Xavier Arnan

Universidade de Pernambuco | UPE

To understand how food resource use and partitioning by closely related species allows local coexistence, it is key to determine whether a species’ diet reflects food availability or food preferences. Here, we analysed the diets, seed selection, and seed preferences of three closely related harvester ants: Messor barbarus, M. bouvieri, and M. capit...

European harvester ants, Messor species, are important ecosystem engineers. In Catalonia (Spain), among others, the three species Messor barbarus, M. bouvieri, and M. capitatus occur. At one Catalan site, a cluster of nest samples of unknown identity was found, raising the possibility of either a hybrid lineage or a currently unexplored species in...

Optimized food acquisition is challenging because foraged diet items are chemically complex and often nutritionally imbalanced. These challenges are likely magnified when foraged foods are used to provision others (e.g. offspring, nestmates, symbionts) with different nutritional requirements. We used a theoretical framework of nutritional niches to...

Chronic anthropogenic disturbances (chronic disturbances) and climate change can eliminate sensitive species and support the proliferation of disturbance-adapted ones leading native communities to biotic homogenization. We investigate the individual and interactive effects of increasing chronic disturbances and aridity on the biotic homogenization...

A knowledge gap in the cognitive processes regarding socioeconomic variables and younger people exists in relation to different elements of nature. This study aims to analyze young people's knowledge and perception about a dry forest, and to associate their knowledge with socioeconomic variables. The first stage of the research consisted of collect...

Tropical forest regeneration across old fields has been mainly described as a predictable sequence of functional plant assemblages in response to environmental filtering. However, the way plant reproductive diversity is organized along forest regeneration and how the reproductive profile of woody flora may impact regeneration have been poorly inves...

To understand species’ responses to climate change, we must better comprehend the factors shaping physiological critical thermal limits. One factor of potential importance is nutrient availability. Carbohydrates are an energy source that can directly affect an organism's physiological state. Ants are among the most omnipresent and ecologically rele...

To understand how food resource use and partitioning by closely related species allows local coexistence, it is key to determine whether a species’ diet reflects food availability or food preferences; the latter can be rooted in functional traits and/or phylogenetic history. Here, we analysed the diets, seed selection and seed preferences of three...

Differences in pollination effectiveness (PE) among pollinators have been widely documented. However, the morphological and behavioural traits underlying these differences have been less investigated. We used single-visit pollen deposition to apple flowers to explore the relationship between pollinator traits and PE. Our objectives were to determin...

When studying forest disturbances, it is essential to examine biodiversity from different perspectives, which includes considering its taxonomic and functional facets. Indeed, different taxa may respond differently based on their functional traits. We analyzed the short-term effects of a wildfire on epigeic ant and spider communities in a Mediterra...

Ecological interactions in tropical ecosystems are being modified by chronic anthropogenic disturbances (CAD) and climate change. Pollination is a key mutualistic interaction that can be affected by disturbance and climate change due to alterations in the composition, diversity, and distribution of plants, floral resources, and pollinators. We test...

Physiological thermal limits can mediate species coexistence at local scales. However, it is challenging to untangle the role they play when coexisting species are also highly related, given that phylogeny may inform physiology. However, if species exploit similar trophic resources, there must be a degree of niche differentiation that precludes com...

Plant–herbivore networks comprise over 40% of the global biodiversity and are negatively impacted by habitat loss and fragmentation. However, the extent to which these networks are affected by chronic anthropogenic disturbances and aridity, the most common threats to biodiversity in dry forests, remain unknown. In this study, we examined plant and...

Critical thermal limits (CTLs) constrain the performance of organisms, shaping their abundance, current distributions, and future distributions. Consequently, CTLs may also determine the quality of ecosystem services as well as organismal and ecosystem vulnerability to climate change. As some of the most ubiquitous animals in terrestrial ecosystems...

Chronic anthropogenic disturbance (CAD) and climate change represent two of the major threats to biodiversity globally, but their combined effects are not well understood. Here we investigate the individual and interactive effects of increasing CAD and decreasing rainfall on the composition and taxonomic (TD), functional (FD) and phylogenetic diver...

Extrafloral nectaries (EFNs) are anti‐herbivory defense‐related glands. We measured morphological and anatomical EFN traits in Pityrocarpa moniliformis trees along a rainfall gradient in Caatinga dry forest. We observed a reduction in structural EFN traits as rainfall decreased. We conclude that this reduction is a cost‐saving strategy, probably me...

Understanding species adaptations to human‐modified ecosystems is central to evolutionary and conservation biology. It is essential to evaluate trait variations in populations that occur along environmental gradients to understand the adaptive potential of species to human‐driven environmental change. We analyzed morphological trait variations in t...

Functional traits mediate the response of communities to disturbances (response traits) and their contribution to ecosystem functions (effect traits). To predict how anthropogenic disturbances influence ecosystem services requires a dual approach including both trait concepts. Here, we used a response–effect trait conceptual framework to understand...

Exploring shifts in the climatic niches of introduced species can provide significant insight into the mechanisms underlying the invasion process and the associated impacts on biodiversity. We aim to test the phylogenetic signal hypothesis in native and introduced species in Europe by examining climatic niche similarity. We examined data from 134 a...

During crop domestication, human farmers traded greater productivity for higher crop vulnerability outside specialized cultivation conditions. We found a similar domestication trade-off across the major co-evolutionary transitions in the farming systems of attine ants. First, the fundamental nutritional niches of cultivars narrowed over ~60 million...

Apesar da sua importância ecológica, os animais invertebrados são pouco apreciados pelas pessoas. Nas escolas, há uma lacuna na disseminação de informações relativas a esse grupo, principalmente quando se trata de invertebrados de ecossistemas pouco estudados, como é o caso da Caatinga. Assim, torna-se necessária a utilização de ferramentas paradid...

Perturbações antrópicas são consideradas a causa mais importante do declínio da biodiversidade em todo o mundo. Isso também é verdade para a Caatinga, o ecossistema menos estudado e menos protegido do Brasil. Um dos animais mais pluralísticos nesse bioma são as formigas, responsáveis pelos mais variados serviços ecossistêmicos, os quais vêm sendo c...

Most terrestrial species occur in human‐modified landscapes that are experiencing climate change. In addition to direct impacts on species, both anthropogenic disturbance and climate change can have important effects through changes in species interactions, including the disruption of ecological services provided by them. Here we investigate how ch...

Social insects, i.e. ants, bees, wasps and termites, are key components of ecological communities, and are important ecosystem services (ESs) providers. Here, we review the literature in order to (i) analyse the particular traits of social insects that make them good suppliers of ESs; (ii) compile and assess management strategies that improve the s...

Biotic homogenization—the erosion of biological differences among ecosystems due to human disturbance—is a pervasive threat to forest landscapes given the current global biodiversity crisis. In Mediterranean forests, wildfire is a particularly common disturbance that affects biodiversity at local, regional, and global scales. However, little is kno...

Abstract Species assemblages and their interactions vary through space, generating diversity patterns at different spatial scales. Here, we study the local‐scale spatial variation of a cavity‐nesting bee and wasp community (hosts), their nest associates (parasitoids), and the resulting antagonistic network over a continuous and homogeneous habitat....

Abstract Hairiness is a salient trait of insect pollinators that has been linked to thermoregulation, pollen uptake and transportation, and pollination success. Despite its potential importance in pollination ecology, hairiness is rarely included in pollinator trait analyses. This is likely due to the lack of standardized and efficient methods to m...

Functional trait-based approaches are increasingly used for studying the processes underlying community assembly. The relative influence of different assembly rules might depend on the spatial scale of analysis, the environmental context and the type of functional traits considered. By using a functional trait-based approach, we aim to disentangle...

According to the competitive exclusion principle, species with low competitive abilities should be excluded by more efficient competitors; yet, they generally remain as rare species. Here, we describe the positive and negative spatial association networks of 326 disparate assemblages, showing a general organization pattern that simultaneously suppo...

Understanding how ecological networks are assembled is important because network structure reflects ecosystem functioning and stability. Quantitative network analysis incorporates measures of interaction strength as an estimate of the magnitude of the effect of interaction partners on one another. Most plant-pollinator network studies use frequency...

Although extrafloral nectar (EFN) is a key food resource for arboreal ants, its role in structuring ground-nesting ant communities has received little attention, despite these ants also being frequent EFN-attendants. We investigated the role of EFN as a driver of the spatial structure of ground-nesting ant communities occurring in dry forest in nor...

Anthropogenic disturbance and climate change are major threats to biodiversity persistence and functioning of many tropical ecosystems. Although increases in the intensity of anthropogenic disturbance and climate change are associated with reduced taxonomic, phylogenetic and functional diversities of several organisms, little is known about how suc...

Understanding how local environmental factors affect communities and compositional patterns are crucial to biodiversity conservation, especially in environments that were severally affected by anthropic actions. We analyzed the effects of fine-scale local environmental conditions on alpha and beta diversity of fern communities in three Atlantic for...

Climate change is projected to exacerbate the effects of anthropogenic disturbance, with negative impacts on ecosystem stability and functioning. We evaluate the additive and combined effects of chronic anthropogenic disturbance (CAD) and rainfall variation on the temporal stability of mutualistic EFN‐bearing plant‐ant networks in a Caatinga dry fo...

This study examined how chronic anthropogenic disturbance impacts the spatiotemporal dynamics of ant foraging activity and the role played by behavioral traits. Ten plots (0.1 ha) along a gradient of chronic disturbance intensity were sampled in Catimbau National Park (Caatinga vegetation, Brazil). Vegetative structure, ground surface temperature,...

Large‐scale spatial variability in plant‐pollinator communities (e.g., along geographic gradients, across different landscapes) is relatively well understood. However, we know much less about how these communities vary at small scales within a uniform landscape. Plants are sessile and highly sensitive to microhabitat conditions, whereas pollinators...

The emerging field of nutritional geometry (NG) provides powerful new approaches to test whether and how organisms prioritize specific nutritional blends when consuming chemically complex foods. NG approaches can thus help move beyond food-level estimates of diet breadth to predict invasive success, for instance by revealing narrow nutritional nich...

As global temperatures rise, the mechanistic links between temperature, physiology and behaviour will increasingly define predictions of ecological change. However, for many taxa, we currently lack consensus about how thermal performance traits vary within and across populations, and whether and how locally adaptive trait plasticity can buffer warm...

Flower and leaf herbivory might cause relevant and negative impacts on plant fitness. While flower removal or damage by florivores produces direct negative effects on plant fitness, folivores affect plant fitness by reducing resource allocation to reproduction. In this study, we examine the effects of both flower and leaf herbivory by leaf-cutting...

Anthropogenic disturbance and climate change are the main drivers of biodiversity loss and ecological services around the globe. There is concern that climate change will exacerbate the impacts of disturbance and thereby promote biotic homogenization, but its consequences for ecological services are unknown. We investigated the individual and inter...

Ecological communities are composed of species that interact with each other forming complex interaction networks. Although interaction networks have been usually treated as static entities, interactions show high levels of temporal variation, mainly due to temporal species turnover. Changes in taxonomic composition are likely to bring about change...

Variable transformations used in analyses. (DOC)

Functional trait descriptions. (PDF)

Functional traits for each host species and literature source. (PDF)

Functional traits for each parasitoid species and literature source. (PDF)

Host and parasitoid species and their code numbers in Figs 1 and 2. (DOC)

Biweekly fluctuations in percent parasitism. Mean percent parasitism for each fortnight (computing percent parasitism in each plot for each fortnight and then computing mean value considering all plots for each fortnight). (TIF)

La biodiversidad comprende las distintas especies de seres vivos, los genes que estos poseen, los ecosistemas que habitan y los procesos que se dan en estos ecosistemas. Generalmente el componente taxonómico es el que más rápido se asocia al estudio de la biodiversidad, pero para comprender las relaciones entre la biodiversidad, las funciones ecoló...

Pollinators in agroecosystems are often exposed to pesticide mixtures. Even at low concentrations, the effects of these mixtures on bee populations are difficult to predict due to potential synergistic interactions. In this paper, we orally exposed newly emerged females of the solitary beeOsmia bicornis to environmentally realistic levels of clothi...

Leafcutter ants are the ultimate insect superorganisms, with up to millions of physiologically specialized workers cooperating to cut and transport vegetation and then convert it into compost used to cultivate co-evolved fungi, domesticated over millions of years. We tested hypotheses about the nutrient-processing dynamics governing this functional...

La biodiversidad comprende las distintas especies de seres vivos, los genes que estos poseen, los ecosistemas que habitan y los procesos que se dan en estos ecosistemas. Generalmente el componente taxonómico es el que más rápido se asocia al estudio de la biodiversidad, pero para comprender las relaciones entre la biodiversidad, las funciones ecoló...

The relationship between levels of dominance and species richness is highly contentious, especially in ant communities. The dominance‐impoverishment rule states that high levels of dominance only occur in species‐poor communities, but there appear to be many cases of high levels of dominance in highly diverse communities. The extent to which domina...

Anthropogenic disturbance and climate change might negatively affect the ecosystem services provided by mutualistic networks. However, the effects of such forces remain poorly characterized. They may be especially important in dry forests, which (1) experience chronic anthropogenic disturbances ( CAD s) as human populations exploit forest resources...

Species flower production and flowering phenology vary from year to year due to extrinsic factors. Inter-annual variability in flowering patterns may have important consequences for attractiveness to pollinators, and ultimately, plant reproductive output. To understand the consequences of flowering pattern variability, a community approach is neces...

Non-metric multidimensional scaling (NMDS) analysis describing yearly and monthly variation in nectar composition. Ellipses correspond to standard deviations of the sampling events of each grouping factor (years or months). 1: March; 2: April; 3: May; 4: June. Points on figure (A) represents transect–year values. Points on figure (B) represents eac...

Mean nectar and pollen production per flower. (PDF)

Descriptive statistics of flower density, flowering peak and flowering duration of the 23 main plant species of the Garraf community. Species ordered by timing of flowering peak. (PDF)

Results of analyses exploring phylogenetic (Bloomberg’s K test) constraints on flowering pattern variability. (PDF)

Database used in the analyses. (ZIP)

The taxonomic diversity (TD) of tropical flora and fauna tends to increase during secondary succession. This increase may be accompanied by changes in functional diversity (FD), although the relationship between TD and FD is not well understood. To explore this relationship , we examined the correlations between the TD and FD of ants and forest age...