Ecological processes in food webs depend on species interactions. By identifying broad-scaled interaction patterns, important information on species ecological roles may be revealed. Here, we use the group model to examine how spatial resolution and proximity influence the group structure. We examine a dataset from the Barents Sea, with species occurrences for both the whole region and 25 subregions. Specifically, we test how the group structure in the networks differ comparing i) the regional metaweb to subregions and ii) subregion to subregion. We find that more than half the species in the metaweb change groups when compared to subregions. Between subregions, networks with similar group structure are usually spatially related. Interestingly, although species overlap is important for similarity in group structure, there are notable exceptions. Our results highlight that species ecological roles differ depending on fine-scaled differences in patterns of interactions, and that local network characteristics are important to consider.

Metabolomics provides an unprecedented window on diverse plant secondary metabolites that represent a potentially critical niche dimension in tropical forests underlying co-existence. Here, we used untargeted metabolomics to evaluate the chemical composition of 358 tree species and its relationship to phylogeny and variation in light environment, soil nutrients, and insect-herbivore leaf damage in a tropical rain forest plot. We found that tree species that co-occur locally are less chemically similar than random, and that local chemical dispersion and metabolite diversity reduce herbivory, especially that of specialist insect herbivores. Our results suggest that plant secondary metabolites have the potential to mediate plant-herbivore interactions in a manner consistent with diversity maintenance at the community scale.

Extreme weather events have become a dominant feature of the narrative surrounding changes in global climate. with large impacts on ecosystem stability, functioning and resilience, however, understanding of their risk of co-occurrence at the regional scale is lacking. Based on the UK Met Office's long-term temperature and rainfall records, we present the first evidence demonstrating significant increases in the magnitude, direction of change and spatial co-localization of extreme weather events since 1961. Combining this new understanding with land use datasets allowed us to assess the likely consequences on future agricultural production and conservation priority areas. All land uses are impacted by the increasing risk of at least one extreme event and conservation areas were identified as hotspots of risk for the co-occurrence of multiple event types. Our findings provide a basis to regionally guide land use optimisation, land management practices and regulatory actions preserving ecosystem services against multiple climate threats.

Plant community productivity generally increases with biodiversity, but the strength of this relationship exhibits strong empirical variation. In meta-food-web simulations, we addressed if the spatial overlap in plants' resource access and movement of animals can explain such variability. We found that spatial overlap of plant resource access is a prerequisite for positive diversity-productivity relationships, but causes exploitative competition that can lead to competitive exclusion. Movement of herbivores causes apparent competition among plants, resulting in negative relationships. However, movement of larger top predators integrates sub-food-webs composed of smaller species, offsetting the negative effects of exploitative and apparent competition and leading to strongly positive diversity-productivity relationships. Overall, our results show that spatial overlap of plant resource access and animal movement can greatly alter the strength and sign of such relationships. In particular, the scaling of animal movement effects opens new perspectives for linking landscape processes without effects on biodiversity to productivity patterns.

We develop a novel approach to trophic metacommunities which allows us to explore how progressive habitat loss affects food webs. Our method combines classic metapopulation models on fragmented landscapes with a Bayesian network representation of trophic interactions for calculating local extinction rates. This means we can repurpose known results from classic metapopulation theory for trophic metacommunities, such as ranking the habitat patches of the landscape with respect to their importance to the persistence of the metacommunity as a whole. We use this to study the effects of habitat loss, both on model communities and the plant-mammal Serengeti food web dataset as a case study. Combining straightforward parameterizability with computational efficiency, our method permits the analysis of species-rich food webs over large landscapes, with hundreds or even thousands of species and habitat patches, while still retaining much of the flexibility of explicit dynamical models.

Biodiversity may increase ecosystem resilience. However, we have limited understanding if this holds true for ecosystems that respond to gradual environmental change with abrupt shifts to an alternative state. We used a mathematical model of anoxic-oxic regime shifts and explored how trait diversity in three groups of bacteria influences resilience. We found that trait diversity did not always increase resilience: greater diversity in two of the groups increased but in one group decreased resilience of their preferred ecosystem state. We also found that simultaneous trait diversity in multiple groups often led to reduced or erased diversity effects. Overall, our results suggest that higher diversity can increase resilience but can also promote collapse when diversity occurs in a functional group that negatively influences the state it occurs in. We propose this mechanism as a potential management approach to facilitate the recovery of a desired ecosystem state.

Climate warming alters the seasonal timing of biological events. This raises concerns that species-specific responses to warming may de-synchronize co-evolved consumer-resource phenologies, resulting in trophic mismatch and altered ecosystem dynamics. Here we explore effects of warming on the temporal coherence of two key phenological events in lakes across Europe: The onset of the phytoplankton spring bloom and the spring/summer maximum of the grazer Daphnia. Simulation of 1,891,744 lake years revealed that, under the current climate, the phenological delay between the two events varies greatly (20-190 days) across lake types and geographic locations. Warming moves both phenological events forward in time and can predictably lengthen or shorten the delay between them by up to 60 days. Our findings expose large extant variation in phenological synchrony of planktonic organisms, provide quantitative predictions of its dependence on physical lake properties and geographic location, and highlight research needs concerning its ecological consequences.

Grassland ecosystems account for more than 10% of the global CH4 sink in soils. A 4-year field experiment found that addition of P alone did not affect CH4 uptake and experimental addition of N alone significantly suppressed CH4 uptake, while concurrent N and P additions suppressed CH4 uptake to a lesser degree. A meta-analysis including 382 data points in global grasslands corroborated these findings. Global extrapolation with an empirical modeling approach estimated that contemporary N addition suppresses CH4 sink in global grassland by 11% and concurrent N and P deposition alleviates this suppression by 6%. The P alleviation of N-suppressed CH4 sink is primarily attributed to substrate competition, defined as the competition between ammonium and CH4 for the methane monooxygenase enzyme. The N and P impacts on CH4 uptake indicate that projected increases in N and P depositions might substantially affect CH4 uptake and alter the global CH4 cycle.

Pollinator foraging behavior determines floral visitation rates, an important proxy to the strength of mutual- istic interactions. Although there is evidence that pollinators modify their behavior in the presence of other foragers, there are equivocal findings regarding whether or not pollinators interfere with one another. We employ a functional-response framework to analyse experimental data of times between floral visits made by a focal pollinator and to estimate pollinator interference by conspecifics and three other species. Additionally we develop and compare models that allow different levels of resource availability and the sub-lethal exposure to a neonicotinoid pesticide to modify how pollinators forage alone and with co-foragers. We found that all co-foragers interfere with a focal pollinator under at least one set of abiotic conditions; for most species, interference was strongest at higher levels of resource availability and with pesticide exposure. Overall our results highlight that density-dependent responses are often context dependent themselves.

Over the past fifteen years, the number of papers focused on “eco-evo dynamics” has increased exponentially (Figure 1). This pattern suggests the rapid growth of a new, integrative discipline. We argue that this overstates the case. First, the terms “eco-evo dynamics” and “eco-evo interactions” are used too imprecisely. As a result, many studies that claim to describe eco-evo dynamics are actually describing basic ecological or evolutionary processes. Second, these terms are often used as if the study of how ecological and evolutionary processes are intertwined is novel when, in fact, it is not. The result is confusion over what the term “eco-evolution” and its derivatives describe, a loss of appreciation for the history of genuine eco-evolutionary studies, and a loss of appreciation for the novelty associated with the original rise of the term. We advocate a more precise definition of eco-evolution that is more useful in our effort to understand and characterize the diversity of ecological and evolutionary processes and that focuses attention on the subset of those processes that offer novel results.

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.

Ecological processes often exhibit time lags. For plant invasions, lags of decades to centuries between species’ introduction and establishment in the wild (naturalisation) are common, leading to the idea of an invasion debt: accelerating rates of introduction result in an expanding pool of introduced species that will naturalise in the future. Here, I show how a concept from survival analysis, the hazard function, provides an intuitive way to understand and forecast time lags. For plant naturalisation, theoretical arguments predict that lags between introduction and naturalisation will have a unimodal distribution, and that increasing horticultural activity will cause the mean and variance of lag times to decline over time. These predictions were supported by data on introduction and naturalisation dates for plant species introduced to Britain. While increasing trade and horticultural activity can generate an invasion debt by accelerating introductions, the same processes could lower that debt by reducing lag times.

Marine microbial ecosystems underpin global biogeochemical cycles and play a central role in the regulation of Earth's climate. These communities are extremely diverse, and their taxonomic composition varies considerably across ocean basins. It has however been difficult to establish links between taxonomic diversity and ecosystem function, and the ecological and evolutionary mechanisms underpinning taxonomic variation are not well understood. Here we use an individual-based eco-evolutionary model in which taxonomic diversity emerges as a consequence of evolutionary history. Using this model we are able to show that virtually unlimited genetic divergence can be supported in highly abundant and rapidly evolving assemblages, even in the absence of niche separation. With a steady stream of genetic, epigenetic and plastic heritable changes to phenotype, competitive exclusion may be weakened, allowing sustained coexistence of nearly neutral phenotypes with highly divergent lineages. This response may help to explain observed patterns of taxonomic diversity and functional redundancy - without recourse to hidden dimensions of niche partitioning. In light of these results we suggest that individual-level variability is a key driver of species coexistence and the maintenance of microbial biodiversity.

Ectotherms in cold environments often spend long winters underground. In 1941 Raymond Cowles proposed a novel ecological trade-off involving depth at which ectotherms overwintered. On warm days, only shallow reptiles could detect warming soils and become active; but on cold days, they risked freezing. Cowles discovered that most reptiles at a desert site overwintered at shallow depths. To extend his study we compiled hourly soil temperatures (5 depths, 90 sites, continental USA) and physiological data, and then simulated consequences of overwintering at fixed depths. In warm localities shallow ectotherms have low energy costs and largest reserves in spring; but in cold localities, shallow ectotherms risk freezing. Ectotherms shifting to the coldest depth potentially reduce energy expenses, but paradoxically sometimes have higher expenses than those at fixed depths. Biophysical simulations for one desert site predict that shallow ectotherms should have elevated opportunities for mid-winter activity but may need to move deep to digest captured food. Our simulations generate testable eco-physiological predictions but rely on physiological responses to acute cold rather to natural cooling profiles. Furthermore, testing ecological predictions requires natural-history data that do not exist. Thus, our simulation approach uncovers “unknown unknowns” and suggests research agendas for studying ectotherms overwintering underground.

Invasive ants shape assemblages and interactions of native species, but their effect on fundamental ecological processes is poorly understood. In East Africa, Pheidole megacephala ants have invaded monodominant stands of the ant-tree Acacia drepanolobium, extirpating native ant defenders and rendering trees vulnerable to canopy damage by vertebrate herbivores. We used experiments and observations to quantify direct and interactive effects of invasive ants and large herbivores on A. drepanolobium photosynthesis over a 2-year period. Trees that had been invaded for ≥ 5 years exhibited 69% lower whole-tree photosynthesis during key growing seasons, resulting from interaction between invasive ants and vertebrate herbivores that caused leaf- and canopy-level photosynthesis declines. We also surveyed trees shortly before and after invasion, finding that recent invasion induced only minor changes in leaf physiology. Our results from individual trees likely scale up, highlighting the potential of invasive species to alter ecosystem-level carbon fixation and other biogeochemical cycles.

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 dynamics of cyclic populations distributed in space result from the relative strength of synchronising influences and the limited dispersal of destabilising factors (activators and inhibitors), known to cause multi-annual population cycles. However, while each of these have been well studied in isolation, there is limited empirical evidence about how the processes of synchronisation and activation-inhibition act together, largely owing to the scarcity of datasets with sufficient spatial and temporal scale. We assessed a variety of models that could be underlying the spatio-temporal pattern, designed to capture both theoretical and empirical understandings of travelling waves using large-scale (> 35,000 km2), multi-year (2011-2017) field monitoring data on abundances of common vole (Microtus arvalis), a cyclic agricultural rodent pest. We found most support for a pattern formed from the summation of two radial travelling waves with contrasting speeds that together describe population growth rates across the region.

Plant-microbe interactions in the rhizosphere shape carbon and nitrogen cycling in soil organic matter (SOM). However, there is conflicting evidence on whether these interactions lead to a net loss or increase of SOM. In part, this conflict is driven by uncertainty in how living roots and microbes alter SOM formation or loss in the field. To address these uncertainties, we traced the fate of isotopically labeled litter into SOM using root and fungal ingrowth cores incubated in a Miscanthus x giganteus field . Roots stimulated litter decomposition, but balanced this loss by transferring carbon into more persistent, aggregate associated SOM. Further, roots selectively mobilized nitrogen from litter without additional carbon release. Overall, our fundings suggest that roots can efficiently mine nitrogen and build persistent soil carbon.