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.

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.

Growing evidence indicates that the tendency to synchronize community dynamics may be a general phenomenon in nature related to metaecosystem stability. Synchronized dynamics reduce stability since local variations in biomass or richness are directly propagated to variations in metacommunity dynamics. Asynchronous dynamics have a strong stabilizing effect because of the cancelling out of local variations. Synchronization of biodiversity dynamics may occur due to dispersal among communities and similar responses of different communities to correlated environmental variations---the generalized Moran effect. This congruent response of different communities to environmental dynamics depends on their similar functional composition, which is determined by the similarity in local conditions and the spatial distance between them. In a metacommunity of 51 temporary ponds that were surveyed for 14 years, we evaluated the existence of synchronized dynamics in plant richness and biomass among communities, and their association with temporal stability. A path analysis based on Mantel tests was used to evaluate the hypothesized determinants of synchrony and stability. Community-community matrices for Mantel tests were constructed with synchrony in biomass and richness, and with the Euclidean distance in geographic location, environmental conditions, and functional composition. Elements of the stability matrices were the inverse of variation in richness and biomass for each pair of ponds. A wide range of dynamics from asynchronous to synchronous rhythms was observed, and stability decreased with the coupling of community dynamics. Geographic, environmental, and functional distances between pairs of communities decoupled their dynamics in richness but weakly affected biomass synchrony. The role of rare species in richness dynamics and of dominant species in biomass dynamics may explain the observed discrepancies. While evidence for biodiversity synchrony is accumulating, evaluating the role of the proposed determinants becomes essential. Our results support the main hypotheses but also identify discrepancies that may devote further attention.

Understanding the factors influencing how fast populations can spread across the landscape will be crucial as species ranges shift due to climate change. While the role of abiotic factors in determining expansion speed has been well studied in theory and empirical research, how interspecific interactions such as competition impact speed has received far less attention. Here, we investigated how seed dispersal distances change in response to competition and how these changes to seed distributions impact expansion speed. We dispersed four genotypes of the annual plant Arabidopsis thaliana with variation in life history traits into greenhouse mesocosms of either empty habitat or habitat containing the annual grass competitor, Lolium multiflorum. We found that competition decreased both mean and maximum dispersal distance. We then built a simulation model of range expansion with experimental data from this and a prior experiment to understand whether competition slows species expansions primarily through decreasing dispersal or fecundity. We found that competition primarily slows expansion speed through decreases in dispersal, but that when competition impacts both dispersal and fecundity, expansions slow more than with dispersal alone. The genotype with traits associated with longer distance dispersal was the most affected by competition in both experimental dispersal and simulations. This research suggests that not only does competition slow range expansions through decreases in both fecundity and dispersal, but that there may be consequences for evolutionary processes at the leading edge.

The importance of fine-root diameter for ecosystem functioning is increasingly recognized; yet, much remains to be learned about the variation in fine-root diameter at large scale. We conducted an analysis of fine-root diameter for 1,163 plant species to detect root diameter patterns in relation to resource availability (e.g. carbon, nitrogen and water), stress intensity (e.g. plant/soil biodiversity, soil bulk density) and temperature. First- to fourth-order root diameter showed non-linear relationships with latitude and/or mean annual temperature (except for first-order root diameter). The diameter of five root orders decreased with increasing mean annual precipitation, but increased with net primary production (NPP), which was the strongest determinant of fine-root diameter. Increasing soil biodiversity was associated with decreasing root diameter of fourth- to fifth-order roots while increased plant biodiversity was associated with decreasing diameter of first- to third-order roots. Total soil nitrogen had a positive effect on first-order root diameter, but a negative effect on fourth- and fifth-order root diameter. The patterns reversed for total soil phosphorus. First- to third-order and fifth-order root diameters increased with increasing soil bulk density. Second- to fourth-order root diameter increased with soil pH. Overall, the variables related to climate, biology and soil explained 44% to 63% of the total variance in the diameter of the different root orders. The unique patterns of plasticity observed in fine-root diameter across root orders in response to varying environmental conditions contributes to a diversification of strategies for nutrient/water acquisition and transport under climate change.

Herbivores in the tundra interact with vegetation through several mechanisms, especially defoliation, trampling and nutrient addition through urine and faeces. Through these mechanisms, herbivores drive shifts in plant species composition, richness and diversity. As reindeer effects on vegetation accumulate over time, they might cascade to other trophic levels, but how and when this happens is poorly understood. Since it is methodologically demanding to measure biodiversity across spatial gradients, an alternative approach is to assess it indirectly via biodiversity indices of vascular plants. Values from the Index of Biodiversity Relevance were coupled with vegetation data from a network of 96 fenced and paired grazed plots across Fennoscandia. We analysed the role herbivory has on plant richness and diversity, and on the number of organisms that depend on the vegetation according to the index values. We also explored how herbivores affect the competitive effects of shrubs on other plants since the dominance of a vegetation type links directly to biodiversity. Vegetation richness and diversity did not present any differences between treatments, yet reindeer had an increasing effect on plant diversity when testing the interaction between grazing and herbaceous vegetation. Three out of six biodiversity indexes were higher in fenced plots indicating a higher number of interactions between plants and organisms from other trophic levels. Finally, herb abundance was negatively related to shrubs in both treatments but with a faster decline in the absence of herbivores, suggesting that herbivory increases plant diversity and decreases the diversity of other taxa by reducing shrub abundance. This study highlights the importance of maintaining herbivore populations in the Arctic to prevent the expansion of climate-driven biodiversity into the tundra. The effect of herbivores on ecological communities is not merely a product of plant diversity but can be quantitatively and qualitatively different.

Interactions between species, such as seed-dispersal interactions, can shape many aspects of those species' life, as well as ecological patterns and evolutionary dynamics. Yet, sampling interactions in the field is challenging. Even with extensive sampling efforts we can hardly obtain a comprehensive picture of which species interact with each other. Such missing interactions can produce important gaps that affect how we perceive and interpret the network formed by species interactions and the roles of individual species within those networks. In this study we propose two methods that combine data on species interactions with information on species traits and phylogenies to estimate potentially missing interactions. We use one of the largest datasets on plant-frugivore interactions, depicting thousands of interactions between birds and plants in the Atlantic Forest hotspot, to test those methods and analyze how adding newly estimated interactions change the structure and the topological importance of the species within the seed dispersal network. We show that estimated missing interactions more than tripled the number of interactions in the network and impact the general topological properties of the network increasing nestedness and reducing modularity. Both models generated networks with a similar structure and were effective in estimating new interactions, accurately predicting known interactions without overestimating interactions in place of true absences. More importantly, added interactions changed our perception on the topological role of species, with several under-sampled species earning several interactions and becoming more central to network structure. This shows that estimating interactions can be helpful to get a more complete idea of how a network may look like and may help inform which interactions should be focused on in further sampling efforts.