Northern Distribution Research Articles

Polyploidy confers better cold tolerance in Daphnia

Despite decades of studies on the differential distribution of polyploid organisms, the causes of this pattern have yet to be elucidated. This study aimed to explore some of the possible physiological mechanisms explaining the differential northern distribution of polyploid clones of Daphnia pulex compared to the one of the diploid parental species. The critical thermal minimum (CTmin) was measured in 17 D. pulex clones of contrasted ploidy (diploid and triploid) and geographic origins (temperate and subarctic climates) reared under low and high temperatures (16 and 24°C). Triploid clones had better cold tolerance (lower CTmin) than both sympatric and temperate diploid clones. No significant association was found between CTmin and body size nor with cell size. We suggest that triploids might express a cold shock resistant phenotype related to higher gene expression and/or fatty acid profiles. Cold tolerance can be viewed as one of the possible reasons for polyploid preponderance in subarctic climates.

Influence of Temperature and Photoperiod on Survival and Development of Eoreuma loftini (Lepidoptera: Crambidae)

The Mexican rice borer, Eoreuma loftini (Lepidoptera: Crambidae) is an economically important pest of sugarcane, rice, and corn in Louisiana, Texas, and Mexico. This pest is considered invasive in the US and is expanding its range northward. Due to its subtropical origin, E. loftini’s northern distribution might be limited by cold tolerance. A series of assays determined the influence of temperature and photoperiod on E. loftini life table parameters. Adult oviposition was reduced at temperatures > 30 °C. Egg viability was reduced at 20 and 36 °C relative to intermediate temperatures. Egg development time was greatest at 18 °C. Larvae did not develop to the pupal stage at temperatures ≤ 20 °C. Larval duration decreased with increasing temperature from 22 to 36 °C. Adult longevity decreased with increasing temperature from 18 °C (15 d) to 34 °C (7 d). Exposure to a short-day photoperiod decreased larval mortality at −5 °C. Larval survival of >80% up to 5 days at −5 °C suggests E. loftini cold tolerance is sufficient to minimize the influence of hard freezes on overwintering populations. Larval survival for 5 d at 40 °C was 75%. Exposure to 45 °C for periods > 1 d caused 100% mortality. These results suggest that E. loftini exhibits considerable thermal plasticity and cold tolerance, which may facilitate its range expansion in the United States.

Deep-sea benthic hydroids (Cnidaria, Hydrozoa) from Antarctic submarine ridges off the Ross Sea (Antarctica)

AbstractKnowledge of benthic hydroids inhabiting the Antarctic continental shelf waters, particularly of relatively well-studied areas, has increased in recent years. This has allowed us to recognise them as one of the main and most characteristic zoological groups of the Antarctic benthos. However, little is known about the hydroids dwelling on the continental slope or in deeper waters, let alone about those inhabiting the seafloor far away from the Antarctic continent, despite the Southern Ocean extending significantly northwards. This study contributes to reducing that knowledge gap by studying material collected from a series of deep-sea ridges north of the Ross Sea, from which hydrozoans have never been reported. Twelve species, including Halecium divergens sp. nov., have been found and studied. Except for Turritopsis sp., belonging to the Anthoathecata family Oceaniidae, all species belong to Leptothecata, in particular to the families Campanulariidae, Haleciidae, Lafoeidae, Phylactothecidae, Sertularellidae, and Symplectoscyphidae. Lafoeidae is the most represented family with four species. Sertularella pseudovervoorti and Filellum liberum are found for the second time. The discovery of Symplectoscyphus frondosus, a species previously considered endemic to the shelf and slope of the eastern Ross Sea, significantly extends its known northern distribution limit. Tulpa diverticulata and the genus Tulpa are reported in Antarctic waters for the first time. The lower limit of the bathymetric range for several species has been extended. Despite being well within Antarctic waters, the studied area hosts a very distinctive fauna, markedly different from the typical Antarctic benthic hydroid fauna. Its endemisms, the presence of species unknown in the Antarctic region and the absence of representatives of the most characteristic Antarctic genera account for its originality.

Factors affecting early red oak (Quercus rubra L.) regeneration near its northern distribution limit in Quebec

Red oak is an important species within the North American landscape, with climate change projections indicating a potential northward shift in its distribution. However, understanding the factors influencing its regeneration success at the northern limit remains limited. Site conditions and seed provenance adaptability may play critical roles. To bridge this knowledge gap, we conducted a seed transfer study in two northern red oak stands in Quebec. We firstly investigated stand regeneration history through dendrochronological characterization. Then, we monitored the survival and growth of saplings for four red oak provenances across a south-to-north gradient in field and greenhouse settings, with varying soil nutrient levels due to fertilization, and with or without protection from large herbivores. Results indicated that stands have similar age structures with red oak establishment coinciding with the last major fire disturbance in the early 1920s. However, tree species composition and density differed, suggesting differences in fire disturbance regime or ecological succession status prior to fire. Site had the largest influence on red oak regeneration, with the highest tree density and soil water availability site exhibiting a 29% higher survival rate. Protection against large herbivores also significantly impacted red oak seedling performance, leading to a 16% higher survival rate. Germination, survival and growth also significantly differed between provenances. The local (northernmost) provenance exhibited the poorest overall performance with 28 to 42% lower germination, survival and growth rates, while the two southernmost provenances exhibited superior germination and sprout survival. An increase in soil nutrient availability was beneficial to red oak in the greenhouse, but only marginally benefited survival and growth in the field, suggesting that this factor is of less importance than other factors (e.g., water and light availability) for red oak early regeneration. The findings of this study suggest that silvicultural efforts to favor red oak should focus on site and provenance selection, and that water availability is currently limiting red oak regeneration success at acorn and early seedling life stages (i.e., 1 year old seedlings) near its northern distribution limit.

Spatiotemporal distribution of the non-indigenous peach blossom jellyfish Craspedacusta sowerbii in British Columbia, Canada

The introduction of non-indigenous species (NIS) to exotic habitats can have tremendous impacts on native biodiversity, food webs, and ecosystem services. One globally distributed aquatic NIS is the hydrozoan Craspedacusta sowerbii Lankester, 1880. The species’ northern distribution boundary in North America is situated in British Columbia (BC), Canada. It is thus of paramount interest to understand its ecology in this warming invaded habitat, allowing for insights into other regions. Specimens of the genus Craspedacusta have been reported in 34 freshwater systems since August 1990. These reported locations are generally shallow (<10 m), most often of natural origin, and have a small surface area (<0.1 km2). We observed an exponential trend of medusa observations from 1990 till the end of the 2020s. The first seasonal records are in July and the latest in October, with peak sightings reported in August and September. After 2012, regional temperature anomalies during July and August were mostly positive, which overlaps with the period of the majority of reported C. sowerbii sightings. Until this day, all examined medusae are males.

Climatic limitations of nearly endangered Juniperus rigida populations at their range edges in semiarid China

The treat of climate warming is expected to increase the frequency and severity of droughts and significantly affect tree growth and distribution ranges, particularly in regions without monsoons. The distribution limits of tree species are highly susceptible to climate change. A deeper understanding of how tree species respond to climate across their distribution ranges is crucial for accurately predicting forest dynamics in the face of climate warming. Using tree ring width data from 586 trees at 19 sites spanning the northernmost and southernmost limits of Juniperus rigida (near-threatened, IUCN: NT), we assessed the growth responses of J. rigida to climate at different distribution range limits. We observed significant differences in tree-growth variability between the southern and northern populations of J. rigida, characterized by an increasing growth trend at the southern range limit, but a decreasing trend at the northern limit since 1996. Moreover, tree growth at their northern limit was hindered by high temperatures and SPEI during summer months, whereas it was constrained by low temperatures in March and precipitation in June at the southern limit. Particularly noteworthy is the increased sensitivity of growth to SPEI and precipitation in recent decades (1996–2018) compared to previous decades (1961–1995), particularly at their northern distribution edge. We therefore conclude that the growth of J. rigida trees at the southern limit could benefit from climate warming, while increasing warming and drought could limit tree growth or even cause tree mortality at the northern range limits. These findings may serve as an early warning for the growth and survival of J. rigida trees in open forests at their northern distribution edges in the face of future climate warming.

Northernmost record of Macropipus rugosus (Decapoda, Brachyura, Polybiidae) in the Canary Islands

Abstract We are reporting for the first time the presence of the crab Macropipus rugosus (Doflein, 1904) (Polybiidae) in the Canary Islands. This finding is based on the collection of three individuals off Tenerife. The collection, at coordinates 28°10′38″N, establishes a new northern distribution limit for this species. The species was previously known from tropical and subtropical seas off the west coast of Africa, has recently been reported in the waters of Cape Verde, and now we report it for the Canary Islands.

Interpopulation Variation of Leaf Polyphenol Content in Spiraea aquilegifolia (Rosaceae) from the Republic of Buryatia.

The composition and content of polyphenols in leaves was studied in Spiraea aquilegifolia Pall. plants from nine natural populations of the Republic of Buryatia (Western Transbaikalia) by high-performance liquid chromatography (HPLC). At least 24 compounds were detected in hydroethanolic extracts of S. aquilegifolia leaves by HPLC. Of these, three phenol carboxylic acids (chlorogenic, p-hydroxybenzoic, and p-coumaric acids) and six flavonols (hyperoside, isoquercitrin, avicularin, astragalin, quercetin, and kaempferol) were identified. Hyperoside (2.9-8.2 mg/g), avicularin (3.0-5.8 mg/g), and isoquercitrin (0.8-2.5 mg/g) were the main flavonols found in leaf hydroethanolic extracts. Plants from populations located at the northern distribution limit in Western Transbaikalia were found to have higher contents of phenol carboxylic acids (near the village Koma) and flavonols (near the village Klyuchi). Plants from populations located at the eastern limit (near the villages Kusoty and Zagan) showed the lowest concentration of the identified phenolic compounds. The contents of the identified free phenolic acids and flavonols were moderate or high in S. aquilegifolia leaves as compared to other Spiraea species examined, rendering it important to further study the composition of phenolic compounds in S. aquilegifolia.

Warming stimulates mangrove carbon sequestration in rising sea level at their northern limit: An in situ simulation

AbstractGlobal warming and sea‐level rise are directly influencing the growth, distribution, and greenhouse gas emissions of mangrove forests. However, mangrove forests growing at their latitudinal limits are relatively susceptible to warming; nevertheless, few studies have focused on GHG emissions of latitudinal limits mangrove forests as related to global climate change. To address this knowledge gap, a multiyear in situ control experiment was established in a restored plantation at the northern distribution limit of Kandelia obovata, the most cold‐tolerant mangrove species in China, to simulate both warming and sea‐level rise. We investigated the growth patterns and sediment greenhouse gas emissions of a K. obovata population and identified the primary factors contributing to these changes. The results showed that warming and moderate sea‐level rise enhanced biomass by more than 18%, indicating that warming stimulated plant growth while excessive sea‐level rise inhibited it. The sediment greenhouse gas emissions ranged from 45.5 to 484.6 mgCO2 m−2 h−1, 5.6 to 590.3 μgCH4 m−2 h−1, and 11.4 to 385 μgN2O m−2 h−1, which increased with warming while decreased with sea‐level rise, acting as the net source of greenhouse gas emission. Our study predicted that sea‐level rise, while directly changing sediment properties, had combined effects with warming on these studied mangrove forests that were predicted to emit more greenhouse gases from sediments in the future. These findings indicated that K. obovata plantations within their latitudinal limits tend to accumulate more CO2 for biomass carbon storage under warming conditions, while stimulating sediment greenhouse gas emissions, which will offset their climate mitigating effect in future climatic scenarios.

Pogonoloma macrorhizum (Basidiomycota, Agaricales) in Slovak landscape: a distinct fungus of Quercus cerris stands transitional in space and time

The lack of precise data on the environmental requirements of the conspicuous fungus with a northern distribution limit in Slovakia, Pogonoloma macrorhizum, initiated our study. Its identity was verified by sequencing of ITS and 28 S nrDNA regions. The analysis of trophic status by stable-isotope ratio of carbon and nitrogen suggested that the species is probably ectomycorrhizal. For the seventeen sampling sites, environmental data were obtained and information on landscape development and management were retrieved from historical maps and aerial orthophotographs. All these parameters were analysed by multivariate ordination methods. In Slovakia, P. macrorhizum is found in thermophilous to mesophilous stands on acidic soils with a pH ranging from 4.1 to 6.2. These habitats are dominated by Quercus cerris, with non-frequent tree taxa of Carpinus betulus and Quercus petraea agg. The key environmental drivers shaping the habitat of P. macrorhizum were identified as time since deforestation, with the presence of old Q. cerris individuals (former solitary trees of pastures) and soil characteristics. The fungus appears to be a species of transitional habitats historically affected by grazing. These transitions occur between thermophilic and mesophilic sites, including oak forest communities, dry steppic grasslands and forest edges, as well as spontaneously overgrown pastures and forests with a closed canopy. It is regrettable that the Q. cerris stands in Slovakia are under threat, particularly because of felling and the lack of grazing in forests. Furthermore, recent silvicultural practices have resulted in the replacement of oaks (Quercus spp.) by hornbeam (Carpinus betulus) and the formation of closed stands.

Temperature dependence of feeding activity in the invasive freshwater snail Pomacea canaliculata: implications for its response to climate warming

AbstractPomacea canaliculata, a freshwater snail native to South America, has become widely naturalised in many countries, causing serious damage to agricultural and native ecosystems. Although climate warming is likely to expand the distribution of this species, limited information exists regarding its impact on feeding activities. In this study, we examined the effects of temperature on the feeding activity of this species and estimated the impact of climate warming on its feeding potential. The feeding activity was determined by measuring the amount of standard food (Japanese mustard spinach, komatsuna) ingested at different temperatures. It tended to increase from 15 to 25 °C but became almost stable from 25 to 35 °C. The respiration rate determined by the O2 consumption rate, showed a similar response to temperature. Based on these findings, we constructed a simple model to estimate the relative feeding activity using climatic data recorded at meteorological stations throughout the Japanese Archipelago. The model estimated that, with warming of + 2 °C, annual feeding potential (relative value) increased by 21.1% at the present northern distribution limit of this species. The effect of warming on percentage increase in feeding potential was estimated to be smaller at the southern distribution limit (9.9%), although the absolute feeding potential was larger than that at the northern sites. The model also suggested that if this species expanded its northern distribution range as a result of climate warming, it would have a high feeding potential comparable to that of the southern regions.

Spatiotemporal modelling of northern shrimp Pandalus borealis distribution patterns throughout Canada’s subarctic and arctic regions

Northern shrimp Pandalus borealis occur throughout Canada’s Atlantic Ocean, where they are thought to form a single population spanning from Baffin Bay to the tail of the Grand Bank. Here, they play an important role in the ecosystem as prey for many taxa and have been targeted by a lucrative large-scale fishery since the 1970s. Yet, we still understand little about which (and how) ecosystem and environmental factors influence their distribution and abundance. We used survey data collected over 29 yr throughout 23 degrees of latitude to develop a spatiotemporal model predicting northern shrimp density. We confirmed that both top-down drivers (e.g. predation pressure), as well as bottom-up drivers (e.g. bottom temperature) play important roles in determining both the presence and abundance of northern shrimp. The model was used to predict the density of northern shrimp throughout the entire study area from 2005 to 2022. Our results highlight the importance of understanding ecosystem and environmental dynamics in relation to northern shrimp population patterns and trends within resource assessments.

New insights into the diversity and distribution of Leptanillinae (Formicidae) within China.

Leptanillinae is an ant subfamily of low taxonomic diversity and limited distribution within the Old World. Species within this subfamily are hypogaeic and are notoriously difficult to find and collect. As a result of their rarity, comparatively little is known about their natural history and distributions. Based upon new sampling efforts, we present significant new records of Leptanillinae from Mainland China, and Hong Kong SAR. Opamyrma hungvuong Yamane et al., 2008 is newly recorded from Sichuan Province, alongside a potential easterly record from Zhejiang Province, greatly extending its northern and eastern range distribution. Further, Protanilla lini Terayama, 2009 is recorded from Mainland China for the first time from Fujian Province and Hong Kong. We provide detailed collecting accounts for all newly recorded species, including associated habitat, nesting locality, colony composition, and for P. lini dietary information. All new localities for both species significantly extend their previously assumed distributions. Additional records of Leptanilla bethyloides Griebenow, 2024, and a note on L. japonica Baroni Urbani, 1977 from Hong Kong are provided. An updated distribution checklist of Leptanillinae from Mainland China and Taiwan is also provided. Our new records point towards an under sampled ant fauna of Mainland China underlying the need for new sampling approaches within the region.

A survey of Phlebotomine sand flies across their northern distribution range limit in Western Europe

Abstract Sand flies are vectors of Leishmania spp. protozoa, phleboviruses and Bartonella bacilliformis. In this study we surveyed areas of central-western Europe, encompassing the northern limit of the known sand fly distribution, and investigated the relationship between their presence and environmental variables. In this area, very limited occurrence data exists, none of them recent. Sampling was performed in July and August 2023 using CDC-light traps, sticky traps and human landing captures, at 179 selected sites in 48 municipalities. A total of 55 sand fly specimens were collected at 11% (20/179) of the sites sampled – including 16 sites in France, 2 in Luxembourg and 1 in Germany – comprising the first published records for Luxembourg and the Trier-Saarburg County of Germany. No sand flies were detected in Belgium or in the Netherlands. Two species were captured: Phlebotomus mascittii (37 females, 2 males) and Ph. perniciosus (1 female, 15 males). The latter species was only found in Savoie, the southernmost region sampled in France, while the former species was detected as far north as latitude 50°N. Logistic regression modelling indicated that the probability of sand fly presence gradually decreased with increasing latitude and altitude (P < 0.05), and it was not associated to other analysed landscape features in the proximity of the traps. The study confirms and provides new evidence for the presence of sand flies in areas of Western Europe and highlights the need to be aware of potential autochthonous transmission of sand fly-borne pathogens in these areas.

The roles of abiotic and biotic factors in driving range shifts: An invasive Pomacea snail facilitates Rostrhamus sociabilis (Snail Kite) northward range expansion

Abstract Rostrhamus sociabilis (Snail Kite) have recently expanded their range in Florida, tracking the invasion of a Pomacea snail (P. maculata), and exhibiting considerable changes in bill size and feeding niche. This range expansion is not aligned with changes in climatic conditions or the distribution of their historic prey (P. paludosa). The Eltonian Noise Hypothesis (ENH), which posits that interactive (biotic) factors have stronger effects on species’ distributions at local scales, predicts that noninteractive (abiotic) factors are generally more relevant at geographic extents. However, in this study, we explore the R. sociabilis range shift as a potential counterexample of the ENH. Under the biotic-abiotic-mobility framework (BAM), we explore the role of biotic and abiotic factors in the northward range expansion of this endangered species. Over the past 15 years, R. sociabilis have begun consuming the more-abundant invasive snails more often, while increasing in bill size, expanding ~175 km northward from previous range limits in the Kissimmee River Valley. We developed ecological niche models using 3 algorithms (Maxent, generalized linear model, ellipsoids) and found stability in climatic suitability between past and present models. Moreover, although native snails occur in northern Florida, R. sociabilis have had a historically patchy northern distribution due in part to the availability of appropriate wetland conditions. We found a strong latitudinal cline, with bill length increasing with latitude at least through 2020, suggesting that this morphological change broadened the species’ biotic suitable area and distributional potential. The interplay between changes in phenotype and biotic interactions has been poorly documented in distributional ecology, given a lack of rich occurrence datasets. Here, we highlight a case in which a biological invasion and subsequent changes in morphology and diet have facilitated the expansion of a specialized predator into areas that were unsuitable until recently.

Interactive effects of predation and climate on the distributions of marine shellfish in the Northwest Atlantic

As climate change transforms marine environments globally, species distributions correspondingly shift to locations where conditions have become or remain favourable. The ability to model these distributional shifts has been facilitated by species distribution models (SDMs). However, current SDM approaches have largely ignored climate‐driven changes in species interactions, which ultimately can have an important influence on species distributions. In this study, we utilize a long‐term, large‐scale dataset spanning 48 years and approximately 30 degrees latitude across the Canadian Atlantic shelf. We examine how climate influences the distribution and predation patterns of two invertebrates, northern shrimp Pandalus borealis and snow crab Chionoecetes opilio, aiming to evaluate the impacts of climate change on prey distributions. We found that both invertebrate species have a pronounced predicted response to climate change, with a northern shift in the distribution of northern shrimp and an overall reduction in abundance of both snow crab and shrimp associated with warming temperatures. Including predatory interactions as predictors in the SDMs (either directly via predator densities or via estimated predation rates) improved prediction accuracy for northern shrimp but not for snow crab. This is consistent with the ecology of these two species, as northern shrimp is more vulnerable to predation than snow crab. We found that the projections of future northern shrimp distributions are sensitive to the predicted spatial distribution and abundance of predators, highlighting the inherent complexity of predicting species response to climate change. Collectively, these results contribute to a broader literature that seeks to improve the capabilities of models to predict the effects of species interactions on species distributions under changing ecological conditions.

Short-term responses of growth and leaf physiology of the sclerophyllous Cryptocarya alba (Molina) seed sources to water restriction

ABSTRACT There are concerns about the vulnerability of some dominant sclerophyllous species in Mediterranean zones to water restriction, especially at outplanting, and much of the efforts for active restoration are on identifying proper seed sources. This study aimed to determine the short-term responses of growth, biomass partitioning, and leaf-physiological traits of Cryptocarya alba provenances to water restriction in nursery conditions. Three seed sources from xeric sites (northern distribution) and one from a more mesic site (southern distribution) were subjected to water restriction for three months and then evaluated in increments in root collar diameter and height, biomass components (leaves, shoots, roots), gas-exchange and fluorescence parameters, and carbon (Δ13) and oxygen (δ18O) isotopic ratios. Water restriction decreased growth and leaf biomass as a short-term response, but this effect was not expressed in stem and root biomass. Similarly, water restriction decreased the photosynthetic rate (Asat), stomatal conductance (gs), and maximum efficiency of PSII. Moreover, water restriction also increased the intrinsic water use efficiency (WUEint), but it had no effect on Δ13 or δ18O. Seed sources did not differ in any traits except in stem and total biomass. The results did not confirm a better performance of seed sources from xeric than mesic origin sites to water restriction.

Taraxacum sect. Erythrosperma (Asteraceae, Cichorioideae) in Slovakia IV. Distribution of T. erythrospermum and synonymisation of T. slovacum

The group of lesser dandelions (Taraxacum sect. Erythrosperma) is represented by more than 215 species growing in mostly xerothermic habitats throughout Europe. The only known species with sexual reproduction in this section is the diploid T. erythrospermum. It occurs in southern parts of Europe and reaches its northern limit in central Europe. In this study, we aimed at a detailed mapping of the species distribution in Slovakia in order to understand the spatial distribution at its northern range limits. We found that it is the most common xerothermous species in Slovakia, growing on various substrates such as limestone, dolomite, travertine, volcanic rocks and sands, while it is less common on brown soils and ruderal biotopes. It is a characteristic species of the class Festuco-Brometea with an altitudinal range extending from 120 to 650 m above sea level. We delimited the northern distribution and documented its highest occurrence at approximately ca 1500 m a.s.l. Two taxa, T. slovacum and T. punctatum, were described from the territory of Slovakia and we discuss their relationships to T. erythrospermum, with which T. slovacum is synonymised here for the first time. We also present new data on the genome size of T. erythrospermum in Slovakia, which range from 1.529 to 1.604 pg with a mean of 1.554 pg (± 0.024 SD), and provide chorological data on a remarkable morphological variant with grey-coloured achenes.

The Quantitative Role of Moisture and Vertical Motion in Shaping Summer Heavy Rainfall over North China under Two Distinct Large-Scale Weather Patterns

Abstract Two distinct categories of weather patterns, denoted as Type 1 and Type 2, which show higher-than-expected frequency of summer heavy rainfall days (HRDs) over North China (NC), are selected from nine weather patterns categorized by the self-organizing map algorithm during 1979–2019. The respective HRDs over NC exhibit dissimilar characteristics, with Type 1 showing a northern distribution and Type 2 a southern distribution. The quantitative disparities in terms of moisture content and vertical motion are discussed in reactions to the synoptic-scale patterns associated with HRDs. The outcomes of a 20-day backward tracking, using the so-called Water Accounting Model-2layers, reveal noteworthy contrasts in moisture sources. Type 1 predominantly receives moisture from the western North Pacific, while Type 2 relies more on contributions from the Arabian Sea, Bay of Bengal, and Eurasia. However, the major moisture sources with grid cells contributing more than 0.01 mm show a consistent cumulative contribution of 77% for Type 1 and 80% for Type 2. The finding suggests that the discrepancy between the two types cannot be solely attributed to moisture supply. Further examination of the transverse and shearwise Q-vector components provides insights into how these distinct weather patterns influence HRDs by the alteration of vertical motion. In Type 1, an upper-level jet entrance induces a thermally direct secondary circulation that enhances vertical motion, while a baroclinic trough plays a dominant role in generating vertical motion in Type 2. Moreover, these unique configurations for each type of weather pattern are not only pre-existing but also intensified during HRDs.

Using DNA metabarcoding to separate natural and human provided food in wild boar diet at the northern distribution range of Europe

Wild boar Sus scrofa is increasing in numbers and extending its distribution across Europe and is difficult to control due to high reproductive potential. Dietary quality is a main determinant of wild boar population dynamics, and the extent to which they rely on human‐provided food provide a key to limit their distribution. Yet, we lack data on wild boar diet from northern Europe. Here we use DNA‐metabarcoding of faecal samples (n = 50) to determine wild boar diet during fall and winter in Norway. We mainly aimed to quantify the extent to which wild boar relies on natural or human‐provided food sources. A secondary aim was to determine whether diet varies with individual characteristics (sex, age or weight), season (winter or fall), and between the two regions with wild boar in Norway. We found a high degree of diet variability between individuals. Individuals consuming high amounts of edible fungi consumed low amounts of plant material. The (heavier) male wild boars consumed 50% more human provided food than the (lighter) female wild boars. There was no clear effect of age, season (winter versus fall), or region on diet with the sample size available. The negative correlation between plants and fungi in each sample suggests that using multiple primers targeting different taxa can provide quantitative diet information, and points to an important role of fungi (truffles) during winter and fall. The large individual variation in diet may reflect opportunistic feeding tactics in Scandinavian boreal forests, driven by a lack of acorns and few crops. Our study has relevance for understanding limitations of wild boars at their northern distribution range in Europe, and thus also provides important information for management.