Boreal forests soils are important global carbon sinks, with significant storage in the organic topsoil. Decomposition of these stocks requires oxidative enzymes, uniquely produced by fungi, of which many live in ectomycorrhizal symbiosis with the trees. Here we show that presence of a group of closely related species of ectomycorrhizal fungi – Cortinarius acutus s.l. – decreased local carbon storage in the organic topsoil by 33% across Swedish forests. Our findings challenge the prevailing view that ectomycorrhizal fungi generally act to increase carbon storage in soils and show that certain ectomycorrhizal fungi can complement free-living decomposers, maintaining nutrient cycling and tree productivity under nutrient poor conditions. The finding that a narrow group of fungi exerts a major influence on carbon cycling refutes the prevailing dogma of functional redundancy among microbial decomposers. Cortinarius acutus s.l. responds negatively to forestry, and population declines are likely to increase soil carbon sequestration while impeding nutrient cycling.

A recent review on optimal strategies for preserving biodiversity within human-modified landscapes suggests that that forest cover needs to be restored or maintained to at least 40%. While we agree that it is paramount to protect and increase cover in forested biomes, no evidence is presented to support this 40% threshold. Furthermore, there are several issues regarding implementation of such policy or social-economic constraints that makes this suggestion unhelpful and potentially dangerous.

The nutritional diversity of resources can affect the adaptive evolution of consumer metabolism and consumer diversification. Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) have a high potential to affect consumer fitness, through their widespread effects on reproduction, growth, and survival. However, few studies consider the evolution of fatty acid metabolism within an ecological context. In this review, we first document the extensive diversity in both primary producer and consumer n-3 LC-PUFA distributions among major ecosystems, between habitats, and among species within habitats. We highlight some of the key nutritional contrasts that can shape behavioral and/or metabolic adaptation in consumers, discussing how consumers can evolve in response to the spatial, seasonal, and community-level variation of resource quality. We propose a hierarchical trait-based approach for studying the evolution of consumers’ metabolic networks, and review the evolutionary genetic mechanisms underpinning consumer adaptation to n-3 LC-PUFA distributions. In doing so, we consider how the metabolic traits of consumers are hierarchically structured, from cell membrane function to maternal investment, and have strongly environment-dependent expression. Finally, we conclude with an outlook on how studying the metabolic adaptation of consumers within the context of nutritional landscapes can open up new opportunities for understanding evolutionary diversification.

Size and shape profoundly influence an organism’s ecophysiological performance and evolutionary fitness, suggesting a link between morphology and diversity. However, not much is known about how body shape is related to taxonomic richness, in particular in the microbial realm. Here we analyse global datasets of unicellular phytoplankton, a major photosynthetic group with an exceptional diversity of cell sizes and shapes. Using two measures of cell shape elongation, we quantify taxonomic diversity as a function of cell size and shape. We find that cells of intermediate volume have the greatest shape variation, from oblate to extremely elongated forms, while small and large cells are mostly compact (e.g., spherical or cubic). Taxonomic diversity is strongly related with cell elongation and cell volume, with both traits, in combination, explaining up to 92% of total variance. Diversity decays exponentially with cell elongation and displays a log-normal dependence on cell volume, peaking for compact, intermediate-volume cells. These previously unreported broad patterns in phytoplankton diversity reveal selective pressures and ecophysiological constraints on the geometry of phytoplankton cells which may improve our understanding of marine ecology and the evolutionary rules of life.

The Maximum Entropy Theory of Ecology (METE) predicts the shapes of macroecological metrics in relatively static ecosystems using constraints imposed by static state variables. In disturbed ecosystems, however, with time-varying state variables, its predictions often fail. We extend macroecological theory from static to dynamic by combining the MaxEnt inference procedure with explicit mechanisms governing disturbance. In the static limit, the resulting theory, DynaMETE, reduces to METE but also predicts new scaling relationships among static state variables. Under disturbances, expressed as shifts in demographic, ontogenic growth, or migration rates, DynaMETE predicts the time trajectories of the state variables as well as the time-varying shapes of macroecological metrics such as the species abundance distribution and the distribution of metabolic rates over individuals. An iterative procedure for completely solving the dynamic theory is presented. In a lowest-order iteration, characteristic signatures of the deviation from static predictions of macroecolgoical patterns are shown to result from different kinds of disturbance. Because DynaMETE combines MaxEnt inference with explicit dynamical mechanisms, but does not assume any specific trait distributions over species or individuals, it is widely applicable across diverse ecosystems. This makes it a promising theory of macroecology for ecosystems responding to anthropogenic or natural disturbances.

Alpine large herbivores have developed physiological and behavioral mechanisms to cope with fluctuations in climate and resource availability, but climate warming might induce behavioral maladaptation. We verified this hypothesis in female Alpine ibex (Capra ibex) by modelling seasonal and daily movement and activity patterns in function of temperature and vegetation productivity, based on bio-logging data and climate change projections. In late spring, ibex moved upslope, tracking the green-wave in plant phenology. Ibex sharply decreased diel activity above a threshold mean daily temperature of 13°C, indicating thermal stress, but compensating behaviorally by foraging earlier at dawn, and later at dusk, and by moving upslope higher than on cooler days. This temperature threshold will be exceeded more than three times as often under climate change projections. In such scenarios, the imperative requirement for thermal shelter may force Alpine ibex towards topographic edges, impacting individual performance and population distribution of this emblematic mountain ungulate.

In ectothermic predator-prey relationships, the capacity for prey to successfully evade predation will depend upon physiological and behavioural responses that relate to both players’ thermal biology. On the Izu Islands of Japan, we investigated how a prey lizard species has responded physiologically and thermally to the presence of a snake predator over evolutionary time in addition to recent climatic warming. Foraging lizard body temperatures have increased by 1.0°C from 1981 to 2019 while lizard body temperatures were 3.4°C warmer on islands where the snake predator is present relative to snake-free islands. We also found that warmer prey body temperatures result in faster running speeds of the prey at temperatures suboptimal for the snake predator. The results show that lizard body temperatures have increased with warming but not to the same extent as that exerted by predation pressure. However, further warming could irrevocably alter this and other ectothermic predator-prey relationships.

Forecasts of forest responses to climate variability are governed by climate exposure and ecosystem sensitivity, but ecosystem model projections and process representations are under-constrained by data at multidecadal and longer timescales. Here, we assess ecosystem sensitivity to centennial-scale hydroclimate variability, by comparing dendroclimatic and pollen-inferred reconstructions of drought, forest composition and biomass for the last millennium with five ecosystem model simulations. In both observations and models, spatial patterns in ecosystem responses to hydroclimate variability are strongly governed by ecosystem sensitivity rather than climate exposure. Ecosystem sensitivity was highest in simpler models and higher than observations, suggesting that interactions among biodiversity, demography, and ecophysiology processes dampen the sensitivity of forest composition and biomass to climate variability and change. By integrating ecosystem models with observations from timescales extending beyond the instrumental record, we can better understand and forecast the mechanisms regulating forest sensitivity to climate variability in a complex and changing world.

The recent upsurge in the edible insect market has seen industrialisation and intensification without adequate regulatory policy guidelines in place. The species being reared and sold are often non-native, in rearing centres not equipped to contain the species, and in areas without regional or national pre-entry regulations, post-entry monitoring guidelines and early response programs to address escapee species. Such unregulated transport, trade and rearing of species, compounded by the policy and implementation loopholes at the regional, national and international levels will most likely lead to new biological invasions, as has been witnessed with other unregulated trade practices. To avoid this, it is necessary to monitor and regulate the species to be reared, to improve the quarantine guidelines of the rearing centres, and to be more stringent about the policies and practices that allow movements of non-native species across international borders.

Interactions with microbial symbionts have yielded great macroevolutionary innovations across the tree of life, like the origins of chloroplasts and the mitochondrial powerhouses of eukaryotic cells. There is also increasing evidence that host-associated microbiomes influence patterns of microevolutionary adaptation in plants and animals. Here we describe how microbes can facilitate adaptation in plants and how to test for and differentiate between the two main mechanisms by which microbes can produce adaptive responses in higher organisms: microbe-mediated local adaptation and microbe-mediated adaptive plasticity. Microbe-mediated local adaptation is when local plant genotypes have higher fitness than foreign genotypes because of a genotype-specific affiliation with locally important microbes. Microbe-mediated adaptive plasticity occurs when local plant phenotypes have higher fitness than foreign phenotypes as a result of interactions with locally important microbes. These microbial effects on adaptation can be difficult to differentiate from traditional modes of adaptation but may be prevalent. Ignoring microbial effects may lead to erroneous conclusions about the traits and mechanisms underlying adaptation, hindering management decisions in conservation, restoration, and agriculture.

Despite widespread evidence that biological invasion influences both the biotic and abiotic soil environments, the extent to which these two pathways underpin the effects of invasion on plant traits and performance is unknown. Leveraging a long-term (14-yr) field experiment, we show that an allelochemical-producing invader affects plants through biotic mechanisms, altering the soil fungal community composition, with no apparent shifts in soil nutrient availability. Changes in belowground fungal communities result in high costs of nutrient uptake for native perennials and a shift in functional traits linked to their water and nutrient use efficiencies. Some species in the invaded community compensate for high nutrient costs by reducing nutrient uptake and maintaining photosynthesis by expending more water, which demonstrates a trade-off in trait investment. For the first time, we show that the disruption of belowground nutritional symbionts can drive native plants toward novel regions in order to maintain their water and nutrient economics.

Pollination is an important ecological process. However, the needs of plants and pollinators are not always met. Pollen limitation commonly reduces seed set and bees often experience nectar dearth. Using a theoretical cost-benefit optimization model we show that natural selection acting at the level of individual plants and pollinators will result in positive feedback that exacerbates pre-existing imbalances between nectar supply and demand. When pollinators are scarce plants will be selected to produce more nectar to outcompete other plants in attracting pollinators, and when pollinators are abundant plants will be selected to produce less nectar. We encourage the testing of this novel hypothesis and propose several ways of doing this via comparative study and experimental manipulation. We also suggest that evidence for seasonal variation in foraging conditions provides preliminary empirical support. If our hypothesis is correct it means that pollination faces a particular challenge in balancing nectar supply with demand.

Changing environments and habitat structure likely affect eco-evolutionary processes involved in the spatial spread of disease. Exploitative parasites are predicted to evolve in highly connected populations or in expanding epidemics. However, many parasites rely on host dispersal to reach new populations, potentially causing conflict between local transmission and global spread. We performed experimental range expansions in interconnected microcosms of the protozoan Paramecium caudatum, allowing natural dispersal of hosts infected with the bacterial parasite Holospora undulata. Parasites from range front treatments were less virulent and interfered less with host dispersal, but also invested less in horizontal transmission than parasites from range cores. An epidemiological model fitted on experimental time-series data confirmed this trade-off between dispersal adaptation and transmission, so far rarely considered in theoretical models. Our study illustrates the importance of the ecology and evolution of dispersal-related traits in spatial non-equilibrium scenarios, including emerging diseases, metapopulations or biological invasions.

Natural systems are always fluctuating: no two years are identical, with population and community sizes varying from one year to the next. Such variation has led to “equilibrium” becoming almost a dirty word in ecology. Some researchers see the world as being in permanent flux, and consider our field’s historical focus on equilibria as out-dated. But this view is flawed, is driven by current day observations of a world out of kilter, and risks downplaying the risks of ongoing anthropogenic change to civilisation and perhaps too to life on Earth. In this viewpoint, I mount a defence for equilibria.

The frequency distribution of individual body sizes in animal communities (i.e. the size spectrum) provides powerful insights for understanding the energy flux through food webs. However, studies of size spectra in rocky and coral reef communities typically focus only on fishes or invertebrates due to taxonomic and data constraints, and consequently ignore energy pathways involving the full range of macroscopic consumer taxa. We analyse size spectra with co-located fish and mobile macroinvertebrate data from 3,391 reef sites worldwide, specifically focusing on how the addition of invertebrate data alters patterns. The inclusion of invertebrates steepens the size spectrum, more so in temperate regions, resulting in a consistent size spectrum slope across latitudes, and bringing slopes close to theoretical expectations based on energy flow through the system. These results highlight the importance of understanding contributions of both invertebrates and fishes to reef food webs worldwide.

Soil ecological stoichiometry provides powerful theories to integrate the complex interplay of element cycling and microbial communities into biogeochemical models. One essential assumption is that microbes maintain stable C:N:P (carbon:nitrogen:phosphorus) ratios independent of resource supply, although such homeostatic regulations have rarely been assessed in individual microorganisms. Here, we report an unexpected high flexibility in C:N and C:P values of saprobic fungi along nutrient supply gradients, overall ranging between 7-126 and 20-1488, respectively, questioning microbial homeostasis. Fungal N:P varied comparatively less due to simultaneous reductions in mycelial N and P contents. As a mechanism, internal recycling processes during mycelial growth and an overall reduced N and P uptake appear more relevant than element storage. The relationships among fungal stoichiometry and growth disappeared in more complex media. These findings affect our interpretation of stoichiometric imbalances among microbes and soils and are highly relevant for developing microbial soil organic carbon and nitrogen models.

Ant Forest, a mobile app by the monolithic Alibaba Group, is greening individuals' daily activities and transforming human capacity to reverse global environmental degradation. Over 500 million e-trees being cultivated every day in China using Ant Forest. Over 122 million trees planted over more than 112,000 ha of degraded land areas. This is a showcase of how innovation via internet technology combined with digital finance is contributing to solving environmental issues, also the potential to match an individual's daily footprint to their digital footprint and converting this to an ecological footprint.

Non-consumptive predator effects (NCEs) are now widely recognized for their capacity to shape ecosystem structure and function. Yet, forecasting the propagation of these predator-induced trait changes through particular communities remains a challenge, in part because we lack a predictive framework that accounts for environmental and species context. Accordingly, focusing on plasticity in prey anti-predator behaviors, we conceptualize the multi-stage process by which predators trigger direct and indirect NCEs, review and then distill potential drivers of NCE contingencies into three key categories (properties of the prey, predator, and setting), and conduct a meta-analysis to quantify the extent to which prey behavioral plasticity in response to predation risk hinges on a well-studied driver – prey energetic state. Our synthesis underscores the myriad factors that can generate NCE contingencies while guiding how research might better anticipate and account for them. We highlight two key knowledge gaps that continue to hinder development of a comprehensive framework for exploring non-consumptive predator-prey interactions. These are insufficient exploration of 1) context-dependent indirect NCEs and 2) the ways in which direct and indirect NCEs are shaped interactively by multiple drivers of context dependence.