Blind measurements did not confirm effects of forest fragmentation on fluctuating asymmetry of a tropical butterfly Morpho helenor.

Re-evaluation of photographs of the tropical butterfly Morpho helenor from a previous study (Pignataro et al. 2023) revealed that its conclusion regarding increased wing fluctuating asymmetry in forest edge habitats compared to forest interior habitats could not be replicated. This discrepancy likely arises from (i) original measurements not being conducted blindly, (ii) insufficient photograph quality hindering accurate landmark selection, and (iii) a lack of detailed description of the measurement protocol. The likelihood of false positive discoveries within the published data concerning the impacts of environmental stress on the fluctuating asymmetry of plants and animals is probably higher than previously assumed.

Fairy moths of the genus Nemophora Hoffmannsegg, 1798 (Lepidoptera: Adelidae) from Myanmar, Thailand, Laos, Cambodia and Vietnam.

This study provides a comprehensive account of 40 species (52 valid names and one preoccupied name) of the genus Nemophora Hoffmannsegg, 1798 described or recorded from Myanmar, Thailand, Laos, Cambodia and Vietnam. A key to the species based on external characters and on male genitalia is provided; 14 new species are described: N. auricapitella Kozlov, sp. nov., N. chalcoptera Kozlov, sp. nov., N. karsholti Kozlov, sp. nov., N. kuznetzovi Kozlov, sp. nov., N. meyi Kozlov, sp. nov., N. nielseni Kozlov, sp. nov., N. nieukerkeni Kozlov, sp. nov., N. nigripunctella Kozlov, sp. nov., N. punctifasciella Kozlov, sp. nov., N. rubicunda Kozlov, sp. nov., N. szabokyi Kozlov, sp. nov., N. thailandensis Kozlov, sp. nov., N. vietnamensis Kozlov, sp. nov. and N. yeni Kozlov, sp. nov. Lectotypes are designated for four species, including one junior synonym: Nemotois diplophragma Meyrick, 1938, Nemotois sinicella Walker, 1863, Nemotois cleodoxa Meyrick, 1922 and Adela satrapodes Meyrick, 1894. Eight new synonyms for four species are proposed: Nemophora badagongshana Liao, Hirowatari & Huang in Liao, Hirowatari, Yagi, Wang, Wang & Huang, 2023, syn. nov. of Nemophora aurifera (Butler, 1881); Nemotois chrysocharis Caradja, 1938, syn. nov. of Nemophora sinicella (Walker, 1863); Nemotois diplophragma Meyrick, 1938, syn. nov. of Nemophora melichlorias (Meyrick, 1907); Nemophora basalistriata Liao, Hirowatari & Huang in Liao, Hirowatari, Yagi, Wang, Wang & Huang, 2023, syn. nov. of Nemophora melichlorias (Meyrick, 1907); Nemotois limenites Meyrick, 1914, syn. nov. of Nemophora aurifera (Butler, 1881); Nemophora quadrata Liao, Hirowatari & Huang in Liao, Hirowatari, Yagi, Wang, Wang & Huang, 2023, syn. nov. of Nemophora aurifera (Butler, 1881); Nemotois rubrofascia formosicola Matsumura, 1931, syn. nov. of Nemophora sakaii (Matsumura, 1931); Nemotois servata Meyrick in Caradja, 1925, syn. nov. of Nemophora aurifera (Butler, 1881). Four new combinationsare introduced: Nemophora aglaospila (Meyrick, 1928), comb. nov.; Nemophora cleodoxa (Meyrick, 1922), comb. nov.; Nemophora melichlorias (Meyrick, 1907), comb. nov.; and Nemophora sinicella (Walker, 1863), comb. nov. Of 40 species considered, 16 were recorded in Myanmar, 21 in Thailand, 4 in Laos, 4 in Cambodia and 13 in Vietnam.

Phenotypic Diversity of a Leafroller Archips podana (Lepidoptera, Tortricidae) Does Not Change along an Industrial Pollution Gradient.

Morphological polymorphism offers rich opportunities for studying the eco-evolutionary mechanisms that drive the adaptations of local populations to heterogeneous and changing environments. In this study, I explore the association between pollution load, abundance of large fruit-tree tortrix Archips podana and its within-species diversity (expressed in the presence of apical and/or lateral prongs on the phallus in male genitalia) across 26 study sites located 0.5 to 31 km from the industrial city of Lipetsk in central Russia. The Shannon diversity index, calculated from the frequencies of four morphs, correlated neither with the distance to the nearest industrial polluter (a proxy of pollution load) nor with the number of moths captured by pheromone traps (a measure of population abundance). The statistical power of the correlation analysis was sufficient (67%) to detect a medium effect (i.e., Pearson correlation coefficient with an absolute value of 0.40), if it existed. I conclude that the four phenotypes of A. podana do not differ in tolerance to industrial pollution and similarly respond to pollution-induced environmental disturbance. This is the first study of industrial pollution impacts on within-species diversity of insects expressed in the discrete traits of their male genitalia.

The identities of Nemophora augites (Meyrick, 1938) and Nemophora amatella (Staudinger, 1892): correction of misidentifications and description of a new species (Lepidoptera: Adelidae) from China.

This study corrects misidentifications found in a recently published paper by Sun, Wang & Li (2022; Zootaxa 5219, 301-338). These authors used the name ?Nemophora amatella (Staudinger, 1892)' for N. augites (Meyrick, 1938) and the name ?N. augites (Caradja et Meyrick, 1938)' for an undescribed species. To resolve these problems, I set aside the earlier (erroneous) lectotype fixation of N. augites (Meyrick, 1938) and replace it with a new lectotype, designate a lectotype of N. amatella (Staudinger, 1892), provide differential diagnoses and morphological descriptions of these species, and describe N. yunnanica Kozlov, sp. nov. from Lijiang (Yunnan, China). The reported misidentifications show that any revision of a taxonomically challenging group like the fairy moth genus Nemophora Hoffmannsegg, 1798 should always be based on the examination of all survived primary types of previously described species.

Fairy moths of the genus Nemophora Hoffmannsegg, 1798 (Lepidoptera: Adelidae) of India and Sri Lanka.

This study provides a comprehensive account of 40 species of the genus Nemophora Hoffmannsegg, 1798 described or recorded from India and Sri Lanka. A key to the species based on external characters and on male genitalia is provided; twelve new species are described: Nemophora angustialata Kozlov, sp. nov., N. ceylonella Kozlov, sp. nov., N. costimaculella Kozlov, sp. nov., N. ferruginea Kozlov, sp. nov., N. fletcherella Kozlov, sp. nov., N. fuscomaculella Kozlov, sp. nov., N. kashmirella Kozlov, sp. nov., N. manipurella Kozlov, sp. nov., N. nitidulella Kozlov, sp. nov., N. ornamentella Kozlov, sp. nov., N. phryganeella Kozlov, sp. nov. and N. tenuitella Kozlov, sp. nov. Lectotypes are designated for 19 species, including four junior synonyms. The following new synonyms of seven species are proposed: Nemotois pollinaris (Meyrick, 1907), syn. nov. of Nemophora engraptes (Meyrick, 1907); Adela suavis Caradja, 1938, syn. nov. of Nemophora fluorites (Meyrick, 1907); Adela latifasciella Warren, 1888, syn. nov. of Nemophora gemmella (Walsingham, 1880); Nemotois chrysogona Meyrick, 1922, syn. nov. of Nemophora indica (Walker, 1863); Nemotois xanthargyra Meyrick, 1922, syn. nov. of Nemophora scitulella (Walker, 1864); Nemotois zonoreas Meyrick, 1924, syn. nov. of Nemophora solstitiella (Walsingham in Walsingham & Durrant, 1900); and Nemotois xanthophracta Meyrick, 1930, syn. nov. of Nemophora athlophora (Meyrick, 1912). Eleven new combinations are introduced: Nemophora sporodesma (Meyrick, 1928), comb. nov., N. engraptes (Meyrick, 1907), comb. nov., N. chalcomis (Meyrick, 1907), comb. nov., N. neurias (Meyrick, 1922), comb. nov., N. gemmella (Walsingham, 1880), comb. nov., N. indica (Walker, 1863), comb. nov., N. scitulella (Walker, 1864), comb. nov., N. amphimetalla (Meyrick, 1912), comb. nov., N. pyrotechna (Meyrick, 1912), comb. nov., N. chrysidias (Meyrick, 1928), comb. nov., and N. athlophora (Meyrick, 1912), comb. nov. Nemophora chalcomis (Meyrick, 1907) and N. mediseorsa Sun et Li, 2023 are for the first time reported from India; N. smaragdaspis (Meyrick, 1924) is for the first time reported from Nepal; N. chrysoprasias (Meyrick, 1922) is for the first time reported from Myanmar; N. solstitiella (Walsingham in Walsingham & Durrant, 1900) is for the first time reported from Pakistan and China (Taiwan); and N. augantha (Meyrick, 1907) is for the first time reported from Vietnam. The previous records of Adela croesella (Scopoli, 1763), N. satrapodes (Meyrick, 1894) and N. degeerella (Linnaeus, 1758) from India are dismissed as based on misidentifications. Currently, the fairy moth faunas of India and Sri Lanka include 38 and four species, respectively.

A replacement name for Nemophora divina Diakonoff, 1951 (Lepidoptera: Adelidae), a secondary junior homonym of Nemophora divina (Caradja, 1939).

Caradja (1939) described a fairy moth (Lepidoptera: Adelidae) species, Nemotois divina, from Ho Shan, Shanxi province of China. The genus Nemotois Hübner [1825] is a junior subjective synonym of the genus Nemophora Hoffmannsegg, 1798 (Fletcher 1929; Janse 1945; Jacobs 1949; Diakonoff 1951; Powell 1969; Nielsen 1980), and the combination Nemophora divina (Caradja, 1939) was first proposed by Kozlov (1997). This action made Nemophora divina Diakonoff, 1951, described from Indonesia, a secondary junior homonym of Nemophora divina (Caradja, 1939). No synonyms are known for this junior homonym; therefore, a new replacement name is proposed according to ICZN (1999: Art. 60.3). This name is based on the same holotype as the replaced name (ICZN 1999: Art. 72.7).

Poleward increase in feeding efficiency of leafminer Stigmella lapponica (Lepidoptera: Nepticulidae) in a latitudinal gradient crossing a boreal forest zone.

Damage to plant communities imposed by insect herbivores generally decreases from low to high latitudes. This decrease is routinely attributed to declines in herbivore abundance and/or diversity, whereas latitudinal changes in per capita food consumption remain virtually unknown. Here, we tested the hypothesis that the lifetime food consumption by a herbivore individual decreases from low to high latitudes due to a temperature-driven decrease in metabolic expenses. From 2016 to 2019, we explored latitudinal changes in multiple characteristics of linear (gallery) mines made by larvae of the pygmy moth, Stigmella lapponica, in leaves of downy birch, Betula pubescens. The mined leaves were larger than intact leaves at the southern end of our latitudinal gradient (at 60°N) but smaller than intact leaves at its northern end (at 69°N), suggesting that female oviposition preference changes with latitude. No latitudinal changes were observed in larval size, mine length or area, and in per capita food consumption, but the larval feeding efficiency (quantified as the ratio between larval size and mine size) increased with latitude. Consequently, S. lapponica larvae consumed less foliar biomass at higher latitudes than at lower latitudes to reach the same size. Based on space-for-time substitution, we suggest that climate warming will increase metabolic expenses of insect herbivores with uncertain consequences for plant-herbivore interactions.

Predation risk estimated on live and artificial insect prey follows different patterns.

Models mimicking prey organisms are increasingly used in ecological studies, including testing fundamental ecological and evolutionary theories. The general consensus is that predation risk estimated on artificial models may not quantitatively correspond to predation pressure on live prey, but it still can be used in various comparisons. We tested whether the use of live and artificial prey reveals the same patterns of variation in predation risk. We exposed live prey (blowfly larvae and puparia) and plasticine models of blowfly puparia in two boreal forest sites, both openly and in ant- and bird-exclusion treatments, and we quantified attacks by both avian and invertebrate predators. Bird attack rates were always higher on live puparia than on their plasticine models, but the magnitude of this difference declined from 8.4-fold in early summer to 2-fold in mid- and late-summer. We attribute these changes to different responses to prey by experienced adult birds that dominate the bird communities in early summer versus explorative juvenile birds that are abundant later in the season. Invertebrate daily predation rates on maggots decreased from 56% in early summer to 28% in late summer, but invertebrate attacks on plasticine models showed no seasonal changes. Overall, invertebrate predation on maggots was 67-fold greater than their predation on models. Observations showed that wood ants did not attack plasticine models and did not leave on them any damage marks. Estimates based on artificial prey indicate a much greater role of bird predation than invertebrate predation, while estimates based on live prey suggest the opposite pattern. Thus, using live and artificial prey may lead to different conclusions about relative importance of different predator groups in a locality. Moreover, for both avian and invertebrate predators, predation risk based on artificial and live prey shows different seasonal changes and may potentially demonstrate different spatial patterns.

Diversity but Not Overall Abundance of Moths and Butterflies (Insecta: Lepidoptera) Decreases around Two Arctic Polluters.

Alarming reports on the rapid decline of insects during the past decades call for the exploration of potential drivers of this process. Here, we test the hypothesis that the overall abundance and diversity of moths and butterflies (Lepidoptera) decrease under the impact of industrial pollution in the fragile arctic environment. For this purpose, experienced collectors netted adult Lepidoptera at five tundra sites located 0.5 to 45.3 km from the ore-roasting plant in Zapolyarnyy and at five forest sites located 1.4 to 37.8 km from the copper-nickel smelter at Nikel, in the Murmansk region of Russia. The analysis of the 100 samples collected from 2003 to 2008 and containing 2312 individuals of 122 species revealed that the diversity of Lepidoptera declined significantly near both of these polluters due to both decreases in species richness and changes in the abundance of individual species, whereas the overall abundance of moths and butterflies was independent of the pollution load. These patterns did not differ between Nikel and Zapolyarnyy, and they were consistent with patterns previously found near the copper-nickel smelter at Monchegorsk. The abundances of Lepidoptera species showed variable changes along pollution gradients, from significantly negative to significantly positive, but individual species showed similar density changes around these three polluters. Disproportional increases in the abundance of a few pollution-tolerant species change the community structure and explain why the overall abundance of moths and butterflies does not decline even in localities experiencing extreme loads of sulphur dioxide and heavy metals.

Elevational changes in insect herbivory on woody plants in six mountain ranges of temperate Eurasia: Sources of variation.

Current theory predicts that the intensity of biotic interactions, particularly herbivory, decreases with increasing latitude and elevation. However, recent studies have revealed substantial variation in both the latitudinal and elevational patterns of herbivory. This variation is often attributed to differences in study design and the type of data collected by different researchers. Here, we used a similar sampling protocol along elevational gradients in six mountain ranges, located at different latitudes within temperate Eurasia, to uncover the sources of variation in elevational patterns in insect herbivory on woody plant leaves. We discovered a considerable variation in elevational patterns among different mountain ranges; nevertheless, herbivory generally decreased with increasing elevation at both the community-wide and individual plant species levels. This decrease was mostly due to openly living defoliators, whereas no significant association was detected between herbivory and elevation among insects living within plant tissues (i.e., miners and gallers). The elevational decrease in herbivory was significant for deciduous plants but not for evergreen plants, and for tall plants but not for low-stature plants. The community-wide herbivory increased with increases in both specific leaf area and leaf size. The strength of the negative correlation between herbivory and elevation increased from lower to higher latitudes. We conclude that despite the predicted overall decrease with elevation, elevational gradients in herbivory demonstrate considerable variation, and this variation is mostly associated with herbivore feeding habits, some plant traits, and latitude of the mountain range.

Population dynamics of herbivorous insects in polluted landscapes.

Environmental pollution is one cause of insect decline in the Anthropocene, but the underlying mechanisms remain obscure due to a paucity of pollution-impact studies on insects that address density-dependent processes. Long data series (19-26 years) are available only for a few species monitored around two industrial polluters in north-western Russia. A particularly exciting current finding is that industrial pollution determines the relative strength of rapid (stabilising) and delayed (destabilising) density dependence operating on a herbivore population. Most studies address acute effects of traditional pollutants (e.g. sulphur dioxide and trace elements) and nitrogen deposition on agricultural pests, whereas the effects of realistic concentrations of ozone, particulate matter and emerging pollutants on insects feeding on noncultivated plants are unknown. The accumulated evidence remains insufficient to predict the effects of pollutants of global concern on the population dynamics of herbivorous insects.

Meta-analysis of elevational changes in the intensity of trophic interactions: Similarities and dissimilarities with latitudinal patterns.

The premise that the intensity of biotic interactions decreases with increasing latitudes and elevations is broadly accepted; however, whether these geographical patterns can be explained within a common theoretical framework remains unclear. Our goal was to identify the general pattern of elevational changes in trophic interactions and to explore the sources of variation among the outcomes of individual studies. Meta-analysis of 226 effect sizes calculated from 134 publications demonstrated a significant but interaction-specific decrease in the intensity of herbivory, carnivory and parasitism with increasing elevation. Nevertheless, this decrease was not significant at high latitudes and for interactions involving endothermic organisms, for herbivore outbreaks or for herbivores living within plant tissues. Herbivory similarly declined with increases in latitude and elevation, whereas carnivory showed a fivefold stronger decrease with elevation than with latitude and parasitism increased with latitude but decreased with elevation. Thus, although these gradients share a general pattern and several sources of variation in trophic interaction intensity, we discovered important dissimilarities, indicating that elevational and latitudinal changes in these interactions are partly driven by different factors. We conclude that the scope of the latitudinal biotic interaction hypothesis cannot be extended to incorporate elevational gradients.

Strategic roadmap to assess forest vulnerability under air pollution and climate change.

Although it is an integral part of global change, most of the research addressing the effects of climate change on forests have overlooked the role of environmental pollution. Similarly, most studies investigating the effects of air pollutants on forests have generally neglected the impacts of climate change. We review the current knowledge on combined air pollution and climate change effects on global forest ecosystems and identify several key research priorities as a roadmap for the future. Specifically, we recommend (1) the establishment of much denser array of monitoring sites, particularly in the South Hemisphere; (2) further integration of ground and satellite monitoring; (3) generation of flux-based standards and critical levels taking into account the sensitivity of dominant forest tree species; (4) long-term monitoring of N, S, P cycles and base cations deposition together at global scale; (5) intensification of experimental studies, addressing the combined effects of different abiotic factors on forests by assuring a better representation of taxonomic and functional diversity across the ~73,000 tree species on Earth; (6) more experimental focus on phenomics and genomics; (7) improved knowledge on key processes regulating the dynamics of radionuclides in forest systems; and (8) development of models integrating air pollution and climate change data from long-term monitoring programs.

Recovery of moth and butterfly (Lepidoptera) communities in a polluted region following emission decline.

Environmental pollution is one of the major drivers of the present-day decline in global biodiversity. However, the links between the effects of industrial pollution on insect communities and the underlying species-specific responses remain poorly understood. We explored the spatial pattern in insect communities by analysing 581 samples of moths and butterflies (containing 25,628 individuals of 345 species) collected along a strong pollution gradient in subarctic Russia, and we recorded temporal changes in these communities during the pollution decline that occurred from 1992 to 2006. In the 1990s, the diversity of the Lepidoptera community was positively correlated with the distance from the copper-nickel smelter at Monchegorsk. The overall abundance of Lepidoptera did not change along the pollution gradient, although the abundance of many species decreased with increasing pollution. The responses of each individual species to pollution were associated with its life history traits. The abundances of monophagous species that fed inside live plant tissues and hibernated as imagoes or pupae were not affected by pollution, whereas the abundances of oligophagous and polyphagous species that fed externally on plants and hibernated as larvae generally declined near the smelter. Substantial decreases in aerial emissions from the smelter between 1992 and 2006 resulted in an increase in the diversity of moths and butterflies in severely polluted habitats, whereas their overall abundance did not change. This recovery of the Lepidoptera community occurred due to the reappearance of rare species that had been previously extirpated by pollution and was observed despite the lack of any signs of recovery of the vegetation in the heavily polluted sites. We conclude that the recovery trajectories of insect communities following emission control can be predicted from studies of their changes along spatial pollution gradients by using space-for-time substitution.

Herbivory on the pedunculate oak along an urbanization gradient in Europe: Effects of impervious surface, local tree cover, and insect feeding guild.

Urbanization is an important driver of the diversity and abundance of tree-associated insect herbivores, but its consequences for insect herbivory are poorly understood. A likely source of variability among studies is the insufficient consideration of intra-urban variability in forest cover. With the help of citizen scientists, we investigated the independent and interactive effects of local canopy cover and percentage of impervious surface on insect herbivory in the pedunculate oak (Quercus robur L.) throughout most of its geographic range in Europe. We found that the damage caused by chewing insect herbivores as well as the incidence of leaf-mining and gall-inducing herbivores consistently decreased with increasing impervious surface around focal oaks. Herbivory by chewing herbivores increased with increasing forest cover, regardless of impervious surface. In contrast, an increase in local canopy cover buffered the negative effect of impervious surface on leaf miners and strengthened its effect on gall inducers. These results show that-just like in non-urban areas-plant-herbivore interactions in cities are structured by a complex set of interacting factors. This highlights that local habitat characteristics within cities have the potential to attenuate or modify the effect of impervious surfaces on biotic interactions.

Insect herbivory increases from forest to alpine tundra in Arctic mountains.

Current theory holds that the intensity of biotic interactions decreases with increases in latitude and elevation; however, empirical data demonstrate great variation in the direction, strength, and shape of elevational changes in herbivory. The latitudinal position of mountains may be one important source of this variation, but the acute shortage of data from polar mountains hampers exploration of latitude effects on elevational changes in herbivory. Here, we reduce this knowledge gap by exploring six elevation gradients located in three Arctic mountain ranges to test the prediction that a decrease in herbivory occurs with increasing elevation from forest to alpine tundra. Across the 10 most abundant evergreen and deciduous woody plant species, relative losses of foliage to insect herbivores were 2.2-fold greater at the highest elevations (alpine tundra) than in mid-elevation birch woodlands or low-elevation coniferous forests. Plant quality for herbivores (quantified by specific leaf area) significantly decreased with elevation across all studied species, indicating that bottom-up factors were unlikely to shape the observed pattern in herbivory. An experiment with open-top chambers established at different elevations showed that even a slight increase in ambient temperature enhances herbivory in Arctic mountains. Therefore, we suggest that the discovered increase in herbivory with elevation is explained by higher temperatures at the soil surface in open habitats above the tree line compared with forests at lower elevations. This explanation is supported by the significant difference in elevational changes in herbivory between low and tall plants: herbivory on low shrubs increased fourfold from forest to alpine sites, while herbivory on trees and tall shrubs did not change with elevation. We suggest that an increase in herbivory with an increase in elevation is typical for high-latitude mountains, where inverse temperature gradients, especially at the soil surface, are common. Verification of this hypothesis requires further studies of elevational patterns in herbivory at high latitudes.

Foliar stable isotope ratios of carbon and nitrogen in boreal forest plants exposed to long-term pollution from the nickel-copper smelter at Monchegorsk, Russia.

Long-term exposure to primary air pollutants, such as sulphur dioxide (SO2) and nitrogen oxides (NOx), alters the structure and functions of forest ecosystems. Many biochemical and biogeochemical processes discriminate against the heavier isotopes in a mixture; thus, the values of δ13C and δ15N (i.e. the ratio of stable isotopes 13C to 12C and that of 15 N to 14 N, respectively) may give insights into changes in ecosystem processes and identify the immediate drivers of these changes. We studied sources of variation in the δ13C and δ15N values in the foliage of eight boreal forest C3 plants at 10 sites located at the distance of 1-40 km from the Monchegorsk nickel-copper smelter in Russia. From 1939‒2019, this smelter emitted over 14,000,000 metric tons (t) of SO2, 250,000 t of metals, primarily nickel and copper, and 140,000 t of NOx. The δ13C value in evergreen plants and the δ15N value in all plants increased near the smelter independently of the plant mycorrhizal type. We attribute the pollution-related increase in the foliar δ13C values of evergreen species mainly to direct effects of SO2 on stomatal conductance, in combination with pollution-related water stress, which jointly override the potential opposite effect of increasing ambient CO2 concentration on δ13C values. Stomatal uptake of NOx and root uptake of 15N-enriched organic N compounds and NH4+ may explain the increased foliar δ15N values and elevated foliar N concentrations, especially in the evergreen trees (Pinus sylvestris), close to Monchegorsk, where the soil inorganic N supply is reduced due to the impact of long-term SO2 and heavy metal emissions on plant biomass. We conclude that, despite the uncertainties in interpreting δ13C and δ15N responses to pollution, the Monchegorsk smelter has imposed and still imposes a great impact on C and N cycling in the surrounding N-limited subarctic forest ecosystems.

Changes in Biomass and Diversity of Soil Macrofauna along a Climatic Gradient in European Boreal Forests.

Latitudinal gradients allow insights into the factors that shape ecosystem structure and delimit ecosystem processes, particularly climate. We asked whether the biomass and diversity of soil macrofauna in boreal forests change systematically along a latitudinal gradient spanning from 60° N to 69° N. Invertebrates (3697 individuals) were extracted from 400 soil samples (20 × 20 cm, 30 cm depth) collected at ten sites in 2015-2016 and then weighed and identified. We discovered 265 species living in soil and on the soil surface; their average density was 0.486 g d·w·m-2. The species-level diversity decreased from low to high latitudes. The biomass of soil macrofauna showed no latitudinal changes in early summer but decreased towards the north in late summer. This variation among study sites was associated with the decrease in mean annual temperature by ca 5 °C and with variation in fine root biomass. The biomass of herbivores and fungivores decreased towards the north, whereas the biomass of detritivores and predators showed no significant latitudinal changes. This variation in latitudinal biomass patterns among the soil macrofauna feeding guilds suggests that these guilds may respond differently to climate change, with poorly understood consequences for ecosystem structure and functions.

Climate shapes the spatiotemporal variation in color morph diversity and composition across the distribution range of Chrysomela lapponica leaf beetle.

Color polymorphism offers rich opportunities for studying the eco-evolutionary mechanisms that drive the adaptations of local populations to heterogeneous and changing environments. We explored the color morph diversity and composition in a Chrysomela lapponica leaf beetle across its entire distribution range to test the hypothesis that environmental and climatic variables shape spatiotemporal variation in the phenotypic structure of a polymorphic species. We obtained information on 13 617 specimens of this beetle from museums, private collections, and websites. These specimens (collected from 1830-2020) originated from 959 localities spanning 33° latitude, 178° longitude, and 4200 m altitude. We classified the beetles into five color morphs and searched for environmental factors that could explain the variation in the level of polymorphism (quantified by the Shannon diversity index) and in the relative frequencies of individual color morphs. The highest level of polymorphism was found at high latitudes and altitudes. The color morphs differed in their climatic requirements; composition of colour morphs was independent of the geographic distance that separated populations but changed with collection year, longitude, mean July temperature and between-year temperature fluctuations. The proportion of melanic beetles, in line with the thermal melanism hypothesis, increased with increasing latitude and altitude and decreased with increasing climate seasonality. Melanic morph frequencies also declined during the past century, but only at high latitudes and altitudes where recent climate warming was especially strong. The observed patterns suggest that color polymorphism is especially advantageous for populations inhabiting unpredictable environments, presumably due to the different climatic requirements of coexisting color morphs.

Seasonal variations in bird selection pressure on prey colouration.

The direction and strength of selection for prey colouration by predators vary in space and time and depend on the composition of the predator community. We tested the hypothesis that bird selection pressure on prey colouration changes through the season due to changes in the proportion of naïve juvenile individuals in the bird community, because naïve and educated birds differ in their responses to prey colours. Bird predation on caterpillar-shaped plasticine models in two boreal forest sites increased sevenfold from early summer to mid-summer, and the time of this increase coincides with the fledging of juvenile birds. In early summer, cryptic (black and green) models were attacked at fivefold higher rates compared with conspicuous (red and yellow) models. By contrast, starting from fledging time, cryptic and conspicuous models were attacked at similar rates, hinting at a lower selectivity by naïve juvenile birds compared with educated adult birds. Cryptic models exposed in a group together with conspicuous models were attacked by birds at a threefold lower rate than cryptic models exposed singly, thus supporting the aposematic commensalism hypothesis. However, this effect was not observed in mid- and late summer, presumably due to the lack of avoidance of conspicuous prey by the juvenile birds. We conclude that selection pressure on prey colouration weakens considerably when naïve birds dominate in the community, because the survival advantages of aposematic colouration are temporarily lost for both the conspicuous and their neighbouring cryptic prey.