Insect biodiversity is under threat from multiple stressors, including climate change and extreme weather. For butterflies, nectar resource use is an understudied trait in relation to population trajectories and responses to global change. Here, we characterize nectar breadth for 50 species of montane butterflies occurring in the Sierra Nevada mountains of California and Nevada. These species displayed a wide spectrum of nectar use, including relative specialists and extreme generalists. Further, we examined how nectar breadth and other species traits, including latent variables indicating ecological flexibility and dispersal potential, were indicative of long-term population trajectories and responses to an extreme drought event from 2011 to 2015. Species that were more nectar-generalized were more likely to be declining, but nectar breadth did not predict how a species responded to extreme drought. Greater ecological flexibility, as reflected in other traits, was positively associated with population performance, while dispersal potential was negatively associated with population trajectories. Drought response was strongly associated with flight period, where species that fly later in the season are more susceptible to the negative effects of drought. Our study highlights the importance of considering butterfly nectar breadth in predicting population resilience and challenges assumptions about dietary generalism as a buffer against environmental change.

The dynamic balance between primary production and herbivory is key to the resilience of plant-dominated ecosystems across the world. However, many vegetated ecosystems are becoming increasingly susceptible to herbivore-triggered collapses, as this balance is disrupted due to predator declines, increasing nutrients, and other interacting impacts of global change. Yet without accessible, cost-effective tools to evaluate the production-consumption relationship, it is difficult to know how close an ecosystem is to imminent overgrazing collapse. Here, we explore the effectiveness of individually formed sea urchin grazing halos as robust indicators of marine habitat vulnerability to overgrazing. Halos are grazed patches of bare rock on macrophyte-dominated substrates that represent the balance between macrophyte production and per capita herbivore consumption. We measured 1211 halos in 31 locations across the Mediterranean Sea to characterize how plant-herbivore interactions are mediated by endogenous (i.e., species identity, habitat type, and sea urchin size) and exogenous factors (i.e., environmental factors influencing biotic and abiotic contexts: depth, nutrients, temperature, or protection level). Our results show that halo size was effective in detecting differences in the effect of endogenous and exogenous factors on these interactions. Across locations, halo size was sensitive to differences in (i) species identity, with some species being more impactful than others; (ii) the type of habitat, with some habitats being more vulnerable than others; (iii) protection level, with halo size consistently lower inside marine protected areas; (iv) urchin size, with halo size increasing consistently with herbivore size; (v) nutrient conditions, with halo size increasing as nutrient availability decreased; as well as (vi) depth, with halo size increasing consistently with depth. These results indicate that overgrazing vulnerability is highly contingent on local ecological contexts, which strongly mediate plant-herbivore interactions. While drivers of ecosystem collapse may be global, the ability of ecosystems to cope is often inherently local. We need locally responsive measures and contextually meaningful solutions to manage ecological integrity in the face of global change. In this context, individually measured grazing halos can be a powerful tool in assessing and managing the resilience of macrophyte ecosystems.

GloNAF is a continuously updated, curated compilation of alien naturalized vascular plant inventories for geographic regions worldwide. Building on its predecessor, GloNAF 2.0 now contains 16,429 taxa and introduces major updates, including the standardization of taxonomic names using the World Checklist of Vascular Plants (WCVP), removal of outdated records, and the net addition of 117,229 new records. These new entries have substantially increased the size of GloNAF, resulting in a 26% increase in the number of naturalized taxa in the database and a 31% increase in the number of geographic regions compared to GloNAF 1.2. We provide an overview of GloNAF 2.0, highlighting its expanded geographic and taxonomic coverage. In addition, we have aligned GloNAF with FAIR data principles through improvements in data accessibility, metadata standards, and support for data reuse. GloNAF 2.0 represents a significant and comprehensive resource for researchers aiming to advance our understanding of the drivers and consequences of biological invasions and naturalization success. The dataset is published under a CC-BY 4.0 license; thus, when using these data, please give credit to this paper.

COVER PHOTO: Arctic lemmings, such as Dicrostonyx groenlandicus, shelter beneath the snowpack during winter to protect themselves from cold temperatures and predation. While they prefer to dig through soft snow layers, weather events such as melt–freeze and rain‐on‐snow can harden the snow and hamper their movement. Poirier et al. (Ecology, Volume 106, Issue 10, Article e70216; doi:10.1002/ecy.70216) evaluated how moderate weather events such as those found in the Canadian High Arctic affect lemming demography. They show that the intensity of winter reproduction declines with increasing frequency of melt–freeze and rain‐on‐snow events. This study highlights the potential detrimental impact of climate change on a key species in Arctic ecosystems. Photo credit: Mathilde Poirier. image

Many insects damage leaves, a phenomenon that is foundational to their impacts on terrestrial ecosystems. Leaf traits, including chemistry, shape these interactions. In turn, leaf-surface (phylloplane) microbes can act directly or in concert with leaf chemistry to influence leaf choice, especially by insects whose reproductive success is tied to prolonged contact with leaf surfaces. Leafcutter bees (Megachile spp.) cut disks from leaves to line their nests, with leaves and their associated microbes forming the environment in which bees' offspring develop. We hypothesized that phylloplane microbial communities act in concert with leaf chemistry to mediate interactions between the leafcutter bee M. lippiae and the plants they cut. We surveyed phylloplane communities on rose (Rosa × hybrida, Rosaceae) leaflets that were cut versus not cut by wild M. lippiae. Microbial communities differed between cut and non-cut leaflets, with Aspergillus spp. overrepresented on cut leaflets, and Alternaria sp. and Bacillus sp. overrepresented on non-cut leaflets. Then, we inoculated rose leaves in the field to test the effect of these microbial taxa on cutting. When inoculated onto rose leaves, Alternaria and Bacillus had no effect on cutting, but Aspergillus resulted in twice as many cuts as on sham-inoculated leaves. To test whether Aspergillus could protect bee nests against pathogens, we grew Aspergillus with two pathogenic fungi: the generalist insect pathogen Beauveria bassiania and three strains of Ascosphaera that cause chalkbrood disease in bee larvae. Aspergillus did not inhibit the growth of Beauveria, but it markedly slowed the growth of Ascosphaera. To clarify whether these phylloplane microbes reflect differences in leaf chemistry or are instead independent cues that influence leaf cutting, we used liquid chromatography-mass spectroscopy to characterize the metabolome of cut and non-cut leaflets. Chemistry did not differ between cut and non-cut leaflets, nor did it vary as a function of microbial community composition. Our results suggest that Aspergillus, a common member of rose phylloplane communities, mediates interactions between leafcutter bees and roses, potentially affecting the fitness of both partners. This study reveals a previously unexplored role for phylloplane microbes in plant-insect associations.

Disturbance is fundamental to ecosystem dynamics, and its management is foundational to effective ecosystem management for the conservation of biodiversity. Fire is a key agent of disturbance influencing faunal communities in many terrestrial ecosystems, and it underpins the conservation management of fire-prone ecosystems. However, we have a limited understanding of how faunal communities in fire-prone ecosystems respond to variation in fire frequency. Here, we use a long-term fire experiment to investigate the effect of fire frequency on lizard assemblages in an Australian tropical savanna. We sampled lizards using pitfall traps, funnel traps, and direct searches in replicate (n = 3) 1-ha plots that had been burnt every 1, 3, or 5 years or left unburnt for 18 years. We found no significant variation in total lizard abundance or the collective abundances of mesic, semiarid, or widespread biogeographic groups. The abundance of only one of the five most common species was significantly related to fire frequency. Species richness decreased with increased fire frequency and showed a humped relationship with woody cover. Species composition was slightly better explained by variation in woody cover than by fire frequency, with both effects relatively weak. Although woody cover declined with increasing fire frequency, it varied markedly both within and among plots experiencing the same fire treatment, which explains why fire frequency was not as strong a predictor of variation in lizard assemblages as woody cover. Our findings show that the diverse lizard assemblage in our tropical savanna system exhibits a very limited response to variation in long-term fire frequency and attribute this to the marked small-scale variation in woody cover that was inherent under any fire treatment. We conclude that small-scale patchiness in vegetation cover plays a critical role in the responses to fire of faunal species with relatively small foraging territories, reducing a need for larger scale fire mosaics under a "pyrodiversity begets biodiversity" paradigm.

Biological communities are facing profound upheaval induced by global environmental change. While changes in community composition over time are now well documented, much less is known about whether concomitant shifts in trophic structure also manifest. Here, we leveraged a 10‐year dataset of freshwater fish communities and stable isotope compositions in nine lakes to test whether compositional changes (i.e., changes in community structure) and local environmental factors drove trophic trajectories over time. We found marked changes in the trophic structure of fish communities across all lakes, with a general tendency toward narrower trophic niches dominated by trophically redundant species. The variations in trophic trajectories among lakes were primarily linked to differences in the temporal pace and directionality of change. Specifically, lakes exhibiting greater compositional changes displayed more irregularity in their trajectory, and communities dominated by non‐native species displayed elevated trophic stability over time. Our findings reveal species turnover as the dominant factor shaping trophic dynamics, through the addition or removal of predatory species and trophic turnover. The trophic stability observed in communities that were already invaded at the start of the study could be driven by their reduced susceptibility to compositional change caused by subsequent invasions. These findings highlight the existence of strong changes in trophic niches and unveil the intricate interplay between compositional changes and biological invasions in governing the trophic trajectories of communities and food web architecture, with subsequent implications for ecosystem functioning.

Climate change is altering habitat suitability and driving shifts in species distributions. To understand potential responses by mobile animals, it is essential to assess levels of plasticity in habitat use, ranging from transience to long-term fidelity. Here, we evaluate the fidelity of hawksbill sea turtles (Eretmochelys imbricata) to habitats used while foraging (our primary focus), migrating, and nesting. After satellite tracking 17 adult females from three Western Atlantic nesting areas, we then re-tracked them in a subsequent year. Of 15 turtles with sufficient data to assess interannual foraging area fidelity, 14 returned to the same home range, exhibiting overlap between successive 50% utilization distributions (UDs); the 15th individual shifted <10 km. Mean precision of fidelity, here expressed as the distance between centroids of successive foraging UDs, was 1.45 ± SD 2.3 km-less than the error associated with many satellite fixes. We also observed fidelity to inter-nesting home ranges and migratory pathways, though distinct deviations in migratory routes occurred. A paradigm of precise habitat fidelity is likely appropriate for adult hawksbills, yet merits further investigation across life history stages and global populations. Our results suggest that adult transience may have limited potential to contribute to projected distributional shifts.