Journals
2025 EN
Clermont Jeanne · Duludede Broin Frédéric · Poulin MariePier
+1 more
ABSTRACT The probability of encountering conspecifics shapes animal behaviour, particularly for territorial individuals which often increase vigilance and scent marking when approaching home range boundaries. However, whether the foraging behaviours of territorial predators also vary with the probability of encountering neighbouring territory owners is poorly understood. We monitored 23 Arctic foxes occupying neighbouring home ranges during 2 years of contrasting resource availability on Bylot Island, Nunavut, Canada. First, based on simultaneous GPS tracking of individuals, we established which individuals used a territory by estimating the spatial distribution of the probability of encountering a neighbour within their home range. Second, using GPS and accelerometry data, we evaluated if the probability of encountering a neighbour influenced foraging behaviours, and whether this relationship differed between territorial and non‐territorial individuals. When resources were abundant, only breeding individuals excluded other foxes from a part of their home range and were thus territorial. When resources were rare, none of the foxes reproduced, and all but one were territorial. Non‐territorial individuals were less likely to cache prey in areas with a high probability of encounter, possibly to reduce cache pilfering. Territorial individuals were slightly more likely to cache prey as the probability of encountering neighbours increased, suggesting that they do not actively avoid interactions while foraging. We suggest Arctic foxes use different tactics to secure resources based on their degree of territoriality. The presence of non‐territorial predators, whose home ranges overlap those of territorial neighbours, may influence the distribution of predation risk by creating zones where predator density is high, potentially influencing predator–prey interactions.
Journals
2025 EN
Mouron Samuel · Dominique Yannick · Eme David
+7 more
ABSTRACT At continental to global scales, energy‐related predictors relate positively to regional species richness, often explaining much of its variation in different ecosystems. However, the influence of energy on local species richness (LSR) has received much less attention. In aquatic ecosystems, LSR is predicted to increase with increasing catchment terrestrial productivity. Greater food resources resulting from increased terrestrial subsidies of nutrients and organic matter to the stream can support more individuals, thereby enabling more species to attain viable local populations, a hypothesis known as the more‐individuals hypothesis (MIH). We used generalized linear models and variance partitioning to quantify the unique and shared effects of nine local predictors and nine catchment predictors on LSR of hyporheic communities sampled at 228 sites in tropical New Caledonia streams. We found that productivity proxies, including the proportions of peridotite and bare soil in the catchment, and the normalized difference vegetation index (NDVI), correlated strongly with proxies of sediment metabolism (dissolved oxygen and pH), which in turn accounted for much of the variation in LSR. However, the positive relationship between LSR and catchment productivity, and the resulting dominance of shared effects of local and catchment predictors, were largely driven by fast‐growing taxa. Their richness and abundance increased monotonically with increasing catchment productivity. The LSR of slow‐growing taxa was largely explained by local predictors, and it showed a weak, hump‐shaped relationship to catchment productivity. The additional food resources from more productive catchments could either not be assimilated by slow‐growing taxa or were monopolized by fast‐growing taxa. Hence, other processes than those underlying the MIH, including the competitive ability of taxa to acquire available resources, likely play a role in controlling the species‐energy relationship in hyporheic invertebrate communities.
Journals
2025 EN
Paltrinieri Laura · Razgour Orly · Santini Luca
+52 more
According to Bergmann's and Allen's rules, climate change may drive morphological shifts in species, affecting body size and appendage length. These rules predict that species in colder climates tend to be larger and have shorter appendages to improve thermoregulation. Bats are thought to be sensitive to climate and are therefore expected to respond to climatic changes across space and time. We conducted a phylogenetic meta‐analysis on > 27 000 forearm length (FAL) and body mass (BM) measurements from 20 sedentary European bat species to examine body size patterns. We assessed the relationships between body size and environmental variables (winter and summer temperatures, and summer precipitation) across geographic locations, and also analysed temporal trends in body size. We found sex‐specific morphological shifts in the body size of European bats in response to temperature and precipitation patterns across space, but no clear temporal changes due to high interspecific variability. Across Europe, male FAL decreased with increasing summer and winter temperatures, and BM increased with greater precipitation. In contrast, both FAL and BM of female bats increased with summer precipitation and decreased with winter temperatures. Our data can confirm Bergmann's rule for both males and females, while females' BM variations are also related to summer precipitation, suggesting a potential link to resource availability. Allen's rule is confirmed only in males in relation to summer temperature, while in females FAL and BM decrease proportionally with increasing temperature, maintaining a constant allometric relationship incompatible with Allen's rule. This study provides new insights into sex and species‐dependent morphological changes in bat body size in response to temperature and precipitation patterns. It highlights how body size variation reflects adaptations to temperature and precipitation patterns, thus providing insights into potential species‐level morphological responses to climate change across Europe.
Journals
2025 EN
Bourel Marie · Faustin Eva · Tixier Philippe
+2 more
Abstract Ants are one of the most widespread groups of insects, but the mechanisms allowing them to coexist despite having similar nutritional needs remain unclear. In this study, we investigated the structure and competitive dynamics of ant assemblages in pineapple agrosystems of La Réunion Island. Using an imagery approach that combined in‐field image captures and a computer vision algorithm based on convolutional neural networks, we analyzed ant dominance hierarchies, foraging and recruitment behaviors, niche partitioning between day and night, as well as the impact of environmental variables. This approach provided highly detailed data on the strategies of individual species. Additionally, to better understand the resource exploitation strategies employed by ant species, we then tested the discovery‐dominance trade‐off. Our results revealed that Pheidole megacephala and Solenopsis geminata were the two dominant species, displaying high recruitment investment and frequent bait monopolization, particularly at night. In contrast, Brachymyrmex cordemoyi used a scout‐based foraging strategy that allowed it to rapidly locate baits and maintain moderate dominance levels, during both day and night periods. With lower abilities to discover and control baits, subordinate species had to rely on alternative foraging strategies to persist. We found a significant positive correlation between the discovery and dominance abilities supporting a discovery–defense strategy rather than a discovery‐dominance trade‐off. This finding implies that resource monopolization in simplified ecosystems may benefit species optimizing both rapid resource location and competitive defense. Environmental factors, including plant species richness, plant cover, and mulch cover, influenced species abundance and occurrence, even though dominant species appeared to remain unaffected by habitat variations. The impacts of environmental factors highlight the role of habitat complexity in mediating competitive interactions shaping ant coexistence.
Journals
2025 EN
LabrecqueFoy JuliePascale · Lemay MarcAndré · Gennaretti Fabio
+2 more
Abstract In North America, forest ecosystems have changed drastically since European settlement due to logging, land‐use changes, and altered disturbance regimes. For example, red and white pine stands declined significantly in the last three centuries, and this decline was attributed to their extensive harvesting during settlement. Human‐induced changes in fire regime is another probable cause of pine forests' decline that has gained attention in the last decades. However, the study of red and white pine forests can be challenging, because few pre‐settlement pine forests remain today, as they were extensively harvested during the 19th century. During this extensive exploitation of pine forests, logs were transported via log driving, and many of them sunk to the bottom of lakes. These sinker logs represent an opportunity to study pre‐settlement pine forests and their natural disturbance regimes. The aim of this research was to reconstruct fire regimes from the pre‐settlement period to late 20th century (1700–1970) in eastern Canadian pine forests. To achieve this goal, 1151 submerged logs were extracted from lakes in the Témiscamingue region (Québec), 60 of which exhibited fire scars. We built a reference chronology using 140 living pines to cross‐date 81 scars and were able to reconstruct fire activity since 1717. We then modeled the relative probability of fire occurrence across settlement periods using a Bayesian approach. Our results showed that the probability of fire occurrence almost doubled following the beginning of settlement (1840), highlighting the impact of intensified logging and land conversion on fire frequency. Our study is among the first to use sinker logs and a Bayesian approach to reconstruct and model preindustrial fire regimes in pine forests. This new knowledge is crucial to develop sustainable forest management practices and conservation strategies in red and white pine forests in North America.
Journals
2025 EN
Brimacombe Chris · Bodner Korryn · Gravel Dominique
+3 more
Abstract Large collections of freely available food webs are commonly reused by researchers to infer how biological or environmental factors influence the structure of ecological communities. Although reusing food webs expands sample sizes for community analysis, this practice also has significant drawbacks. As food webs are meticulously crafted by researchers for their own specific research endeavors and resulting publications (i.e., books and scientific articles), the structure of these webs inherently reflects the unique methodologies and protocols of their source publications. Consequently, combining food webs sourced from different publications without accounting for discrepancies that influence network structure may be problematic. Here, we investigate the determinants of structure in freely available food webs sourced from different publications, examining potential disparities that could hinder their effective comparison. Specifically, we quantify structural similarity across 274 commonly reused webs sourced from 105 publications using a subgraph technique. Surprisingly, we found no increased structural similarity between webs from the same ecosystem nor webs built using similar network construction methodologies. Yet, webs sourced from the same publication were very structurally similar with this degree of similarity increasing over time. As webs sourced from the same publication are typically sampled, constructed, and/or exposed to similar biological and environmental factors, publications likely holistically drive their own webs' structure to be similar. Our findings demonstrate the large effect that publications have on the structure of their own webs, which stymies inference when comparing the structure of webs sourced from different publications. We conclude by proposing different approaches that may be useful for reducing these publication‐related structural issues.
Journals
2025 EN
Bolduc David · Fauteux Dominique · Gauthier Gilles
+1 more
Abstract The exact mechanisms behind population cycles remain elusive. An ongoing debate centers on whether predation by small mustelids is necessary and sufficient to generate rodent cycles, as stipulated by the specialist predator hypothesis (SPH). Specifically, the SPH predicts that the predator should respond numerically to the abundance of its prey with a delay of approximately one year, leading to delayed density‐dependence in the dynamics of the prey population. Here, we analyze the numerical response of a small mustelid, the seasonality of its interaction with rodents, and its impact on population cycles using long‐term seasonal data on ermines and cyclic lemmings in the High Arctic. Our results show that the numerical response of ermines to lemming fluctuations was delayed by one year and could mediate delayed density‐dependence in lemming growth rate. The impact of ermines on the growth rate of lemmings was small but mostly circumscribed to winter, a critical period when shifts in cycle phases occur and direct density‐dependence seems relaxed. Our simulations of lemming population with and without ermines suggest that these small mustelids are neither necessary, nor sufficient to generate cycles per se. However, the presence of small mustelids may be necessary to prolong the low‐abundance phase and delay the recovery of lemming populations, promoting the presence of a multiannual low phase typical of lemming cycles. Our study corroborates the idea that population declines of cyclic populations are best explained by direct density‐dependence; however, the delayed response of specialized predators induces the multiannual low phase and leads to longer periodicities, which are typically of 3–5 years in rodents.
Journals
2025 EN
Poirier Mathilde · Gauthier Gilles · Dominé Florent
+1 more
Abstract Changing snow conditions due to climate warming may negatively affect the northern fauna that depend on it for their winter survival. To avoid cold temperatures, Arctic lemmings seek refuge in areas with deep snowpack where they build nests in which they can reproduce if conditions are favorable. The presence of a soft depth hoar layer ensures efficient digging and facilitates lemming movement in the snow, but such favorable conditions are highly dependent on weather conditions at the beginning of winter. Using a 17‐year time series, we assessed the impact of snow conditions and specific weather events on lemming winter reproduction and population growth on Bylot Island in the Canadian High Arctic, a site characterized by a cold and dry Arctic climate. We focused on snow onset date, snow depth, and weather events leading to a hardening of the snow basal layer (i.e., rain‐on‐snow, melt‐freeze, and freezing rain) at the beginning of winter. We also examined possible differences between two lemming species, the brown lemming ( Lemmus trimucronatus ) and the collared lemming ( Dicrostonyx groenlandicus ), the latter presenting unique morphological adaptations to snowy environments. We found that the intensity of winter reproduction of both species was negatively related to the intensity of rain‐on‐snow, melt‐freeze, and freezing rain events. Winter population growth was also negatively related to the intensity of rain‐on‐snow and melt‐freeze events in brown lemmings but not in collared lemmings. Contrary to our expectation, no relationship was found between lemming demography and snow onset date or snow depth. We found a higher reproductive rate in collared than in brown lemmings, suggesting a more effective strategy to save energy for winter reproduction in the former species. Overall, this study shows that even moderate weather events, in comparison with other Nordic sites, can impact lemming population growth in winter, likely by reducing their capacity to reproduce due to a hardening of the snowpack. The expected increase in such weather events with climate change may threaten lemming populations even in the High Arctic, as well as predators that depend upon them.
Journals
2025 EN
Moisan Louis · Bideault Azenor · Gauthier Gilles
+6 more
Abstract Arctic ecosystems present unique opportunities for community‐wide monitoring, in part due to their relatively low species richness. However, conducting research in these remote environments poses significant logistical challenges, resulting in long‐term monitoring being exceedingly rare. Here, we focus on the long‐term, intensive ecological monitoring efforts conducted on the south plain of Bylot Island (~400 km 2 , Nunavut, Canada), which has generated a remarkable dataset spanning up to 30 years, a rarity in tundra ecosystems. Our goals are to (1) provide long‐term time‐series of annual vertebrate density measured at various spatial scales and for the broadest possible range of species and years, to allow the assessment of interannual variability and trends in species density; and (2) upscale annual vertebrate abundance or sometimes long‐term averages to the landscape scale (400 km 2 ) to allow food web modeling. Monitoring data include intensive capture–mark–recapture density estimates of lemmings on trapping grids, systematic or opportunistic nest monitoring conducted across the entire study area or within specific plots for all bird species, transects of vertebrate counts distributed throughout the study area, daily incidental observations of vertebrates, and satellite tracking of foxes. We standardized data obtained with different field methods to provide a readily usable dataset for community ecologists. Long‐term time‐series of vertebrate densities span 3–27 years, with a median of 16.5 years for 22 species. We estimated landscape‐scale abundance for all 35 species of the community based on annual time‐series for 15 of them and average abundance for the remaining 20 species. Furthermore, we provide body mass data for each species, based on empirical onsite measurements for 18 species and from the literature for the remaining species. Body mass is essential to convert species abundance into biomass for studies of trophic fluxes and ecosystem processes. Daily climatic data recorded since 1992 from weather stations within the study area are also available and complement the vertebrate dataset. The ecological data presented offer a rare opportunity for holistic empirical studies of community structure and dynamics. Considering that the study site is a pristine and protected area that has experienced minimal direct anthropogenic impact, it also provides an ideal baseline for investigating the impacts of global changes on high‐latitude terrestrial ecosystems. There are no copyright restrictions on the data or code, and this data paper should be cited when these items are reused.
Journals
2025 EN
BrownVuillemin Sarah · Bernatchez Louis · Normandeau Eric
+6 more
ABSTRACT Beaked redfishes ( Sebastes fasciatus and Sebastes mentella ) of the northwest Atlantic have recently reached record abundance levels in the estuary and northern Gulf of St. Lawrence, dominated by Sebastes mentella . Knowledge of their diet composition is essential to understand the trophic role that these groundfish play in the ecosystem. The objective of the present study was to compare the performance of visual examination and DNA metabarcoding of stomach contents of the same individual redfish caught in the estuary and northern Gulf of St. Lawrence. Using a universal metazoan mitochondrial cytochrome c oxidase subunit I (COI) marker, we identified a total of 24 taxonomic groups, composed of 22 species and two genera in the content of 185 stomachs with DNA metabarcoding. We compared these results to the 25 prey types, eight identified at the genus and nine at the species level, obtained with visual stomach content analysis (SCA). While both techniques revealed a similar diet composition, our results showed that the SCA and DNA metabarcoding perform differently for particular prey categories, both in terms of detectability and taxonomic resolution, as well as in the estimated relative importance of weight and occurrence in the diet. The use of DNA metabarcoding along with SCA validates and improves the taxonomic resolution of visually determined prey, which supports the concept that both techniques provide useful complementary information on the diet of redfish and likely other fish species.