Multiple models for outbreak decision support in the face of uncertainty.

Policymakers must make management decisions despite incomplete knowledge and conflicting model projections. Little guidance exists for the rapid, representative, and unbiased collection of policy-relevant scientific input from independent modeling teams. Integrating approaches from decision analysis, expert judgment, and model aggregation, we convened multiple modeling teams to evaluate COVID-19 reopening strategies for a mid-sized United States county early in the pandemic. Projections from seventeen distinct models were inconsistent in magnitude but highly consistent in ranking interventions. The 6-mo-ahead aggregate projections were well in line with observed outbreaks in mid-sized US counties. The aggregate results showed that up to half the population could be infected with full workplace reopening, while workplace restrictions reduced median cumulative infections by 82%. Rankings of interventions were consistent across public health objectives, but there was a strong trade-off between public health outcomes and duration of workplace closures, and no win-win intermediate reopening strategies were identified. Between-model variation was high; the aggregate results thus provide valuable risk quantification for decision making. This approach can be applied to the evaluation of management interventions in any setting where models are used to inform decision making. This case study demonstrated the utility of our approach and was one of several multimodel efforts that laid the groundwork for the COVID-19 Scenario Modeling Hub, which has provided multiple rounds of real-time scenario projections for situational awareness and decision making to the Centers for Disease Control and Prevention since December 2020.

Association of PLXND1 with a novel subtype of anomalous pulmonary venous return.

Anomalous pulmonary venous return (APVR) is a potentially lethal congenital heart disease. Elucidating the genetic etiology is crucial for understanding its pathogenesis and improving clinical practice, whereas its genetic basis remains largely unknown because of complex genetic etiology. We thus performed whole-exome sequencing for 144 APVR patients and 1636 healthy controls and report a comprehensive atlas of APVR-related rare genetic variants. Novel singleton, loss-of-function and deleterious missense variants (DVars) were enriched in patients, particularly for genes highly expressed in the developing human heart at the critical time point for pulmonary veins draining into the left atrium. Notably, PLXND1, encoding a receptor for semaphorins, represents a strong candidate gene of APVR (adjusted P = 1.1e-03, odds ratio: 10.9-69.3), accounting for 4.17% of APVR. We further validated this finding in an independent cohort consisting of 82 case-control pairs. In these two cohorts, eight DVars were identified in different patients, which convergently disrupt the GTPase-activating protein-related domain of PLXND1. All variant carriers displayed strikingly similar clinical features, in that all anomalous drainage of pulmonary vein(s) occurred on the right side and incorrectly connected to the right atrium, which may represent a novel subtype of APVR for molecular diagnosis. Studies in Plxnd1 knockout mice further revealed the effects of PLXND1 deficiency on severe heart and lung defects and cellular abnormalities related to APVR such as abnormal migration and vascular formation of vascular endothelial cells. These findings indicate the important role of PLXND1 in APVR pathogenesis, providing novel insights into the genetic etiology and molecular subtyping for APVR.

KF-catalyzed direct thiomethylation of carboxylic acids with DMSO to access methyl thioesters.

With dimethyl sulfoxide (DMSO) as the methylthio source, a KF-catalyzed strategy was employed for the direct thiomethylation of carboxylic acids with DMSO for the preparation of methyl thioesters. In this process, a wide range of methyl thioesters were obtained in moderate to excellent yields. This novel strategy features the first use of DMSO as a methylthiolating agent for the construction of methyl thioesters, transition metal-free conditions, inexpensive reagents, easy workup, broad substrate scope and sustainability. Additionally, this procedure can be readily scaled up to a gram scale.

Natural pyrethrins induce cytotoxicity in SH-SY5Y cells and neurotoxicity in zebrafish embryos (Danio rerio).

Natural pyrethrins are widely used in agriculture because of their good insecticidal activity. Meanwhile, natural pyrethrins play an important role in the safety evaluation of pyrethroids as precursors for structural development of pyrethroid insecticides. However, there are fewer studies evaluating the neurological safety of natural pyrethrins on non-target organisms. In this study, we used SH-SY5Y cells and zebrafish embryos to explore the neurotoxicity of natural pyrethrins. Natural pyrethrins were able to induce SH-SY5Y cells damage, as evidenced by decreased viability, cycle block, apoptosis and DNA damage. The apoptotic pathway may be related to the involvement of mitochondria and the results showed that natural pyrethrins induced a rise in Capase-3 viability, Ca2+ overload, a decrease in adenosine triphosphate (ATP) and a collapse of mitochondrial membrane potential in SH-SY5Y cells. Natural pyrethrins may mediate DNA damage in SH-SY5Y cells through oxidative stress. The results showed that natural pyrethrins induced an increase in reactive oxygen species (ROS) levels, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and catalase (CAT) activity, and induced a decrease in glutathione peroxidase (GPx) activity in SH-SY5Y cells. In vivo, natural pyrethrins induced developmental malformations in zebrafish embryos, which were mainly characterized by pericardial edema and yolk sac edema. Meanwhile, the results showed that natural pyrethrins induced damage to the Huc-GFP axis and disturbed lipid metabolism in the head of zebrafish embryos. Further results showed elevated ROS levels and apoptosis in the head of zebrafish embryos, which corroborated with the results of the cell model. Finally, the results of mRNA expression assay of neurodevelopment-related genes indicated that natural pyrethrins exposure interfered with their expression and led to neurodevelopmental damage in zebrafish embryos. Our study may raise concerns about the neurological safety of natural pyrethrins on non-target organisms.

Sunitinib resistance in renal cell carcinoma: From molecular mechanisms to predictive biomarkers.

Currently, renal cell carcinoma (RCC) is the most prevalent type of kidney cancer. Targeted therapy has replaced radiation therapy and chemotherapy as the main treatment option for RCC due to the lack of significant efficacy with these conventional therapeutic regimens. Sunitinib, a drug used to treat gastrointestinal tumors and renal cell carcinoma, inhibits the tyrosine kinase activity of a number of receptor tyrosine kinases, including vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), c-Kit, rearranged during transfection (RET) and fms-related receptor tyrosine kinase 3 (Flt3). Although sunitinib has been shown to be efficacious in the treatment of patients with advanced RCC, a significant number of patients have primary resistance to sunitinib or acquired drug resistance within the 6-15 months of therapy. Thus, in order to develop more efficacious and long-lasting treatment strategies for patients with advanced RCC, it will be crucial to ascertain how to overcome sunitinib resistance that is produced by various drug resistance mechanisms. In this review, we discuss: 1) molecular mechanisms of sunitinib resistance; 2) strategies to overcome sunitinib resistance and 3) potential predictive biomarkers of sunitinib resistance.

Paospora carinifang n. gen., n. sp. (Microsporidia: Spragueidae), a parasite of the ridgetail white prawn, Palaemon carinicauda.

A new microsporidian disease of the pond-reared ridgetail white prawn, Palaemon carinicauda, was found in China. Light microscopy, pathology, and scanning electron microscopy showed that the parasite infected the host's skeletal muscle tissue and formed spherical sporophorous vesicles (SPOVs). Electron microscopy revealed that its merogonic life stages developed in direct contact with the host cytoplasm. The sporogonic life stages underwent octosporoblastic sporogony with the formation of eight uninucleate spores in each SPOV. Fresh SPOVs were 5.4 ± 0.55 µm in diameter. The octospores were oval and measured 2.3 × 1.5 µm (fresh) and 1.96 × 1.17 µm (fixed). The isofilar polar filament was coiled with 9-10 turns and arranged in two rows. Phylogenetic analysis based on the SSU rRNA gene suggests that this microsporidium has close affinities with members of the genera Potaspora and Apotaspora, but represents an independent generic taxon. We therefore propose the establishment of a new genus and species (Paospora carinifang n. gen., n. sp.) within the family Spragueidae. We also propose a taxonomic revision to transfer Potaspora macrobrachium to this new genus and reclassify it as Paospora macrobrachium comb. nov.

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.

Short-term postmortem interval estimation by detection of apoptosis-related protein in skin.

Time-of-death extrapolation has always been one of the most important issues in forensic practice. For a complicated case in which a corpse is destroyed with little evidence, judging the time of death of the deceased is a major challenge, which also enables criminals to escape legal sanctions. To find a method to roughly judge the time of death of a corpse with only a small amount of skin tissue, in this study, we established an early death model by using mice; furthermore, the postmortem interval was estimated by determining the protein and mRNA levels of Bax and Bcl-2 in the skin. In this process, 0 h after death was used as the control group, and the expression levels of Bax and Caspase-3 reached the maximum value at 8-12 h, while Bcl-2, as an inhibitor of apoptosis protein, peaked after 24 h. The mRNA expression levels of related proteins in postmortem skin tissues were also different. The results of these data indicate that the protein and mRNA levels of Bax and Bcl-2 in the skin have potential application in early time-of-death estimation.

Molecular subtyping based on immune cell marker genes predicts prognosis and therapeutic response in patients with lung adenocarcinoma.

OBJECTIVE: Lung adenocarcinoma (LA) is one of the most common malignancies and is responsible for the greatest number of tumor-related deaths. Our research aimed to explore the molecular subtype signatures of LA to clarify the correlation among the immune microenvironment, clinical outcomes, and therapeutic response. METHODS: The LA immune cell marker genes (LICMGs) identified by single-cell RNA sequencing (scRNA-seq) analysis were used to discriminate the molecular subtypes and homologous immune and metabolic traits of GSE72094 LA cases. In addition, the model-building genes were identified from 1441 LICMGs by Cox-regression analysis, and a LA immune difference score (LIDscore) was developed to quantify individual differences in each patient, thereby predicting prognosis and susceptibility to immunotherapy and chemotherapy of LA patients. RESULTS: Patients of the GSE72094 cohort were divided into two distinct molecular subtypes based on LICMGs: immune activating subtype (Cluster-C1) and metabolically activating subtype (cluster-C2). The two molecular subtypes have distinct characteristics regarding prognosis, clinicopathology, genomics, immune microenvironment, and response to immunotherapy. Among the LICMGs, LGR4, GOLM1, CYP24A1, SFTPB, COL1A1, HLA-DQA1, MS4A7, PPARG, and IL7R were enrolled to construct a LIDscore model. Low-LIDscore patients had a higher survival rate due to abundant immune cell infiltration, activated immunity, and lower genetic variation, but probably the higher levels of Treg cells in the immune microenvironment lead to immune cell dysfunction and promote tumor immune escape, thus decreasing the responsiveness to immunotherapy compared with that of the high-LIDscore patients. Overall, high-LIDscore patients had a higher responsiveness to immunotherapy and a higher sensitivity to chemotherapy than the low-LIDscore group. CONCLUSIONS: Molecular subtypes based on LICMGs provided a promising strategy for predicting patient prognosis, biological characteristics, and immune microenvironment features. In addition, they helped identify the patients most likely to benefit from immunotherapy and chemotherapy.

The role of demographic compensation in stabilising marginal tree populations in North America.

Demographic compensation-the opposing responses of vital rates along environmental gradients-potentially delays anticipated species' range contraction under climate change, but no consensus exists on its actual contribution. We calculated population growth rate (λ) and demographic compensation across the distributional ranges of 81 North American tree species and examined their responses to simulated warming and tree competition. We found that 43% of species showed stable population size at both northern and southern edges. Demographic compensation was detected in 25 species, yet 15 of them still showed a potential retraction from southern edges, indicating that compensation alone cannot maintain range stability. Simulated climatic warming caused larger decreases in λ for most species and weakened the effectiveness of demographic compensation in stabilising ranges. These findings suggest that climate stress may surpass the limited capacity of demographic compensation and pose a threat to the viability of North American tree populations.

Genomic Consequences of Long-Term Population Decline in Brown Eared Pheasant.

Population genetic theory and empirical evidence indicate that deleterious alleles can be purged in small populations. However, this viewpoint remains controversial. It is unclear whether natural selection is powerful enough to purge deleterious mutations when wild populations continue to decline. Pheasants are terrestrial birds facing a long-term risk of extinction as a result of anthropogenic perturbations and exploitation. Nevertheless, there are scant genomics resources available for conservation management and planning. Here, we analyzed comparative population genomic data for the three extant isolated populations of Brown eared pheasant (Crossoptilon mantchuricum) in China. We showed that C. mantchuricum has low genome-wide diversity and a contracting effective population size because of persistent declines over the past 100,000 years. We compared genome-wide variation in C. mantchuricum with that of its closely related sister species, the Blue eared pheasant (C. auritum) for which the conservation concern is low. There were detrimental genetic consequences across all C. mantchuricum genomes including extended runs of homozygous sequences, slow rates of linkage disequilibrium decay, excessive loss-of-function mutations, and loss of adaptive genetic diversity at the major histocompatibility complex region. To the best of our knowledge, this study is the first to perform a comprehensive conservation genomic analysis on this threatened pheasant species. Moreover, we demonstrated that natural selection may not suffice to purge deleterious mutations in wild populations undergoing long-term decline. The findings of this study could facilitate conservation planning for threatened species and help recover their population size.

Not out of the woods yet: Signatures of the prolonged negative genetic consequences of a population bottleneck in a rapidly re-expanding wader, the black-faced spoonbill Platalea minor.

The long-term persistence of a population which has suffered a bottleneck partly depends on how historical demographic dynamics impacted its genetic diversity and the accumulation of deleterious mutations. Here we provide genomic evidence for the genetic effect of a recent population bottleneck in the endangered black-faced spoonbill (Platalea minor) after its rapid population recovery. Our data suggest that the bird's effective population size, Ne , had been relatively stable (7500-9000) since 22,000 years ago; however, a recent brief yet severe bottleneck (Ne  = 20) which we here estimated to occur around the 1940s wiped out >99% of its historical Ne in roughly three generations. Despite a >15-fold population recovery since 1988, we found that black-faced spoonbill population has higher levels of inbreeding (7.4 times more runs of homozygosity) than its sister species, the royal spoonbill (P. regia), which is not thought to have undergone a marked population contraction. Although the two spoonbills have similar levels of genome-wide genetic diversity, our results suggest that selection on more genes was relaxed in the black-faced spoonbill; moreover individual black-faced spoonbills carry more putatively deleterious mutations (Grantham's score > 50), and may therefore express more deleterious phenotypic effects than royal spoonbills. Here we demonstrate the value of using genomic indices to monitor levels of genetic erosion, inbreeding and mutation load in species with conservation concerns. To mitigate the prolonged negative genetic effect of a population bottleneck, we recommend that all possible measures should be employed to maintain population growth of a threatened species.

Potential millennial-scale avian declines by humans in southern China.

Mounting observational records demonstrate human-caused faunal decline in recent decades, while accumulating archaeological evidence suggests an early biodiversity impact of human activities during the Holocene. A fundamental question arises concerning whether modern wildlife population declines began during early human disturbance. Here, we performed a population genomic analysis of six common forest birds in East Asia to address this question. For five of them, demographic history inference based on 25-33 genomes of each species revealed dramatic population declines by 4- to 48-fold over millennia (e.g. 2000-5000 thousand years ago). Nevertheless, summary statistics detected nonsignificant correlations between these population size trajectories and Holocene temperature variations, and ecological niche models explicitly predicted extensive range persistence during the Holocene, implying limited demographic consequence of Holocene climate change. Further analyses suggest high negative correlations between the reconstructed population declines and human disturbance intensities and indicate a potential driver of human activities. These findings provide a deep-time and large-scale insight into the recently recognized avifaunal decline and support an early origin hypothesis of human effects on biodiversity. Overall, our study sheds light on the current biodiversity crisis in the context of long-term human-environment interactions and offers a multi-evidential framework for quantitatively assessing the ecological consequences of human disturbance.

Vote-processing rules for combining control recommendations from multiple models.

Mathematical modelling is used during disease outbreaks to compare control interventions. Using multiple models, the best method to combine model recommendations is unclear. Existing methods weight model projections, then rank control interventions using the combined projections, presuming model outputs are directly comparable. However, the way each model represents the epidemiological system will vary. We apply electoral vote-processing rules to combine model-generated rankings of interventions. Combining rankings of interventions, instead of combining model projections, avoids assuming that projections are comparable as all comparisons of projections are made within each model. We investigate four rules: First-past-the-post, Alternative Vote (AV), Coombs Method and Borda Count. We investigate rule sensitivity by including models that favour only one action or including those that rank interventions randomly. We investigate two case studies: the 2014 Ebola outbreak in West Africa (37 compartmental models) and a hypothetical foot-and-mouth disease outbreak in UK (four individual-based models). The Coombs Method was least susceptible to adding models that favoured a single action, Borda Count and AV were most susceptible to adding models that ranked interventions randomly. Each rule chose the same intervention as when ranking interventions by mean projections, suggesting that combining rankings provides similar recommendations with fewer assumptions about model comparability. This article is part of the theme issue 'Technical challenges of modelling real-life epidemics and examples of overcoming these'.

Standing genetic variation as the predominant source for adaptation of a songbird.

What kind of genetic variation contributes the most to adaptation is a fundamental question in evolutionary biology. By resequencing genomes of 80 individuals, we inferred the origin of genomic variants associated with a complex adaptive syndrome involving multiple quantitative traits, namely, adaptation between high and low altitudes, in the vinous-throated parrotbill (Sinosuthora webbiana) in Taiwan. By comparing these variants with those in the Asian mainland population, we revealed standing variation in 24 noncoding genomic regions to be the predominant genetic source of adaptation. Parrotbills at both high and low altitudes exhibited signatures of recent selection, suggesting that not only the front but also the trailing edges of postglacial expanding populations could be subjected to environmental stresses. This study verifies and quantifies the importance of standing variation in adaptation in a cohort of genes, illustrating that the evolutionary potential of a population depends significantly on its preexisting genetic diversity. These findings provide important context for understanding adaptation and conservation of species in the Anthropocene.

Photoluminescence properties of anodic aluminium oxide films formed in a mixture of malonic acid and oxalic acid.

In this work, porous anodic aluminium oxide (AAO) films were fabricated by anodization in an electrolyte mixture with various concentration ratios of malonic acid and oxalic acid at room temperature. The photoluminescence (PL) properties of the AAO films before and after annealing from 300°C to 650°C in air or vacuum conditions were investigated, showing a strong PL band in the range 300-550 nm. We observed a weak PL in the AAO film formed in the malonic acid electrolyte, whereas the films fabricated using an electrolyte mixture showed strong PL emissions, exhibiting a maximum. The broad PL band was decomposed into three Gaussian sub-bands, in which the first two sub-bands could be attributed to the luminescence centre oxygen vacancies (F+ and F defect centres), whereas the latter transformed from malonic impurities and oxalic impurities. More interestingly, the redshift of the PL bands occurred with increasing oxalic acid concentration, and the PL wavelength and intensity could be modulated by varying the concentration ratios in the malonic acid and oxalic acid electrolyte mixture.

Patchouli alcohol protects against myocardial ischaemia-reperfusion injury by regulating the Notch1/Hes1 pathway.

CONTEXT: Patchouli alcohol (PA) has protective effects on cerebral ischaemia/reperfusion (I/R) injury, but its efficacy on myocardial ischaemia-reperfusion (MI/R) has yet to be addressed. OBJECTIVE: To examine the therapeutic effect of PA on myocardial ischaemia-reperfusion (I/R) injury. MATERIALS AND METHODS: C57BL/6 male mice were randomly divided into sham, MI/R, MI/R + PA-10, MI/R + PA-20 and MI/R + PA-40 groups. In vivo MI/R model was established by ligating the anterior descending coronary artery of the heart. In vitro stimulated IR cell model was constructed by using the rat cardiomyocyte H9C2 cell line. Mice in the treatment groups were intraperitoneally injected with PA (10, 20, 40 mg/kg) for 30 days then subjected to surgery, and cells in the experimental group were pre-treated with PA (1, 10 or 100 µmol/L). After treatment, mouse heart function, myocardial injury markers, myocardial infarction and Notch1/Hes1 expression, endoplasmic reticulum stress markers, and apoptosis-related proteins were determined. RESULTS: In vivo, PA treatment improved hemodynamic parameter changes and myocardial enzymes, increased the left ventricular ejection fraction and left ventricular fractional shortening, reduced the left ventricular end-systolic diameter and inhibited CK-MB, cTnI and cTnT levels. In addition, PA attenuated myocardial tissue damage and apoptosis. PA treatment elevated Notch1, NICD and Hes1 levels and suppressed the levels of ATF4, p-PERK/PERK, and cleaved caspase-3/caspase-3 in vitro and in vivo. DISCUSSION AND CONCLUSION: PA protects against MI/R, possibly by modulating ER stress, apoptosis and the Notch1/Hes1 signalling pathways. These findings indicate that PA may be a promising candidate for treating ischaemic heart diseases.

The AWPM-19 Family Protein OsPM1 Mediates Abscisic Acid Influx and Drought Response in Rice.

Abscisic acid (ABA) regulates plant stress responses and development. However, how the ABA signal is transmitted in response to stresses remains largely unclear, especially in monocots. In this study, we found that rice (Oryza sativa) OsPM1 (PLASMA MEMBRANE PROTEIN1), encoded by a gene of AWPM-19 like family, mediates ABA influx through the plasma membrane. OsPM1 is predominantly expressed in vascular tissues, guard cells, and mature embryos. Phenotypic analysis of overexpression, RNA interference (RNAi), and knockout (KO) lines showed that OsPM1 is involved in drought responses and seed germination regulation. 3H-(±)ABA transport activity and fluorescence resonance energy transfer assays both demonstrated that OsPM1 facilitates ABA uptake into cells. The physiological isomer of ABA, (+)-ABA, is the preferred substrate of OsPM1. Higher ABA accumulation and faster stomatal closure in response to ABA treatment were observed in the overexpression lines compared with the wild-type control. Many ABA-responsive genes were upregulated more in the OsPM1-overexpression lines but less in the RNAi lines compared with wild-type plants. Further investigation revealed that OsPM1 expression is regulated by the AREB/ABF family transcription factor OsbZIP46. Our results thus revealed that OsPM1 is an ABA influx carrier that plays an important role in drought responses.

A novel Diels-Alder adduct of mulberry leaves exerts anticancer effect through autophagy-mediated cell death.

Guangsangon E (GSE) is a novel Diels-Alder adduct isolated from leaves of Morus alba L, a traditional Chinese medicine widely applied in respiratory diseases. It is reported that GSE has cytotoxic effect on cancer cells. In our research, we investigated its anticancer effect on respiratory cancer and revealed that GSE induces autophagy and apoptosis in lung and nasopharyngeal cancer cells. We first observed that GSE inhibits cell proliferation and induces apoptosis in A549 and CNE1 cells. Meanwhile, the upregulation of autophagosome marker LC3 and increased formation of GFP-LC3 puncta demonstrates the induction of autophagy in GSE-treated cells. Moreover, GSE increases the autophagy flux by enhancing lysosomal activity and the fusion of autophagosomes and lysosomes. Next, we investigated that endoplasmic reticulum (ER) stress is involved in autophagy induction by GSE. GSE activates the ER stress through reactive oxygen species (ROS) accumulation, which can be blocked by ROS scavenger NAC. Finally, inhibition of autophagy attenuates GSE-caused cell death, termed as "autophagy-mediated cell death." Taken together, we revealed the molecular mechanism of GSE against respiratory cancer, which demonstrates great potential of GSE in the treatment of representative cancer.

Strict allopatric speciation of sky island Pyrrhula erythaca species complex.

Increasing evidence of post-divergence gene flow between taxa is shifting our understanding on the mode of speciation. A fundamental question arises concerning the circumstances under which strict allopatric speciation still holds true. Sky island populations might undergo reduced gene flow by niche conservatism to highland habitats and follow divergence in an allopatric manner. In this study, we tested this hypothesis in the sky island Grey-headed Bullfinch (Pyrrhula erythaca) species complex via statistical analyses of both genetic and ecological data. Results of coalescent-based analysis of multiple nuclear loci suggested that P. e. owstoni likely colonized Taiwan island during the severe mid-Pleistocene glacial climate followed by strictly allopatric divergence from P. e. erythaca distributed in Himalayas-Hengduan mountains and central North China. Results of ecological niche modeling suggested that their speciation may be attributed to the niche conservatism of these birds and the lack of a suitable ecological corridor during subsequent milder glacial episodes. In addition, we delimited the traditionally defined P. erythaca into two full species, P. erythaca in the Asian mainland and P. owstoni on the island of Taiwan, based on both genetic and behavioural evidences. These results suggest that ecology can have a dynamic role in allowing highland populations to expand their ranges and isolated by habitat barriers to diversify in a strictly allopatric manner.