Mixed-species animal groups are dynamic systems whose structure and functioning is contingent on biotic (e.g., food acquisition) and abiotic (e.g., climatic conditions) processes. Understanding the interactions among such factors, and the temporal scales at which they operate, can help to understand the mechanisms driving community structure and anticipate the consequences of human-driven alterations in ecosystem functioning. We used network analyses and Bayesian causal inference to study how direct and indirect effects of biotic and abiotic factors affected the structure of mixed-species groups of army ant-following birds (a bird aggregation specialized on feeding at army ant swarms). Our study revealed that the structure of interactions among birds visiting ant swarms was modulated by short-term rainfall, swarm traits, and the food resources they provide. Specifically, we found that ant-follower groups had 29% to 54.7% more species when swarms were larger, provided higher food resources, and the environment experienced high precipitation during the previous 15 days. Similarly, the ant-follower groups were 34% more cohesive (i.e., a tendency toward the formation of densely connected subgroups), attendant birds interacted with 55% more partners, and interactions in the groups were more evenly distributed among partners in swarms with high food resources. Our data suggest that rainfall effects have the potential to propagate through swarm size and food availability to affect the structure of ant-followers, but direct effects still occupy the primary role. Notably, the effects of biotic and abiotic predictors were contingent on the season and location along a rainfall gradient. Our study highlights three key points: (1) the factors modulating the structure of mixed-species animal groups are interlinked, with both abiotic and biotic factors influencing structure; (2) the effect of short-term rainfall is only detected at particular lagged time windows; and (3) the processes explaining the structure of mixed-species groups are strongly influenced by seasonality and location along a rainfall gradient. Our study emphasizes the importance of evaluating interdependent relationships between biotic and abiotic processes, their direct and indirect effects on interacting species, appropriate temporal scales, and the consequences of climatic cycles in understanding the mechanisms influencing the structure of mixed-species groups.

Winters are warming faster than other seasons, and ice cover duration on temperate lakes is shortening. How ectotherms respond to these changes during poorly studied winter periods remains unclear. Here, we use acoustic telemetry to determine whether the same individuals of a model warm-adapted fish, smallmouth bass (Micropterus dolomieu), change their depth and space use to maintain consistent experienced temperatures and low activity across three winters with different conditions. Despite considerable variability among individuals, the population demonstrated plasticity in depth use that regulated experienced temperatures across warmer (year 1) to colder (year 2) to shorter (year 3) winters. Activity was low during all winters but increased 2 weeks earlier when temperatures warmed earlier in year 3, consistent with previous reports of earlier overwinter emergence in terrestrial ectotherms under a warming global climate. Whether consumption rates increased with increasing temperatures determined the bioenergetic outcomes of earlier spring warming. This study demonstrates that ectotherms that spend winter in a state of reduced activity can behaviorally respond, at individual and population levels, to changing winter conditions. Variation in winter habitat use and activity could have consequences for reproduction and growth in open water seasons and remains an important area for future research.

Biological resistance plays a key role in minimizing plant invasions, even when abiotic conditions are favorable for invasion. Through competition with native plants and herbivory by native herbivores, invasive plants can impact ecosystem functions profoundly. While the effect of invasive plants on native plants& performance via competition has been well documented across ecosystems, less is known about the role of facilitation versus inhibition by herbivores in plant invasions, especially in stressful environments. Our main aims were to investigate the role of herbivores (crabs) in plant invasions in coastal wetlands and understand the underlying mechanisms of competition and herbivory on invader performance (i.e., growth and reproduction). We investigated the crabs' effects on the growth (plant mean height, relative growth rate (RGR), and aboveground biomass) and reproduction (sprout density) of the invasive species Spartina alterniflora and the native grass Phragmites australis in East China. Thereto, we conducted a 2-year crab exclusion experiment across three different habitats (low S. alterniflora zone, middle S. alterniflora and P. australis zone, and high P. australis zone) in a salt marsh wetland and a feeding preference trial of crabs in terms of plant traits in the lab. Our results showed that crabs had a strong negative effect on the plant mean height, aboveground biomass, RGR, and sprout regeneration of P. australis in both the high P. australis zone and the middle zone where the two plant species co-occurred. In contrast, the absence of crabs significantly decreased the density of new sprouts of S. alterniflora in both the low S. alterniflora zone and the middle zone. Our lab feeding experiments showed that crabs had a feeding preference for P. australis, as related to its lower total organic carbon content and smaller C/N ratio, and higher N content and N/P ratio compared to S. alterniflora. These findings are consistent with the enemy release hypothesis as opposed to the biological resistance hypothesis. That is to say, S. alterniflora appeared to benefit from not having co-evolved with native herbivorous crabs, hence the preferential feeding by native crabs on P. australis facilitated the success of S. alterniflora introduced to a novel wetland area. Thus, our study provides a new perspective for understanding how native herbivores contribute to the competitive advantage of an invasive plant species to outcompete the native reed through enemy release.

How a community responds to warming depends on both intraspecific variation in thermal limits and variation in acclimation capacity across community members. These factors are often overlooked, however, leading to uncertainties about how climate change affects biodiversity. In temperate regions, communities are exposed to large seasonal temperature fluctuations, providing an opportunity to examine community-wide effects of acclimation under natural conditions. Generating a weekly physiological time series over a one-year period, we examined seasonal variation in upper thermal limits for the entire community of calanoid copepods in Lake Champlain, a large and highly seasonal lake in North America. Thermal limits varied substantially between species, with winter-dominant species having lower thermal limits than summer-dominant species. Our high-resolution temporal data also revealed substantial but variable acclimation capacities across community members. Hindcasted vulnerability estimates highlight the importance of species-specific estimates of acclimation capacity for robust predictions about the impacts of warming. Over the course of our collections, we also recorded two novel species occurrences in Lake Champlain, both of which were notable for their high upper thermal limits. Our results highlight the importance of acclimation in shaping population responses to temperature variation under natural conditions.

Research on ecosystem multifunctionality (EMF) has mainly quantified the magnitude of multiple functions within local communities (alpha multifunctionality [alpha-EMF]), whereas less is known about variation in function profiles among communities (beta multifunctionality [beta-EMF]). We asked how plant diversity affects variation in ecosystem function profiles among communities and whether this relationship depends on community history. We analyzed 5-year means of six ecosystem functions from 240 subplots in the DELTa-BEF, short for DEterminants of Long-Term Biodiversity Effects on Ecosystem Functioning Experiment, comparing new communities without experimental plant or soil history, resown communities retaining soil history, and old communities with continuous plant and soil histories. We adapted a variance-based beta diversity framework to quantify beta-EMF and partition it into local contributions to beta multifunctionality (LCBM) and function contributions to beta multifunctionality (FCBM). Plant diversity increased alpha-EMF in all treatments, with stronger increases in resown and old than in new communities. Richness was not detectably related to LCBM in new communities but was associated with lower LCBM in resown communities and higher LCBM in old communities, with the clearest contrast between the resown and old treatments. Leaf area index contributed more to beta-EMF than expected under equal contributions (20.2%), whereas basal respiration contributed less (13.2%); the other four functions did not differ from the equal-contribution expectation. Thus, similar gains in local multifunctionality can be accompanied by contrasting patterns of spatial functional heterogeneity, depending on community history. Partitioning beta-EMF into local and function contributions provides a practical way to identify which communities and functions contribute to spatial heterogeneity.

Many organisms face alternative selective pressures across cyclically changing environments such as the diel cycle. Energetic and spatial constraints, among other issues, preclude independent day and nighttime or wakeful and sleeping responses to these contrasting sets of selective forces. We tested for behavioral similarity in microhabitat use during daytime wakeful and nighttime sleeping periods in Anolis lizards. We collected 1256 datapoints of sleeping perch height and substrate for 51 species and compared these data to published data on active perch use for these species. We demonstrate that species perch at similar heights but use significantly different perch substrates during sleep and wakefulness. The diel similarity in perch height may indicate a surfeit of adequate sleeping perches within a species' home range. The difference in perch substrate, wherein individuals tend to sleep on compliant perches, likely reflects the special predation risks encountered at night during sleep.

Maternal age and diet can influence offspring development and fitness via maternal effects, but empirical evidence for their interactive effects remains limited. We examined how maternal age at oviposition and maternal dietary conditions influence offspring developmental responses to resource availability in the thelytokous predatory mite Amblyseius herbicolus. Mothers received either a restricted or abundant prey diet, and their offspring were exposed to varying prey availability and monitored for hatching success, survival to adulthood, developmental duration, size at maturity, and prey consumption. We asked how maternal age influences offspring development and whether maternal diet modifies these age-related effects. Offspring of older mothers had higher survival to adulthood, developed for longer, attained a larger size at maturity, and consumed fewer prey during development. Maternal age also interacted with offspring prey availability to influence survival, while maternal diet modified age-related effects on developmental duration, offspring size, and prey consumption. These findings demonstrate that maternal age and nutritional condition jointly shape offspring development and responses to resource availability, highlighting the importance of considering maternal age and environment when examining maternal effects and developmental plasticity.

The drivers of plant dispersal and distribution are poorly understood. For nut-bearing trees, interactions between seeds and caching granivores can have a strong influence on population dynamics as unrecovered caches often recruit new trees. Granivore-seed interactions may be constrained by predators as fear alters caching and foraging behavior. We investigated how predation risk affects caching and foraging behavior in fox squirrels (Sciurus niger) and subsequent recruitment patterns of American turkey oak (Quercus laevis) acorns. We marked and tracked acorns to locate fox squirrel cache and consumption points where we assessed fox squirrel perceived predation risk, measured how caching influenced acorn survival and dispersal, and surveyed juvenile oak distributions. Fox squirrels perceived greater risk at caches than consumption points, suggesting predation risk influences caching decisions and cache distribution. Buried acorns survived at higher rates and only buried acorns germinated, though survival did not vary with dispersal distance. Juvenile oaks and cache locations showed similar hump-shaped patterns of establishment away from nearest potential source trees. We conclude that predation risk indirectly shapes plant establishment by altering granivore behavior.

Understanding how species occupy islands and habitat patches remains a central question in biogeography, landscape ecology, conservation, and management, especially as natural and anthropogenic processes reconfigure habitat size and connectivity over time. The insular distribution function (IDF) provides a framework for predicting occupancy patterns for a species based on island area and isolation as proxies for extinction risk and colonization likelihood. While this model provides a conceptual bridge between island biogeography and metapopulation models, it has seen limited recent application in large part due to reliance on simplistic geometric measures of area and isolation. Here, we advance the implementation of the IDF by pulling from ecological niche modeling and landscape ecology to incorporate ecologically informed quantifications of area and isolation. We apply this framework to the montane sky-islands of the Great Basin of the western United States, testing predictions for the Western Water Shrew (Sorex navigator). Compared with those based on traditional geometric metrics, the ecologically informed IDFs produced a discriminant function with lower classification error, stronger class separation, and different biological conclusions regarding the species' inferred response to isolation and area. The results from the ecologically informed IDF provide a contrast to IDF based on geographic axes and the classical interpretations for the system. Specifically, the steeper slope and lower intercept of the ecologically informed IDF point toward a system structured not so strongly by extinction-driven relaxation, but by a more compensatory trade-off in which both colonization and extinction have shaped occupancy patterns. Simulations of false-absence rates (which affect datasets in lesser-sampled systems) showed that the same inferences persisted in the presence of incomplete sampling. These results highlight the potential of integrating contemporary approaches with classic biogeographic models, as well as strengthening and clarifying links between island biogeography and landscape ecology. This updated analytical framework offers new opportunities for assessing subpopulation vulnerability, incorporating ecologically informed measures into occupancy-based statistical frameworks, forecasting patchy species distributions across a full community, and studying how past and future environmental changes shape biodiversity patterns.

Net ecosystem productivity (NEP) of global grasslands-one of the largest and most variable components of the terrestrial carbon budget-provides critical insight into the magnitude and dynamics of the global carbon balance. Extensive field measurements have been derived from static-chamber techniques; however, these data have remained fragmented at individual sites or regions and have seldom been synthesized into a consistent global product. Here, chamber-based NEP measurements from 221 publications (1992-2023) in global grasslands were obtained, critically filtered, and condensed in a comprehensive global database. This database comprised 1521 individual NEP records from 275 sites across 30 countries. The dataset further included information on site location, ecosystem type, dominant species, climatic variables, soil properties, measurement timing (year, month, and day), and sampling protocol. The study sites encompassed global grasslands with latitudinal range of 62.22° S to 78.88° N, longitudinal range of 156.62° W to 161.51° E, and altitudes from -1 to 4852 m above sea level, covering broad climatic gradients (mean annual temperature: -17°C to 32.1°C; mean annual precipitation: 17-2226 mm; potential evapotranspiration: 152-1819 mm year[-1]). Our database enables (1) elucidation of the biogeographic pattern of grassland NEP, (2) assessment of grassland carbon-sequestration potential under future global-change scenarios, and (3) validation of both machine-learning and process-based model estimates of grassland NEP at the global scale. The database is available under a CC BY 4.0 license. The authors kindly request users to cite this data paper while using the database in acknowledgment of all the hard work that went into compiling the data.

Extending ecological inference from local experiments to broader spatial extents remains a challenge. Here, we leveraged the natural, self-contained aquatic ecosystem of the pitcher plant (Sarracenia purpurea) to test whether locally observed effects of nutrient enrichment are consistent with patterns across a regional gradient of nutrient deposition. We conducted a field experiment at a single bog using realistic nitrogen (N) and phosphorus (P) additions and evaluated 10 ecosystem responses, representing both nutrient pools (stocks) and fluxes. We then compared these to a survey spanning 28 sites from Florida to Maine. The spatial grain of the individual pitcher leaf was held constant while the spatial extent varied by more than 2000 km. Enrichment increased fluid P by an amount equivalent to 92% and 20% of the observed range in the experiment and the survey, respectively, and increased tissue P by amounts equivalent to 276% and 21% of the observed range in the experiment and the survey, respectively. Enrichment also increased tissue N by 23% of its observed range in the survey. Enrichment also elevated Chlorophyta biovolume, whereas microbial responses were primarily mediated by indirect effects via detrital nutrient pools and grazing pressure. More than 80% of the coefficients representing nutrient fluxes in the local experiment matched those from the regional survey, with only slightly stronger nutrient effects in nutrient addition. These results indicate that well-designed site-based nutrient addition manipulations can robustly predict ecosystem responses to nutrient deposition across broad spatial gradients.