Nutrient composition varies greatly across landscapes, influencing the spatiotemporal variation and dynamics of populations, yet few studies have investigated this pattern across multiple scales. We tested how nutrient limitation affects herbivore populations, from individual behavior to landscape-level population dynamics, using the Australian plague locust, Chortoicetes terminifera (Walker), with field populations and long-term survey data from across their range. At the individual level, juvenile locusts selected for a carbohydrate-biased intake target of 1 protein (p) to 2 carbohydrate (c), and exhibited the highest growth and shortest development time when fed artificial diets with that same 1p:2c ratio during the final juvenile instar. At the field level, locusts kept in cages with protein-biased plants redressed their nutritional imbalance by selecting carbohydrate-biased diets (up to a 1p:20c ratio) for over a week after being removed from the protein-biased environment, returning to the 1p:2c intake target once the deficiency was met. At the landscape level, locust outbreaks were negatively correlated with soil nitrogen and showed a non-linear relationship with soil phosphorus, peaking at approximately 4% soil phosphorus. We disentangled the interaction between mean annual precipitation and soil nitrogen using comprehensive locust surveys and remotely sensed soil and weather data spanning decades. This study is the first to integrate lab, field, and remote sensing approaches, demonstrating the importance of nutrient balancing and acquisition across scales for herbivores. Specifically for locusts, we show that low-nitrogen environments promote outbreaks, likely by reducing plant protein-to-carbohydrate ratios. Incorporating soil quality data into locust plague forecasting models could help improve prediction accuracy.

Climate change and anthropogenic alteration of landscapes negatively impact the abundance and diversity of plant and animal communities worldwide. Much less is known about the effects on phylogenetic diversity and community functioning. Here we use long-term observation data (1980 – 2022) from the Austrian Alps to assess how butterfly communities adjust community structures and functionality to increasing temperatures along the elevation gradient and how these changes are linked to trait expression and community functioning? Diversity significantly decreased at low and intermediate, and increased at high altitudes. Functional attribute diversity was significantly lower than expected by a random model at intermediate and high altitudes and increased with time at high, but not at intermediate and low altitudes. Multifunctionality significantly decreased at intermediate and high altitudes Phylogenetic diversity did not show significant temporal trends at low altitude, but significantly increased with time at intermediate and high altitudes. Multifunctionality was not significantly correlated with FAD, but decreased with increasing phylogenetic diversity. We conclude that the ongoing homogenisation of Alpine butterfly communities strongly affect species, functional and phylogenetic diversity. The directions of these changes heavily depend on altitude and therefore on specific climatic conditions. Higher altitudes face decreasing butterfly multifunctionality despite of increasing species richness due to climate induced altitudinal up-hill shifts of many species. The assessment of species richness and diversity alone, as provided by common species surveys, might give a false impression about the state and functioning of Alpine insect communities in the course of climate change.

not-yet-known not-yet-known not-yet-known unknown Roads in cold climate mountains are known to be important vectors in the introduction and spread of non-native plant species. In the same context, mycorrhizal fungi communities are also altered by roads with a known positive effect on arbuscular mycorrhizal (AM) fungi diversity and abundance in disturbed roadsides. However, to what degree these two effects of roads are intertwined and how they are evolving over time is not well understood. In this study we conducted repeated surveys of non-native plants and AM fungi between 2012 and 2022, in the northern Scandes mountains to investigate temporal changes and interactions between roads, mycorrhizal fungi, and non-native plants. We found that the upward spread of non-native plants and lateral spread away from the roadside into the natural vegetation were so far extremely limited, with only two out of 23 non-native species showing an increase in their upper elevational limit. However, non-native plant species cover did increase over the ten year period, especially at lower elevations, and non-native richness increased from 17 to 23 species. Likewise, we saw an increase in AM fungal abundance over the last four years along the roadsides at lower elevations. Furthermore, our results suggest that increases in non-native species are unlikely to be the driving cause of the observed increase in AM fungal abundance, as AM fungi colonization varied independently of non-native species cover dynamics.

not-yet-known not-yet-known not-yet-known unknown Developmental plasticity is the capacity of a single genotype to express multiple phenotypes in response to different early-life environments. Such responses are defined by reaction norms, which may vary among individuals or populations. Variation in developmental reaction norms allows natural selection to operate on plasticity and is rarely examined in vertebrates. We quantified variation in embryonic developmental plasticity within and between populations using the brown anole lizard. We captured lizards from two islands in the Matanzas River (Florida, USA) and incubated their eggs under one of two multivariate treatments that mimicked the temperature, moisture, and substrates of nest sites in either a shaded or open habitat. We measured hatchling morphology, performance, and physiology to quantify variation in family-level reaction norms. We observed evidence of family-level variation in reaction norms for morphology but not for performance or physiology, indicating an opportunity for natural selection to shape plasticity in hatchling body size. Overall, the results indicate that multiple abiotic conditions in natural nests combine to increase or reduce phenotypic variation, and that family-level variation in reaction norms provides a potential for natural selection to shape plasticity.

The scale of influence of hydrological and thermal conditions on plant disease remains uncertain for most natural plant pathosystems, restricting our ability to predict the potential impacts of climate change. Analysis of the spatiotemporal spread of a fungal rust pathogen across four naturally occurring flax populations over the course of five growing seasons reveals both expected relationships with snow cover, relative humidity and temperature, and a novel footprint of severe drought. This indicates that climate change may have substantial drought-mediated impacts on the spread of plant disease, and points to a need for further research integrating population-level epidemiological studies with mechanistic environmental studies to explore the effects of drought on natural plant epidemics.

1. Leaching – the release of elements from organic matter through dissolution in water – plays an important role in biogeochemical cycling and ecosystem processes. However, understanding the patterns in and underlying drivers of element solubility in leaves lags far behind that of other related plant traits. 2. In this study, we quantify the solubility of carbon (C), nitrogen (N), and phosphorus (P) from leaves of Betula pubescens - a widespread boreal tree species - across a 5182 year postfire retrogressive chronosequence. 3. We find that P is much more soluble than C and N, and is released in solution mainly in readily accessible mineral form. Solubility patterns are strongly related to foliar chemical and structural traits, particularly for green leaves, whereas metrics related to stand structure exert a stronger influence over solubility from senesced leaf litter. 4. Overall, our results indicate that leaching could constitute an important flux of nutrients to the soil, particularly of P, and that the rate and spatio-temporal pattern of this flux appear readily predictable from foliar and ecosystem properties. Further application of the method across more species and environmental contexts should allow for rapid integration of leaching-related foliar traits into broader plant trait frameworks.

Body size determines mobility and fitness of insects in various ways. Yet, especially in parasitoid species, drivers of body size are poorly understood, as they can be influenced by complex interactions between parasitoid behaviour, the environment, and their hosts. We measured the body size of 393 individuals of four parasitoid species sampled with trap nests for cavity-nesting bees and wasps in the Southern Black Forest, Germany. We related the body size of the parasitoids to the size of 15 host species and the diameters of their nests along four environmental gradients (canopy cover, structural complexity, herb cover and deadwood diameter). Host identity, nest diameter, and to a lesser extent, size differences within host species, were primary drivers of parasitoid body size, albeit parasitoid species differed in their responses. For instance, when the host Trypoxylon figulus doubled in size, Nematopodius debilis (parasitizing the host directly) increased by 37% in size, while Trichrysis cyanea (parasitizing food resources) increased by only 8%. Across host-parasitoid species combinations, there was only a weak positive relationship between the size of parasitoids and their hosts. In addition, we did not observe size variations in hosts and parasitoids across environmental gradients. Our findings highlight the primary factors influencing parasitoid size, with host identity and nest diameter emerging as influential factors within and between species, though not uniformly across all species. In contrast, the relationship between parasitoid and host size and environmental gradients were less influential. Considering the environmental variables that directly affect body size, such as microhabitat conditions and biotic interactions, may further clarify the dynamics shaping variation in parasitoid size.

Participatory science (or ”citizen science”) records are becoming increasingly useful for wildlife monitoring due to their volume and spatiotemporal coverage. However, statistical analysis using these data can be challenging due to the many sources of bias that need to be corrected. Many previous studies characterize sampling biases across entire participatory science datasets, such as spatial heterogeneity in sampling effort or species preferences. User-level heterogeneity in sampling behavior is less well studied, but it may be just as important as dataset-level bias in contributing to error in downstream analyses. Here, we investigate user-level novelty and specialization bias. Novelty bias occurs when an individual observer preferentially reports species that have not seen before, while specialization bias occurs when an observer preferentially reports species they have previously observed (i.e., they specialize in particular species). We provide the first test of this kind of user-level sampling bias in participatory science data by analyzing the sampling histories of more than 540 observers on the popular participatory science platform iNaturalist in Pennsylvania, USA. We find evidence of specialization or novelty bias in the overall sampling behavior of 66% of the observers considered. Specialization bias was more than 5 times more common than novelty bias, indicating that observers reported species they had reported previously at a higher rate than expected. Looking within taxonomic groups, 41% of observers deviated from unbiased sampling. Novelty bias and specialization bias were both common within taxa. These findings suggest that iNaturalist observers often specialize in favorite taxa or species, while within taxa some users simultaneously seek out previously unobserved species.

Comparing cases of parasitism and predation that lead to victim death, parasites need more time to complete victim exploitation. This longer “interaction durability” delays energy transfer from host to parasite. During exploitation, parasite virulence differentiates the infected from the susceptible host dynamics. However, how this parasite characteristic influences the dynamics of their host and nonhost (insusceptible) species in the same community is largely unknown. Here, we use mathematical modelling to investigate the influence, exemplifying an experimental plankton community. In this community, nonhost zooplankton feeds on edible nonhost phytoplankton (resource competitor of the host) and parasite propagules released from infected inedible phytoplankton (“mycoloop” pathway). To assess the effects of parasite-host durability, we contrast parasite-host implementations as Lotka-Volterra predator-prey interaction (immediate energy transfer) with susceptible-infected (SI) host-parasite interactions. For the latter, parasite energy intake depends on infected host density but not susceptible hosts directly (delayed transfer). We further consider the difference between susceptible and infected host dynamics modulated by parasite virulence via its effect on host nutrient uptake. To assess the within-community effects, subcommunities are also investigated, excluding/including the parasite without/with the mycoloop. Our results show that, besides host elimination, longer interaction durability of the host-parasite interaction delays parasite attacks on susceptible hosts, allowing them to increase further (a hydra effect), independent of parasite virulence level. This effect observed in the isolated host-parasite systems is preserved in larger communities with negative consequences for the nonhost species, independent of the mycoloop. These theoretical results are supported by empirical observations within and beyond plankton realms. Our study reveals distinctive influences of parasites on community shot-term dynamics, which stem from the longer interaction durability.

Resources play an important role in shaping the evolution of plant defensive strategies. Much research has focused on how resource availability impacts the overall concentration of specific defensive compounds, particularly among-species. Yet, how resource availability influences overall phytochemical diversity within species, and how this in-turn might affect herbivore damage is less well understood. Using Monarda fistulosa, a species that produces diverse terpene compounds and distinct chemotypes (i.e., thymol or carvacrol), we addressed three primary questions: 1) How do phytochemical components (i.e., total concentration, Shannon diversity, and chemotypes) vary between distinct populations from two large, widely separated regions that differ in climate and productivity? 2) How do these components influence attack by different herbivore species? 3) What are the growth costs of higher phytochemical levels in different chemotypes? Seeds were collected from 12 populations, six from a low-productivity/resource environment in Montana, and six from a high-productivity/resource environment in Wisconsin. Seedlings produced from these seeds were transplanted to a common garden in Wisconsin. Over two growing seasons, we analyzed terpene concentrations, quantified the number of herbivores damage, and measured plant above-ground biomass. Plants from Montana exhibited higher terpene concentrations but lower diversity, whereas those from Wisconsin displayed lower terpene concentrations but higher diversity. Total terpene concentration emerged as the primary predictor of herbivore damage, although some differences were observed between region of origin and with terpene richness. Herbivores exhibited mixed responses to phytochemistry; some herbivores were negatively affected, while one species, a specialized leaf galler, responded positively. Costs of producing defenses were evident, manifest by negative correlations between plant biomass and total terpene concentration (but not chemical richness or Shannon diversity). Our study revealed that regional differences in resource availability and productivity can influence the evolution of phytochemical concentration and diversity, which, in turn, affects plant damage and incurs growth-related costs.

The adaptation of marine fish to freshwater environments is a prodigious example of rapid evolution, and yet the underlying ecological causes of genomic and phenotypic differentiation are poorly understood for traits associated with lipid content and composition. Threespine stickleback (Gasterosteus aculeatus) have repeatedly colonized, and adapted to, freshwater habitats across the northern hemisphere. These freshwater populations often show elevated copy number of the fatty acid desaturase 2 gene (FADS2), which increases the biosynthetic capacity of ω-3 long-chain polyunsaturated fatty acids (LC-PUFA). The starkly lower content of LC-PUFA in freshwater compared to marine prey, especially docosahexaenoic acid (DHA), likely imposes strong positive selection on freshwater fish for either increased biosynthesis or greater dietary acquisition of LC-PUFA. The threespine stickleback populations in postglacial coastal lakes of Southern Greenland offer an exceptional opportunity to study how variation in the copy number of FADS2 is related to abiotic and biotic conditions of lakes and their morphometry. As expected, we found strong sexual dimorphism in FADS2 copy number in all populations (19 freshwater, 1 marine, and 1 brackish), and an increased dimorphism in some freshwater populations. We also found that FADS2 copy number was negatively correlated, for both males and females, with the abundance of copepods, which are a DHA-rich food source in the zooplankton community. Overall, our results suggest that the prey community context of lakes might influence the process of metabolic adaptation of marine fish colonizing freshwater ecosystems.

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.

Current workflows in academic ecology rarely allow an engagement of ecologists with philosophers, or with contemporary philosophical work. We argue that this is a missed opportunity for enriching ecological reasoning and practice, because many questions in ecology overlap with philosophical questions and with current topics in contemporary philosophy of science. One obstacle to a closer connection and collaboration between the fields is the limited awareness of scientists, including ecologists, of current philosophical questions, developments and ideas. In this article, we aim to overcome this obstacle and trigger more collaborations between ecologists and philosophers. First, we provide an overview of philosophical research relevant to ecologists. Second, we use examples to demonstrate that many ecological questions have a philosophical dimension and point to related philosophical work. We elaborate on one example -- the debate around the appropriate level of complexity of ecological models -- to show in more detail how philosophy can enrich ecology. Finally, we provide suggestions for how to initiate collaborative projects involving both ecologists and philosophers.

Phenological mismatch has been highlighted as a reason why climate change is causing declines of migratory populations. The likelihood of declines due to phenological mismatch might depend on what cues trigger migration. Migrants that use environmental cues (e.g. temperature, resource availability) to trigger migration are often considered to be less vulnerable than migrants that use temporal information (e.g. photoperiod). We develop a model to investigate how migration cue type determines the effects of phenological change of habitat quality on fitness. We show that which cue type performs better depends on the strength of seasonality in the habitats used by a migrant. We use our results to identify scenarios that align and contrast with the prediction that migrants using temporal cues are more vulnerable. We also recommend that future empirical and theoretical work on phenological mismatch more clearly distinguish between the accuracy and efficacy of cues. Similarly, we recommend considering both how the benefits available from migrating and the benefits that are captured by migrants are changing with phenological change. This work improves our understanding of the role of cue in determining migratory populations’ trajectories as climate changes.

The Acoustic Complexity Index (ACI) is one of the most used metrics in ecoacoustics, demonstrating reliability across a broad range of environments and ecological conditions. However, this index requires specific procedures to be applied in the correct way. Based on the “Canberra metric,” the ACI is an unsupervised metric formulated to extract information from fast Fourier transform (FFT) sonic matrices. The ACI measures contiguous differences in acoustic energy of each frequency bin i along temporal steps (ACItf) and of a temporal interval j along the frequency bins (ACIft). The aggregation of data after an FFT using a clumping procedure allows for better scaling of the sonic signals before the computation of the ACI. The application of a filter to reduce the effects of non-environmental signals produced by microphone electrical noise is mandatory to avoid masking effects. Due to a singularity of the index for values equal to 0, ACIs require ad hoc procedures to exclude from the comparisons pairs of elements of which one is equal to 0. The spectral sonic signature and temporal sonic signature are vectors obtained from the sequence of ACItf and ACIft values, respectively. The comparison between sonic signatures using the chord distance index returns spectral and temporal sonic dissimilarities that allow the evaluation of sonic patterns emerging at different temporal and spatial resolutions. The number of frequency bins, sonic variability, and sonic evenness are further derivative metrics that help to interpret sonic heterogeneity by distinguishing the temporal and spatial heterogeneity of sonoscapes. A change of the name of the “Acoustic Complexity Index” to the “Sonic Heterogeneity Index” is recommended.

Living in a seasonal environment poses challenges for small mammals, such as bats, reliant on insects as their primary food source. Bats may adeptly navigate these energetic challenges by reducing their metabolism and body temperature, entering a state of torpor. Particularly during the winter, bats remain torpid for extended periods, but are dependent on sufficient energy reserves to survive until spring. With the onset of autumn and declining temperature, bats face the challenge of building their fat deposits during a time of decreasing food availability. Bats may therefore transition to cooler roosts to initiate torpor, thereby reducing energy expenditure. However, little is still known about torpor use or roost selection by bats in autumn. This study explores the factors influencing roost selection and torpor use and --duration in two bat species during this critical transition period between the breeding and overwintering season. We show that date in autumn is a stronger driver of torpor use than prevailing ambient temperature, and that bats employ specific strategies in which they first increase daytime torpor use before also increasing the use of nighttime torpor during the pre-hibernation fattening period, most likely to facilitate rapid fat accumulation. Notably, bats commenced nighttime torpor use after spending entire days in torpor. These findings underscore the dynamic nature of torpor and the energy-saving strategies employed during the crucial pre-hibernation period, marking the transition from summer to winter.

There is an urgent need for woodland expansion to help mitigate climate change and biodiversity loss. However, the process of natural regeneration of forest ecosystems is often slow, requiring active reforestation approaches. Factors limiting regeneration are complex, but there is increasing evidence that natural expansion of woodlands onto sites that have been treeless for a long period of time may be limited by the loss of microbial woodland-soil properties. This study explored the potential role of mycorrhizal associations in facilitating obligate ectomycorrhizal (ECM) tree establishment. We determined the spatial distribution patterns of ECM tree seedlings – Pinus sylvestris and Betula spp. - outwith the existing woodlands, in relation to established dual-mycorrhizal Salix. There was very strong evidence that ECM tree seedlings were more likely to be found growing within groups around dual-mycorrhizal Salix than as isolated individuals, supporting the view that Salix drives the current spatial distribution patterns by supporting tree establishment. We suggest that the ability of Salix to form dual-mycorrhizal associations with both arbuscular (AM) and ECM fungi allows these plants to become established across the open AM dominated vegetation. Over time these plants can become colonised by ECM fungi via aerial spores and then act as a source of inoculum for obligate ECM tree seedlings, which land as seeds in the vicinity of Salix. This study highlights the potential role of dual-mycorrhizal Salix as a nurse plant in supporting secondary forest succession of obligate ECM boreal/temperate woodland species onto adjacent open areas through nucleation. Overall, we concluded that there is potential for existing ECM networks to aid tree establishment and propose a nature-based approach to maximize reforestation efforts by targeting existing symbiotic fungal networks as nucleation points for tree planting. Our findings contribute to understanding the ecological dynamics involved in woodland expansion and restoration.

To produce viable seeds, plants must simultaneously allocate mass to other reproductive tissues; however, it remains unclear how big these investments are, relative to seeds, and how much the balance of investment across diverse species reflects broader variation in their life history strategies. In particular, species are known to vary in their seed mass, and the amount they invest in pollen attraction versus seed provisioning. We quantified overall reproductive investment and its partitioning among different reproductive tissues for 14 perennial species in a recurrent-fire heath community. Integrating two lineages of evolutionary theory led to the prediction that relative investment in different reproductive tissues would be correlated with a species’ seed size, and the data supported this. Species with larger seeds were found to mature a smaller proportion of ovules, to expend more of pre-zygotic investment on discarded tissues, and to invest more in seed provisioning compared to pollen attraction. A little more than half of this correlation is phylogenetically conservative, reflecting the tendency for many species in Proteaceae to have large seeds, low seed set and relatively lower investment in pollen attraction. The total cost of accessory tissues – reproduction-related mass not directly invested in the seed – ranged from 95.8% to 99.8% of total investment for species in this study. Counting only seeds thus substantially underestimates total reproductive investment. Many studies have established that the seed size of a species positions it along a colonization-competition life-history spectrum. Here we have shown that relative investment in pollen-attraction versus provisioning tissues and in successful versus discarded ovules are also associated with seed size. The seed size spectrum among angiosperms is therefore connected with a spectrum of reproductive allocation strategies.