Moth body size increases with elevation along a complete tropical elevational gradient for two hyperdiverse clades

The body size of an animal is probably its most important functional trait. For arthropods, environmental drivers of body size variation are still poorly documented and understood, especially in tropical regions. We use a unique dataset for two species‐rich, phylogenetically independent moth taxa (Lepidoptera: Geometridae; Arctiinae), collected along an extensive tropical elevational gradient in Costa Rica, to investigate the correlates and possible causes of body‐size variation. We studied 15 047 specimens (794 species) of Geometridae and 4167 specimens (308 species) of Arctiinae to test the following hypotheses: 1) body size increases with decreasing ambient temperature, as predicted by the temperature–size rule; 2) body size increases with increasing rainfall and primary productivity, as predicted from considerations of starvation resistance; and 3) body size scales allometrically with wing area, as elevation increases, such that wing loading (the ratio of body size to wing area) decreases with increasing elevation to compensate for lower air density. To test these hypotheses, we examined forewing length as a proxy for body size in relation to ambient temperature, rainfall, vegetation index and elevation as explanatory variables in linear and polynomial spatial regression models. We analysed our data separately for males and females using two principal approaches: mean forewing length of species at each site, and mean forewing length of complete local assemblages, weighted by abundance. Body size consistently increased with elevation in both taxa, both approaches, both sexes, and also within species. Temperature was the best predictor for this pattern (–0.98 < r < –0.74), whereas body size was uncorrelated or weakly correlated with rainfall and enhanced vegetation index. Wing loading increased with elevation. Our results support the temperature–size rule as an important mechanism for body size variation in arthropods along tropical elevational gradients, whereas starvation resistance and optimization of flight mechanics seem to be of minor importance.     

Increasing winter temperatures explain body size decrease in wintering bird populations of Northern Europe—But response patterns vary along the spatioclimatic gradient

Aim

Recent evidence has shown changes in body size and shape of individuals, which are suggested to be a result of global warming caused by climate change. Here, we explored the spatiotemporal changes in wing length and body mass of 24 wintering bird species in Northern Europe and how these relate to temperature anomaly.

Location

Finland and Sweden, Europe.

Time Period

50 years, 1970 to 2020.

Major Taxa Studied

Birds, 24 species.

Methods

We used site-specific, long-term winter ringing data containing wing length and body mass measurements from across Sweden and Finland for 24 bird species. We modelled wing length and body mass change over time, in relation to the spatioclimatic gradient and as response to temperature anomalies (of [i] the same winter as the ringing took place, [ii] the previous winter and [iii] the previous spring) by accounting for phylogenetic relatedness between species and their species-specific responses to each predictor of interest.

Results

We show that across all species, body size has decreased since the 1970s, with a negative relationship between wing length and temperature anomalies of previous winters, suggesting carry-over effects likely linked to body size-related survival or dispersal. Body mass was negatively related to the temperature anomaly of the same winter, indicating more immediate effects related to reduced fat reserves during mild winters.

Main Conclusions

Our results highlight a climate-driven decrease in body size across several species and its association with positive anomalies in winter temperature in the high latitudes. However, the responses are not spatially uniform and there is considerable species-specific variation, emphasizing the importance of conducting multispecies studies when investigating responses to climate change. The mechanisms of decreasing wing length and body mass seem to differ and underline the immediate and carry-over effects of temperature warming during the nonbreeding season.     

Geographic variation of wing morphology of great fruit‐eating bats (Artibeus lituratus): environmental,genetic and spatial correlates of phenotypic differences

Responses of species to environmental gradients are important and frequent determinants of geographic phenotypic variation that can drive adaptive processes. Nonetheless, random genetic processes such as drift can also result in geographic variation in phenotypes, and should be evaluated before implicating selection as the process driving phenotypic change. We examined geographic variation in wing morphology of Artibeus lituratus among 18 different sites distributed across interior Atlantic Forest of Paraguay and Argentina. Moreover, we contrasted geographic variation with environmental, spatial, and genetic variation to test hypotheses related to selection and drift and their impacts on wing morphology. For A. lituratus distributed across interior Atlantic Forest, significant differences among sites characterized variation in wing morphology. Geographic variation was significantly related to climatic variables but not spatial or genetic distances. Such a pattern suggests that phenotypic variation is related to selection for particular environmental regimes, and not genetic drift. Four significant dimensions of phenotypic variation were determined. Three dimensions were related to variation among individuals in terms of wing tips, whereas one was related to overall body size. Wing tips are important for manoeuverability during flight and differences among sites likely reflect differences in forest and vegetation structure that must be managed during foraging. Although climate provides good surrogates for environmental variation, it is probably only an indirect cue of selection regimes that determine variation in wing morphology. Future studies should evaluate more direct environmental measures such as vegetation structure when attempting to interpret geographical variation in wing morphology.     

Intraspecific trait variation across elevation predicts a widespread tree species' climate niche and range limits

Global change is widely altering environmental conditions which makes accurately predicting species range limits across natural landscapes critical for conservation and management decisions. If climate pressures along elevation gradients influence the distribution of phenotypic and genetic variation of plant functional traits, then such trait variation may be informative of the selective mechanisms and adaptations that help define climatic niche limits. Using extensive field surveys along 16 elevation transects and a large common garden experiment, we tested whether functional trait variation could predict the climatic niche of a widespread tree species (Populus angustifolia) with a double quantile regression approach. We show that intraspecific variation in plant size, growth, and leaf morphology corresponds with the species' total climate range and certain climatic limits related to temperature and moisture extremes. Moreover, we find evidence of genetic clines and phenotypic plasticity at environmental boundaries, which we use to create geographic predictions of trait variation and maximum values due to climatic constraints across the western US. Overall, our findings show the utility of double quantile regressions for connecting species distributions and climate gradients through trait‐based mechanisms. We highlight how new approaches like ours that incorporate genetic variation in functional traits and their response to climate gradients will lead to a better understanding of plant distributions as well as identifying populations anticipated to be maladapted to future environments.     

Global patterns of intraspecific leaf trait responses to elevation

Elevational gradients are often used to quantify how traits of plant species respond to abiotic and biotic environmental variations. Yet, such analyses are frequently restricted spatially and applied along single slopes or mountain ranges. Since we know little on the response of intraspecific leaf traits to elevation across the globe, we here perform a global meta‐analysis of leaf traits in 109 plant species located in 4 continents and reported in 71 studies published between 1983 and 2018. We quantified the intraspecific change in seven morpho‐ecophysiological leaf traits along global elevational gradients: specific leaf area (SLA), leaf mass per area (LMA), leaf area (LA), nitrogen concentration per unit of area (Narea), nitrogen concentration per unit mass (Nmass), phosphorous concentration per unit mass (Pmass) and carbon isotope composition (δ¹³C). We found LMA, Narea, Nmass and δ¹³C to significantly increase and SLA to decrease with increasing elevation. Conversely, LA and Pmass showed no significant pattern with elevation worldwide. We found significantly larger increase in Narea, Nmass, Pmass and δ¹³C with elevation in warmer regions. Larger responses to increasing elevation were apparent for SLA of herbaceous compared to woody species, but not for the other traits. Finally, we also detected evidences of covariation across morphological and physiological traits within the same elevational gradient. In sum, we demonstrate that there are common cross‐species patterns of intraspecific leaf trait variation across elevational gradients worldwide. Irrespective of whether such variation is genetically determined via local adaptation or attributed to phenotypic plasticity, the leaf trait patterns quantified here suggest that plant species are adapted to live on a range of temperature conditions. Since the distribution of mountain biota is predominantly shifting upslope in response to changes in environmental conditions, our results are important to further our understanding of how plants species of mountain ecosystems adapt to global environmental change.     

Examining variation in the leaf mass per area of dominant species across two contrasting tropical gradients in light of community assembly

Understanding variation in key functional traits across gradients in high diversity systems and the ecology of community changes along gradients in these systems is crucial in light of conservation and climate change. We examined inter‐ and intraspecific variation in leaf mass per area (LMA) of sun and shade leaves along a 3330‐m elevation gradient in Peru, and in sun leaves across a forest–savanna vegetation gradient in Brazil. We also compared LMA variance ratios (T‐statistics metrics) to null models to explore internal (i.e., abiotic) and environmental filtering on community structure along the gradients. Community‐weighted LMA increased with decreasing forest cover in Brazil, likely due to increased light availability and water stress, and increased with elevation in Peru, consistent with the leaf economic spectrum strategy expected in colder, less productive environments. A very high species turnover was observed along both environmental gradients, and consequently, the first source of variation in LMA was species turnover. Variation in LMA at the genus or family levels was greater in Peru than in Brazil. Using dominant trees to examine possible filters on community assembly, we found that in Brazil, internal filtering was strongest in the forest, while environmental filtering was observed in the dry savanna. In Peru, internal filtering was observed along 80% of the gradient, perhaps due to variation in taxa or interspecific competition. Environmental filtering was observed at cloud zone edges and in lowlands, possibly due to water and nutrient availability, respectively. These results related to variation in LMA indicate that biodiversity in species rich tropical assemblages may be structured by differential niche‐based processes. In the future, specific mechanisms generating these patterns of variation in leaf functional traits across tropical environmental gradients should be explored.     

Environmental determinants of population divergence in life‐history traits for an invasive species: climate,seasonality and natural enemies

Invasive species cope with novel environments through both phenotypic plasticity and evolutionary change. However, the environmental factors that cause evolutionary divergence in invasive species are poorly understood. We developed predictions for how different life‐history traits, and plasticity in those traits, may respond to environmental gradients in seasonal temperatures, season length and natural enemies. We then tested these predictions in four geographic populations of the invasive cabbage white butterfly (Pieris rapae) from North America. We examined the influence of two rearing temperatures (20 and 26.7 °C) on pupal mass, pupal development time, immune function and fecundity. As predicted, development time was shorter and immune function was greater in populations adapted to longer season length. Also, phenotypic plasticity in development time was greater in regions with shorter growing seasons. Populations differed significantly in mean and plasticity of body mass and fecundity, but these differences were not associated with seasonal temperatures or season length. Our study shows that some life‐history traits, such as development time and immune function, can evolve rapidly in response to latitudinal variation in season length and natural enemies, whereas others traits did not. Our results also indicate that phenotypic plasticity in development time can also diverge rapidly in response to environmental conditions for some traits.     

Moose body mass variation revisited: disentangling effects of environmental conditions and genetics

Large-scale geographical variation in phenotypic traits within species is often correlated to local environmental conditions and population density. Such phenotypic variation has recently been shown to also be influenced by genetic structuring of populations. In ungulates, large-scale geographical variation in phenotypic traits, such as body mass, has been related to environmental conditions and population density, but little is known about the genetic influences. Research on the genetic structure of moose suggests two distinct genetic lineages in Norway, structured along a north-south gradient. This corresponds with many environmental gradients, thus genetic structuring provides an additional factor affecting geographical phenotypic variation in Norwegian moose. We investigated if genetic structure explained geographical variation in body mass in Norwegian moose while accounting for environmental conditions, age and sex, and if it captured some of the variance in body mass that previously was attributed to environmental factors. Genetic structuring of moose was the most important variable in explaining the geographic variation in body mass within age and sex classes. Several environmental variables also had strong explanatory power, related to habitat diversity, environmental seasonality and winter harshness. The results suggest that environmental conditions, landscape characteristics, and genetic structure should be evaluated together when explaining large-scale patterns in phenotypic characters or life history traits. However, to better understand the role of genetic and environmental effects on phenotypic traits in moose, an extended individual-based study of variation in fitness-related characters is needed, preferably in an area of convergence between different genetic lineages.     

Body size variation of a high-Arctic seabird: the dovekie (Alle alle)

Variation in body size among subpopulations of the same species may reflect phenotypic or genetic responses to environmental gradients or geographical distance. Here, we examine geographical variation in the body size of the dovekie (Alle alle), the most numerous high-Arctic seabird. Locations of dovekie breeding sites are largely restricted to the high-Arctic zone of the Atlantic. We compared wing length, head-bill length, body mass, and a body size index of 1,076 birds from nine main colonies spanning a large part of the breeding range of the species. Results suggest morphological variation across the studied populations of dovekies, with a longitudinal increase in body size from west to east. The smallest birds breed in the western part of the population (Greenland and Jan Mayen), middle-sized individuals on Svalbard, and the largest birds (A. a. polaris subspecies) breed in the eastern part of the studied area, Franz Josef Land. Environmental (air temperature, wind speed, and sea surface temperature) and geographical (intercolonial distance) parameters were analyzed to explore potential mechanisms driving differences in body size. The body size of birds increased significantly with decreasing air temperature, but only when the two subspecies were considered. We did not find a relationship between sea surface temperature and body size of birds. Also, no close relationship was revealed between birds’ body size and the geographical distance between colonies. Whether the body size variation of dovekie can be explained by phenotypic plasticity in response to environmental conditions in wintering areas or a pattern of distance-independent gene flow between colonies remains to be explored.     

Altitudinal variation in body size in Abacarus panticis Keifer (Acari: Eriophyidae)

We found that body length of a minute eriophyoid mite, Abacarus panticis Keifer, increased with elevation and rainfall, decreased with temperature, and exhibited a female-biased dimorphism. There was a negative temperature–body length relation in the female instead of the male, whose size remained constant along temperature gradients. In addition, scaling of body length between sexes is not significantly different from one. We conclude that within-species body length of A. panticis conforms to Bergmann’s trend but not Rensch’s rule. Further studies could take advantage of the more rigorous and flexible hierarchical model in the revelation of scale-specific determinants of phenotypic variation.     

Characterizing the contribution of plasticity and genetic differentiation to community‐level trait responses to environmental change

The match between functional trait variation in communities and environmental gradients is maintained by three processes: phenotypic plasticity and genetic differentiation (intraspecific processes), and species turnover (interspecific). Recently, evidence has emerged suggesting that intraspecific variation might have a potentially large role in driving functional community composition and response to environmental change. However, empirical evidence quantifying the respective importance of phenotypic plasticity and genetic differentiation relative to species turnover is still lacking. We performed a reciprocal transplant experiment using a common herbaceous plant species (Oxalis montana) among low‐, mid‐, and high‐elevation sites to first quantify the contributions of plasticity and genetic differentiation in driving intraspecific variation in three traits: height, specific leaf area, and leaf area. We next compared the contributions of these intraspecific drivers of community trait–environment matching to that of species turnover, which had been previously assessed along the same elevational gradient. Plasticity was the dominant driver of intraspecific trait variation across elevation in all traits, with only a small contribution of genetic differentiation among populations. Local adaptation was not detected to a major extent along the gradient. Fitness components were greatest in O. montana plants with trait values closest to the local community‐weighted means, thus supporting the common assumption that community‐weighted mean trait values represent selective optima. Our results suggest that community‐level trait responses to ongoing climate change should be mostly mediated by species turnover, even at the small spatial scale of our study, with an especially small contribution of evolutionary adaptation within species.     

Trait differentiation and adaptation of plants along elevation gradients

Studies of genetic adaptation in plant populations along elevation gradients in mountains have a long history, but there has until now been neither a synthesis of how frequently plant populations exhibit adaptation to elevation nor an evaluation of how consistent underlying trait differences across species are. We reviewed studies of adaptation along elevation gradients (i) from a meta‐analysis of phenotypic differentiation of three traits (height, biomass and phenology) from plants growing in 70 common garden experiments; (ii) by testing elevation adaptation using three fitness proxies (survival, reproductive output and biomass) from 14 reciprocal transplant experiments; (iii) by qualitatively assessing information at the molecular level, from 10 genomewide surveys and candidate gene approaches. We found that plants originating from high elevations were generally shorter and produced less biomass, but phenology did not vary consistently. We found significant evidence for elevation adaptation in terms of survival and biomass, but not for reproductive output. Variation in phenotypic and fitness responses to elevation across species was not related to life history traits or to environmental conditions. Molecular studies, which have focussed mainly on loci related to plant physiology and phenology, also provide evidence for adaptation along elevation gradients. Together, these studies indicate that genetically based trait differentiation and adaptation to elevation are widespread in plants. We conclude that a better understanding of the mechanisms underlying adaptation, not only to elevation but also to environmental change, will require more studies combining the ecological and molecular approaches.     

Dynamics of phenotypic change: wing length declines in a resident farmland passerine despite survival advantage of longer wings

In many taxa, environmental changes that alter resource availability and energetics, such as climate change and land use change, are associated with changes in body size. We use wing length as a proxy for overall structural body size to examine a paradoxical trend of declining wing length within a Yellowhammer Emberiza citrinella population sampled over 21 years, in which it has been previously shown that longer wings are associated with higher survival rates. Higher temperatures during the previous winter (prior to the moult determining current wing length) explained 23% of wing length decrease within our population, but changes may also be correlated with non‐climatic environmental variation such as changes in farming mechanisms linked to food availability. We found no evidence for within‐individual wing length shrinkage with age, but our data suggested a progressive decline in the sizes of immature birds recruiting to the population. This trend was weaker, although not significantly so, among adults, suggesting that the decline in the sizes of recruits was offset by higher subsequent survival of larger birds post‐recruitment. These data suggest that ecological processes can contribute more than selection to observed phenotypic trends and highlight the importance of long‐term studies for providing longitudinal insights into population processes.     

Causes of variation in wing loading among Drosophila species

We examined influences on wing and body size in 11 species (12 strains) of Drosophila. Six measures of wing length and width were closely correlated with wing area and suggested little variation in wing shape among the species. Among ten species wing loading, an important factor in flight costs and manoeuvrability, increased as body mass increased at a rate consistent with expectations from allometric scaling of wing area and body mass to body length. Intraspecific variation in wing loading showed similar relationships to body mass. Density and temperature during larval development influenced wing loading through general allometric relations of body size and wing area. Temperature during the pupal stage, but not during wing hardening after eclosion, influenced wing area independently of body size. Wing area increased as growth temperature decreased. Individuals reared at cooler temperatures thus compensated for a potential allometric increase in wing loading by differentially enlarging the wing area during pupal development.     

Subtle but ubiquitous selection on body size in a natural population of collared flycatchers over 33 years

Understanding the magnitude and long‐term patterns of selection in natural populations is of importance, for example, when analysing the evolutionary impact of climate change. We estimated univariate and multivariate directional, quadratic and correlational selection on four morphological traits (adult wing, tarsus and tail length, body mass) over a time period of 33 years (≈ 19 000 observations) in a nest‐box breeding population of collared flycatchers (Ficedula albicollis). In general, selection was weak in both males and females over the years regardless of fitness measure (fledged young, recruits and survival) with only few cases with statistically significant selection. When data were analysed in a multivariate context and as time series, a number of patterns emerged; there was a consistent, but weak, selection for longer wings in both sexes, selection was stronger on females when the number of fledged young was used as a fitness measure, there were no indications of sexually antagonistic selection, and we found a negative correlation between selection on tarsus and wing length in both sexes but using different fitness measures. Uni‐ and multivariate selection gradients were correlated only for wing length and mass. Multivariate selection gradient vectors were longer than corresponding vector of univariate gradients and had more constrained direction. Correlational selection had little importance. Overall, the fitness surface was more or less flat with few cases of significant curvature, indicating that the adaptive peak with regard to body size in this species is broader than the phenotypic distribution, which has resulted in weak estimates of selection.     

Habitat range and phenotypic variation in salt marsh plants

Ecologists have long speculated that species with wider environmental ranges would have broader ranges in phenotype; however, most tests of this hypothesis have involved small numbers of species and/or closely related taxa. We related phenotypic variation in twelve salt marsh plant species from six families to variation in four environmental variables using multiple regression. Within species, plant phenotype was predictably related to environmental variation. Salinity was the most common predictor of plant traits, followed by organic content, water content and elevation. Across species, regressions of single plant trait CVs on range (2 × SD) of single environmental variables were not significant and did not support the hypothesis that species occupying broad environmental ranges would have broad ranges in phenotypes. However, regression of a composite phenotypic PCA1 on a composite environmental PCA1 showed a marginally significant (P = 0.054). linear relationship for 10 species. Considering the different patterns of response across species, the lack of a relationship between variation in single phenotypic traits and single environmental variables is likely because the distantly-related taxa employed fundamentally different morphological and physiological strategies to respond to environmental stress gradients. The significant relationship between composite environmental and phenotypic variables reflects the complex nature of species phenotypic response to multivariate environmental gradients. Specifically, in this system, species increase variation in the number of leaves, but decrease variation in leaf size in response to an increase in range of salinity and decrease in range of water and organic content.     

Adaptive plasticity in wing melanisation of a montane butterfly across a Himalayan elevational gradient

1. Traits that are significant to the thermal ecology of temperate or montane species are expected to prominently co-vary with the thermal environment experienced by an organism. The Himalayan Pieris canidia butterfly exhibits considerable variation in wing melanisation. We investigated: (i) whether variation in wing melanisation and (ii) activity period of this montane butterfly was influenced by the seasonally and elevationally changing thermal landscape.
2. We discovered that wing melanisation varied across elevation, seasons, sex, and wing surfaces, with the variation strongly structured in space and time: colder seasons and higher elevations produced more melanic individuals. Notably, melanisation did not vary uniformly across all wing surfaces: (i) melanisation of the ventral hindwing co-varied much more prominently with elevation, but (ii) melanisation on all other surfaces varied with seasonal changes in the thermal environment.
3. Observed wing surface-specific patterns indicated thermoregulatory function for this variation in melanisation. Such wing surface-specific responses to seasonal and elevational variation in temperature have rarely been reported in montane insects.
4. Moreover, daily and seasonal thermal cycles were found to strongly influence activity periods of this species, suggesting the potential limits to wing melanisation plasticity.
5. Overall, these results showed that the seasonal and elevational gradients in temperature influence the thermal phenotype as well as activity periods of this Himalayan butterfly. It will be critical to study the phenotypic evolution of such montane insects in response to the ongoing climate change, which is already showing significant signs in this iconic mountain range.

     

The validity of ecogeographical rules is context‐dependent: testing for Bergmann's and Allen's rules by latitude and elevation in a widespread Andean duck

Consistent responses by various organisms to common environmental pressures represent strong evidence of natural selection driving geographical variation. According to Bergmann's and Allen's rules, animals from colder habitats are larger and have smaller limbs than those from warmer habitats to minimize heat loss. Although evidence supporting both rules in different organisms exists, most studies have considered only elevational or latitudinal temperature gradients. We tested for the effects of temperature associated with both elevation and latitude on body and appendage size of torrent ducks (Merganetta armata), a widespread species in Andean rivers. We found a negative relationship between body size and temperature across latitude consistent with Bergmann's rule, whereas there was a positive relationship between these variables along replicate elevational gradients at different latitudes. Limb‐size variation did not support Allen's rule along latitude, nor along elevation. High‐elevation ducks were smaller and had longer wings than those inhabiting lower elevations within a river. We hypothesize that temperature is likely a major selective pressure acting on morphology across latitudes, although hypoxia or air density may be more important along elevational gradients. We conclude that the effect of temperature on morphology, and hence the likelihood of documenting ecogeographical ‘rules’, depends on the environmental context in which temperature variation is examined. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 850–862.     

Environmental heterogeneity,not distance,structures montane epigaeic spider assemblages in north-western Patagonia (Argentina)

There is considerable controversy around the patterns and processes that influence spatial variation in taxonomic composition in mountain environments. We analysed elevational variation in the taxonomic composition of epigaeic spider assemblages across five mountains in north-western Patagonia (Argentina) to examine the relative importance of dispersal (distance) limitation and environmental heterogeneity on a regional scale. The distance limitation hypothesis predicts greater taxonomic similarity between sampling sites separated by short geographical distances than between mountain peaks separated by longer distances, a lack of indicator species of macro-habitats, and weak associations between spider species composition and environmental gradients. Alternatively, the environmental heterogeneity hypothesis predicts that taxonomic differentiation will occur over short distances along elevation gradients in association with the turnover in major habitats and change in environmental conditions, and that indicator species will be present. We collected spiders using 486 pitfall traps arranged in fifty-four 100-m² grid plots of nine traps separated by ~?100 m of elevation, from the base to the summit of each mountain. Multivariate analyses identified spider assemblages that were associated with macro-habitats rather than with mountains. Local environmental variation (mainly in vegetation cover), precipitation and soil characteristics influenced the spatial variation in species composition. Characteristic indicator species showed high specificity and fidelity to macro-habitats, whereas vulnerable species showed high specificity and low fidelity to mountains or macro-habitats. We conclude that, on a regional scale, species adaptation to environmental gradients plays a more important role than dispersal limitation in structuring the taxonomic composition of spider assemblages. Moreover, the presence of indicator species suggests that spiders have a great potential as ecological indicators for evaluating the response of montane biodiversity to future climatic change.     

Do different rates of gene flow underlie variation in phenotypic and phenological clines in a montane grasshopper community?

Species responses to environmental change are likely to depend on existing genetic and phenotypic variation, as well as evolutionary potential. A key challenge is to determine whether gene flow might facilitate or impede genomic divergence among populations responding to environmental change, and if emergent phenotypic variation is dependent on gene flow rates. A general expectation is that patterns of genetic differentiation in a set of codistributed species reflect differences in dispersal ability. In less dispersive species, we predict greater genetic divergence and reduced gene flow. This could lead to covariation in life‐history traits due to local adaptation, although plasticity or drift could mirror these patterns. We compare genome‐wide patterns of genetic structure in four phenotypically variable grasshopper species along a steep elevation gradient near Boulder, Colorado, and test the hypothesis that genomic differentiation is greater in short‐winged grasshopper species, and statistically associated with variation in growth, reproductive, and physiological traits along this gradient. In addition, we estimate rates of gene flow under competing demographic models, as well as potential gene flow through surveys of phenological overlap among populations within a species. All species exhibit genetic structure along the elevation gradient and limited gene flow. The most pronounced genetic divergence appears in short‐winged (less dispersive) species, which also exhibit less phenological overlap among populations. A high‐elevation population of the most widespread species, Melanoplus sanguinipes, appears to be a sink population derived from low elevation populations. While dispersal ability has a clear connection to the genetic structure in different species, genetic distance does not predict growth, reproductive, or physiological trait variation in any species, requiring further investigation to clearly link phenotypic divergence to local adaptation.