Ecological Monographs最新文献

Stream and riparian habitats are meta-ecosystems that can be strongly connected via the emergence of aquatic insects, which form an important prey subsidy for terrestrial consumers. Anthropogenic perturbations that impact these habitats may indirectly propagate across traditional ecosystem boundaries, thus weakening aquatic-terrestrial food web linkages. We investigated how algal production, aquatic invertebrates, and terrestrial spiders influence cross-ecosystem connectivity in temperate streams across four European catchments with varying levels of human disturbance. We used fatty acid biomarkers to measure putative aquatic linkages to riparian spiders. Variation-partitioning analysis indicated that aquatic insect dispersal traits explained a relatively large proportion of variability in the fatty acid profile of spiders. Trophic connectivity, as measured by the proportion of the polyunsaturated fatty acid eicosapentaenoic acid (EPA) and the ratio of EPA to its chemical precursor, alpha-linolenic acid (ALA), was positively associated with abundances of “aerial active” dispersing aquatic insects. However, this positive influence was also associated with changes in environmental context and arachnid beta diversity. Structural equation modeling disentangled how aquatic insect communities influence trophic connectivity with riparian predators after accounting for biological and environmental contingencies. Our results show how subsidies of stream insects are a putative source of essential fatty acids for adjacent terrestrial food webs. Catchment-wide impacts indirectly propagated to the local scale through impacts on aquatic invertebrate communities, thus affecting stream-riparian food webs. Increased riparian tree cover enhanced stream insect subsidies via dispersal traits despite reducing aquatic primary production through shading. Consequently, ecosystem properties such as woody riparian buffers that increase aquatic-terrestrial trophic connectivity have the potential to affect a wide range of consumers in modified landscapes.

Emerging fungal infectious diseases constitute the largest pathogen threat to plants. However, the factors influencing fungal-plant interactions, host shifts, and the emergence of pathogens on a novel host are still not well understood. Evolutionary relationships among hosts appear to be important, with closely related hosts often sharing pathogens and pests, but we typically lack information on the evolutionary history of the pathogens. Here, we gather over 27,000 sequences to construct a comprehensive phylogenetic tree for Botryosphaeriaceae, a fungal family including many emerging pathogens of global concern, and explore the evolutionary conservatism in fungal-plant associations across host and pathogen phylogenies. We reveal a significant influence of both phylogenies in constraining fungal-plant associations. However, we also show that most fungal pathogens are generalists, able to infect multiple hosts, and demonstrate an evolutionary trend toward increased generalism, contrary to theory that suggests that pathogens should evolve toward increased host specialization. We suggest that the anthropogenic movement of plant species and agricultural practices might have allowed some Botryosphaeriaceae to escape phylogenetic constraints on host range via increasing the ecological opportunities for host shifts. Understanding the factors influencing fungal-plant interaction and host breadth of pathogenic fungi could help identify emerging threats, prevent spillover onto naïve plants, and reduce the risk of further host range expansion.

Nearby populations often experience shared environmental fluctuations and have stronger population synchrony than distant populations. However, different species often show different levels of synchrony across the same areas and environments, possibly because some traits influence their susceptibility to environmental stochasticity. In this paper, we compiled a pan-European collection of long-term annual abundance data on birds and butterflies from eight countries to identify how species' life history traits can influence the effects of environmental synchrony. We show that in birds and butterflies, the impact of environmental synchrony on population synchrony depended on key life history traits. For birds, which had stronger evidence for synchronizing effects of temperature compared to precipitation, the environmental effects on population synchrony depended on generation time, dietary diversity, and migratory tactic. The positive effects of environmental synchrony were stronger in bird species with short generation times (i.e., faster lived), higher dietary diversity, resident species, and short-distance migrants. In butterflies, which had stronger evidence for synchronizing effects of precipitation compared to temperature, we found that environmental effects on population synchrony depended on voltinism, with stronger effects in multivoltine (i.e., faster lived) species. Thus, life history can interact with environmental synchrony in shaping patterns of spatial population synchrony, with implications for predicting impacts of environmental change on species abundances over larger spatial scales. Further understanding of drivers of spatial population synchrony based on long-term abundance data is important in the face of increasingly severe threats to biodiversity and could be key for successful future conservation outcomes.

The effects of warming and nutrient enrichment—two drivers of global change—on ecosystems have been studied in isolation for decades. We thus have a limited understanding of how they interact to influence ecosystem metabolism (gross primary production, ecosystem respiration, and net ecosystem production), which supports food webs and influences carbon (C), nitrogen (N), and phosphorus (P) cycling. To better understand stream ecosystem responses to these drivers, we asked three questions: (Q1) Do temperature and nutrients have univariate, additive, or interactive effects on ecosystem metabolism? (Q2) What is the relative effect of dissolved N versus N:P ratios on N-acquisition pathways and how are these dynamics mediated by temperature? (Q3) How do effects of temperature and nutrients on assemblage composition, biomass accumulation, and N sources combine to shape ecosystem metabolism? To answer these questions, we evaluated biofilm response to manipulations of temperature, N and P supply, and N:P ratio in three stream-side channel experiments. (Q1) In our N-limited study system, temperature and N supply had interactive effects on biofilm biomass, composition, N acquisition, and areal rates of ecosystem metabolism; all generally peaked under warm, moderate-N conditions. Biomass accumulation was more important than cellular efficiency in shaping ecosystem responses. (Q2) N uptake and N₂ fixation increased with temperature and were influenced by N supply, not P or N:P ratio. N₂ fixation was inhibited above 3.9 μM N. (Q3) Temperature and N interacted to shape biofilm metabolism by mediating biofilm biomass accumulation, autotroph taxonomic and functional composition, and N-acquisition pathways and rates. Dinitrogen fixers played a role in mediating these interactions; however, it was smaller than expected, potentially due to the relatively small contribution of N₂ fixation to total N acquisition (<30%). Taken together, our results illustrate the complex pathways through which temperature × nutrient interactions influence stream biofilms and ecosystem metabolism. We show that understanding the effects of warming and nutrient enrichment on coupled C and nutrient cycles in stream ecosystems requires consideration of N acquisition, biofilm assemblage composition, and the context-dependent influence of biomass dynamics on ecosystem fluxes.

Insect herbivores are integral to the functioning of forest ecosystems. However, increasing herbivore outbreaks highlight the need to understand the factors driving the spatial and temporal stability of herbivore communities. While the longer term consequences of climatic fluctuations are well established in this context, the role of local-scale interactions between herbivores, their host communities, and local microclimates in influencing herbivore stability remains unclear. In this study, we investigated the relative importance of host tree species richness, functional diversity, trait composition, tree growth dynamics, and climate in driving herbivore spatiotemporal stability and the resulting patterns in abundance and diversity. We focused on Lepidoptera caterpillars as very diverse and functionally highly relevant herbivores in forest ecosystems. Tree species richness promoted mean caterpillar abundance, species richness, and phylogenetic diversity by positively affecting their temporal and spatial stability. These effects were mostly direct but counteracted by largely independent and overall negative effects of tree functional diversity, tree growth stability, and microclimate temperature stability. The strength and direction of these effects varied across seasons, reflecting shifts in environmental conditions and herbivore species turnover. The effects of tree diversity on caterpillar communities were related to compositional changes through distinct pathways by reducing taxonomic beta diversity and thus enhancing species richness stability and by increasing phylogenetic beta diversity which may promote asynchrony among distantly related species. Crucially, our findings suggest that tree diversity buffers herbivore communities against climate fluctuations by enhancing their spatiotemporal stability. In consequence, ongoing biodiversity loss may lead to greater fluctuations in herbivore populations and an increased risk of outbreaks. Our study provides novel insights into the mechanisms underlying bottom-up regulation of herbivores, emphasizing the critical role of tree diversity in maintaining stable herbivore communities in a changing climate.

Grassy biomes (savanna and grasslands) are globally extensive and host a unique biodiversity that is of central importance to human livelihoods. We focus here on the island of Madagascar—a microcosm of the global tropics, covered in 80% grassy biomes—to illustrate how transdisciplinary approaches to research can clarify ecosystem dynamics, from evolutionary history to human land use. Research on Madagascar's human-environment interactions has sparked debates about the role of past and current land use in shaping grassy biomes (e.g., pastoralism, cultivation, fire use). These debates echo those in other regions globally, and highlight obstacles to understanding and supporting both ecosystem and livelihood resilience. Like many tropical biodiversity hotspots, Madagascar faces converging challenges that can be aided by transdisciplinary research, including food and health insecurity, economic inequities, biodiversity loss, climate change, land conversion, and limited resource access. We present a framework to guide transdisciplinary research centered on improved understanding and management of grassy biomes on Madagascar by: (1) establishing a globally common terminology; (2) summarizing data contributions and scientific knowledge gaps relating to Madagascar's grassy biomes; (3) identifying priority research questions for Madagascar with applicability in other regions; and (4) highlighting transdisciplinary, inclusive approaches to research that can co-benefit people and the ecosystems with which they interact.

Variability in traits within species (intraspecific trait variability; ITV) has attracted increased interest in functional ecology, as it can profoundly influence the detection of functional trait patterns, calculations of functional diversity (FD), and assessments of ecosystem functioning. This interest stems from the recognition that species are not homogeneous entities but rather mosaics of individuals with varying trait values. Since multiple methods have emerged to explicitly incorporate ITV into FD calculations, accurate estimates and meaningful interpretations of FD would benefit from a more explicit methodological framework to account for ITV. Some methods treat individuals as the unit of analysis, while others characterize trait distributions around species means. Ecologists navigating this landscape of methods may face challenges in selecting the most appropriate approach to address their research questions, which also depend on data availability. Here, we synthesize the current literature to provide guidelines regarding how and when to use the various available methods to quantify ITV in biological systems and integrate it within FD. We also provide a toolbox to calculate the presented metrics in the form of implemented R code. As a case study, we computed correlations between FD metrics on simulated assemblages with varying degrees of trait variability. Our findings suggest that the choice of FD metric should be guided primarily by the ecological question being addressed and, to a lesser extent, by the number and types of traits, although the type of data available might also impose some limitations. Simulations revealed strong correlations among FD metrics that account for ITV, particularly those indicating the size of the occupied functional trait space. Furthermore, ITV seems to be more important for increasing the functional volume than between-species variability, while regularity metrics (how even species abundances are distributed in the functional trait space) were nearly insensitive to changes in between- or within-species variability. As evidence accumulates and shows how ITV is key to shaping species' fitness and distributions as well as affecting ecosystem functioning, this synthesis will serve as a conceptual and practical tool ideally inspiring and guiding researchers to integrate ITV in FD analyses.

Many organisms with broad distributions show latitudinal variations in morphological phenotypes and life history traits, such as body size and phenology, in relation to environmental changes such as temperature along latitude. Such variations have usually been considered the result of natural selection, but sexual selection may also lead to these latitudinal patterns. Although a recent study has shown the latitudinal pattern in the strength of male–male competition in medaka fish, such a latitudinal pattern related to sexual selection is rarely known in other organisms. Here, we show the latitudinal pattern of a reproductive trait driven by sexual selection in the Japanese black salamander (Hynobius nigrescens), where snout-vent length (SVL) in males predicts the outcome of male–male competition over egg sacs. First, we conducted phylogenetic analyses to examine the phylogenetic pattern along latitude. From the constructed phylogenetic tree, this species was split into five lineages that were roughly divided along latitude. We also used field surveys to examine whether the operational sex ratio (OSR: an index of the strength of male–male competition) varies across lineages with latitude. We found that the OSR was more biased toward males in a lineage distributed at lower latitudes due to its longer breeding period. We measured the SVLs of collected samples to determine if the latitudinal pattern also exists for SVL. Indeed, male SVLs were longer in lineages distributed at lower latitudes, whereas those in females did not differ among lineages. Our common garden experiment also showed that the individuals from a lineage distributed at lower latitudes had longer SVLs even when they grew under the same environmental conditions, suggesting that the latitudinal pattern in SVL is genetically determined. These results suggest that males at lower latitudes have evolved longer SVLs, driven by stronger male–male competition. Our study provides the first example, to the best of our knowledge, of a latitudinal pattern driven by sexual selection and its evolutionary determinant in detail in the wild.

Teittinen, Anette, Miska Luoto, Petteri Muukkonen, Maria-Katariina Myyry, Maria Reiman, Michael Scherer-Lorenzen, and Janne Soininen. 2025. “Cross-Boundary Connections of Biodiversity and Ecosystem Functioning in Boreal Ecosystems.” Ecological Monographs 95(1): e70013. 10.1002/ecm.70013.

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Maes, Tim, Julie Verheyen, Bruno Senghor, Aspire Mudavanhu, Ruben Schols, Bart Hellemans, Enora Geslain, Filip A. M. Volckaert, Hugo F. Gante, and Tine Huyse. 2025. “First Evidence of a Genetic Basis for Thermal Adaptation in a Schistosome Host Snail.” Ecological Monographs 95(1): e70006. 10.1002/ecm.70006.

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Open Access funding was provided by Universitat Innsbruck/KEMÖ.

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