The rise of antibiotic‐resistant bacteria poses a critical global health threat. Previous studies on the evolution of bacterial antibiotic resistance have often overlooked the fact that bacteria frequently exist within complex microbial communities, where they engage in mutually beneficial interactions through nutrient exchange. Here, we studied the evolution of antibiotic resistance in an obligate cross‐feeding population. After 15 days of selection under kanamycin, both co‐cultures and mono‐cultures of auxotrophic strains evolved significantly higher resistance. The increase in resistance was significantly lower in the co‐culture consortium than in each mono‐culture consortium. Strains in the co‐cultures showed higher levels of amino acid secretion and a reduced growth rate than those in the mono‐cultures. This suggests a higher cost of amino acid exchange in the co‐cultures. Exogenous amino acids supplementation reduced the cost of metabolic exchange and intensified competition between the two strains due to niche overlap. This further resulted in decreased kanamycin resistance in both the mono‐evolved and the co‐evolved populations under the kanamycin‐free environment. The interaction among the two auxotrophic strains shifted from positive to negative in co‐evolved population. This supports the stress gradient hypothesis, which posits that facilitation is more common in stressful environments, whereas competition dominates when conditions are more benign. Our findings demonstrate that environmental stress and nutrient availability can modulate bacterial antibiotic resistance by altering microbial interactions and fitness dynamics within communities.

Euphonias (Neotropical passerines in the genera Euphonia and Chlorophonia ) form the quintessential example of a specialized avian frugivore, combining a high reliance on fruit as food and the restriction of fruit taxa exploited. To understand their specialization, we explored the integration of fruit morphological and nutritional traits with their internal processing by euphonias. We made a literature survey of the fruits eaten by euphonias, and compared their digestive morphology (intestine length and internal surface area) and the traits of the fruits they eat (fruit and seed diameters, number of seeds, water, lipids, protein and sugar contents) with other frugivorous bird species. Although eating a variety of fruit species, euphonias concentrate feeding on a few plant families and genera ( Miconia , Ficus , Cecropia , Phoradendron , Rhipsalis ), favoring watery, lipid‐poor, often sugar‐rich fruits with small seeds. They also have longer intestines than the other frugivorous birds, which may contribute to the efficient absorption of nutrients despite their necessity to rapidly pass fruits through the gut. We argue that the specialization of euphonias that make them to rely heavily on particular plant taxa is largely mediated by their fruit processing constraints that limit the functional traits of the fruits exploited. Our results show that birds with most of their diets composed of fruits should not necessarily consume fruits of a wider variety of plant species. It also reinforces the importance of considering the matching between fruit morphology and the internal processing of fruits to understand fruit use by birds.

Investigating the ecological drivers of species richness in the Amazon Basin enhances our understanding of the eco‐evolutionary processes shaping biodiversity across taxonomic groups. Our study investigates the roles of energy availability, water balance, and habitat heterogeneity in shaping the distribution of amphibians and reptiles by testing five ecological hypotheses: energy–environment, energy–water dynamics, productivity, metabolic theory and habitat heterogeneity. We found distinct patterns across taxa. The energy–environment hypothesis received the strongest support overall, with temperature exerting a positive effect on species richness in all groups, while potential evapotranspiration negatively impacted on Gymnophiona and snakes. The energy–water dynamics hypothesis showed moderate, taxon‐specific support, performing best for Anura, snakes, Crocodylia and Testudines. Precipitation had a positive effect across groups, whereas actual evapotranspiration had mixed impacts, with positive impacts on Anura, lizards and snakes but negatively impacting on Crocodylia and Testudines. The productivity hypothesis received weak overall support; net primary productivity positively influenced Anura and snakes but negatively affected lizards. The metabolic theory was moderately supported, with the inverse of absolute temperature (1/kT) consistently showing a negative effect across groups. The habitat heterogeneity hypothesis was generally poorly supported, except for Gymnophiona; landscape heterogeneity negatively influenced Anura, Caudata and snakes, but positive influences on the remaining taxa. Our findings highlight that, although the energy–environment hypothesis has emerged as the most robust across taxa, species richness patterns in amphibians and reptiles are best understood when considering the joint influence of energy, environment, and water availability (i.e. energy + environment + water). This integrated understanding underscores the need for conservation strategies that account for the unique ecological requirements of different taxonomic groups. Our findings highlight that sustaining biodiversity in the Amazon Basin depends primarily on the balance of energy and water dynamics, while the role of landscape heterogeneity appears to be taxon‐specific and context‐dependent.

Quantifying population dynamics is a fundamental challenge in ecology and evolutionary biology, particularly for species that are cryptic, microscopic, or extinct. Traditional approaches rely on continuous representations of population size, but in many cases, the precise number of individuals is unknowable. Here, a coarse‐grained population model is presented that simplifies population dynamics to binary states – high or low – determined by the balance of bottom–up resource availability and top–down predation pressure. This Boolean framework provides a minimal yet analytically tractable addition to traditional Lotka–Volterra‐based models, enabling direct insights into the role of food web structure in shaping community stability. This approach is used to investigate how trophic interactions influence population persistence, cyclic dynamics, and extinction risk across model food webs. Model predictions reveal that top–down effects are a primary driver of cycling, aligning with theoretical expectations from traditional population models, and that trophic position strongly influences extinction risk, with higher‐trophic species more prone to persistent low‐population states. Additionally, the role of trophic short‐circuits – direct interactions between high‐trophic predators and low‐trophic prey – are explored and found to buffer cascades and alter extinction patterns in ways that are often overlooked in classical models. By simplifying population dynamics to a two‐state system, this framework provides a useful tool for disentangling the structural drivers of community stability. These results highlight the potential of coarse‐grained approaches to complement existing models, offering new insights into trophic interactions, extinction risks, and the susceptibility of species to trophic cascades.

The moss–cyanobacteria association contributes nitrogen fixation that provides novel nitrogen inputs to nutrient‐limited ecosystems, playing a non‐negligible role in nitrogen cycling and ecological restoration within nitrogen‐limited ecosystems. However, research remains scarce on the colonization characteristics (including cyanobacterial colonization rate and biomass) of cyanobacteria associated with epilithic mosses and their regulatory mechanisms in severely nitrogen‐deficient degraded karst ecosystems. This study focuses on epilithic mosses, integrating their multidimensional functional traits (morphological, physiological, hydric and chemical characteristics) with environmental factors (karst rocky desertification degree, elevation, light intensity and UV‐A radiation) to elucidate cyanobacterial colonization characteristics and identify the key drivers. Our results reveal high species diversity in the moss–cyanobacteria associations, with 37 moss species and 78 cyanobacterial species identified. Moss species identity, nitrogen (N) content, and pH emerged as critical determinants of cyanobacterial colonization. Notably, the degree of karst ecosystem degradation showed no significant negative impact on cyanobacterial colonization, whereas increasing elevation markedly reduced colonization rates. The widely distributed epilithic moss–cyanobacteria associations may exert positive influences on nitrogen cycling and rocky desertification restoration processes in degraded karst ecosystems. Moreover, elevation and moss chemical characteristics demonstrated stronger predictive capacity for cyanobacterial colonization than other environmental factors and moss traits. These findings elucidate key drivers of cyanobacterial colonization, providing insights for enhancing nitrogen cycling and guiding restoration strategies in degraded karst ecosystems.

Due to the constraints of limited effort and sampling error, observed species interaction networks are an imperfect representation of the ‘true' underlying community. Link prediction methods allow us to construct a potentially more complete representation of a given empirical network by guiding targeted sampling of predicted links, as well as offer insight into potential interactions that may occur as species' ranges shift. Various data types can predict interactions; understanding how different kinds of information compare in their ability to predict links between different types of nodes is important. To this end, we compare random‐forest regression models informed by combinations of phylogenetic structure, species traits, and latent network structure‐hidden features inferred from the observed network topology – in their ability to predict interactions in a diverse network of fruiting plants and frugivorous birds in Brazil's Atlantic forest. We found that for our dataset, latent structure derived through a single‐value decomposition approach was the most important determinant of model predictive performance. While incorporating trait or phylogenetic information alongside latent features had little effect on discriminatory power, they did meaningfully increase overall model accuracy. Our results highlight the potential importance of latent structural features for predicting mutualistic interactions, and encourage a clear conceptual link between prediction performance metrics and the overall goal of predicting cryptic links.

The recovery of large carnivores offers unique opportunities to study their cascading impacts on plant population dynamics. Medium‐sized carnivores, both prey and seed dispersers, are suppressed by apex predators, indirectly increasing seed‐eating rodent's populations and potentially altering plant establishment. We investigated how natural variation in the presence of the Iberian lynx Lynx pardinus , a top predator in southern Spain, triggered cascading effects on the recruitment of the Iberian pear Pyrus bourgaeana through altered seed dispersal patterns by mesopredators and post‐dispersal seed predation by rodents. To assess whether and how the seed‐dispersal effectiveness of the Iberian pear was influenced by lynx presence across different habitats (open, forest) and microsites (shrub, rock and open), we conducted field experiments and observations spanning multiple life‐cycle stages of this fleshy‐fruited tree mainly dispersed by carnivorous mammals. Path analysis revealed that lynx presence decreased seed dispersal by 80% and biased it toward forests, where seedling survival was extremely low (1%). Most of the seeds were delivered in open microsites (61%), particularly in lynx absence by the red fox. Although we detected no direct effect of lynx presence on post‐dispersal seed predation, rodents removed 49 and 116% more seeds under shrubs than in rock and open interspaces, respectively, negatively affecting plant recruitment. Since shrubs provided the most favourable conditions for seedling survival, particularly in open habitats, these results expose a seed‐seedling conflict, whereby microsites with the highest seed predation are also those that maximize seedling establishment. This may limit the expansion potential of the Iberian pear and likely other fleshy‐fruited species given the current global rewilding context. Reintroduction programs of threatened carnivores should account for trophic cascades that may disrupt frugivory interactions and ultimately shape plant recruitment and establishment. This is especially relevant in defaunated ecosystems, where plant–animal mutualisms are often compromised.

Numerous flower visitors exhibit varying preferences for floral characteristics. As one group of flower visitors, the preferences of spiders for flower colour have garnered attention; however, their preferences for the morphological characteristics of flowers remain largely unexplored. This study investigated the preferences of flower‐visiting crab spiders Ebrechtella tricuspidata for flower size, petal density and symmetry, and explored the underlying reasons from the courtship and predation. The results showed that male spiders preferred larger flowers, while females favored densely petaled flowers and symmetrical flowers under the experimental conditions. Additionally, males showed a tendency to choose females that sitting on larger flowers than on smaller ones. Furthermore, consistent with spider choices, the potential prey houseflies and honeybees, also tended to visit larger, densely petaled, and symmetrical flowers in visitation experiments. We propose that prey preferences for floral characteristics may be a primary factor influencing spider preferences. We hypothesize that the flower characteristics influence insect visitation preferences, which may extend to third trophic level predators, thereby determining the preferences of flower‐visiting spiders. Overall, our research provides new insights and evidence regarding spider selection behavior toward floral characteristics, emphasizing that these preferences may facilitate both predation and mating in spiders.

Scavenging is a foraging strategy widely used across the animal kingdom and apex predators provide a large amount of energy in a food web by provisioning carrion. In the harsh environmental conditions of the Arctic, apex predators such as polar bears Ursus maritimus can provide scavenging opportunities for many species. Carrion can act as a buffer when food resources are low, and some terrestrial species use the marine environment for cross‐ecosystem resource subsidies. We present an overview of scavenging as a foraging strategy in the Arctic marine environment and examine the contribution of prey provided by polar bears to the Arctic scavenging assemblage. As obligate predators of seals, polar bears contribute a substantial amount of carrion to the marine ecosystem, particularly to the sea ice surface where it is accessible for seasonal scavenging opportunities. We estimated that an average polar bear kills approximately 1001 kg of marine mammal biomass annually and given preferential feeding of blubber and abandonment of carcasses, we estimate that 30% of the biomass is left as available carrion. Consequently, polar bears provision approximately 7.6 × 10 6 kg year –1 of carrion biomass for scavengers across their range, equivalent to 3.93 × 10 7 MJ of energy. Eleven vertebrate species are known to scavenge polar bear kills, and an additional eight are possible scavengers. While foraging associations with polar bear kills for some species are better understood, others are scarce or undocumented. We provide an overview of what is known about the role of polar bears as carrion providers, the network of scavenging species on the sea ice, and the possible consequences of trophic downgrading in this ecosystem and recipient ecosystems.