Effects Of Intraspecific Variation Research Articles

Effects of intraspecific variation in a native species' phenology on its coexistence with non‐native plants

Intraspecific trait variation is ubiquitous and is likely to influence species coexistence. Despite theoretical progress, empirical work on the effects of intraspecific variation on the dynamics of competing species is rare. This is because of the formidable empirical requirements necessary to link intraspecific variation in species' functional traits with intraspecific variation in the demographic and competitive rates that mediate coexistence. Here we partially overcome these challenges to determine how intraspecific variation in reproductive phenology in a native Californian annual plant species Lasthenia californica affects its ability to coexist with two non‐native species Bromus madritensis and Lactuca serriola that display contrasting phenological patterns. Using data from a field experiment, we empirically parameterize a model of competitive population dynamics, accounting for the effects of intraspecific phenological trait variation on the native species' response to both intra‐ and interspecific competition. We find that intraspecific variation in phenology drives differences in the native species' response to competition. Moreover, simulations of the parameterized model show that this variation improves the competitive performance of the native species. This occurs because of the effects of nonlinear averaging mediated by a nonlinear, concave‐up competition function that is a general feature of competition across a wide range of taxa. While intraspecific variation improves competitive performance, we also find that the magnitude of the benefit is predicted to be insufficient to prevent competitive exclusion against the non‐native species with early phenogy Bromus. Against the second non‐native species with later phenology Lactuca, intraspecific variation is predicted to result in coexistence where competitive exclusion would otherwise occur, but we could not rule out alternative qualitative outcomes for this interaction.

Adaptive immune response selects for postponed maturation and increased body size

Abstract The Major Histocompatibility Complex (MHC) genes encode proteins that initiate the adaptive immune response by presenting pathogen‐derived antigenic peptides to T lymphocytes. Host–pathogen coevolution drives MHC polymorphism, introducing intraspecific variation in host life expectancy. This variation interacts with optimal growth strategy, as growth increases reproductive potential. While mortality rate and body size‐dependent fecundity are major factors shaping life histories, the effect of intraspecific variation in MHC‐based immunity on the evolution of growth strategies and host body size remains unknown. Here, we model how host MHC–pathogen coevolution—and its concomitant impact on host mortality—can affect the evolution of host life histories, as represented by age at maturation and body size. Life histories were compared in scenarios with and without adaptive immune response under equal population‐level mortality rates. We show that host–pathogen coevolutionary dynamics selects for postponed maturation and increased body size. Although MHC genes and genes that determine body size were physically unlinked, selection imposed by the Red Queen process generated linkage disequilibrium between immunocompetent MHC alleles and the maturation‐postponing alleles that prolong growth phase and increase body size. Particularly large body size was attained when pathogens mutated slowly, thus allowing the advantage of resistant MHC alleles to persist over multiple generations. The emergence of adaptive immunity, which is pathogen‐specific and enables immunological memory, is considered a major evolutionary innovation of vertebrates. Our work suggests that the adaptive immune response, mediated by polymorphic MHC genes, may drive the evolution of host body size. This form of adaptive immunity may have thus predisposed vertebrates to evolve large body size and exhibit the macroevolutionary patterns of increasing body size over time that have been detected in comparative studies. Read the free Plain Language Summary for this article on the Journal blog.

The Evolutionary Importance of Intraspecific Variation in Sexual Communication Across Sensory Modalities.

The evolution of sexual communication is critically important in the diversity of arthropods, which are declining at a fast pace worldwide. Their environments are rapidly changing, with increasing chemical, acoustic, and light pollution. To predict how arthropod species will respond to changing climates, habitats, and communities, we need to understand how sexual communication systems can evolve. In the past decades, intraspecific variation in sexual signals and responses across different modalities has been identified, but never in a comparative way. In this review, we identify and compare the level and extent of intraspecific variation in sexual signals and responses across three different modalities, chemical, acoustic, and visual, focusing mostly on insects. By comparing causes and possible consequences of intraspecific variation in sexual communication among these modalities, we identify shared and unique patterns, as well as knowledge needed to predict the evolution of sexual communication systems in arthropods in a changing world.

Evaluating individual tree species classification performance across diverse environments

Vegetation species mapping using airborne imaging spectroscopy yields accurate results and is important for advancing conservation objectives and biogeographic studies. As these data become more readily available owing to the upcoming launch of spaceborne imaging spectrometers, it is necessary to understand how these data can be used to consistently classify species across large geographic scales. However, few studies have attempted to map species across multiple ecosystems; therefore, little is known regarding the effect of intra-specific variation on the mapping of a single species across a wide range of environments and among varying backgrounds of other non-target species. To explore this effect, we developed and tested species classification models for Metrosideros polymorpha, a highly polymorphic canopy species endemic to Hawai’i, which is found in a diverse array of ecosystems. We compared the accuracies of support vector machine (SVM) and random forest models trained on canopy reflectance data from each of eight distinct ecosystems (ecosystem-specific) and a universal model trained on data from all ecosystems. When applied to ecosystem-specific test datasets, the ecosystem-specific models outperformed the universal model; however, the universal model retained high (>81%) accuracies across all ecosystems. Additionally, we found that models from ecosystems with broad variation in M. polymorpha canopy traits, as estimated using chemometric equations applied to canopy spectra, accurately predicted M. polymorpha in other ecosystems. While species classifications across ecosystems can yield accurate results, these results will require sampling procedures that capture the intra-specific variation of the target species.

The effects of intraspecific variation on forecasts of species range shifts under climate change

As global climate change is altering the distribution range of macroalgae across the globe, it is critical to assess its impact on species range shifts to inform the biodiversity conservation of macroalgae. Latitude/environmental gradients could cause intraspecific variability, which may result in distinct responses to climate change. It remains unclear whether geographical variation occurs in the response of species' populations to climate change. We tested this assumption using the brown alga Sargassum thunbergii, a habitat-forming macroalgae encompassing multiple divergent lineages along the Northwest Pacific. Previous studies revealed a distinct lineage of S. thunbergii in rear-edge populations. Given the phylogeographic structure and temperature gradients, we divided these populations into the southern and northern groups. We assessed the physiological responses of the two groups to temperature changes and estimated their niche differences using n-dimensional hypervolumes. A higher photosynthetic rate and antioxidative abilities were detected in the southern group of S. thunbergii than in the northern group. In addition, significant niche differentiation was detected between the two groups, suggesting the possibility for local adaptation. Given these results, we inferred that the southern group (rear-edge populations) may be more resilient to climate change. To examine climate-driven range shifts of S. thunbergii, we constructed species- and lineage-level species distribution models (SDMs). Predictions of both levels showed considerable distribution contracts along the Chinese coasts in the future. For the southern group, the lineage-level model predicted less habitat loss than the species-level model. Our results highlight the importance of considering intraspecific variation in climate change vulnerability assessments for coastal species.

Consequences of intraspecific variation in seed size: does the presence of small seeds reduce predation on large ones?

Seeds produced by individual plants often vary substantially in size. Typically, larger seeds produce seedlings that have higher chances of establishment and survival relative to seedlings produced by smaller seeds. However, larger seeds are also preferred by granivores due to larger caloric content. While choosing the patch to forage, granivores might avoid the ones with smaller, less preferred seeds. We tested a novel hypothesis that the production of different size seeds by a plant may be a strategy to decrease predation by granivores. We conducted a 3-year seed removal experiment. We presented Quercus robur acorns in forests in three configurations: large acorns alone, medium acorns alone, and large acorns mixed with small ones. The impact of seed size on seed survival was inconsistent: in the first year of the study, survival probability for seeds in the mixed treatment was significantly higher than survival probability of large seeds alone, supporting our hypothesis. However, in the following years, results were non-significant, probably because of reduced granivore selectivity in poor seed crop years. Our study demonstrated that the impact of neighbourhood of different size seeds seed survival varied over time in Q. robur. This provides limited evidence that intraspecific variation in seed size could evolve to shift the interaction between trees and scatter hoarders away from predation and towards mutualism.

The effect of plant–plant interactions as a key biotic process mediating the spatial variation of phenotypes in a Pinus sylvestris forest

Key messageIn this work, we highlighted the importance of the phenotypic structure of forest in regulating inter-tree competition with scattered individuals showing larger growth than close neighbours, with lower growth rates.Plant interactions are among the fundamental processes shaping the structure and functioning of ecosystems as they modulate competitive dynamics. However, the connection between the response of individual growth to neighbours and to environmental conditions and the mechanisms determining interactions in monospecific stands remain poorly understood. Here, we followed a phenotypic-based approach to disentangle the effect of plant size, neighbourhood interactions and microhabitat effects on Pinus sylvestris growth and traits, as well as their spatial variation of growth. We mapped all adult trees (1002 pines) in a 2 ha stand and measured their height, DBH and crown projection. For each individual, we assessed its growth and a competition index in relation to the closest neighbours. Soil chemical and physical properties and ground cover were also measured in a grid within the stand. We analysed the effects of tree size, neighbour competition and microhabitat variation on tree growth with a linear model. We also used spatial mark-correlation functions to explore the spatial dependence of tree age, secondary growth and phenotypic traits. Our results showed that trees with close neighbours displayed lower growth rates, whilst individuals with larger growths appeared scattered throughout the stand. Moreover, we found that growth depended on competition, tree height and crown area while tree growth poorly correlated with age or microhabitat conditions. Our findings highlight the importance of forest structure, in regulating inter-tree competition and growth in a Mediterranean pure stand and they provide insight into the causes and consequences of intraspecific variation in this system.

Nutrient foraging ability promotes intraspecific competitiveness in the clonal plant Hydrocotyle vulgaris

Many plant species forage for nutrients by accumulating more biomass or ramets where soil nutrient availability is high. Nutrient foraging ability differs between species and between genotypes within species, can increase plant performance when nutrients are patchy, and may lead to differences in competitive ability and have community-level effects. Effects of intraspecific variation in nutrient foraging ability could be particularly strong in clonal species, in which individual genotypes can form large clones and persist for long times. We tested the hypotheses that clones with greater foraging ability (1) have greater ability to compete with other clones of the same species but (2) experience greater competition within a clone. Sets of clonal fragments of five clones of the perennial, creeping herb Hydrocotyle vulgaris were grown alone, with a fragment of a different clone, or with a second fragment of the same clone in pots with a uniform or patchy distribution of soil nutrients. Consistent with the first hypothesis, foraging ability and between-clone competitiveness as measured by less negative competitive response were positively related when nutrients were patchy but not when they were uniform. Contrary to the second hypothesis, foraging and within-clone competitiveness were negatively related. Intraspecific competition both between and within clones could thus select for greater foraging ability. If this in turn increases ability to compete with other species, it may help explain the dominance of some clonal species.

Divergent predator activity muddies the dynamic landscape of fear

AbstractThe landscape of fear (LOF) hypothesis is a unifying idea explaining the effects of predators on the space use of their prey. However, empirical evidence for this hypothesis is mixed. Recent work suggests that the LOF is dynamic, depending on the daily activity of predators, which allows prey to utilize risky places during predator down times. While this notion clarifies some discrepancies between predictions and observations, support for a dynamic LOF remains mixed. The underlying assumption of a dynamic LOF is strong predictability in predator activity cycles. Work in multi‐predator systems demonstrates the effect of differential behavior between predator species on the predictions of prey space use. However, none have considered the effect of intraspecific variation in predator behavior. Most, if not all, dynamic LOF studies base inference on the species‐level average activity pattern, implicitly assuming similarity within the predator population. We examined the dynamics and intraspecific variation in activity cycles within a population of coyotes (Canis latrans). We found seasonality in the predictability of coyote behavior, as well as divergent nocturnal and crepuscular activity patterns between individuals during summer. Activity dynamics were not related to range size, sex, body mass, or habitat complexity, but did vary by year. These results suggest that the predictability of activity patterns is seasonally dynamic, and failure to account for intraspecific variation in activity may cloud inference in LOF studies. We argue that future studies should not neglect the potential complexity of predator behavior with simplistic assumptions. By considering intraspecific variation in activity patterns, we may gain a clear picture of LOF dynamics.

Testing the limits of plant drought stress and subsequent recovery in four provenances of a widely distributed subtropical tree species.

Drought-induced tree mortality may increase with ongoing climate change. Unraveling the links between stem hydraulics and mortality thresholds, and the effects of intraspecific variation, remain important unresolved issues. We conducted a water manipulation experiment in a rain-out shelter, using four provenances of Schima superba originating from a gradient of annual precipitation (1124-1796 mm) and temperature (16.4-22.4°C). Seedlings were droughted to three levels of percentage loss of hydraulic conductivity (i.e., P50 , P88 and P99) and subsequently rewatered to field capacity for 30 days; traits related to water and carbon relations were measured. The lethal water potential associated with incipient mortality was between P50 and P88 . Seedlings exhibited similar drought responses in xylem water potential, hydraulic conductivityand gas exchange. Upon rehydration, patterns of gas exchange differed among provenances but were not related to the climate at the origin. The four provenances exhibited a similar degree of stem hydraulic recovery, which was correlated with the magnitude of antecedent drought and stem soluble sugar at the end of the drought. Results suggest that there were intraspecific differences in the capacity of S. superba seedlings for carbon assimilation during recovery, indicating a decoupling between gas exchange recovery and stem hydraulics across provenances.

Natural variation identifies a Pxy gene controlling vascular organisation and formation of nodules and lateral roots in Lotus japonicus.

Forward and reverse genetics using the model legumes Lotus japonicus and Medicago truncatula have been instrumental in identifying the essential genes governing legume-rhizobia symbiosis. However, little information is known about the effects of intraspecific variation on symbiotic signalling. Here, we use quantitative trait locus sequencing (QTL-seq) to investigate the genetic basis of the differentiated phenotypic responses shown by the Lotus accessions Gifu and MG20 to inoculation with the Mesorhizobium loti exoU mutant that produces truncated exopolysaccharides. We identified through genetic complementation the Pxy gene as a component of this differential exoU response. Lotus Pxy encodes a leucine-rich repeat receptor-like kinase similar to Arabidopsis thaliana PXY, which regulates stem vascular development. We show that Lotus pxy insertion mutants displayed defects in root and stem vascular organisation, as well as lateral root and nodule formation. Our work links Pxy to de novo organogenesis in the root, highlights the genetic overlap between regulation of lateral root and nodule formation, and demonstrates that natural variation in Pxy affects nodulation signalling.

Limits to load-lifting performance in a passerine bird: the effects of intraspecific variation in morphological and kinematic parameters.

Although more massive flight muscles along with larger wings, higher wingbeat frequencies and greater stroke amplitudes enhance force and power production in flapping flight, the extent to which these parameters may be correlated with other morphological features relevant to flight physiology and biomechanics remains unclear. Intraspecifically, we hypothesized that greater vertical load-lifting capacity would correlate with higher wingbeat frequencies and relatively more massive flight muscles, along with relatively bigger hearts, lungs, and stomachs to enhance metabolic capacity and energy supply, but also with smaller body size given the overall negative allometric dependence of maximum flight performance in volant taxa. To explore intraspecific correlates of flight performance, we assembled a large dataset that included 13 morphological and kinematic variables for a non-migratory passerine, the Eurasian tree sparrow (Passer montanus). We found that heavier flight muscles and larger wings, heavier stomachs and shorter bills were the most important correlates of maximum load-lifting capacity. Surprisingly, wingbeat frequency, wing stroke amplitude and masses of the heart, lungs and digestive organs (except for the stomach) were non-significant predictor variables relative to lifting capacity. The best-fit structural equation model (SEM) indicated that load-lifting capacity was positively correlated with flight muscle mass, wing area and stomach mass, but was negatively correlated with bill length. Characterization of individual variability in flight performance in a free-ranging passerine indicates the subtlety of interaction effects among morphological features, some of which differ from those that have been identified interspecifically for maximum flight performance in birds.

Causes and consequences of intraspecific variation in animal responses to anthropogenic noise.

Anthropogenic noise is a recognized global pollutant, affecting a wide range of nonhuman animals. However, most research considers only whether noise pollution has an impact, ignoring that individuals within a species or population exhibit substantial variation in responses to stress. Here, we first outline how intrinsic characteristics (e.g., body size, condition, sex, and personality) and extrinsic factors (e.g., environmental context, repeated exposure, prior experience, and multiple stressors) can affect responses to environmental stressors. We then present the results of a systematic search of the anthropogenic-noise literature, identifying articles that investigated intraspecific variation in the responses of nonhuman animals to noise. This reveals that fewer than 10% of articles (51 of 589) examining impacts of noise test experimentally for intraspecific variation in responses; of those that do, more than 75% report significant effects. We assess these existing studies to determine the current scope of research and findings to-date, and to provide suggestions for good practice in the design, implementation, and reporting of robust experiments in this field. We close by explaining how understanding intraspecific variation in responses to anthropogenic noise is crucial for improving how we manage captive animals, monitor wild populations, model species responses, and mitigate effects of noise pollution on wildlife. Our aim is to stimulate greater knowledge and more effective management of the harmful consequences of this global pollutant.

Different phenotypic plastic responses to predators observed among aphid lineages specialized on different host plants

The role of intraspecific variation in the magnitude and direction of plastic responses in ecology and evolution is increasingly recognized. However, the factors underlying intraspecific variation in plastic responses remain largely unexplored, particularly for the hypothesis that the herbivores’ phenotypic response to predators might vary amongst lineages associated with different host plants. Here, we tested whether plant-specialized lineages of the pea aphid, Acyrthosiphon pisum, differed in their transgenerational phenotypic response to ladybird predators (i.e., the asexual production of winged offspring by wingless mothers). In a full factorial laboratory experiment, we found that six aphid clonal lineages each specialized either on alfalfa or clover significantly differed in their transgenerational phenotypic response to predators. Some lineages produced an increased number of winged aphids in predator presence while others did not respond. Aphid lineages specialized on alfalfa had stronger phenotypic responses to predators than those specialized on clover. Although we tested only six aphid lineages from two biotypes, our results imply that intraspecific variation in prey phenotypic response of herbivores to predators differs amongst lineages specialized on different host plants. Our findings therefore raise the question of the influence of plant specialization in shaping herbivore phenotypic responses, and highlight the need to consider multi-trophic interactions to understand the causes and consequences of intraspecific variation in complex phenotypic traits.

Sex differences in pollinator behavior: Patterns across species and consequences for the mutualism.

Intraspecific variation in floral visitor behaviour and pollination efficiency has been much less studied than interspecific variation. Nevertheless, it is clear that large differences in these traits exist within species, and in particular between sexes within species. With the exception of a few well-studied interactions, however, the consequences of these differences in the pollinators and visited plants remain to be investigated. In this review, we document large and consistent differences in the foraging patterns of male and female pollinators that have been demonstrated to directly affect plant reproduction or that have clear potential to do so. Males and females differ in visitation frequency, type of flowers visited, and per-visit pollen transfer. Females gather more and different resources from flowers compared to males, and males generally tend to show more mobile foraging patterns than females. We argue that these sex-associated patterns have broad generality across pollinators, and that sex-associated differences can in some cases be larger than differences between species. We offer predictions about how these patterns will influence pollinator preference, specialization, and fidelity, as well as the cost, quality and quantity of pollination service to plants. In the face of increasing threats to plant-pollinator interactions, understanding their basic functioning and the variation inherent in their component parts is critical. We advocate for more attention to sex-based differences among pollinators in particular, and the consequences of intraspecific variation more broadly.

Consequences of intraspecific variation in seed dispersal for plant demography, communities, evolution and global change.

As the single opportunity for plants to move, seed dispersal has an important impact on plant fitness, species distributions and patterns of biodiversity. However, models that predict dynamics such as risk of extinction, range shifts and biodiversity loss tend to rely on the mean value of parameters and rarely incorporate realistic dispersal mechanisms. By focusing on the mean population value, variation among individuals or variability caused by complex spatial and temporal dynamics is ignored. This calls for increased efforts to understand individual variation in dispersal and integrate it more explicitly into population and community models involving dispersal. However, the sources, magnitude and outcomes of intraspecific variation in dispersal are poorly characterized, limiting our understanding of the role of dispersal in mediating the dynamics of communities and their response to global change. In this manuscript, we synthesize recent research that examines the sources of individual variation in dispersal and emphasize its implications for plant fitness, populations and communities. We argue that this intraspecific variation in seed dispersal does not simply add noise to systems, but, in fact, alters dispersal processes and patterns with consequences for demography, communities, evolution and response to anthropogenic changes. We conclude with recommendations for moving this field of research forward.

Trait expression and signatures of adaptation in response to nitrogen addition in the common wetland plant Juncus effusus.

Wetland ecosystems are known to mitigate high nutrient loadings and thus can improve water quality and prevent potential biodiversity loss caused by eutrophication. Plant traits affect wetland processes directly through effects on accumulation or metabolization of substances, and indirectly by affecting microbial transformation processes in the soil. Understanding the causes and consequences of intraspecific variation in plant functional traits and associated ecosystem processes can aid applied ecological approaches such as wetland restoration and construction. Here we investigated molecular variation and phenotypic variation in response to three levels of nitrogen availability for a regional set of populations of the common wetland plant Juncus effusus. We asked whether trait expression reveals signatures of adaptive differentiation by comparing genetic differentiation in quantitative traits and neutral molecular markers (QST—FST comparisons) and relating trait variation to soil conditions of the plant’s origin. Molecular analyses showed that samples clustered into three very distinct genetic lineages with strong population differentiation within and among lineages. Differentiation for quantitative traits was substantial but did not exceed neutral expectations when compared across treatments or for each treatment and lineage separately. However, variation in trait expression could be explained by local soil environmental conditions of sample origin, e.g. for aboveground carbon-to-nitrogen (C:N) ratios, suggesting adaptive differentiation to contribute to trait expression even at regional level.

Independent and interactive effects of plant genotype and environment on plant traits and insect herbivore performance: A meta‐analysis with Salicaceae

Abstract Ecological research has increasingly highlighted the importance of intraspecific variation in shaping the structure and function of communities and ecosystems. Indeed, the effects of intraspecific variation can match or exceed those of interspecific variation. Previous reviews of intraspecific variation in plant traits across heterogeneous environments have focused primarily on mean phenotypic effects. We propose that a richer and fuller understanding of the ecological causes and consequences of intraspecific variation would be provided by partitioning trait variance into its subcomponents (genetic, environment, genotype by environment interaction). We used a meta‐analysis of 352 sets of genetic, environment and genotype by environment (G×E) variation estimates from 72 studies of Salicaceae to compare these sources of variation across plant traits (growth, foliar nitrogen, defence compounds), insect herbivore performance metrics (e.g., survival, growth, fecundity) and environmental conditions (e.g., soil nutrients, water, defoliation). Our findings revealed that variation in levels of defence compounds (both condensed tannins and salicinoids) and insect herbivore performance were primarily genetically determined, while variation in plant growth and foliar nitrogen was more environmentally determined. Plasticity in plant growth, foliar nitrogen levels and insect herbivore performance varied substantially across different sites (year × location), and nutrient, water and carbon dioxide environments. Plasticity was lowest for chemical defence traits and all traits in contrasting ozone and defoliation environments. Our quantitative review also revealed several gaps in the literature, including a need for surveying more mature plants, a wider variety of insect herbivore species (e.g., leaf‐galling insects, specialist insects) and underrepresented environmental treatments (e.g., competition, defoliation, disease, light and water availability). Findings from this analysis highlight the importance of, and patterns within, intraspecific variation with respect to shaping the evolvability and plasticity of traits and governing the interactions of plants and insects. A plain language summary is available for this article.

Trait-based ecology of terrestrial arthropods.

ABSTRACTIn focusing on how organisms' generalizable functional properties (traits) interact mechanistically with environments across spatial scales and levels of biological organization, trait‐based approaches provide a powerful framework for attaining synthesis, generality and prediction. Trait‐based research has considerably improved understanding of the assembly, structure and functioning of plant communities. Further advances in ecology may be achieved by exploring the trait–environment relationships of non‐sessile, heterotrophic organisms such as terrestrial arthropods, which are geographically ubiquitous, ecologically diverse, and often important functional components of ecosystems. Trait‐based studies and trait databases have recently been compiled for groups such as ants, bees, beetles, butterflies, spiders and many others; however, the explicit justification, conceptual framework, and primary‐evidence base for the burgeoning field of ‘terrestrial arthropod trait‐based ecology’ have not been well established. Consequently, there is some confusion over the scope and relevance of this field, as well as a tendency for studies to overlook important assumptions of the trait‐based approach. Here we aim to provide a broad and accessible overview of the trait‐based ecology of terrestrial arthropods. We first define and illustrate foundational concepts in trait‐based ecology with respect to terrestrial arthropods, and justify the application of trait‐based approaches to the study of their ecology. Next, we review studies in community ecology where trait‐based approaches have been used to elucidate how assembly processes for terrestrial arthropod communities are influenced by niche filtering along environmental gradients (e.g. climatic, structural, and land‐use gradients) and by abiotic and biotic disturbances (e.g. fire, floods, and biological invasions). We also review studies in ecosystem ecology where trait‐based approaches have been used to investigate biodiversity–ecosystem function relationships: how the functional diversity of arthropod communities relates to a host of ecosystem functions and services that they mediate, such as decomposition, pollination and predation. We then suggest how future work can address fundamental assumptions and limitations by investigating trait functionality and the effects of intraspecific variation, assessing the potential for sampling methods to bias the traits and trait values observed, and enhancing the quality and consolidation of trait information in databases. A roadmap to guide observational trait‐based studies is also presented. Lastly, we highlight new areas where trait‐based studies on terrestrial arthropods are well positioned to advance ecological understanding and application. These include examining the roles of competitive, non‐competitive and (multi‐)trophic interactions in shaping coexistence, and macro‐scaling trait–environment relationships to explain and predict patterns in biodiversity and ecosystem functions across space and time. We hope this review will spur and guide future applications of the trait‐based framework to advance ecological insights from the most diverse eukaryotic organisms on Earth.

Landscape permeability and individual variation in a dispersal-linked gene jointly determine genetic structure in the Glanville fritillary butterfly.

There is now clear evidence that species across a broad range of taxa harbor extensive heritable variation in dispersal. While studies suggest that this variation can facilitate demographic outcomes such as range expansion and invasions, few have considered the consequences of intraspecific variation in dispersal for the maintenance and distribution of genetic variation across fragmented landscapes. Here, we examine how landscape characteristics and individual variation in dispersal combine to predict genetic structure using genomic and spatial data from the Glanville fritillary butterfly. We used linear and latent factor mixed models to identify the landscape features that best predict spatial sorting of alleles in the dispersal‐related gene phosphoglucose isomerase (Pgi). We next used structural equation modeling to test if variation in Pgi mediated gene flow as measured by Fst at putatively neutral loci. In a year when the population was recovering following a large decline, individuals with a genotype associated with greater dispersal ability were found at significantly higher frequencies in populations isolated by water and forest, and these populations showed lower levels of genetic differentiation at neutral loci. These relationships disappeared in the next year when metapopulation density was high, suggesting that the effects of individual variation are context dependent. Together our results highlight that (1) more complex aspects of landscape structure beyond just the configuration of habitat can be important for maintaining spatial variation in dispersal traits and (2) that individual variation in dispersal plays a key role in maintaining genetic variation across fragmented landscapes.