Phenology is a major component of animals' breeding, as they need to adjust their breeding timing to match optimal environmental conditions. While the effects of shifting phenology are well-studied on populations, few studies emphasise its ecological causes and consequences at the inter-individual level. Using a 20-year monitoring of more than 2500 breeding events from ~ 500 breeding little penguins (Eudyptula minor), a very asynchronously breeding seabird, we investigated the consequences of late breeding on present and next breeding events. We found that individuals breeding later had reduced breeding success, lighter chicks at fledging, lower probability of laying a second clutch, and decreased parents' post-breeding body condition. Importantly, we found important cycling effects where delayed breeding during a given year led to significantly later laying date, lower breeding probability and lower breeding success when they breed during the next season, suggesting potential carry-over effects from one season to the next. To further understand the causes of such variability in phenology while earlier breeding is associated with better individual fitness, we aimed to assess intrinsic differences amongst individuals. We showed that the heterogeneity in breeding timing was partly fixed, the laying date being a significantly repeatable behaviour (17%), asking for more studies on heritability or early-development effects. This extensive study highlights the combined roles of carry-over effects and intrinsic differences on individual phenology, with important implications on breeding capacity through life.

Background matching and disruptive coloration are defense mechanisms of animals against visual predators. Disruptive coloration tends to evolve in microhabitats that are visually heterogeneous, while background matching is favored in microhabitats that are chromatically homogeneous. Controlling for the phylogeny, we explored the evolution of the coloration and the marking patterns in the sexual dichromatic and widely distributed neotropical grasshoppers of the genus Sphenarium. These grasshoppers represent an excellent model to investigate the evolution of cryptic coloration on insects due to the heterogeneity of the environments where they have evolved. We found a correlation between the grasshoppers' coloration and disruptive markings with the chromatic properties of their environments that was inferred by the levels of precipitation during the rainy season. The results suggest that colors and marking patterns could evolve due to predation pressures. Color in both sexes could offer camouflage that is not perfectly background matched to a single habitat but instead offers a degree of resemblance to multiple backgrounds. Moreover, we found that males and females chromatic properties differ between them and precipitation levels where the species are found. This suggests that the sexes have diverged in their response to the environments, favoring the evolution of sexual dichromatism in these grasshoppers.

Alien species can influence populations of native species through individual-level effects such as predation, competition, and poisoning. For alien species that possess strong defensive chemicals, poisoning is one of the most powerful mechanisms of individual-level effects on native biota. Although toxic alien species could potentially negatively affect survival (lethal effects) or life history traits (sub-lethal effects) of native predators via poisoning, previous studies have mainly focused on acute lethal effects. Thus, delayed effects on predator life history traits have been largely overlooked. To fill this knowledge gap, we conducted laboratory and field experiments to investigate whether toxic alien prey (hatchlings and tadpoles of an invasive toad, Bufo formosus) affect the survival and/or growth and development of a native predatory salamander (larvae of Hynobius retardatus) on Hokkaido, Japan. The laboratory experiment revealed that consumption of a single toad hatchling exerted non-lethal effects on salamanders, but suppressed both salamander growth and development of an ecological phenotype (broad-gape) normally induced by environmental conditions. Furthermore, the field experiment in a natural pond showed that the presence of toad hatchlings and tadpoles resulted in reduced salamander growth (smaller body size) and lower survival of salamanders in the later larval period. The results of the laboratory and field experiments are complementary evidence of the life history impacts of the toxic alien toad on native salamanders. Thus, the poisoning effects of toxic alien species can affect the life history of native predators even if they do not exert acute lethality.

Land-based inputs, such as runoff, rivers, and submarine groundwater, can alter biologic processes on coral reefs. While the abiotic factors associated with land-based inputs have strong effects on corals, corals are also affected by biotic interactions, including other neighboring corals. The biologic responses of corals to changing environmental conditions and their neighbors are likely interactive; however, few studies address both biotic and abiotic interactions in concert. In a manipulative field experiment, we tested how the natural environmental gradient created by submarine groundwater discharge (SGD) affected holobiont and symbiont metabolic rates and endosymbiont physiology of Porites rus. We further tested how the effect of SGD on the coral was mediated by intra and interspecific interactions. SGD is a natural land-sea connection that delivers nutrients, inorganic carbon, and other solutes to coastal ecosystems worldwide. Our results show that a natural gradient of nutrient enrichment and pH variability as a result of acute SGD exposure generally benefited P. rus, increasing gross photosynthesis, respiration, endosymbiont densities, and chlorophyll a content. Conspecifics in direct contact with the a neighboring coral, however, altered the relationship between coral physiology and SGD, lowering the photosynthetic and respiration rates from expected values when the coral had no neighbor. We show that the response of corals to environmental change is dependent on the types of nearby neighbor corals and how neighbors alter the chemical or physical environment around the coral. Our study underscores the importance of considering biotic interactions when predicting the physiologic responses of corals to the environment.

The effects of climate warming on the distribution of range-expanding species are well documented, but the interactive effects of climate warming and range-expanding species on recipient communities remain understudied. With climate warming, range-expanding species may threaten local biodiversity due to their relatively stronger competitive or predatory effects on potentially weakened, or less well-adapted recipient communities. Acanthinucella spirata is a predatory marine gastropod that has expanded its distribution north along the California coast since the Pleistocene via a poleward range shift, tracking climatic warming. To assess whether A. spirata has stronger predatory effects on the recipient community in their expanded range and is better suited to a warming climate than a local predatory snail, we used a combination of field and laboratory studies to examine the feeding activity of A. spirata and the predatory whelk (Nucella lamellosa) on shared prey under ambient and elevated conditions. From field surveys, we concluded that A. spirata is a potential competitive threat to N. lamellosa, due to its high local abundance, overlapping habitat, and shared prey on Cape Mendocino. In the laboratory, we observed that A. spirata was a more efficient consumer of prey than N. lamellosa overall and ate significantly more prey than N. lamellosa under warmer conditions. As climate change continues, environmental conditions will become more stressful for all species; however, range-expanding A. spirata populations may be at a competitive advantage relative to N. lamellosa, as they are more abundant and have higher feeding rates at warmer temperatures than the local whelk.

Foliar traits can reflect fitness responses to environmental changes, such as changes in nutrient availability. Species may respond differently to these changes due to differences in traits and their plasticity. Traits and community composition together can influence forest nutrient cycling. We compared five traits-foliar N, foliar P, specific leaf area (SLA), leaf dry matter content (LDMC), and leaf carbon isotope ratio (δC)-in six northern hardwood tree species (Acer rubrum, Acer saccharum, Betula alleghaniensis, Betula papyrifera, Fagus grandifolia, and Prunus pensylvanica) in a nitrogen (N) and phosphorus (P) fertilization study across 10 mid- and late-successional forest stands in New Hampshire, USA. We also analyzed the response of tree growth to N and P addition. Nutrient addition shifted trait values towards the "acquisitive" side of the spectrum for all traits except δC, reflecting a tradeoff between water-use efficiency and nutrient-use efficiency. Treatment responses in relative basal area increment revealed that the Betula species were N-limited, but traits of all species responded to either or both N and P addition in ways that suggest N and P co-limitation. Two species displayed lower foliar P under N addition, and three species displayed lower foliar N under P addition, which also suggests co-limitation. These indications of co-limitation were reflected at the community level. Specific leaf area, LDMC, and δC differed with stand age within several species. Examining trait responses of tree species and communities to nutrient availability increases our understanding of biological mechanisms underlying the complex effects of nutrient availability on forests.

Seminatural habitats in agroecosystems support diverse communities of natural enemies and are expected to promote biological control in crop fields. However, complex landscapes may also support agricultural pests, with undesirable outcomes for crop production. Here, we monitored populations of leafhopper pests and their egg parasitoids in two habitats: vineyards and seminatural habitats. Our results showed that the composition of the agricultural matrix strongly influences the spatio-temporal dynamics of leafhoppers and their egg parasitoids. Specifically, seminatural habitat cover in the landscape was positively correlated to leafhopper abundance in vineyards and to parasitoid abundance in both habitats. Vineyard cover in the landscape instead influenced leafhopper abundance in seminatural habitats. Our analyses indicate that seminatural habitats might be a greater source of leafhoppers than of their egg parasitoids in Mediterranean agroecosystems, with negative implication for their sustainable control in organic vineyards. Although seminatural habitats play a fundamental role in supporting farmland diversity and ecosystem service provision, they might not contribute to mitigate leafhopper impact in Mediterranean vineyards.

Vertical seed dispersal towards higher or lower altitudes is an important process for plants' adaptation to climate change. Although many plants depend on animals for seed dispersal, studies on vertical seed dispersal by animals, determined by complex animal behaviours, are scarce. Previous studies hypothesised that animals inhabiting temperate regions disperse seeds uphill in spring/summer and downhill in autumn/winter due to their seasonal movement following the altitudinal gradients in food phenology. However, this hypothesis has only been tested in seed dispersal by mammals on one mountain range. Vertical seed dispersal by birds might differ from that by mammals, and frugivorous megafauna extinction and mountain topography may affect seed dispersal patterns. Here we assessed the vertical seed dispersal of summer and summer-to-autumn fruiting cherries by mammals and birds across three Japanese mountain ranges, two of them with presence of a megafauna, the Asian black bear. We found strong uphill seed dispersal of summer fruiting cherry species and weak downhill seed dispersal of summer-to-autumn fruiting cherry species, irrespective of the frugivore community and mountain topography. These indicate that the fruiting phenology affects the direction of vertical seed dispersal by mammals and birds across mountains. Mammals and birds dispersed seeds over a similar vertical profile, although birds are likely to be low-quantity seed dispersers. The absence of bears, which dispersed the majority of the seeds, was not compensated by the remaining mammal species. The results suggest that the fruiting phenology and megafauna presence affect whether animal-dispersed temperate plants can migrate efficiently under climate change.

Immigration and emigration are key demographic processes of animal population dynamics. However, we have limited knowledge on how fine-scale movement varies over space and time. We developed a Bayesian integrated population model using individual mark-recapture and count data to characterize fine-scale movement of stream fish at 20-m resolution in a 740-m study area every two months for 28 months. Our study targeted small-bodied fish, for which imperfect capture was accounted for (bluehead chub Nocomis leptocephalus, creek chub Semotilus atromaculatus and mottled sculpin Cottus bairdii). Based on data from 2021 individuals across all species, we found that proportions of immigrants in 20-m sections averaged 30-42% among the study species, but they varied over space and time. Creek chub immigrants increased during warmer intervals when individuals grew more and transitioned between body size classes, suggesting that immigration was due to ontogenetic habitat shifts. There was a weak pattern across the species that individuals were more likely to leave 20-m sections when flow was higher. Water-column species (bluehead chub and creek chub) were more likely to immigrate into and stay in deeper sections with more pool area. Across all species and occasions, number of immigrants to stream sections did not decrease with number of individuals that survived and stayed in the same sections. Thus, the habitat did not appear saturated, and our data provided no evidence that intra-specific interactions affected fine-scale movement at our fish densities. In conclusion, high turnover rates characterized fish movement among stream sections and their variation was associated with temporal and spatial shifts in abiotic conditions.

Light pollution disrupts the natural dark-light rhythmicity of the world and alters the spectral composition of the nocturnal sky, with far-reaching impacts on natural systems. While the costs of light pollution are now documented across scales and taxa, community-level mitigations for arthropods remain unclear. To test two light pollution mitigation strategies, we replaced all 32 streetlights in the largest visitor center in Grand Teton National Park (Wyoming, USA) to allow wireless control over each luminaries' color and brightness. We captured fewer arthropods, across most Orders, in the blended-red light compared to white (3000 K). Interestingly, we found an effect of light brightness and color, suggesting that, overall, more arthropods were attracted by brighter, and white color hues compared to blended-red. Our findings provide valuable insights into the mitigation of artificial light at night, likely one of the primary drivers of global arthropod declines.

Rapid environmental changes across Europe include warmer and increasingly variable temperatures, changes in soil nutrient availability, and pollinator decline. These abiotic and biotic changes can affect natural plant populations and force them to optimize resource use against competitors. To date, the evolution of competitive ability in the context of changes in nutrient availability remains understudied. In this study, we investigated whether the common calcareous grassland herb Leontodon hispidus recently evolved its competitive ability and response to nutrient availability. We compared ancestors sampled in 1995 and descendants sampled in 2018 and applied a competition treatment in combination with weekly nutrient treatments (no fertilizer, nitrogen, phosphorus, and both). We found evidence for evolution of increased competitive ability, with descendants producing more vegetative biomass than ancestors when grown under competition. Furthermore, supplementing nutrients (especially N) reduced differences in competitive ability between ancestors and descendants, suggesting that nutrients are a limiting factor in interspecific competition, which could be linked to the decreasing nitrogen emissions into the atmosphere since the 1990s. Our study demonstrates rapid contemporary evolution of competitive ability, but also the complexity of the underlying processes of contemporary evolution, and sheds light on the importance of understudied potential selection agents such as nutrient availability.

Although numerous studies have shown that grazing gives rise to community succession from the communities or even species perspective, there is a lack of discussion about how grazing drives community assembly based on plant functional traits in a long-term experiment. We find different grazing intensities lead to temporal effects on trait-mediated multidimensional community assembly processes, including community-weighted trait mean (CWM), trait filtering, and trait distribution (divergence/convergence). CWM, trait filtering, and trait distribution of different traits transformed over the 16-year grazing experiment. Major findings include the following: (1) CWM changed rapidly under higher grazing intensity, and the removal of unsuitable traits from communities over time was accelerated with higher grazing intensity, such as higher specific leaf area (SLA), rich epidermal appendages (PAP), deep root system (RD), and growth form (shrub and subshrub) and dispersal mode (DM, e.g., insect spread) with higher scores. (2) Patterns of trait filtering strongly depended on grazing intensity and trait types, most traits, such as SLA, DM, PAP, RD, and onset of flowering (OFL), were filtered at high grazing intensity area, and effects of trait filtering in the community assembly process strengthened with grazing time. (3) Traits related to the cycling of biological matter, such as leaf area (LA), SLA, reproductive height (RH), photosynthetic (PHO), and GF more frequently diverged after long-term grazing, especially in higher grazing areas. Community assembly in intensely grazed ecosystems takes over a decade to support fundamental functions, highlighting the need for grazing intensity thresholds for sustainable grassland use.

Trophic niche has fundamental ecological importance, but many studies consider few niche metrics and most neglect critical structuring processes. Multiple processes shape trophic niches, including inter and intra-specific competition, predation and resource diversity. These processes interact and effects vary with time and taxa. The White Sands dunefield provides an ecological gradient ideal for understanding variation in niches. We measured population niche width, trophic position and individual specialization in four lizard species across habitats over 2 years. The habitats include White Sands interior, the surrounding desert scrub, and their ecotone. We used arthropod, lizard and plant stable isotopes to quantify niches. We sampled lizard competitors, predators and prey as proxies for ecological processes. We found substantial variation in niches across populations but convergence between species. Individual specialization and population niche width were surprisingly decoupled. Specialization was highest in habitats with low species diversity (White Sands) and population niche width highest at intermediate diversity (ecotone). White Sands lizards may exhibit 'ultra partitioning'; high specialization alongside low individual niche widths. Population niche width is likely constrained within White Sands by low prey diversity. High ecotonal population niche widths may be due to fewer natural enemies than desert scrub but higher resource diversity than White Sands. Trophic position and specialization were positively correlated, suggesting stronger intraspecific competition at higher trophic levels. Prey diversity, inter and intra-specific competition, and predation all interacted to shape niches. Our results highlight the need for measuring multiple components of community structure and niches, as results are likely misleading in isolation.

Mutualisms may be more or less sensitive to environmental conditions depending on the diversity and responses of the species involved. Ants frequently form mutualistic associations with plants bearing extrafloral nectaries (EFNs): the ants protect the plants from herbivores and receive food resources (i.e., nectar) in return. As ectotherms, ants are strongly influenced by temperature, and temperature shifts can affect ant-plant interactions in ways that often depend on species functional traits. In this study, we explored the influence of EFN size and leaf surface temperature on ant-plant interactions in a Caatinga dry forest in Brazil. We observed the ants visiting 14 EFN-bearing plant species at different times of day over 12 sampling months; we also measured leaf surface temperatures during these periods. We next quantified EFN size for 68 individuals from the 14 plant species. The observational data were used to characterize the heat tolerance of the attendant ant species (i.e., based on levels of foraging activity). We then evaluated the mutualism's degree of functional resilience using two indices: functional redundancy (i.e., the number of ant species interacting with a given plant species) and thermal response diversity (i.e., variability in the heat tolerance of the ant species interacting with a given plant species). We found that leaf surface temperature, but not EFN size, had an influence on mutualism functional resilience. As temperatures increased, both functional redundancy and thermal response diversity decreased. This result implies that warmer global temperatures could heighten the vulnerability of facultative ant-plant mutualisms, regardless of plant traits.

Plant litter is a well-defined pool of organic matter (OM) in which the influence of manganese (Mn) on decomposition (both decomposition rate and the mix of compounds ultimately transferred to soil OM) has been clearly demonstrated in temperate forests. However, no similar study exists on grasslands and the effect of foliar Mn versus soil-derived Mn on litter decomposition is poorly known. We used a 5-month and 12-month field, and 10-month laboratory experiments to evaluate litter decomposition on the Kohala rainfall gradient (Island of Hawai'i) in areas with different foliar and soil Mn abundances, and on which a single plant species (Pennisetum clandestinum) dominates primary production and the litter pool. The chemical imaging analyses of decomposed litter revealed that Mn oxidized to Mn and Mn on grass litter during decompositions-hallmarks of Mn-driven litter oxidation. However, these transformations and Mn abundance did not predict greater litter mass loss through decomposition. These observations demonstrate that the importance of Mn to an ecosystem's C cycle does not rely solely on the metal's abundance and availability.

Plants host an array of microbial symbionts, including both bacterial and fungal endophytes located within their roots. While bacterial and fungal endophytes independently alter host plant growth, response to stress and susceptibility to disease, their combined effects on host plants are poorly studied. To tease apart interactions between co-occurring endophytes on plant growth, morphology, physiology, and survival we conducted a greenhouse experiment. Different genotypes of Spartina alterniflora, a foundational salt marsh species, were inoculated with one bacterial endophyte, Kosakonia oryzae, one fungal endophyte, Magnaporthales sp., or co-inoculated. Within the greenhouse, an unplanned herbivory event occurred which allowed insight into the ways bacteria, fungi, and co-inoculation of both endophytic microbes alters plant defense chemicals and changes herbivory. Broadly, the individual inoculation of the bacterial endophyte increased survival, whereas the fungal endophyte increased plant growth traits. Following the herbivory event, the proportion of stems grazed was reduced when plants were inoculated with the individual endophytes and further reduced when both endophytes were present. Across genotypes, anti-herbivore defense chemicals varied by individual and co-inoculation of endophytes. Bacterial inoculation and genotype interactively affected above:below-ground biomass and S. alterniflora survival of ungrazed plants. Overall, our results highlight the variable outcomes of endophyte inoculation on Spartina growth, morphology, phenolics, and survival. This study furthers our understanding of the combined effects of symbionts and plant multitrophic interactions. Further, exploring intra and inter specific effects of plant--microbe symbiosis may be key in better predicting ecosystem level outcomes, particularly in response to global change.

Among the many changes associated with the urbanization process, changes in resource availability can directly impact local wildlife populations. Urban areas suppress native vegetation and convert natural environments into impervious surfaces, modifying the composition and quantity of available food resources. Understanding the food requirements of species is crucial, mainly because it is one of the main elements that characterize their ecological niche and structure local communities. Our aim in this study was to assess the impact of urbanization intensity on the isotopic niche space of birds commonly found in urban areas of Brasília, the capital of Brazil, a big city in central Brazil with approximately 3 million inhabitants. By analyzing the δC and δN isotopic metrics of feathers from bird species found along a gradient of urbanization intensity, we evidenced a simplification but not a displacement of the bird assembly isotopic space due to urban intensification. Bird assemblage access similar food resources in the higher urban intensification areas, although less diversified than in lower urban intensification areas. In most cases, the response to urban intensification is more specific than convergent among guild members. The studied species maintain themselves in highly intensified urban areas by restricting, changing, and expanding their access to resources. The trophic dimension is one of the key components of the species' ecological niche, and understanding the urban intensification impacts on this dimension is essential for maintaining biodiversity and ecosystem services in cities.

Anthropogenic climate change poses a significant threat to species on the brink of extinction. Many non-avian reptiles are endangered, but uncovering their vulnerability to climate warming is challenging, because this requires analyzing the climate sensitivity of different life stages and modeling population growth rates. Such efforts are currently hampered by a lack of long-term life-history data. In this study, we used over 3 decades of mark-recapture data from a natural population of the endangered meadow viper (Vipera ursinii ursinii) to unravel the patterns of temporal variation in reproductive traits, the local climatic determinants of inter-annual variation in reproduction, and the potential buffering effects of life cycle on population growth rate. We found significant inter-annual variation in body growth, gestation length, post-parturition body condition, clutch success, and offspring traits at birth, while reproductive effort showed little temporal variation. Temperature during gestation was the most critical factor, reducing gestation length and increasing both clutch success and post-parturition body condition. In contrast, neither air humidity nor global radiation affected reproductive outcomes. This population had a negative growth rate with minimal temporal variation, indicating a rapid decline largely independent of climatic conditions. Overall, the viper's life-history traits appeared to be buffered against temporal variation in climatic conditions, with this declining population potentially benefiting on the short term from rising local temperatures.

An animal's diet breadth is a central aspect of its life history, yet the factors determining why some species have narrow dietary breadths (specialists) and others have broad dietary breadths (generalists) remain poorly understood. This challenge is pronounced in herbivorous insects due to incomplete host plant data across many taxa and regions. Here, we develop and validate machine learning models to predict pollen diet breadth in bees, using a bee phylogeny and occurrence data for 682 bee species native to the United States, aiming to better understand key drivers. We found that pollen specialist bees made an average of 72.9% of their visits to host plants and could be predicted with high accuracy (mean 94%). Our models predicted generalist bee species, which made up a minority of the species in our dataset, with lower accuracy (mean 70%). The models tested on spatially and phylogenetically blocked data revealed that the most informative predictors of diet breadth are plant phylogenetic diversity, bee species' geographic range, and regional abundance. Our findings also confirm that range size is predictive of diet breadth and that both male and female specialist bees mostly visit their host plants. Overall, our results suggest we can use visitation data to predict specialist bee species in regions and for taxonomic groups where diet breadth is unknown, though predicting generalists may be more challenging. These methods can thus enhance our understanding of plant-pollinator interactions, leading to improved conservation outcomes and a better understanding of the pollination services bees provide.

Nitrogen deposition continues to change grassland plant community composition particularly in more mesic systems; however, whether these altered plant communities will respond differently to other global change factors remains to be seen. Here, we explore how nutrient-altered tallgrass prairie responds to drought. Seven years of nutrient treatments (control, nitrogen (N), phosphorus (P), and N + P) resulted in significantly different plant communities. Within this experimental context we imposed a 3-year drought followed by 3 years of recovery from drought. The response of plant functional types depended on the nutrient treatment. During recovery years, C grasses recovered in the first year in all treatments but the N + P treatment, where instead annual grasses increased. These differential responses during recovery resulted in greater shifts in community composition in the N + P treatment compared with the controls. Despite the effects on community composition, we found no interaction between nutrient treatment and drought treatment on species richness or evenness and standing biomass during drought or recovery. We found drought induced shifts in plant functional groups led to the composition of previously droughted N + P plot becoming more dominated by annual grasses during the recovery years, likely creating a lasting legacy of drought.

Accurate identification of decreasing trends is a prerequisite for successful conservation, but can be challenging when immigration compensates local declines in abundance. Here, we show that a potential declining trend driven by low vital rates was overridden and converted into a spectacular increase by massive immigration into the population of a semi-social raptor, the black kite Milvus migrans, breeding in a highly contaminated area near a major landfill. Immigration was promoted by a growing food-base of live prey, coupled with the attraction exerted by the progressive gathering of a large flock of non-breeders at the area, resulting in an "attraction spiral" that lured large numbers of breeders to settle into a contaminated population incapable of self-sustenance. Immigration was so prevalent that, in little more than a decade, over 95% of the original population was substituted by immigrants, which showed the enormous potential of immigration as a rescue mechanism. At the same time, immigration may hide cryptic threats, as shown here, and expose some species, especially group-living mobile ones, to rapid attraction to anthropogenic subsidies, whose potential role as evolutionary traps is well known. The dynamics exposed here may become increasingly common, affecting many other species in our growingly anthropogenic world. Our results remark the often overlooked importance of immigration in ecology, evolution, and conservation as a key player for population dynamics and their more realistic forecast.