Oecologia

Spatial and temporal partitioning of habitat may facilitate diversity and have important impacts on ant communities. To investigate niche overlap in an ant community in a northern California oak woodland, we observed ant foraging on trees in 4 seasonal surveys, each lasting 2 weeks, in a 9.5-hectare plot over the course of a year. Foraging activity in all 5 observed ant species differed by season, time of day, and/or the genera of trees used. Of the 3 ant species most frequently observed, Camponotus semitestaceus was most active during spring and summer nights, Formica moki was most active during spring and summer days, and Prenolepis imparis was most active during both day and night of fall and winter. All ant species preferred native trees to exotic trees and preferred evergreen trees to deciduous trees. Our results suggest that native evergreen oaks such as Quercus agrifolia, currently threatened by sudden oak death (Phytophthora ramorum), may be important for supporting ant biodiversity.

Mutualisms between plants and ants are common features of tropical ecosystems around the globe and can have cascading effects on interactions with the ecological communities in which they occur. In an African savanna, we assessed whether acacia ants influence nest site selection by tree-nesting birds. Birds selected nest sites in trees inhabited by ant species that vigorously defend against browsing mammals. Future research could address the extent to which hatching and fledging rates depend on the species of ant symbiont, and why ants tolerate nesting birds but not other tree associates (especially insects).

Understanding how resource availability shapes herbivore competitive interactions is crucial for predicting pest dynamics under changing agricultural practices. Interspecific competition among herbivorous insects is mediated by host plant quality, yet mechanisms underlying competitive outcomes under varying nutrient conditions remain unclear. We investigated how fertilization affects population dynamics and competitive interactions between the legume-specialist Megoura crassicauda and the generalist Aphis craccivora on pea shoots (Pisum sativum) under fertilized and unfertilized conditions. Aphid population dynamics were monitored for 30 days in single-species and mixed-species treatments, and plant survival and biomass changes were assessed. Unexpectedly, fertilization reduced aphid population growth in both species, challenging conventional assumptions about nutrient effects on herbivores. Fertilization significantly affected M. crassicauda population growth but not that of A. craccivora. In mixed treatments, A. craccivora consistently excluded M. crassicauda by day 25, regardless of nutrient status. Plant mortality occurred in all aphid treatments except M. crassicauda under fertilized conditions. Our findings demonstrate that nutrient enrichment reduced herbivore performance but did not alleviate interspecific competition. The consistent competitive dominance of the generalist suggests that intrinsic species traits, rather than resource availability, determine competitive hierarchies. These findings have implications for pest management under changing agricultural practices.

Arachis pintoi (Fabaceae) is a common relative of the cultivated peanut, and folds its four leaflets up to look like one at night. The adaptive significance of this behavior (foliar nyctinasty) is unknown. To test the hypothesis that leaflet folding alone can deter herbivores, a leaf preference experiment was performed on Chromacris trogon grasshoppers. Small oval cutouts were made from leaves of the grasshoppers preferred food source, Iochroma arborescens (Solanaceae), and were combined with small pieces of tape and dry grass to construct artificial leaves resembling the day and night form of A. pintoi. In the experiment, groups of three grasshoppers were starved for 24 hours and then placed in petri dishes containing one closed and one open artificial leaf. After 30 six-hour trials, the average herbivory of open leaves was 12.3%, while closed leaves was 5.2% (p = 0.00145), indicating a significant preference for open leaves. This suggests that the folded configuration of A. pintoi leaves can be a defense against herbivory.

Coastal salt marshes serve as the margin between terrestrial and marine biomes, provide a variety of important services, and are dynamic ecosystems characterized by keystone species that shape trophic networks. In coastal salt marshes of the Eastern Atlantic and Gulf of Mexico, marsh periwinkle snails (Littoraria irrorata) exhibit high abundance and form critical trophic pathways as important herbivores and detritivores. Specifically, snails forage on Spartina alterniflora and associated fungal growth, for which L. irrorata may act as a top-down control on plant growth. Yet, L. irrorata occupies other salt marsh plants, suggesting its habitat niche may be broader than previously reported. Here, we documented snail densities and size distributions in a Louisiana (USA) salt marsh composed of multiple marsh graminoids and report the results of behavioral choice experiments designed to test snail habitat preferences as a potential mechanism underlying their field distribution. We observed higher snail densities on S. alterniflora stalks (283.0 snails m-2) than other plant species, however, snails were highly abundant on S. patens (115.6 snails m-2), Juncus roemerianus (94.8 snails m-2), and Distichlis spicata (56.9 nails m-2) with densities comparable or higher on all species than reported on S. alterniflora in other studies along the U.S. Atlantic and Gulf coasts. Snails found on S. alterniflora and J. roemerianus, both plants with tall and rigid stalks, were also larger than snails found on other plant species. In species preference experiments, snails preferred S. alterniflora over S. patens and D. spicata, but no clear preferences were observed between S. alterniflora and J. roemerianus, nor between any combinations of S. patens, D. spicata, and J. roemerianus. Finally, we found that snails preferred senescing and dead S. alterniflora tissue over fresh S. alterniflora. Interpreting these results in tandem, this study suggests L. irrorata snails have consistent patterns of field distributions that match their habitat preferences, and future studies should test potential processes driving snail habitat selection, such as dietary habits and predator refugia (i.e., climbing sturdy stalks to avoid aquatic predators). Considering the abundance and trophic role of L. irrorata in coastal salt marshes, snail behavior may be a key modulator for salt marsh trophic networks.

We investigated the influence of small-scale topographic and associated microclimatic drivers on the elevational patterns of functional alpha and beta diversity in ant communities of eastern Himalayas. Ants were sampled along three elevational transects spanning [~]1000-2000 m on two nearby mountain slopes, but differing in aspect, inclination and summit height. Ant genera were quantified at the quadrat level, yielding an abundance of 3090 genus-quadrats (from 22577 individuals in 1215 quadrats), almost evenly split between the two mountain slopes. Each ant was assigned to guilds along functional axes of thermal niche, trophic position and competitive abilities. Comparative analyses of functional diversity profiles along the two mountain slopes revealed no differences in the composite multi-guild alpha and beta diversity but significant differences amongst individual guild profiles. Seven of the eleven functional guilds showed strong elevational trends along the steeper north-facing slope, compared to only two of eleven on the shallower south-facing slope. These results indicate that similar functional space can be maintained despite taxonomic turnover within guilds or shifts in their relative abundances highlighting the influence of fine-scale topographic variation on community assembly. Alternatively, these findings demonstrate that the pattern of multivariate functional diversity across elevation does not necessarily provide an understanding of changing composition of the communities therein.

O_LIGastro-intestinal nematode (GIN) parasites play an important role in the ecological dynamics of many animal populations. Recent studies suggest fine-scale spatial variation in GIN infection dynamics are important in wildlife systems, but the environmental drivers underlying this variation remain poorly understood. C_LIO_LIWe used data from over two decades of GIN parasite egg counts, host space use, and spatial vegetation data from a long-term study of Soay sheep on St Kilda to test how spatial autocorrelation and vegetation in an individuals home range predict parasite burden across three age groups. We developed a novel approach to quantify the plant functional traits present in a home range to describe the quality of vegetation present. C_LIO_LIEffects of space and vegetation varied between age classes. In immature lambs, strongyle parasite faecal egg counts (FEC) were spatially structured, being highest in the north and south of our study area. Independent of host body weight and spatial autocorrelation, plant functional traits predicted parasite egg counts. Higher egg counts were associated with more digestible and preferred plant functional traits, suggesting the association could be driven by host density and habitat preference. C_LIO_LIIn contrast, we found no evidence that parasite FEC were related to plant functional traits in the host home range in yearlings or adult sheep. Adult FEC were spatially structured, with highest burdens in the north-east of our study area, while yearling FEC showed no evidence of spatial structuring. C_LIO_LIOur findings support the importance of fine-scale environmental variation for wildlife disease ecology and provides new evidence that such effects may vary across demographic groups within a population. Parasite burdens in immature individuals appear more readily influenced by fine-scale spatial variation in the environment, highlighting the importance of such heterogeneity for our understanding of wildlife epidemiology and health. C_LI

O_LIClimate change is expected to alter habitat more rapidly than the pace of evolution, leading to tree populations that are maladapted to new local conditions. Assisted migration is a mitigation strategy that proposes preemptively identifying and planting genotypes that are robust to the expected climate change-induced alterations of an area. Assisted migration however, may impact the broader community, including herbivores which often coevolved with local plant genotypes and their defenses. Although this question has been examined in arthropod herbivores, few studies have assessed this question in mammalian herbivores, and fewer still have leveraged experimental design to disentangle the genetic contribution to herbivore preference. C_LIO_LIWe examined the hypothesis that North American porcupine (Erethizon dorsatum) browsing on Fremont cottonwood (Populus fremontii) is under genetic control in a common garden, which allowed us to uncouple genetic and environmental contributions to browse preference. C_LIO_LIGenerally, porcupines selected local trees and trees from climatically similar areas, where trees from local and cooler climate populations suffered over 2x more extensive herbivory than trees from warmer areas. Plant genotype was a significant factor for selection, with the most heavily browsed genotype having on average >10x more herbivory than the least heavily browsed. Because genotypes within and among populations were replicated, we calculated broad-sense heritability in which tree palatability by porcupines was H2B = 0.28 (95% CI: 0.13-0.48) among genotypes. C_LIO_LISynthesis and applications. Our results indicate a genetic component to tree defenses against porcupine herbivory that can be predicted by the climate of the source population. This result has important implications for mammalian herbivores if climate change renders local tree genotypes maladaptive to new conditions. We recommend assisted migration efforts consider this implication and plant stock from both warmer and climatically similar areas to maintain genetic diversity in a changing environment, productivity and forage for mammalian herbivores. C_LI

Variation in defense traits likely depends on access to different resources and risk from herbivory. Plant defense theories have predicted both positive and negative associations between defense traits and access to resources, but relatively few studies have explored intraspecific variation in defense traits along multiple resource and mammalian herbivory risk gradients. We assessed relationships between herbivory intensity, multiple resources, and plant defense traits using a widely distributed tropical savanna herb, Solanum incanum. As independent measures of risk from large mammal herbivores are rare, we used a satellite-based vegetation index to predict herbivory intensity at the landscape scale. We found that the satellite-based estimate of herbivory intensity was positively associated with browser abundance and total soil P, but negatively associated with rainfall. Intraspecific defense traits too varied substantially across sites (n=43) but only variation in spine density was associated with herbivory intensity and plant resources, such that spine density was positively associated with both rainfall and soil P, but bimodally associated with herbivory intensity. Taken together, it suggests that defenses maybe favored either where resources for defense are abundant under low but still present risk (i.e, at high rainfall sites) or where resource-expensive plant tissue is at high risk (i.e, at high soil P sites). This hints at the possibility of a shift from a resource-associated (bottom-up) to an herbivory-associated (top-down) control of allocation to defenses along an environmental gradient. Additionally, the independent effect of soil P on a carbon-based defense, spine density, suggests potential for resources that are not components of defenses to also influence allocation to defense traits. Thus, our study provides evidence for the influence of multiple drivers, resources, and herbivory intensity, on anti-herbivore defenses and their shifting relative importance on allocation to defenses along an environmental gradient.

Many species of plants and animals shift to higher altitudes in response to the ongoing climate warming. Such shifts of species distributions lead to the co-occurrence of species that have not previously lived in the same environment and allow the emergence of novel plant-animal interactions with potential implications for species diversity and community composition in mountain habitats. According to the enemy release hypothesis, the spread of plants in new geographic regions may be facilitated by the reduction of damage caused by natural enemies, such as herbivores. While the importance of this mechanism for the spread of invasive exotic species has been established, it is unclear whether the movement of plants uphill within their native region in response to increasing temperatures may be also facilitated by the reduction of herbivory at sites above their current upper altitudinal limit. In our study, we experimentally tested this hypothesis. We compared herbivory damage of six species of lowland plants grown in pots exposed to herbivores at their native sites in the lowland and at sites above their current upper altitudinal limit. As a control, we also measured herbivory damage of six plants growing naturally across the entire range of altitude. We found that lowland plants had reduced herbivory damage when they were moved to highland sites, while herbivory damage of species naturally growing at both altitudes did not differ. Changes of herbivory damage were modulated by leaf dry matter content and to a lesser degree also by specific leaf area and plant height. Our results provide support for the enemy release hypothesis in the novel context of altitudinal range shifts. We conclude that the reduction of herbivory damage may facilitate the spread of plants above their current upper altitudinal limit in response to increasing temperature.

Animals consume foods in specific quantities and ratios to meet a multi-dimensional nutrient target that maximizes their fitness. Attempts to reach this target in an ever-changing nutritional landscape often influence animal foraging behavior, habitat choice, and food-web interactions. Consequently, understanding the nutritional ecology of a species is instrumental in developing efficient management plans for its conservation. We quantified the dietary considerations of a critically endangered population of Acacia gazelles (Gazella arabica acacia), and compared their diet and nutrition to that of the sympatric Gazella dorcas, using behavioral observations coupled with nutritional and secondary metabolite quantification, and morphological measurements of trees. Acacia gazelles mainly consumed resources from two subspecies of the umbrella-thorn acacia (Vachellia tortilis) that differ in morphology, nutritional composition, and phenology, and prioritized consumption of specific trees based on their nutritional and defensive traits. Gazelles maintained a narrow nutritional target, tightly regulated their protein intake, and prioritized consumption of non-structural carbohydrates. Dorcas gazelles consumed a very different diet from the Acacia gazelle, but converged to a similar intake target. We conclude that suitable habitats for Acacia gazelle reintroduction must include sympatric populations of the two V. tortilis subspecies, that nutritional deficiency is unlikely to play a major role in explaining the slow rate of population recovery, and that the seemingly low competition between the two gazelle species does not necessitate controlling the Dorcas gazelle population. Our work demonstrates the importance of nutritional ecology as a major conservation tool.

Rodent population cycles are observed in highly seasonal environments. As most rodents are herbivorous, the availability and the quality of their food resources varies greatly across seasons. Furthermore, it is well documented that herbivore densities have a measurable effect on vegetation and conversely. So, many studies investigated whether rodent population cycles could be induced by bottom-up regulation. A recent review summarized several sub-hypotheses leading to rodent population cycles: cycles may be due to inherent inter-annual variations of plant quantity, to overshoot of carrying capacity by overgrazing (i.e. lack of quantity), to changes in quality of food (decrease of quality of preferred food or switch towards less quality food) in response to rodent grazing (e.g. plant defences). If some sub-hypothesis seems to be more important than others, there is currently a prerequisite to construct scientific consensus: dietary description is still overlooked in many systems and should be more investigated. This study focuses on fossorial water vole. It shows contrasted population dynamics depending on its geographical locations. It is known to be able to exhibit large outbreaks in grasslands in highly seasonal climate. It is thus a good model species to investigate plant hypotheses, first beginning by diet description. The diet of water vole was investigated in and out of the outbreak area with a combination of approaches in the field, in different sampling sites and considering seasonality. We demonstrated that voles have a very large fundamental trophic niche, but strong behavioural selection, inducing a narrower realised niche, especially during winter. We created an experimental device based on camera trap and cafeteria tests. We observed a strong preference for dandelion (Taraxacum officinale) in wild water voles, that results in exclusive selection during winter for food stores. These preferences were constant across seasons, altitudes and grassland productivity gradients, despite the scarcity of this species in some experimental sites. First, we conclude on the importance of using different methods to fully describe the diet of rodents Second, we assess that dandelion is a winter key resource for water vole. It thus might be interesting to investigate the role of dandelion in vole population dynamics.

O_LIRecent studies suggest that changes in leaf traits due to interactions between plants affect the resource utilisation and distribution of herbivores. However, this has not yet been confirmed experimentally. Here, we investigated the effects of phenotypic plasticity in leaf traits of Rumex obtusifolius (host plant) in response to the intra- and interspecific interaction on distribution of two leaf beetles, Gastrophysa atrocyanea (specialist herbivore) and Galerucella grisescens (generalist herbivore). C_LIO_LIWe investigated the local population density of R. obtusifolius plants and the presence of leaf beetles on the plants at five study sites. Leaf chemicals (condensed tannins and total phenolics) were compared between aggregated and solitary R. obtusifolius plants. To clarify the effects of the interaction environment of R. obtusifolius plants on their leaf traits and resource utilisation by leaf beetles, we conducted cultivation and preference experiments. Leaf chemicals (chlorophylls, organic acids, primary metabolites, condensed tannins and total phenolics) and preferences of adult leaf beetles were compared between intraspecific, interspecific plant interaction, or no-interaction treatments. Finally, we evaluated the effects of interaction between R. obtusifolius on leaf beetle distribution in mesocosm experiments. C_LIO_LIIn the field, the presence of the specialist leaf beetle, G. atrocyanea, was positively correlated with the local population density (rosette overlap ratio) of R. obtusifolius plants; however, no correlation was observed in the case of the generalist leaf beetle, G. grisescens. In the cultivation experiment, plants in the intraspecific interaction treatment increased their leaf contents of condensed tannins and total phenolics, and G. atrocyanea consumed more of these leaves than leaves in other treatments. Similar results were observed in the field. In the mesocosm experiment, larger numbers of G. atrocyanea were distributed on R. obtusifolius plants exposed to below-ground intraspecific interaction than on plants not exposed to intraspecific interaction. C_LIO_LIOur results provide experimental evidence that leaf-trait changes in response to intraspecific interaction between host plants influence specialist herbivore distribution. This highlights the need to integrate plant-plant interactions into our understanding of plant-animal interactions. C_LI

While interspecific variation in seed dispersal, a critical ecosystem process in tropical forests, is relatively well-studied, intraspecific variation as a consequence of differences in body size, foraging behaviours, and ranging patterns among age-sex categories within a species is relatively understudied. Among vertebrates, primates play a critical role in seed dispersal and exhibit behavioural differences between age and sex categories, making them a suitable study system for intraspecific variation in seed dispersal. Lion-tailed macaques Macaca silenus, an endemic and predominantly frugivorous primate species in the Western Ghats Biodiversity Hotspot, provide an excellent model for such studies. We examined the influence of age and sex on 1) the diversity and 2) the quantity of native and non-native fruits consumed, 3) the number of seeds dispersed, 4) seed dispersal distance, and 5) seed deposition substrates in lion-tailed macaques. We conducted over 375 hours of focal animal watches, distributed evenly across adult males, females, and subadults. Our findings showed that subadults consumed a higher diversity of native and non-native fruits than females and males. They dispersed fewer Ficus seeds than females. We found differences in the proportions of non-native fruits in the diets of different age- sex categories. Males consumed more Coffea liberica, whereas females and subadults fed on Coffea and Lantana. We found weak evidence suggesting that males were more likely to disperse Ficus seeds on trees, which are suitable substrates for Ficus establishment. Our study highlights that age and sex significantly influence seed dispersal patterns of native and non- native species by an endemic, frugivorous primate species with potential influence on recruitment.

O_LITrait-based community assembly studies have mostly been addressed along spatial gradients, and do not consider explicitly a fundamental dimension governing community assembly, the time. Nevertheless, such consideration seems particularly necessary in systems in which organisms have to face regular disturbances and rapid changes in vegetation phenology, such as in intensively managed farmlands. C_LIO_LIIn this study, we aimed at understanding how the functional diversity of carabid beetle communities varied across the growing season in response to crop type. We tested three alternative hypotheses on mechanisms underlying the community assembly. C_LIO_LIWe used data from a long-term monitoring conducted over nine years in an intensively-managed farmland in central western France, in a total of 625 fields. First, we measured morphological traits related to body size, dispersal mode, and resource acquisition on the 13 dominant carabid species (> 85 % of all trapped individuals) and identified three independent dimensions of functional specialization within our species pool along axes of a PCA and highlighted key traits for community assembly. Second, we evaluated the community assembly temporal dynamics and the impact of habitat filtering and niche differentiation in the different crop types with time, using linear mixed-effects models. C_LIO_LIWe showed that functional species assembly of carabid beetle communities occurring in crop fields varies importantly intra-annually, with strong variations in these dynamics depending on crop type and crop phenology. Each crop acted as a filter on carabid communities for body size and resource-acquisition traits, and functional differentiation between crops increased with time. We did not find any evidence of habitat filtering on traits related to dispersal mode. C_LIO_LIOur results emphasize the major role of crop phenology but also disturbances involved by agricultural practices such as crop harvesting on changes in community assembly, likely due to seasonal and inter-annual redistributions of species in agricultural landscapes in response to such changes. The temporal dimension cannot be ignored to understand the assembly of local carabid communities in farmlands. C_LI

One strategy animals perform to cope scarcity of food resources is to shift in number of individuals according towards areas with available resources. This strategy can be more marked in species that are constrained by high energetic requirements such as hummingbirds. We aim to determine the extent to which the availability of food resources could be predictor of hummingbird numbers within and across hummingbird species in a temperate forest of central Mexico. We anticipate fluctuations in the number of hummingbirds grouped by species is best explained by monthly fluctuations in flowering resources species compared to pooled data. Our results indicate all seven hummingbird species fluctuate monthly in number across the year, which corresponds to monthly fluctuations of plant species they feed upon. The Basilinna leucotis and the Salvia elegans were present and interact in the study area almost all year-round, guiding the abundance pattern of both plants and hummingbirds in the study site. Generalized Linear Mixed Models indicate that although considering the abundance of the number of flowers for all plant species together could explain the fluctuation in all hummingbird species pooled together, considering both plant species and hummingbird species separately can provide a better explanation for changes in bird abundance. The model that analyzed species indicate that the interaction between the year-round species B. leucotis and S. elegans recorded the highest significant size effect. Our results highlight the fact that abundant species guiding abundance patterns could obscure by-species hummingbird trends and the processes guiding their patterns of abundance. We point out the need for performing adequate analytical approaches that can detect important biological interactions, and the likelihood of changes in habitat changing the pattern observed. RESUMENUna estrategia los colibries usan para lidiar con la escasez de alimento es realizar cambios en numero de individuos a zonas con recursos disponibles. Esta estrategia es mas marcada en especies que son limitadas por altos requerimientos energeticos como los colibries. Nuestro objetivo fue determinar el grado con el cual la disponibilidad de alimento puede ser un predictor de numero de individuos en un bosque templado del Centro de Mexico. Anticipamos fluctuaciones en numero de colibries agrupados por especies serian mejor explicadas por fluctuaciones mensuales en recursos florales al comparar con datos combinados. Nuestros resultados indican que las siete especies de colibries fluctuaron mensualmente en numeros a lo largo del ano de acuerdo a fluctuaciones mensuales de las especies de plantas que ellos se alimentan. Basilinna leucotis y Salvia elegans estuvieron presente e interactuaron en la zona de estudio casi todo el ano, guiando el patron de abundancia tanto de colibries como de plantas. Los Modelos Lineales Generalizados Mixtos indicaron que aunque considerar la abundancia del numero de flores para todas las especies juntas podria explicar la fluctuacion en todas las especies juntas, considerar las especies de colibries y de plantas por separado provee una mejor explicacion para los cambios en abundancia de aves. El modelo analizando especies indico que la interaccion entre las especies anuales B. leucotis y S. elegans tuvieron el tamano del efecto significativo mas alto. Nuestros resultados destacan el hecho de que especies abundantes guiando el patron de abundancia podrian obscurecer tendencias especificas por especie y los procesos guiando su patron de abundancia. Indicamos la necesidad de usar enfoques analiticos adecuados que puedan detectar interacciones biologicas importantes, asi como la probabilidad de que cambios en el habitat pueden cambiar el patron observado. Palabras claveBosque templado, abundancia estacional, uso del habitat, asociacion colibri-comida, fluctuaciones temporales en abundancia Lay summaryO_LIHummingbirds, as many animals with high energy requirements, might cope with food resources shortage using different strategies C_LIO_LIOne strategy to face food shortage is the local shifting in number of individuals. C_LIO_LIWe used monthly surveys of hummingbirds and flowering plants in a temperate forest of central Mexico to evaluate the association of resources availability, seasonality, species identity, and vegetation condition on hummingbird abundance. C_LIO_LIAll seven hummingbird species fluctuate in number across the year, which matches to fluctuations of plant species they feed upon. C_LIO_LIHummingbird species Basilinna leucotis and the plant species Salvia elegans are the most abundant and largely guide the general abundance pattern. C_LIO_LIBoth plant and hummingbird species separately are better explanting changes in hummingbirds abundance than species abundance combined. C_LIO_LIAbundant species may guide the plant and hummingbird abundance patterns, which complicates understanding underlying processes per species for the whole community. C_LIO_LIGiven the current trends of habitats modification and the fact that habitat condition may influence the presence of key plant species for hummingbirds, we need to protect habitats where these key food plant species for hummingbirds are, particularly if they are specific to habitats C_LI

Plant fitness is shaped by interactions with insect mutualists and antagonists. Vegetative (leaf) herbivory often results in increased allocation of resources to defense in order to deter further damage. This allocation to defense can reduce floral or reproductive allocation. Reductions in floral allocation can have negative effects on pollinator attraction and therefore decrease plant fitness. However, defense-induced changes in reproductive tissues may also be protective against antagonistic fruit-feeding insects (frugivores). This may have important implications for plant fitness when plants experience multiple types of insect damage, but the potential protective effect of herbivory against frugivory is not well-understood. In this study, we tested the prediction that herbivory mediates interactions between plants and their antagonistic frugivores. In the greenhouse, we manipulated vegetative induction in Physalis pubescens (Solanaceae) and measured the effects on plant fitness via changes in floral and fruit allocation, herbivore resistance in the next generation, and deterrence of an antagonistic frugivore (Chloridea virescens (Lepidoptera)). Vegetative induction in P. pubescens enhanced plant resistance to Chloridea virescens frugivores with minimal negative effects on plant reproductive traits. Vegetative induction reduced C. virescens larval growth rate on fruits. Chloridea virescens also avoided induced plants for larval fruit feeding and oviposition. While leaf induction reduced flower size, induction did not negatively affect fruit size, seed set, or seed germination. Furthermore, offspring of induced plants showed increased resistance to Manduca sexta leaf herbivory. These findings indicate that herbivore-induced resistance may benefit plant fitness when plants are under simultaneous pressure from herbivores and frugivores.

The ability to use small molecule alkaloids as defensive chemicals, often acquired via trophic interactions, has evolved in many organisms. Animals with diet-derived defenses must balance food choices to maintain their defense reservoirs along with other physiological needs. Poison frogs accumulate skin alkaloids from their arthropod diet, but whether they show preference for specific prey remains unexplored. Here, we explore the role of leaf litter prey availability and diet preferences in shaping poison frog chemical defenses along a geographic gradient. We examined skin alkaloid composition, stomach contents and leaf litter ants in aposematic diablito frogs (Oophaga sylvatica) at five sites in northwestern Ecuador, and in sympatric, cryptic Chimbo rocket frogs (Hyloxalus infraguttatus) at one site. We found that differential availability of leaf litter ants influenced alkaloid profiles across diablito populations, and low levels of alkaloids were observed in the sympatric, undefended Chimbo rocket frog. Ants were the primary dietary component of the defended species, while undefended species ate other prey categories including beetles and larvae in addition to ants. A prey selection analysis suggested that defended and undefended frogs both feed on a high proportion of specific small ant genera that naturally contain alkaloids, suggesting that selectivity for toxic prey is not restricted to classically aposematic and highly toxic species. These findings suggest that poison frogs use of feeding resources relative to availability may be an understudied and important selection factor in the evolution of acquired defenses. ResumenLa capacidad de usar alcaloides como productos quimicos defensivos ha evolucionado en muchos organismos, a menudo a traves de interacciones troficas. Los animales con defensas que se derivan de la dieta deben balancear la seleccion de los alimentos para mantener sus reservas defensivas junto con otras necesidades fisiologicas. Las ranas venenosas acumulan alcaloides en la piel procedentes de su dieta de artropodos, pero aun no se ha explorado si muestran preferencia por presas especificas. En este estudio, investigamos el papel de la disponibilidad de presas en la hojarasca y las preferencias dietarias en la configuracion de las defensas quimicas de las ranas venenosas a lo largo de un gradiente geografico. Examinamos la composicion de alcaloides en la piel, el contenido estomacal y la presencia de hormigas de la hojarasca en ranas aposematicas diablito (Oophaga sylvatica) en cinco sitios del noroeste de Ecuador, asi como en la especie criptica y simpatrica rana cohete de Chimbo (Hyloxalus infraguttatus) en un sitio. Encontramos que la disponibilidad diferencial de hormigas en la hojarasca influyo en los perfiles de alcaloides en las poblaciones de diablito, y se detectaron niveles bajos de alcaloides en la rana cohete de Chimbo, previamente considerada indefensa. Las hormigas fueron el componente principal de la dieta en la especie defendida, mientras que la especie indefensa consumio otras categorias de presas, incluidos escarabajos y larvas, ademas de hormigas. Un analisis de seleccion de presas indico que tanto las ranas defendidas como las indefensas prefieren ciertos generos de hormigas pequenas que contienen alcaloides de forma natural, lo que sugiere que la preferencia por presas toxicas no esta restringida a especies clasicamente aposematicas y altamente toxicas. Estos hallazgos sugieren que las preferencias de comportamiento pueden ser un factor de seleccion poco estudiado, pero crucial, en la evolucion de las defensas adquiridas.

Fouquieria splendens is a stem-succulent native to the Chihuahuan, Mojave, and Sonoran Deserts that spans Mexico and the American Southwest. It is well-known for its variable morphology, the underlying reason for which remains incompletely understood. Here, we attempt to quantify the effect of topographic and interspecific factors on F. splendens morphology and distribution. To this end, we measured 27 ocotillos located in the Organ Pipe Cactus National Monument within the Sonoran Desert during June of 2019. We also quantified the spatial distribution of interspecific neighbors relative to F. splendens within two topographically different sites: a bajada gradient and a plain. Using ocotillo morphology, the distances to the nearest neighbors of ocotillos, and hydrographic data extracted from the National Hydrography Dataset, we demonstrate 1) the effect of major interspecific neighbors, i.e. shrubs and cacti, on ocotillo morphology; 2) the effect of elevation on intraspecific spacing as individuals compete for limited space; and 3) a trade-off between height and number of branches. This places F. splendens morphology in its larger environmental and ecological context, highlighting the importance of individual traits and associated trade-offs among traits affected by topography and interspecific neighbors. By examining the ocotillo in a multi-species community and diverse landscape, this study provides empirical insight into a wider range of factors contributing to the variation in F. splendens morphology and spacing.

Devils gardens are among the most striking ant-plant mutualisms in Amazonian forests. In this system, the tree Duroia hirsuta is associated with the ant Myrmelachista schumanni, which actively removes neighboring vegetation and maintains nearly monodominant patches of the host plant. Despite the apparent efficiency of this system, repeated field observations at the Tiputini Biodiversity Station, Yasuni Biosphere Reserve, revealed that individuals of Palicourea alba recurrently occur within active devils gardens. Palicourea alba closely resembles dead plant material, exhibiting leaf morphology and coloration that strongly mimic the surrounding litter layer, and appears to be uncommon outside these gardens. To our knowledge, this "dead-leaf" masquerade has not been previously documented in this intensively studied system, making it a particularly striking and unexpected observation. To evaluate whether this masquerade facilitates persistence within devils gardens, we surveyed 35 gardens and recorded P. alba in 19 (52.8%). When present, P. alba covered on average 27% of plot area, while mean herbivory across sampled leaves remained low (8.6%). Generalized linear mixed models showed that P. alba cover decreased significantly with increasing herbivory (F = 8.09, p = 0.0159), whereas herbivory increased with leaf-litter cover (F = 8.73, p = 0.0120). Field observations further revealed that many individuals are nearly indistinguishable from dry leaf litter, suggesting a role for visual crypsis or masquerade. Together, these results indicate initially, that the persistence of P. alba within devils gardens is mediated by a multi-layered ecological filtering process. First, masquerade likely reduces detection by M. schumanni, allowing seedlings to escape ant-mediated removal. Second, low herbivory suggests either enemy avoidance or reduced apparency to herbivores within the simplified understory. Third, spatial heterogeneity in leaf-litter cover may create microhabitats where both ant activity and herbivore pressure are modulated, reinforcing establishment success. This system thus represents a previously undocumented mechanism in which plant-litter resemblance enables persistence within a highly structured, biotically filtered habitat, highlighting how subtle trait-mediated interactions may modulate outcomes in otherwise strongly deterministic mutualisms.