The Chinese pine genome and methylome unveil key features of conifer evolution.

Conifers dominate the world's forest ecosystems and are the most widely planted tree species. Their giant and complex genomes present great challenges for assembling a complete reference genome for evolutionary and genomic studies. We present a 25.4-Gb chromosome-level assembly of Chinese pine (Pinus tabuliformis) and revealed that its genome size is mostly attributable to huge intergenic regions and long introns with high transposable element (TE) content. Large genes with long introns exhibited higher expressions levels. Despite a lack of recent whole-genome duplication, 91.2% of genes were duplicated through dispersed duplication, and expanded gene families are mainly related to stress responses, which may underpin conifers' adaptation, particularly in cold and/or arid conditions. The reproductive regulation network is distinct compared with angiosperms. Slow removal of TEs with high-level methylation may have contributed to genomic expansion. This study provides insights into conifer evolution and resources for advancing research on conifer adaptation and development.

Climate change, human health, and resilience in the Holocene.

Climate change is an indisputable threat to human health, especially for societies already confronted with rising social inequality, political and economic uncertainty, and a cascade of concurrent environmental challenges. Archaeological data about past climate and environment provide an important source of evidence about the potential challenges humans face and the long-term outcomes of alternative short-term adaptive strategies. Evidence from well-dated archaeological human skeletons and mummified remains speaks directly to patterns of human health over time through changing circumstances. Here, we describe variation in human epidemiological patterns in the context of past rapid climate change (RCC) events and other periods of past environmental change. Case studies confirm that human communities responded to environmental changes in diverse ways depending on historical, sociocultural, and biological contingencies. Certain factors, such as social inequality and disproportionate access to resources in large, complex societies may influence the probability of major sociopolitical disruptions and reorganizations-commonly known as "collapse." This survey of Holocene human-environmental relations demonstrates how flexibility, variation, and maintenance of Indigenous knowledge can be mitigating factors in the face of environmental challenges. Although contemporary climate change is more rapid and of greater magnitude than the RCC events and other environmental changes we discuss here, these lessons from the past provide clarity about potential priorities for equitable, sustainable development and the constraints of modernity we must address.

Age-dependent seasonal growth cessation in Populus.

In temperate and boreal regions, perennial plants adapt their annual growth cycle to the change of seasons. In natural forests, juvenile seedlings usually display longer growth seasons compared to adult trees to ensure their establishment and survival under canopy shade. However, how trees adjust their annual growth according to their age is not known. In this study, we show that age-dependent seasonal growth cessation is genetically controlled and found that the miR156-SPL3/5 module, a key regulon of vegetative phase change (VPC), also triggers age-dependent growth cessation in Populus trees. We show that miR156 promotes shoot elongation during vegetative growth, and its targets SPL3/5s function in the same pathway but as repressors. We find that the miR156-SPL3/5s regulon controls growth cessation in both leaves and shoot apices and through multiple pathways, but with a different mechanism compared to how the miR156-SPL regulon controls VPC in annual plants. Taken together, our results reveal an age-dependent genetic network in mediating seasonal growth cessation, a key phenological process in the climate adaptation of perennial trees.

Near-term tropical cyclone risk and coupled Earth system model biases.

Most current climate models predict that the equatorial Pacific will evolve under greenhouse gas-induced warming to a more El Niño-like state over the next several decades, with a reduced zonal sea surface temperature gradient and weakened atmospheric Walker circulation. Yet, observations over the last 50 y show the opposite trend, toward a more La Niña-like state. Recent research provides evidence that the discrepancy cannot be dismissed as due to internal variability but rather that the models are incorrectly simulating the equatorial Pacific response to greenhouse gas warming. This implies that projections of regional tropical cyclone activity may be incorrect as well, perhaps even in the direction of change, in ways that can be understood by analogy to historical El Niño and La Niña events: North Pacific tropical cyclone projections will be too active, North Atlantic ones not active enough, for example. Other perils, including severe convective storms and droughts, will also be projected erroneously. While it can be argued that these errors are transient, such that the models' responses to greenhouse gases may be correct in equilibrium, the transient response is relevant for climate adaptation in the next several decades. Given the urgency of understanding regional patterns of climate risk in the near term, it would be desirable to develop projections that represent a broader range of possible future tropical Pacific warming scenarios-including some in which recent historical trends continue-even if such projections cannot currently be produced using existing coupled earth system models.

Assessing the climate adaptive potential of imported Chili in comparison with local cultivars through germination performance analysis.

BACKGROUND: The study offers insightful information about the adaptability of local and imported Chili cultivars. This experiment examines how three different chili cultivars Tanjung, Unpad, and Osaka perform in the germination and early growth phases while considering a wide range of environmental conditions. Research conducted in Jatinangor, Sumedang Regency, Indonesia, highlights the differences between cultivars and the varied possibilities for adaptability each variation possesses. RESULTS: Among them, Tanjung stands out as the most promising cultivar; its robust performance is demonstrated by its high germination index 91.7. Notable features of Osaka include the highest biomass output (1.429 g), the best water usage efficiency (WUE) at 0.015 g/liter, and the best distribution uniformity (91.2%) and application efficiency (73.6%) under different irrigation conditions. Tanjung's competitiveness is further evidenced by the fact that it trails Osaka closely on several metrics. Lower performance across criteria for Unpad suggests possible issues with flexibility. CONCLUSION: The value of this information becomes apparent when it comes to well-informed breeding programs and cultivation techniques, especially considering uncertain climate patterns and global climate change. This research contributes significantly to the body of knowledge, enabling well-informed choices for environmentally dynamic, sustainable chili farming.

Mosquito thermal tolerance is remarkably constrained across a large climatic range.

How mosquitoes may respond to rapid climate warming remains unknown for most species, but will have major consequences for their future distributions, with cascading impacts on human well-being, biodiversity and ecosystem function. We investigated the adaptive potential of a wide-ranging mosquito species, Aedes sierrensis, across a large climatic gradient by conducting a common garden experiment measuring the thermal limits of mosquito life-history traits. Although field-collected populations originated from vastly different thermal environments that spanned over 1200 km, we found limited variation in upper thermal tolerance between populations. In particular, the upper thermal limits of all life-history traits varied by less than 3°C across the species range and, for most traits, did not differ significantly between populations. For one life-history trait-pupal development rate-we did detect significant variation in upper thermal limits between populations, and this variation was strongly correlated with source temperatures, providing evidence of local thermal adaptation for pupal development. However, we found that maximum environmental temperatures across most of the species' range already regularly exceed the highest upper thermal limits estimated under constant temperatures. This result suggests that strategies for coping with and/or avoiding thermal extremes are likely key components of current and future mosquito thermal tolerance.

Weak local adaptation to drought in seedlings of a widespread conifer.

Tree seedlings from populations native to drier regions are often assumed to be more drought tolerant than those from wetter provenances. However, intraspecific variation in drought tolerance has not been well-characterized despite being critical for developing climate change mitigation and adaptation strategies, and for predicting the effects of drought on forests. We used a large-scale common garden drought-to-death experiment to assess range-wide variation in drought tolerance, measured by decline of photosynthetic efficiency, growth, and plastic responses to extreme summer drought in seedlings of 73 natural populations of the two main varieties of Douglas-fir (Pseudotsuga menziesii var. menziesii and var. glauca). Local adaptation to drought was weak in var. glauca and nearly absent in menziesii. Var. glauca showed higher tolerance to drought but slower growth than var. menziesii. Clinal variation in drought tolerance and growth species-wide was mainly associated with temperature rather than precipitation. A higher degree of plasticity for growth was observed in var. menziesii in response to extreme drought. Genetic variation for drought tolerance in seedlings within varieties is maintained primarily within populations. Selective breeding within populations may facilitate adaptation to drought more than assisted gene flow.

Local climate change velocities and evolutionary history explain multidirectional range shifts in a North American butterfly assemblage.

Species are often expected to shift their distributions either poleward or upslope to evade warming climates and colonise new suitable climatic niches. However, from 18-years of fixed transect monitoring data on 88 species of butterfly in the midwestern United States, we show that butterflies are shifting their centroids in all directions, except towards regions that are warming the fastest (southeast). Butterflies shifted their centroids at a mean rate of 4.87 km year-1. The rate of centroid shift was significantly associated with local climate change velocity (temperature by precipitation interaction), but not with mean climate change velocity throughout the species' ranges. Species tended to shift their centroids at a faster rate towards regions that are warming at slower velocities but increasing in precipitation velocity. Surprisingly, species' thermal niche breadth (range of climates butterflies experience throughout their distribution) and wingspan (often used as metric for dispersal capability) were not correlated with the rate at which species shifted their ranges. We observed high phylogenetic signal in the direction species shifted their centroids. However, we found no phylogenetic signal in the rate species shifted their centroids, suggesting less conserved processes determine the rate of range shift than the direction species shift their ranges. This research shows important signatures of multidirectional range shifts (latitudinal and longitudinal) and uniquely shows that local climate change velocities are more important in driving range shifts than the mean climate change velocity throughout a species' entire range.

Exposure of protected areas in Central America to extreme weather events.

Central America and the Caribbean are regularly battered by megadroughts, heavy rainfall, heat waves, and tropical cyclones. Although 21st-century climate change is expected to increase the frequency, intensity, and duration of these extreme weather events (EWEs), their incidence in regional protected areas (PAs) remains poorly explored. We examined historical and projected EWEs across the region based on 32 metrics that describe distinct dimensions (i.e., intensity, duration, and frequency) of heat waves, cyclones, droughts, and rainfall and compared trends in PAs with trends in unprotected lands. From the early 21st century onward, exposure to EWEs increased across the region, and PAs were predicted to be more exposed to climate extremes than unprotected areas (as shown by autoregressive model coefficients at p < 0.05 significance level). This was particularly true for heat waves, which were projected to have a significantly higher average (tested by Wilcoxon tests at p < 0.01) intensity and duration, and tropical cyclones, which affected PAs more severely in carbon-intensive scenarios. PAs were also predicted to be significantly less exposed to droughts and heavy rainfall than unprotected areas (tested by Wilcoxon tests at p < 0.01). However, droughts that could threaten connectivity between PAs are increasingly common in this region. We estimated that approximately 65% of the study area will experience at least one drought episode that is more intense and longer lasting than previous droughts. Collectively, our results highlight that new conservation strategies adapted to threats associated with EWEs need to be tailored and implemented promptly. Unless urgent action is taken, significant damage may be inflicted on the unique biodiversity of the region.

Ciclones, olas de calor, sequías y lluvias intensas son eventos comunes en Centroamérica y el Caribe, cuya frecuencia, intensidad y duración se espera aumente durante el siglo XXI a causa del cambio climático. Sin embargo, en la actualidad, se desconoce cuál será la incidencia de estos eventos meteorológicos extremos (EME) dentro de las áreas protegidas. En este estudio examinamos la exposición histórica y futura a los extremos climáticos y comparamos el grado de exposición dentro y fuera de las áreas protegidas de toda la región por medio de 32 métricas que describen distintas dimensiones (intensidad, duración y frecuencia) de las olas de calor, los ciclones, las sequías y las precipitaciones. Los resultados indican que a medida que aumente el número de EME, las áreas protegidas estarán más expuestas a los extremos climáticos que las áreas no protegidas. Esto es especialmente cierto en el caso de las olas de calor, que, según las proyecciones, tendrán una intensidad y una duración medias significativamente mayores, y de los ciclones tropicales, que afectarán más gravemente a las zonas protegidas en los escenarios intensivos en carbono. Nuestros resultados también indican que las zonas protegidas estarán significativamente menos expuestas a sequías o lluvias torrenciales que las zonas no protegidas. Sin embargo, las sequías que podrían amenazar la conectividad entre áreas protegidas son cada vez más frecuentes en esta región. Se estima que aproximadamente el 65% del área de estudio experimentará al menos un episodio de sequía más intenso y duradero que las sequías anteriores. En conjunto, nuestros resultados ponen de relieve la necesidad de diseñar y aplicar con prontitud nuevas estrategias de conservación adaptadas a las amenazas asociadas a los EWE. A menos que se tomen medidas urgentes, la biodiversidad única de la región podría sufrir daños considerables.

The dynamic feasibility of resisting (R), accepting (A), or directing (D) ecological change.

Ecological transformations are occurring as a result of climate change, challenging traditional approaches to land management decision-making. The resist-accept-direct (RAD) framework helps managers consider how to respond to this challenge. We examined how the feasibility of the choices to resist, accept, and direct shifts in complex and dynamic ways through time. We considered 4 distinct types of social feasibility: regulatory, financial, public, and organizational. Our commentary is grounded in literature review and the examples that exist but necessarily has speculative elements because empirical evidence on this newly emerging management strategy is scarce. We expect that resist strategies will become less feasible over time as managers encounter situations where resisting is ecologically, by regulation, financially, or publicly not feasible. Similarly, we expect that as regulatory frameworks increasingly permit their use, if costs decrease, and if the public accepts them, managers will increasingly view accept and direct strategies as more viable options than they do at present. Exploring multiple types of feasibility over time allows consideration of both social and ecological trajectories of change in tandem. Our theorizing suggested that deepening the time horizon of decision-making allows one to think carefully about when one should adopt different approaches and how to combine them over time.

La viabilidad dinámica de resistir (R), aceptar (A) o dirigir (D) el cambio ecológico Resumen Las transformaciones ecológicas ocurren por el cambio climático, lo que representa un reto para los enfoques tradicionales para decidir en torno a la gestión de tierras. El marco resistir­aceptar­dirigir (RAD) ayuda a los gestores a considerar cómo responder a este reto. Analizamos cómo la viabilidad de las opciones para resistir, aceptar y dirigir cambia de manera compleja y dinámica con el tiempo. Consideramos cuatro tipos distintos de viabilidad: regulatoria, económica, pública y de organización. Nuestro comentario está basado en la revisión bibliográfica y los ejemplos que existen, pero por necesidad tiene elementos especulativos ya que la evidencia empírica sobre esta estrategia emergente de gestión es escasa. Esperamos que las estrategias de resistir se vuelvan menos viables con el tiempo conforme los gestores encuentren situaciones en las que resistir no es viable de forma ecológica, económica, pública o por regulación. Al igual esperamos que cada vez más los marcos regulatorios permitan su uso, si el costo disminuye, y si el público los acepta, los gestores verán cada vez más viables las estrategias de aceptar y dirigir que las que utilizan actualmente. La exploración de varios tipos de viabilidad a lo largo del tiempo permite considerar las trayectorias sociales y ecológicas del cambio en conjunto. Nuestra teoría sugiere que profundizar en el horizonte temporal de las decisiones permite que se analice con cuidado sobre cuando se deben adoptar enfoques diferentes y cómo combinarlos con el tiempo.

Climate change influences on the streamflow and sediment supply to the Chao Phraya River basin, Thailand.

This study investigates the effects of climate change on the sediment loads of the Ping and Wang River basins and their contribution to the sediment dynamics of the lower Chao Phraya River basin in Thailand. The various climate models under different Representative Concentration Pathways (RCPs) scenarios are employed to project sediment loads in future. The findings indicate a significant increase in river flow approximately 20% in the Ping River (PR) and 35% in the Wang River (WR) by the mid-21st century and continuing into the distant future. Consequently, this is expected to result in sediment loads up to 0.33 × 106 t/y in the PR and 0.28 × 106 t/y in the WR. This escalation is particularly notable under the RCP 8.5 scenario, which assumes higher greenhouse gas emissions. Additionally, the research provides insights into the potential positive implications for the Chao Phraya Delta's coastal management. Without further damming in the Ping and Wang River basins, the anticipated rise in sediment supply could aid in mitigating the adverse effects of land subsidence and sea-level rise, which have historically caused extensive shoreline retreat in the delta region, particularly around Bangkok Metropolis. The paper concludes that proactive adaptation strategies are required to manage the expected changes in the hydrological and sediment regimes to protect vulnerable coastal zones and ensure the sustainable management of the Chao Phraya River Basin in the face of climate change.

The association between gender equality and climate adaptation across the globe.

INTRODUCTION: Climate change has a disproportionate impact on women in comparison to men, and women have a key role to play in climate adaptation. However, evidence is lacking on how gender inequalities may be associated with climate vulnerability and ability to respond at country level. METHODS: This ecological study investigated the association between climate adaptation, measured by the Notre Dame Global Adaptation Initiative Country Index (ND-GAIN), and gender equality, measured by the Global Gender Gap Index (GGGI) developed by the World Economic Forum and the Gender Inequality Index (GII) developed by the United Nations. Simple linear regression was used to estimate the associations between the indices and their subdomains for 146 countries. RESULTS: There was an approximately linear association between the GGGI and climate adaptation. Each 1% increase in gender equality was associated with a 0.6% increase in the ND-GAIN score (the slope was 0.59, with a 95% confidence interval [0.33 to 0.84]). This was driven by a negative association between gender equality and vulnerability (-0.41 [-0.62 to -0.20]), and a positive association between gender equality and readiness (0.77 [0.44 to 1.10]). The strongest associations between gender equality and climate adaptation were observed for the education domain of the GGGI. There was a strong negative linear association between the GII and climate adaptation, which explained most (86%) of the between-country variation in climate adaptation. Each 1% increase in gender inequality was associated with a 0.5% decrease in the ND-GAIN score (-0.54 [-0.57 to -0.50]). The association between gender inequality and readiness was stronger than the association with vulnerability (0.41 [0.37 to 0.44] for vulnerability versus - 0.67 [-0.72 to -0.61] for readiness). CONCLUSIONS: Gender inequality, measured broadly across different domains of life, is associated with climate adaptation at country level, both in terms of vulnerability to impact and readiness to respond.

Mental models for inclusive, socially-just disaster planning: a multi-community study in Saint Martin after Hurricane Irma.

Local perspectives provide different insights into disaster planning and response as compared to those of experts. Eliciting them, however, can be challenging, particularly for marginalised groups whose viewpoints have historically been excluded from planning processes. Fuzzy cognitive mapping (FCM) provides a semi-quantitative approach to representing the collective understanding or 'mental models' of diverse individuals and communities. This study involved 23 FCM interviews across three neighbourhoods of Saint Martin to comprehend: (i) how individuals' mental models of Hurricane Irma (2017) differ based on their context; (ii) how aligned mental models are with policy and planning documents; and (iii) the implications for the inclusiveness and representativeness of disaster response policies. It found that the residents of different neighbourhoods provided unique insights into the factors driving the social-ecological system, and that official policies aligned closely with priorities. The paper argues that the inclusion of the perspectives of different groups in disaster recovery is essential for an equitable process.

This land is your land, this could be marsh land: Property parcel characteristics of marsh migration corridors in Rhode Island, USA.

Salt marshes, critical habitats offering many ecosystem services, are threatened by development, accelerated sea level rise (SLR) and other anthropogenic stressors that are projected to worsen. As seas rise, some salt marshes can migrate inland if there is adjacent, permeable, undeveloped land available. Facilitating marsh migration is necessary for coastal resilience efforts, but extensive coastal development can make finding suitable migration corridors challenging. This work seeks to characterize changes in land use, ownership, and economic value at the property parcel level within current versus future marsh areas for the state of Rhode Island, USA. We find that most parcels currently containing salt marsh are publicly owned, whereas most adjacent parcels projected to contain new salt marsh in 2050 are privately owned. Additionally, parcels containing new marsh in 2050 have 47% higher per-hectare assessed values than parcels containing current marsh. We describe the locations and characteristics of parcels within migration corridors with the lowest per-hectare values that may be the most cost-effective for marsh conservation practitioners to protect. This study highlights the expanding land use types and landowner sets that will be involved in marsh conservation decisions, and the economic value of potential migration corridors where costly tradeoffs may be necessary to promote coastal resilience.

The sword of damocles: Understanding the carbon abatement effects of top-down environmental management practices -- insights from China's campaign-style governance.

Inspection, standing for top-down environmental management practices, also known as campaign-style governance, is used by central governments to lessen local environmental pollution. However, there is no causal evidence for carbon abatement. Employing staggered difference-in-differences (DiD), I find that inspected cities mitigate carbon intensity and carbon emissions by 3.72% and 2.34%, respectively, with economic significance. Conducting a triple difference strategy, I suggest the channels are the local people's congresses and political consultative conferences' proposals, government attention, environmental regulation, industrial structure, and green innovation. Also, the heterogeneous effects suggest that municipal party secretaries assigned to their birthplace, the older the party standing and age, and those with natural sciences majors, are more conducive to the inspection achieving carbon mitigation. An alternative DiD specification shows that the "look-back" inspection achieves sustained carbon reduction. I support the argument that top-down inspection helps achieve resilience to climate change and reduce greenhouse gas emissions.

Climate change impact and adaptation assessment for road drainage systems.

Climate change exhibits a clear trend of escalating frequency and intensity of extreme weather events, posing heightened risks to drainage systems along the existing road networks. However, very few studies to date have investigated the consequences of projected future changes in rainfall on main road drainage and the resulting risk of road flooding. The work presented in this paper builds on the limited research by introducing a probabilistic model for assessing the impact of climate change on road drainage systems, incorporating climate uncertainty and drainage system variation. The probabilistic scenario-based model and associated framework offer a practical and innovative method for estimating the impact of short-duration storms under future climates for 2071-2100, in the absence of fine-resolution spatio-temporal data. The model also facilitates the assessment of the effectiveness of a climate adaptation strategy. An illustrative case-study of a road drainage system located in the south of Ireland is presented. It was found that the probability of road flooding during intense rainfall is projected to surpass the current acceptable limits set by Irish standards. Assessment of a proactive climate adaptation strategy implemented in 2015 indicated it may need to be adjusted to further reduce climate change impacts and optimise adaptation costs.

Eastern Australian Farmers Managing and Thinking Differently: Innovative Adaptation Cycles.

The uncertainty of climate change is a significant challenge prompting Australian farmers to create different thinking and different management systems that ensure sustained farm business viability and continuity, particularly in extreme environments. The purpose of this study was to explore the conditions and adaptive processes for managing farm resilience and cyclic adaptation pathways, in response to climate change. A positive deviance sample of farmers was interviewed, and data was collected from a cohort of twenty-two climate change innovators across Eastern Australia. Grounded theory analysis of data identified three processes and two transactional maps of climate change adaptation, in this under studied farmer cohort. The development of the transactional maps found the resilience and preparedness processes as adaptive learning responses to the stressors of climate change. The processes of managing the business and resources were identified as markers of preparedness and resilience that ensured business viability and continuity. Farmers prepared for climate change through transforming make-over processes as an adaptive learning response to climate challenges. Mapping the cycle of adaptation identified the processes of socio-cognitive agency, learning from feedback and consequences, and contextual variables as critical elements of adaptation. The intervening socio-ecological processes of intelligence gathering and influencing, and socio-cognitive precursors, were found to regulate the adaptation cycle. The cycle was found to have both incremental and transformative transmission processes, and intervening processes of climate and contextual variables. The changing patterns and extremes of climate change were found to impact the growing season, and its potential, as unique variables that demand farm adaptation. Ultimately, this study identified potential points of influence for leveraging preparedness behaviours.

Trend analysis of extreme rainfall indices from CHIRPS precipitation estimates over the Lake Tana sub-basin, Abbay Basin of Ethiopia.

Ethiopia is among the African nations most susceptible to climate change because of its frequent droughts and heavy rainfall. Therefore, hydrological and water management problems require an investigation of regional variability and extreme rainfall patterns. This study analyzed the spatiotemporal trends of extreme rainfall in the Lake Tana sub-basin (LTSB) of Ethiopia's upper Blue Nile basin (UBNB) between 1981 and 2019. The trend and geographic patterns of ten extreme rainfall indices are evaluated using high-resolution data from Climate Hazards Group InfraRed Precipitation Stations (CHIRPS). The researcher used RClimDex, an R software tool, to analyze the ten severe rainfall indices. The variability of the extreme rain indices was also assessed by applying the standard anomaly index (SAI). The trend analysis shows that the majority of rainfall indices decreased in the majority of station locations. Among the rainfall locations, the decreasing trend was only significant in 40% consecutive wet days (CWD), 13.33% (R95p and R99p), and 6.66% highest rainfall amount in a 1-day period (RX1day). In contrast, significant positive patterns were revealed in the incidence of rainfall events of number of heavy precipitation days (R10mm), annual total wet day rainfall (PRCPTOT), and consecutive dry days (CDD), with significant positive trends of 26.66% (R10mm) and 40% (PRCPTOT). Furthermore, a spatial distribution result of extreme rainfall trends reveals considerable variations between stations location. Thus, these findings point to the necessity of creating adaptation and mitigation plans for climate change variability within the sub-basin.

Sustainable and Resilient Health Care in the Face of a Changing Climate.

Climate change is a threat multiplier, exacerbating underlying vulnerabilities, worsening human health, and disrupting health systems' abilities to deliver high-quality continuous care. This review synthesizes the evidence of what the health care sector can do to adapt to a changing climate while reducing its own climate impact, identifies barriers to change, and makes recommendations to achieve sustainable, resilient health care systems.

New insights into the variability of upper airway morphology in modern humans.

The biological adaptation of the human lineage to its environment is a recurring question in paleoanthropology. Particularly, how eco-geographic factors (e.g., environmental temperature and humidity) have shaped upper airway morphology in hominins have been subject to continuing debate. Nasal shape is the result of many intertwined factors that include, but are not limited to, genetic drift, sexual selection, or adaptation to climate. A quantification of nasal airway (NA) morphological variation in modern human populations is crucial to better understand these multiple factors. In the present research, we study 195 in vivo CT scans of adult individuals collected in five different geographic areas (Chile, France, Cambodia, Russia, and South Africa). After segmentation of the nasal airway, we reconstruct 3D meshes that are analyzed with a landmark-free geometric morphometrics method based on surface deformation. Our results highlight subtle but statistically significant morphological differences between our five samples. The two morphologically closest groups are France and Russia, whose NAs are longer and narrower, with an important protrusion of the supero-anterior part. The Cambodian sample is the most morphologically distinct and clustered sample, with a mean NA that is wider and shorter. On the contrary, the Chilean sample form the most scattered cluster with the greatest intra-population variation. The South African sample is morphologically close to the Cambodian sample, but also partially overlaps the French and Russian variation. Interestingly, we record no correlation between NA volume and geographic groups, which raises the question of climate-related metabolic demands for oxygen consumption. The other factors of variation (sex and age) have no influence on the NA shape in our samples. However, NA volume varies significantly according both to sex and age: it is higher in males than in females and tends to increase with age. In contrast, we observe no effect of temperature or humidity on NA volume. Finally, we highlight the important influence of asymmetries related to nasal septum deviations in NA shape variation.