Geographic Shifts Research Articles

Persistent Trends and Geographic Traits of Heat Waves in a Changing Climate

Abstract By adopting a heatwave (HW) definition with a ~4-year recurrence frequency at world hot spots, we first examined the 1940-2022 HW climatology and trends in lifespan (duration), severity and recurrence frequency, by comparing the first and last 20-year periods of this 83- year record. Generally, HWs are becoming more frequent and more severe in the extra-tropic and mid-latitude regions. Increased HWs are not temporally uniform and tend to cluster together, posing a one-two punch for ecosystems. North America, regions affected by HWs in the early 21st Century expanded by ~47% relative to those in the mid-20th Century, contributed primarily by regions starting to be exposed to HWs in the early 21st Century. Mid-latitude basins are vulnerable areas. Geographic shifts can be attributed to adjustments in planetary wavelengths due to increased air viscosity (related to global warming). Polar amplified warming, leading to a reduced equator to pole temperature gradients and an overall reduction in zonal wind speeds across midlatitudes, promotes amplified planetary wave amplitudes, leading to more severe and persistent blockings and cutoffs, thus an increase in HW frequency, severity, and duration. Climate model simulations under a business-as-usual emission scenario corroborate trends in HW severity and lifespan increases, supported by a strong intermodal consensus. HW periods correspond to heightened planetary boundary layer (PBL) depths, which increase with eddy viscosity. The temperature-dependent nature of air viscosity underscores the similarity between trends in PBL depth and HW areal extent in a warming climate.

A bibliometric analysis of research on physical activity and fitness among preschool children in Asia (2020-2024)

Background: Physical activity (PA) and physical fitness (PF) are essential for preschool children's development. However, rising childhood obesity and sedentary lifestyles are concerning. A comprehensive analysis of the research landscape is necessary to inform better interventions and policies. Research Objectives: This study aims to conduct a bibliometric analysis of research on physical activity and physical fitness among preschool children in Asia from 2020 to 2024. Methods: The analysis was based on publications from Scopus and Web of Science, focussing on keyword co-occurrence, citation analysis, and co-authorship networks. We used tools like ScientoPy and VOSviewer to assess key metrics such as the number of publications, citations, and influential contributors. Findings/Results: The study reveals significant trends, with a peak in research productivity in 2022, reflecting heightened global attention on early physical health. China, Japan, and Iran led contributions, with China dominating in publication volume. Notable researchers included Saeed Ghorbani and emerging contributors Ahmad Chaeroni and Amir Dana. Leading journals, such as the International Journal of Environmental Research and Public Health and Frontiers in Public Health, were prominent sources. Conclusion: Despite a decline in productivity post-2022, PA and PF research for preschoolers remains important. These shifting trends provide opportunities for researchers to explore new areas or innovate approaches. Significant contributions from Asian researchers also indicate a geographic shift in the global research focus. This study also highlights the importance of physical activity in preschoolers and how trends in scientific publications can help policymakers formulate more effective interventions to improve children's fitness.

The macroecology of Mesozoic dinosaurs

Dinosaurs thrived for over 160 million years in Mesozoic ecosystems, displaying diverse ecological and evolutionary adaptations. Their ecology was shaped by large-scale climatic and biogeographic changes, calling for a ‘deep-time’ macroecological investigation. These factors include temperature fluctuations and the break up of Pangaea, influencing species richness, ecological diversity and biogeographic history. Recent improvements in the dinosaur fossil record have enabled large-scale studies of their responses to tectonic, geographic and climatic shifts. Trends in species diversity, body size and reproductive traits can now be analysed using quantitative approaches like phylogenetic comparative methods, machine learning and Bayesian inference. These patterns sometimes align with, but also deviate from, first-order macroecological rules (e.g. species–area relationship, latitudinal biodiversity gradient, Bergmann’s rule). Accurate reconstructions of palaeobiodiversity and niche partitioning require ongoing taxonomic revisions and detailed anatomical descriptions. Interdisciplinary research combining sedimentology, geochemistry and palaeoclimatology helps uncover the environmental conditions driving dinosaur adaptations. Fieldwork in under-sampled regions, particularly at latitudinal extremes, is crucial for understanding the spatial heterogeneity of dinosaur ecosystems across the planet. Open science initiatives and online databases play a key role in advancing this field, enriching our understanding of deep-time ecological processes, and offering new insights into dinosaur macroecology and its broader implications.

Projecting Untruncated Climate Change Effects on Species' Climate Suitability: Insights From an Alpine Country.

Climate projections for continental Europe indicate drier summers, increased annual precipitation, and less snowy winters, which are expected to cause shifts in species' distributions. Yet, most regions/countries currently lack comprehensive climate-driven biodiversity projections across taxonomic groups, challenging effective conservation efforts. To address this gap, our study evaluated the potential effects of climate change on the biodiversity of an alpine country of Europe, Switzerland. We used a state-of-the art species distribution modeling approach and species occurrence data that covered the climatic conditions encountered across the full species' ranges to help limiting niche truncation. We quantified the relationship between baseline climate and the spatial distribution of 7291 species from 12 main taxonomic groups and projected future climate suitability for three 30-year periods and two greenhouse gas concentration scenarios (RCP4.5 and 8.5). Our results indicated important effects of projected climate changes on species' climate suitability, with responses varying by the taxonomic and conservation status group. The percentage of species facing major changes in climate suitability was higher under RCP8.5 (68%) compared to RCP4.5 (66%). By the end of the century, decreases in climate suitability were projected for 3000 species under RCP8.5 and 1758 species under RCP4.5. The most affected groups under RCP8.5 were molluscs, algae, and amphibians, while it was molluscs, birds, and vascular plants under RCP4.5. Spatially, by 2070-2099, we projected an overall decrease in climate suitability for 39% of the cells in the study area under RCP8.5 and 10% under RCP4.5, while projecting an increase for 50% of the cells under RCP8.5 and 73% under RCP4.5. The most consistent geographical shifts were upward, southward, and eastward. We found that the coverage of high climate suitability cells by protected areas was expected to increase. Our models and maps provide guidance for spatial conservation planning by pointing out future climate-suitable areas for biodiversity.

Culture goes East: Mapping the shifting geographies of urban cultural capital through major cultural buildings

Culture has become a major component of policies to put cities on the global map. This article traces the shifting geographies of urban cultural capital using the lens of major cultural buildings, such as the Guggenheim Bilbao Museum and the Louvre Abu Dhabi, which cities often mobilise to compete for attention, reputation, tourists and investment. Based on a custom-built database containing 438 major cultural buildings opened worldwide between 1990 and 2019, this article finds a strong growth in the number and total cost of these buildings throughout the three decades, far exceeding global GDP growth. What is more, there is a geographical shift from the established cities of high culture in North America and Western Europe towards Asia, with a particular concentration in China and the Gulf region. The growth of investment in culture and its fast-changing urban geographies urge a more profound integration of culture in urban studies and a deeper consideration of the role of cultural capital in making global cities.

Bibliometric Analysis of Reference Materials and Certified Reference Materials Applied to Geochemistry

The use of reference materials (RMs) and certified reference materials (CRMs) is essential to guarantee the reliability of measurement procedures ‐ a major factor motivating the efforts of the geoanalytical community. This work quantifies trends and patterns in the scientific literature concerning RMs and CRMs in geochemistry for specific timespans, with the aim of evaluating historical developments, research fields, geographic shifts of research centres, and current trends. The Scopus database was surveyed for peer‐reviewed full‐texts (14,201 documents), which were subsequently exploited for statistical description, bibliometric mapping and cluster analysis. Mineral exploration and trace element geochemistry stimulated early research, whereas environmental subjects have grown in importance mainly since the year 2000. International standardisation was coincident with an increase of publications covering CRMs and geochemistry, and is thought to reflect the impact of ISO guidelines in this scientific activity. Other factors include investments in research facilities, creation of specialised geoanalytical journals and organisation of international meetings. The analysis shows that RMs are typically used for petrogenetic research topics, whereas CRMs are equally important for environmental sciences, chemistry and geosciences. Environmental sciences are mostly concerned with anthropogenic contamination of ecosystems by heavy metals, whereas geological interest is mainly driven by isotope geochemistry. Scientific frontiers in geoanalytical research comprise microanalytical methodologies, unconventional isotopes, rare earth elements and environmental monitoring. New trends in CRM applications also include biogeochemistry and radionuclides.

Climate-driven global redistribution of an ocean giant predicts increased threat from shipping

AbstractClimate change is shifting animal distributions. However, the extent to which future global habitats of threatened marine megafauna will overlap existing human threats remains unresolved. Here we use global climate models and habitat suitability estimated from long-term satellite-tracking data of the world’s largest fish, the whale shark, to show that redistributions of present-day habitats are projected to increase the species’ co-occurrence with global shipping. Our model projects core habitat area losses of >50% within some national waters by 2100, with geographic shifts of over 1,000 km (∼12 km yr−1). Greater habitat suitability is predicted in current range-edge areas, increasing the co-occurrence of sharks with large ships. This future increase was ∼15,000 times greater under high emissions compared with a sustainable development scenario. Results demonstrate that climate-induced global species redistributions that increase exposure to direct sources of mortality are possible, emphasizing the need for quantitative climate-threat predictions in conservation assessments of endangered marine megafauna.

Economic gains from geographic shifts in international sourcing

The geographic evolution of global value chains (GVCs) has been significantly changing the pace and structure of economic development in many countries. We first employ a global input-output (IO) model to quantify the contribution of geographic shifts in international sourcing to China's economic gains. In 2019, China's GDP per capita was 11% below the world average. We show, however, that the gap would have been 39% if there had been no international sourcing shifts between 1995 and 2019. We subsequently propose an optimization model in the global IO framework to explore potential strategies which further improve China's GDP per capita. The optimization results suggest that import substitution and export promotion could be two possible strategies. However, these strategies could fail if all countries adopt the same strategies and participate in the non-cooperative competition. Instead, our results suggest that promoting technological upgrading provides more sustainable opportunities for improving a country's gains.

Projected impact of climate change on human health in low- and middle-income countries: a systematic review

Low- and middle-income countries (LMICs) contribute relatively little to global carbon emissions but are recognised to be among the most vulnerable parts of the world to health-related consequences of climate...

Abstract B166: Impact of rurality on early-onset colorectal cancer outcomes: Age, geographic disparities, and the need for improved access and awareness in the United States

Abstract BACKGROUND: While overall colorectal cancer (CRC) rates have stabilized or declined in the United States (U.S.), early-onset CRC (EO-CRC), diagnoses before age 50, has increased. Rural U.S. residents face a higher CRC incidence (43.9 vs. 40.1 per 100,000) than urban residents. CRC mortality, once highest in the Northeast, is now most prevalent in the South and Midwest, particularly among Non-Hispanic Black populations. This geographic shift is also evident in EO-CRC. Existing literature lacks comprehensive analysis on the influence of rurality and age at CRC diagnosis. In this study, we sought to elucidate the relationships between age at diagnosis with CRC outcomes, while examining the moderating role of rurality. Methods: We used data from the 2006-2020 Surveillance, Epidemiology, and End Results (SEER) Program. Rurality was defined using census tract level U.S. Department of Agriculture (USDA)’s 2010 Rural Urban Commuting Area (RUCA) codes: rural (codes 8, 9, 10) and urban (all other listed codes). We conducted multilevel regression modeling (logistic and Cox proportional hazards) to examine the associations between age at diagnosis, rurality, and CRC outcomes (late-stage diagnosis and survival), adjusting for race, marital status, sex, and year of diagnosis. Results: We identified 835,907 patients aged 20-79 from the 2006-2020 SEER program. Most patients lived in urban areas (86%), were non-Hispanic white (66%), and married (41%). After adjusting for marital status, race, sex, and diagnosis year, we found that patients aged 30-39 (aOR: 1.49, 95% CI: 1.44–1.55) and 40-49 (aOR: 1.43, 95% CI: 1.39–1.46) had over a 40% increased likelihood of late-stage CRC compared to patients aged 50-59. Urban patients aged 30-39 had a 52% higher likelihood of late-stage CRC (aOR: 1.52, 95% CI: 1.46–1.58). Patients aged 20-29 (aOR: 0.81, 95% CI: 0.77–0.86) had a reduced risk of CRC death compared to those aged 50-59. Conversely, patients aged 40-49 (aOR: 1.09, 95% CI: 1.07–1.11), 60-69 (aOR: 1.16, 95% CI: 1.14–1.17), and 70-79 (aOR: 1.39, 95% CI: 1.28–1.36) had increased risks of CRC death compared to patients aged 50-59. Rural patients aged 20-29 (aOR: 0.79, 95% CI: 0.68–0.94) and 30-39 (aOR: 0.95, 95% CI: 0.87–1.03) had a reduced risk of CRC death compared to rural patients aged 50-59. Conclusion: We observed that patients aged 30-49 were more likely to be diagnosed with late- stage CRC compared to those aged 50-59, particularly in urban areas. To reduce the burden of EO-CRC and prevent advanced-stage diagnoses in young adults, it is essential to enhance access to care and raise awareness of CRC symptoms among younger Americans. Future research should explore urban -rural barriers to healthcare access, including the role of healthcare infrastructure, transportation, and provider availability, to develop strategies for improving EO-CRC early detection and treatment outcomes. Citation Format: Meng-Han Tsai, Justin X. Moore, Caitlyn Grunert. Impact of rurality on early-onset colorectal cancer outcomes: Age, geographic disparities, and the need for improved access and awareness in the United States [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr B166.

Climate Change and Herbivores: Forty Years in a Bunchgrass Prairie.

Wild herbivore responses to anthropogenic climate change are often projected to be habitat and geographic range shifts as warmer conditions reduce the quantity and nutritional quality of forage plants, which makes species presence/absence a focus. Since 1978, herbivore abundances at the National Bison Range, MT, USA, were measured for grasshoppers (catch-effort), microtine rodents (runway density), and ungulates (drives and round-ups), along with climate and vegetation quantity (biomass) and quality (nitrogen content and chemical solubility related to digestibility). Counter to expectation with warming and drying, forage biomass increased as grass biomass increased more than dicot biomass decreased, and forage quality (solubility) increased. Consequently, herbivores that consume a grass diet (>25% grass: certain grasshoppers, microtines, bighorn sheep, elk, bison) increased in abundance, while herbivores consuming less grass declined (certain grasshoppers, pronghorn, whitetail, and mule deer). The result is an 18% increase in herbivore abundance and herbivory, counter to climate change expectations. Historically, grasshoppers consumed 46% more vegetation than mammals; now, they consume only 14% more, as grasshoppers did not increase as expected with climate change. Therefore, herbivores respond rapidly to climate-induced vegetation changes, and this is not a simple loss/addition of species, but changing trophic dynamics, which requires more knowledge of ecosystem dynamics.

Advances in breeding phenology outpace latitudinal and elevational shifts for North American birds tracking temperature.

Terrestrial species can respond to a warming climate in multiple ways, including shifting in space (via latitude or elevation) and time (via phenology). Evidence for such shifts is often assessed independent of other temperature-tracking mechanisms; critically, no study has compared shifts across all three spatiotemporal dimensions. Here we used two continental-scale monitoring databases to estimate trends in the breeding latitude (311 species), elevation (251 species) and phenology (111 species) of North American landbirds over 27 years, with a shared pool of 102 species. We measured the magnitude of shifts and compared them relative to average regional warming (that is, shift ratios). Species shifted poleward (1.1 km per year, mean shift ratio 11%) and to higher elevations (1.2 m per year, mean shift ratio 17%), while also shifting their breeding phenology earlier (0.08 days per year, mean shift ratio 28%). These general trends belied substantial variation among species, with some species shifting faster than climate, whereas others shifted more slowly or in the opposite direction. Across the three dimensions (n = 102), birds cumulatively tracked temperature at 33% of current warming rates, 64% of which was driven by advances in breeding phenology as opposed to geographical shifts. A narrow focus on spatial dimensions of climate tracking may underestimate the responses of birds to climate change; phenological shifts may offer an alternative for birds-and probably other organisms-to conserve their thermal niche in a warming world.

Local environmental factors drive distributions of ecologically-contrasting mosquito species (Diptera: Culicidae)

Mosquitoes are important vectors of disease pathogens and multiple species are undergoing geographical shifts due to global changes. As such, there is a growing need for accurate distribution predictions. Ecological niche modelling (ENM) is an effective tool to assess mosquito distribution patterns and link these to underlying environmental preferences. Typically, macroclimatic variables are used as primary predictors of mosquito distributions. However, they likely undervalue local conditions and intraspecific variation in environmental preferences. This is problematic, as mosquito control takes place at the local scale. Utilising high-resolution (10 × 10 m) Maxent ENMs on the island of Bonaire as model system, we explore the influence of local environmental variables on mosquito distributions. Our results show a distinct set of environmental variables shape distribution patterns across ecologically-distinct species, with urban variables strongly associated with introduced species like Aedesaegypti and Culexquinquefasciatus, while native species show habitat preferences for either mangroves, forests, or ephemeral water habitats. These findings underscore the importance of distinct local environmental factors in shaping distributions of different mosquitoes, even on a small island. As such, these findings warrant further studies aimed at predicting high-resolution mosquito distributions, opening avenues for preventative management of vector-borne disease risks amidst ongoing global change and ecosystem degradation.

Widespread cultural change in declining populations of Amazon parrots.

Species worldwide are experiencing anthropogenic environmental change, and the long-term impacts on animal cultural traditions such as vocal dialects are often unknown. Our prior studies of the yellow-naped amazon (Amazona auropalliata) revealed stable vocal dialects over an 11-year period (1994-2005), with modest shifts in geographic boundaries and acoustic structure of contact calls. Here, we examined whether yellow-naped amazons maintained stable dialects over the subsequent 11-year time span from 2005 to 2016, culminating in 22 years of study. Over this same period, this species suffered a dramatic decrease in population size that prompted two successive uplists in IUCN status, from vulnerable to critically endangered. In this most recent 11-year time span, we found evidence of geographic shifts in call types, manifesting in more bilingual sites and introgression across the formerly distinct North-South acoustic boundary. We also found greater evidence of acoustic drift, in the form of new emerging call types and greater acoustic variation overall. These results suggest cultural traditions such as dialects may change in response to demographic and environmental conditions, with broad implications for threatened species.

Ensuring China's food security in a geographical shift of its grain production: Driving factors, threats, and solutions

Grain production in China has increased over time despite limited access to natural resources. However, this has led to China's grain supply system becoming increasingly vulnerable and unsustainable due to a northward shift of its grain production. Here, we establish a framework to guide future grain policy formulation in response to previous practices and lessons learned from China's past grain production. This framework integrated the spatial gravity model, spatial mismatch index, logarithmic mean Divisia index (LMDI), and Monte Carlo simulation to identify the key drivers behind grain growth, analyze their impacts on food security, and propose countermeasures. We found that grain production increase in China is not universally attributable to increased input of farmland and water resources, but rather, socio-economic factors including agricultural technology and irrigation facilities have improved efficiency. The spatial heterogeneity in their driving effects in different major grain producing regions has led grain production to shifted to the northern regions that have few natural resources, posing new challenges for food security: without new policies, China will not be poised to meet increased grain demand projected from 2025 to 2030, especially for rice and soybeans. From a comparison across four grain policies, it is found that region-specific policies will most effectively accelerate transitions to sustainable food production systems. We urge decision-makers to reach beyond natural resource inputs and focus on socio-economic factors, particularly inputs for replanting abandoned farmland and irrigation facilities that can ensure food security in the future.

Distribution of and Relationships between Epidemiological and Clinicopathological Parameters in Canine Leishmaniosis: A Retrospective Study of 15 Years (2009-2023).

Leishmaniosis is a vector-borne disease caused by protozoan parasites of the genus Leishmania, which are zoonotic and have an important impact on animal and public health globally. Between 2009 and 2023, blood samples from domestic dogs with clinical suspicion of leishmaniosis were received from 286 veterinary medical centres throughout mainland Portugal. An enzyme-linked immunosorbent assay (ELISA) was utilised to detect antibodies against Leishmania infantum antigens. Additionally, a complete blood count and tests for total proteins, urea, creatinine and alanine aminotransferase, as well as protein electrophoresis, were also performed. No significant relationship between sex and breed was observed. The age distribution was bimodal, with the highest prevalence of disease occurring at 2-5 years of age and a secondary peak occurring at 6 years or over (p < 0.001). No statistical correlation was observed between creatinine and urea across the ELISA serological groups. In contrast, both the gamma globulin levels (r = 0.45; p < 0.001) and the albumin/globulin ratio (r = -0.36; p < 0.001) exhibited moderate correlations with the ELISA. These findings support recent seroprevalence studies in dogs, with some geographical areas in Northern Portugal exhibiting the highest values, which may be the result of geographical shifts in parasite circulation due to climate change.

Multi-landscapes of Hà Nội in three poetic generations of ethnic minorities

Born with the August Revolution in 1945, the generations of modern Vietnamese ethnic minority writers form their own appearance, contributing to creating unique voices and identities. In this paper, we argue that three generations of ethnic minority poets, which represent three waves of writers, create three types of geographical landscapes of Hanoi. Firstly, the country’s capital in wartime is portrayed vaguely in the dreams of the periphery. It is a central geographical entity that holds the beliefs and aspirations of the entire nation. Secondly, Hanoi is presented through its everyday appearance, which is full of contradictions that make residents leave and dream of an idealised mountainous region. Finally, Hanoi is described as a decentralised metropolis through the gazes of ethnic minority poets who were born in Hanoi. This creates in their poetry the process of deterritorialization, i.e. the process of becoming the Other. It can be said that geographical shifts have created new spaces, thus giving people different concepts of home.

The future of plant diversity within a Mediterranean endemism centre: Modelling the synergistic effects of climate and land-use change in Peloponnese, Greece

Climate- and land-use change stand as primary threats to terrestrial biodiversity. Yet, their synergistic impacts on species distributions remain poorly understood. To address this knowledge gap, we conducted the first-ever comprehensive species distribution analysis on an entire regional endemism centre within an eastern Mediterranean country, incorporating dynamic land-use/land-cover change data together with climate change scenarios. Specifically, we apply species distribution modelling and spatial data analysis techniques to compare the individual and synergistic effects of these environmental drivers on the endemic vascular flora of Peloponnese, focusing on potential range contractions, altitudinal shifts, and habitat fragmentation levels. Moreover, we identify fine-scale present and potential future endemism hotspots within our study area, incorporating taxonomic and phylogenetic information. Overall, we aim to enhance our current understanding of endemism patterns and contribute to the development of future-proof conservation strategies for safeguarding Greece's endangered endemic flora. The integration of land-use change projections with climate change yielded less severe impacts compared to the effects anticipated when considering climatic variables alone. Most taxa are expected to undergo significant range declines and nearly half might experience increased habitat fragmentation, due to the synergistic effects of climate- and land-use change. We identified endemism hotspots, which are concentrated in or along the main Peloponnesian mountain massifs. However, our predictions indicate that areas presently recognized as endemism hotspots will undergo a concerning area decline, across all future scenarios considered in this study. Our findings highlight the importance of including dynamic land-use variables alongside climatic predictors when projecting species distributions under global change. Moreover, we showed that endemism hotspots are not static and considering their potential geographic shifts is paramount to delineate effective forward-looking conservation strategies.

Defoliator outbreaks track with warming across the Pacific coastal temperate rainforest of North America

The biogeography of irruptive insect herbivores is determined by host availability and climate conditions. As such, outbreak distributions are sensitive to climatic change, especially across large latitudinal gradients. Here, we investigate the outbreak distributions of two understudied defoliators, hemlock sawfly Neodiprion tsugae (Hymenoptera) and western blackheaded budworm Acleris gloverana (Lepidoptera), that have both recently impacted the greatest land area recorded across the Pacific coastal temperate rainforest since the establishment of aerial survey programs. We compiled polygon‐based estimates of insect damage collected by aerial observers, forest inventory, and downscaled climatic data to develop gridded estimates of bioclimatic conditions across the extent of the Pacific coastal temperate rainforest, including the continental United States, British Columbia and Alaska. We leveraged these data to develop ensemble machine learning models with the goal of predicting the outbreak distribution of each insect. In this manuscript we: 1) describe the historical patterns of defoliator outbreaks, 2) identify and describe climatic conditions associated with outbreaks in both species and 3) assess whether historic outbreaks have tracked geographic shifts in climate conditions across the region. We demonstrate that outbreaks of hemlock sawfly and western blackheaded budworm have been observed across the Pacific coastal temperature rainforests of North America in each decade since the establishment of the Canadian and United States aerial survey programs. The distribution of outbreaks by both insects were best explained by host availability, a limited range of spring, summer, and winter temperatures, and minimum precipitation. Finally, we demonstrate that outbreaks have tracked the poleward shift in suitable climate over the last century. This study establishes a baseline understanding of the climatic constraints and biogeographic patterns of historic sawfly and budworm outbreaks across the Pacific coastal temperate rainforest and emphasizes the overarching importance of climate in driving the irruptive dynamics of these defoliator species.Keywords: climate envelope, defoliators, hemlock sawfly, Pacific coastal temperate rainforest, population dynamics, western blackheaded budworm

Pushed waves, trailing edges, and extreme events: Eco-evolutionary dynamics of a geographic range shift in the owl limpet, Lottia gigantea.

As climatic variation re-shapes global biodiversity, understanding eco-evolutionary feedbacks during species range shifts is of increasing importance. Theory on range expansions distinguishes between two different forms: "pulled" and "pushed" waves. Pulled waves occur when the source of the expansion comes from low-density peripheral populations, while pushed waves occur when recruitment to the expanding edge is supplied by high-density populations closer to the species' core. How extreme events shape pushed/pulled wave expansion events, as well as trailing-edge declines/contractions, remains largely unexplored. We examined eco-evolutionary responses of a marine invertebrate (the owl limpet, Lottia gigantea) that increased in abundance during the 2014-2016 marine heatwaves near the poleward edge of its geographic range in the northeastern Pacific. We used whole-genome sequencing from 19 populations across >11 degrees of latitude to characterize genomic variation, gene flow, and demographic histories across the species' range. We estimated present-day dispersal potential and past climatic stability to identify how contemporary and historical seascape features shape genomic characteristics. Consistent with expectations of a pushed wave, we found little genomic differentiation between core and leading-edge populations, and higher genomic diversity at range edges. A large and well-mixed population in the northern edge of the species' range is likely a result of ocean current anomalies increasing larval settlement and high-dispersal potential across biogeographic boundaries. Trailing-edge populations have higher differentiation from core populations, possibly driven by local selection and limited gene flow, as well as high genomic diversity likely as a result of climatic stability during the Last Glacial Maximum. Our findings suggest that extreme events can drive poleward range expansions that carry the adaptive potential of core populations, while also cautioning that trailing-edge extirpations may threaten unique evolutionary variation. This work highlights the importance of understanding how both trailing and leading edges respond to global change and extreme events.