly occupied high elevations. Our results suggest that occidentalis evolved from a population of atratus in southwestern South America that colonized the High Andes 300 to 400 kya. The morphological and morphometric differences between occidentalis and atratus may thus be explained by ecological diversification following from the natural selection imposed by this new and extreme, high elevation environment. The sudden evolution of a population with significantly larger body size and different anatomical proportions than atratus thus constitutes an example of punctuated evolution.

The combination of genomic offset and niche modelling provides insights into climate change-driven vulnerability.

Global warming is increasingly exacerbating biodiversity loss. Populations locally adapted to spatially heterogeneous environments may respond differentially to climate change, but this intraspecific variation has only recently been considered when modelling vulnerability under climate change. Here, we incorporate intraspecific variation in genomic offset and ecological niche modelling to estimate climate change-driven vulnerability in two bird species in the Sino-Himalayan Mountains. We found that the cold-tolerant populations show higher genomic offset but risk less challenge for niche suitability decline under future climate than the warm-tolerant populations. Based on a genome-niche index estimated by combining genomic offset and niche suitability change, we identified the populations with the least genome-niche interruption as potential donors for evolutionary rescue, i.e., the populations tolerant to climate change. We evaluated potential rescue routes via a landscape genetic analysis. Overall, we demonstrate that the integration of genomic offset, niche suitability modelling, and landscape connectivity can improve climate change-driven vulnerability assessments and facilitate effective conservation management.

Comparison between short-term stress and long-term adaptive responses reveal common paths to molecular adaptation.

The phenotypic plasticity in responses to short-term stress can provide clues for understanding the adaptive fixation mechanism of genetic variation during long-term exposure to extreme environments. However, few studies have compared short-term stress responses with long-term evolutionary patterns; in particular, no interactions between the two processes have been evaluated in high-altitude environment. We performed RNA sequencing in embryo fibroblasts derived from great tits and mice to explore transcriptional responses after exposure to simulated high-altitude environmental stresses. Transcriptional changes of genes associated with metabolic pathways were identified in both bird and mice cells after short-term stress responses. Genomic comparisons among long-term highland tits and mammals and their lowland relatives revealed similar pathways (e.g., metabolic pathways) with that initiated under short-term stress transcriptional responses in vitro. These findings highlight the indicative roles of short-term stress in the long-term adaptation, and adopt common paths to molecular adaptation in mouse and bird cells.

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. However, its regulatory and metabolic mechanisms remain enigmatic to date. Here, we integrated phenomic, transcriptomic, 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 snow finches. 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 snow finches 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.

Parallel genomic responses to historical climate change and high elevation in East Asian songbirds.

Parallel evolution can be expected among closely related taxa exposed to similar selective pressures. However, parallelism is typically stronger at the phenotypic level, while genetic solutions to achieve these phenotypic similarities may differ. For polygenic traits, the availability of standing genetic variation (i.e., heterozygosity) may influence such genetic nonparallelism. Here, we examine the extent to which high-elevation adaptation is parallel-and whether the level of parallelism is affected by heterozygosity-by analyzing genomes of 19 Paridae species distributed across East Asia with a dramatic east-west elevation gradient. We find that western highlands endemic parids have consistently lower levels of heterozygosity-likely the result of late-Pleistocene demographic contraction-than do parids found exclusively in eastern lowlands, which remained unglaciated during the late Pleistocene. Three widespread species (east to west) have high levels of heterozygosity similar to that observed in eastern species, although their western populations are less variable than eastern ones. Comparing genomic responses to extreme environments of the Qinghai-Tibet Plateau, we find that the most differentiated genomic regions between each high-elevation taxon and its low-elevation relative are significantly enriched for genes potentially related to the oxygen transport cascade and/or thermogenesis. Despite no parallelism at particular genes, high similarity in gene function is found among comparisons. Furthermore, parallelism is not higher in more heterozygous widespread parids than in highland endemics. Thus, in East Asian parids, parallel functional response to extreme elevation appears to rely on different genes, with differences in heterozygosity having no effect on the degree of genetic parallelism.