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opencc-zeroOct 2020View details →

Thermal niche traits of high alpine plant species and communities across the tropical Andes and their vulnerability to global warming

<a name="_Hlk10643461">Aim</a> The Climate Variability Hypothesis (CVH) predicts that locations with reduced seasonal temperature variation select for species with narrower thermal ranges. Here we (1) test the CVH by assessing the effect of latitude and elevation on the thermal ranges of Andean vascular plant species and communities, and (2) assess tropical alpine plants vulnerability to warming based on their thermal traits. Location Tropical Andes Taxon Vascular plants Methods Temperature data for 505 vascular plant species from alpine communities on 49 summits, were extracted from 29,627 geo-referenced occurrences. Species thermal niche traits (TNTs) were estimated using bootstrapping for: minimum temperature, optimum (mean) temperature, and breadth (maximum-minimum). Plant community-weighted scores were estimated using the TNTs of their constituent species. CVH was tested for species, biogeographic species groups and communities. Vulnerability to global warming was assessed for species, biogeographic species groups and communities. Results Species restricted to the equator showed narrower thermal niche breadth than species whose ranges stretch far from the equator, however, no difference in niche breadth was found across summits' elevation. Biogeographic species groups distributed close to the equator and restricted to alpine regions showed narrower niche breadth than those with broader ranges. Community weighted-scores of thermal niche breadth were positively related to distance from equator but not to elevation. Based on their TNTs, species restricted to equatorial latitudes and plant communities dominated by these species were identified as the most vulnerable to the projected 1.5 °C warming, due to a potentially higher risk of losing thermal niche space. Main conclusions Our study confirms that the CVH applies to high tropical Andean plant species and communities, where latitude had a strong effect on the thermal niche breadth. TNTs are identified as suitable indicators of species' vulnerability to warming and are suggested to be included in long-term biodiversity monitoring in the Andes.

opencc-zeroOct 2020View details →

Evaluating a trait-based approach to compare natural enemy and pest communities in agroforestry versus arable systems

Diversified farming systems, for example those that incorporate agroforestry elements, have been proposed as a solution that could maintain and improve multiple ecosystem services. However, habitat diversification in and around arable fields has complex and inconsistent effects on invertebrate crop pests and their natural enemies. This hinders the development of policy recommendations to promote the adoption of such management strategies for the provision of natural pest control services. Here, for the first time we conducted a trait-based approach to investigate the effect of farming system on plant, invertebrate herbivore and invertebrate natural enemy communities. We then evaluated this approach by comparing the results to those generated using a traditional taxonomic approach. At each of three working farms, we sampled within an agroforestry field (a diverse farming system comprising alleys of arable crops separated by tree rows), and within a paired non-diversified area of the farm (arable control field). Each of 96 sample points was sampled between eight and ten times, yielding 393,318 invertebrate specimens from 344 taxonomic groups. Diet specialization or granivory, lack of a pupal stage, and wing traits in invertebrates, along with late flowering, short flowering duration, creeping habit and perenniality in plants, were traits more strongly associated with agroforestry crop alleys than the arable control fields. We hypothesize that this is a result of reduced habitat disturbance and increased habitat complexity in the agroforestry system. Taxonomic richness and diversity were higher in the agroforestry crop alleys compared to the arable control fields, but these effects were stronger at lower trophic levels. However, functional trait diversity of natural enemies was significantly higher in the agroforestry crop alleys than the arable control fields, suggesting an improved level of biocontrol, which was not detected by traditional diversity metrics. Of eight key pest taxa, three were significantly suppressed in the agroforestry system, whilst two were more abundant, compared to the arable control fields. Trait-based approaches can provide a better mechanistic understanding of farming system effects on pests and their natural enemies, therefore we recommend their application and testing in future studies of diversified farming systems.

Adaptive trait syndromes along multiple economic spectra define cold and warm adapted ecotypes in a widely distributed foundation tree species

1. The coordination of traits from individual organs to whole plants is under strong selection because of environmental constraints on resource acquisition and use. However, the tight coordination of traits may provide underlying mechanisms of how locally adapted plant populations can become maladapted because of climate change. 2. To better understand local adaptation in intraspecific trait coordination, we studied trait variability in the widely distributed foundation tree species, Populus fremontii using a common garden near the mid-elevational point of this species distribution. We examined 28 traits encompassing four spectra: phenology, leaf economic spectrum (LES), whole-tree architecture (Corner's Rule), and wood economic spectrum (WES). 3. Based on adaptive syndrome theory, we hypothesized that trait expression would be coordinated among and within trait spectra, reflecting local adaptation to either exposure to freeze-thaw conditions in genotypes sourced from high-elevation populations or exposure to extreme thermal stress in genotypes sourced from low-elevation populations. 4. High-elevation genotypes expressed traits within the phenology and WES that limit frost exposure and tissue damage. Specifically, genotypes sourced from high elevations had later mean budburst, earlier mean budset, higher wood densities, higher bark fractions, and smaller xylem vessels than their low-elevation counterparts. Conversely, genotypes sourced from low elevations expressed traits within the LES that prioritized hydraulic efficiency and canopy thermal regulation to cope with extreme heat exposure, including 40% smaller leaf areas, 67% higher stomatal densities, and 34% higher mean theoretical maximum stomatal conductance. Low-elevation genotypes also expressed a lower stomatal control over leaf water potentials that subsequently dropped to pressures that could induce hydraulic failure. 5. Synthesis. Our results suggest that P. fremontii expresses a high degree of coordination across multiple trait spectra to adapt to local climate constraints on photosynthetic gas exchange, growth, and survival. These results, therefore, increase our mechanistic understanding of local adaptation and the potential effects of climate change that in turn, improves our capacity to identify genotypes that are best suited for future restoration efforts.

opencc-zeroOct 2021View details →

Data from: Sampling beetle communities: trap design interacts with weather and species traits to bias capture rates

Globally, many insect populations are declining, prompting calls for action. Yet these findings have also prompted discussion about sampling methods and interpretation of long-term datasets. As insect monitoring and research efforts increase, it is critical to quantify the effectiveness of sampling methods. This is especially true if sampling biases of different methods covary with climate, which is also changing over time. We assess the effectiveness of two types of flight intercept traps commonly used for beetles, a diverse insect group responsible for numerous ecosystem services, under different climatic conditions in Norwegian boreal forest. One of these trap designs includes a device to prevent rainwater from entering the collection vial, diluting preservatives and flushing out beetles. This design is compared to a standard trap. We ask how beetle capture rates vary between these traps, and how these differences vary based on precipitation levels and beetle body size, an important species trait. Bayesian mixed models reveal that the standard and modified traps differ in their beetle capture rates, but that the magnitude and direction of these differences change with precipitation levels and beetle body size. At low rainfall levels standard traps catch more beetles, but as precipitation increases the catch rates of modified traps overtake those of standard traps. This effect is most pronounced for large-bodied beetles. Sampling methods are known to differ in their effectiveness. Here, we present evidence for a less well-known but likely common phenomenon - an interaction between climate and sampling, such that relative effectiveness of trap types for beetle sampling differs depending on precipitation levels and species traits. This highlights a challenge for long-term monitoring programs, where both climate and insect populations are changing. Sampling methods should be sought that eliminate climate interactions, any biases should be quantified, and all insect datasets should include detailed methodological metadata.

Data from: Stabilizing selection and adaptive evolution in a combination of two traits in an arctic ungulate

Stabilizing selection is thought to be common in wild populations and act as one of the main evolutionary mechanisms which constrain phenotypic variation. When multiple traits interact to create a combined phenotype, correlational selection may be an important process driving adaptive evolution. Here we report on phenotypic selection and evolutionary changes in two natal traits in a semi-domestic population of reindeer (Rangifer tarandus) in northern Finland. The population has been closely monitored since 1969, and detailed data has been collected on individuals since they were born. Over the length of the study period (1969 - 2015), we found directional and stabilizing selection towards a combination of earlier birth date and heavier birth mass with an intermediate optimum along the major axis of the selection surface. In addition, we demonstrate significant changes in mean traits towards earlier birth date and heavier birth mass, with corresponding genetic changes in breeding values during the study period. Our results demonstrate evolutionary changes in a combination of two traits which agree closely with estimated patterns of phenotypic selection. Knowledge of the selective surface for combinations of genetically correlated traits are vital to predict how population mean phenotypes and fitness are affected when environments change.

Simulated pollinator declines intensify selection on floral traits that facilitate selfing and outcrossing in Impatiens capensis

PREMISE OF THE STUDY: Anthropogenic environmental change is causing pollinator populations to decline. These declines should intensify selection for floral traits that facilitate outcrossing by making plants more attractive to pollinators and/or for floral traits that facilitate selfing in the absence of pollinators. However, the effect of pollinator declines on selection on floral traits could be modified by other environmental factors such as herbivores. METHODS: We studied the effect of simulated pollinator declines on selection on floral traits of Impatiens capensis, a mixed-mating species that produces both obligately selfing cleistogamous flowers and primarily outcrossing chasmogamous flowers. We measured directional selection differentials via seeds per plant on two traits that facilitate outcrossing (chasmogamous flower size and number) and one trait that facilitates selfing (cleistogamous flower number) in ambient, reduced pollinator access, and reduced pollinator access + increased foliar herbivory treatments. RESULTS: Reduced pollinator access intensified selection for larger chasmogamous flowers and more cleistogamous flowers. In contrast, increased herbivory did not affect selection on any floral trait. CONCLUSIONS: Reduced pollinator access intensified selection for a trait that facilitates outcrossing, suggesting that even species such as I. capensis that can autonomously self-pollinate have the potential to respond to pollinator declines by evolving floral traits that reinforce interactions between plants and pollinators. However, reduced pollinator access also intensified selection for a trait that facilitates selfing, suggesting that I. capensis could adapt to pollinator declines by evolving floral traits that maintain the production of both selfed and outcrossed seeds.

opencc-by-4.0Dec 2019View details →

zenodo32/100

Once upon a time in the far south: Influence of local drivers and functional traits on plant invasion in the harsh sub-Antarctic islands

Data and R code to replicate the analyses presented in the manuscript "Once upon a time in the far south: Influence of local drivers and functional traits on plant invasion in the harsh sub-Antarctic islands".

Data: Sexual selection increased offspring production via evolution of male and female traits

Phenotypic evolution driven by sexual selection can impact the fitness of individuals and thus population performance through multiple mechanisms, but it is unresolved how and when sexual selection affects offspring production by females.We examined the effects of sexual selection on offspring production by females using replicated experimental evolutionary lines of Callosobruchus chinensis that were kept under polygamy (with sexual selection) or monogamy (without sexual selection) for 21 generations. We found that polygamous-line pairs produced more offspring than monogamous-line pairs, because polygamous-line beetles evolved to be larger than monogamous-line beetles, and larger females were more fecund. Egg hatchability did not differ between polygamous- and monogamous-line pairs, as a result of the positive and negative effects of sexual selection cancelling out. When mated with an individual from a common tester line, both polygamous-line females and males showed higher hatchability in resultant eggs than monogamous ones. Further, cohabitation with a male reduced egg hatchability, and this effect was more pronounced in polygamous- than in monogamous-line males. These results demonstrate multiple mechanisms by which sexual selection affects female fitness, with the net effect being positive. Analyses of how development time, body size and male genital morphology were influenced by selection regime suggest that these results arose from both evolution via good-gene processes and sexually antagonistic selection. Our results are also consistent with the hypothesis that the fitness consequences of sexual selection for females are dependent on the evolutionary history of the population.

opencc-zeroDec 2019View details →

Are leaf, stem and hydraulic traits good predictors of individual tree growth? (FUN2FUN project)

<ol> <li>A major foundation of trait-based ecology is that traits have an impact on individual performance. However, trait-growth relationships have not been extensively tested in trees, especially outside tropical ecosystems. In addition, measuring traits directly related to physiological processes ('hard traits') remains difficult and the differences between inter- and intraspecific relationships are seldom explored.</li> <li> Here, we use individual-level data on a set of hydraulic, leaf and stem traits to explore which traits are the best predictors of basal area increment (BAI) and growth efficiency (BAI per unit of tree leaf area, GE) among and within species for six dominant tree species along a water availability gradient under Mediterranean climate (Catalonia, NE Spain). Measured traits include: leaf mass per area (LMA), leaf nitrogen concentration (N), leaf C isotopic composition (d13C), stem wood density (WD), branch-level estimates of the Huber value (Hv), the sapwood-specific hydraulic conductivity (KS), the leaf-specific hydraulic conductivity (KL) and resistance to xylem embolism (P50), and the leaf water potential at turgor loss (Ptlp).</li> <li>Traits were better predictors of GE than BAI and significant relationships were largely driven by differences among species means. Contrary to our initial hypotheses, high values of both growth metrics were associated with 'conservative' leaf and hydraulic traits. In particular, BAI was negatively associated with wood density and hydraulic efficiency per unit leaf area (KL), while GE increased with LMA, allocation to sapwood relative to leaves (Hv) and resistance to xylem embolism (P50). Climate effects on BAI and GE were indirectly mediated by changes in traits, stand structure and tree size. Overall, these results suggest that maintaining functionality over extended periods of time may be more important that maximum gas exchange or hydraulic capacity to achieve high radial growth under Mediterranean climates.</li> <li>Our study reveals that the relationships between 'functional' traits and tree performance along environmental gradients are complex and do not necessarily conform to simple hypotheses based on our understanding of organ-level processes. Trait integration along common axes of variation together with a revaluation of the variables that better reflect whole-tree performance can greatly improve our understanding of trait-growth relationships.</li> </ol>

Rapid reversal of a potentially constraining genetic covariance between leaf and flower traits in Silene latifolia

Genetic covariance between two traits generates correlated responses to selection, and may either enhance or constrain adaptation. Silene latifolia exhibits potentially constraining genetic covariance between specific leaf area and flower number in males. Flower number is likely to increase via fecundity selection but the correlated increase in specific leaf area increases mortality, and specific leaf area is under selection to decrease in dry habitats. We selected on trait combinations in two selection lines for four generations to test whether genetic covariance could be reduced without significantly altering trait means. In one selection line, the genetic covariance changed sign and eigenstructure changed significantly, while in the other selection line eigenstructure remained similar to the control line. Changes in genetic variance-covariance structure are therefore possible without the introduction of new alleles, and the responses we observed suggest that founder effects and changes in frequency of alleles of major effect may be acting to produce the changes.

opencc-by-4.0Dec 2020View details →

zenodo32/100

Palma et al 2021 Plant functional traits reflect different dimensions of species invasiveness. Ecology. DATASET

Dataset used in publication Palma et al 2021 Plant functional traits reflect different dimensions of species invasiveness. Ecology. It includes: (1) records of Vegetative height and Specific leaf area for 82 exotic species measured in to Victoria, Australia. The location where the plant samples were collected is also described. See tab 'Trait_field_collection'. (2) traits and other variables collected from the literature, including Seed mass, Longevity, Reproduction type, Seed morphology, Dispersion vector, Likely introduction pathway, Management. See tab 'Traits_literature'.

Data from: Using a trait-based approach for assessing the vulnerability and resilience of hillslope seep wetland vegetation cover to disturbances in the Tsitsa River catchment, Eastern Cape, South Africa

Hill slope seep wetlands are ecologically and economically important ecosystems as they supply a variety of ecosystem services to society. In South Africa, livestock grazing is recognised as one of the most important disturbance factors changing the structure and function of hill slope seep wetlands. This study sought to investigate the potential effect of livestock grazing on the resilience and vulnerability of hillslope seep wetland vegetation cover using a trait based approach (TBA). Changes in vegetation cover were used as a surrogate for indicating grazing intensity. The degree of human disturbances was assessed using the Anthropogenic Activity Index (AAI). A TBA was developed using seven plant traits, resolved into 27 trait attributes. Based on the developed approach, plant species were grouped into vulnerable and resilient groups in relation to grazing pressure. It was then predicted that species belonging to the vulnerable group would be less dominant at the highly disturbed sites, as well as in the winter season when grazing pressure is at its peak. The approach developed enabled accurate predictions of the responses of hillslope plant species to grazing pressure seasonally, but spatially, only for the summer season. The predicted responses during the winter season across sites did not match the observed results, which could be attributed to the difficulty in species identification and accurate estimation of vegetation cover during winter. Overall, the approach developed here provides a general framework for applying the TBA and can thus be tested and applied elsewhere.

Cis-regulatory variation in the shavenbaby gene underlies intraspecific phenotypic variation, mirroring interspecific divergence in the same trait

Despite considerable progress in recent decades in dissecting the genetic causes of natural morphological variation, there is limited understanding of how variation within species ultimately contributes to species differences. We have studied patterning of the non-sensory hairs, commonly known as "trichomes," on the dorsal cuticle of first-instar larvae of Drosophila. Most Drosophila species produce a dense lawn of trichomes, but a subset of dorsal trichomes were lost in D. sechellia and D. ezoana due entirely to regulatory evolution of the shavenbaby (svb) gene. Here we describe intraspecific variation in dorsal trichome patterns of first-instar larvae of D. virilis that is similar to the trichome pattern variation identified previously between species. We found that 67% of this difference is explained by a QTL that contains svb and that svb expression correlates with trichome variation within D. virilis . Despite using an experimental design with reasonable power to detect a second locus accounting for the remainder of the variance in trichome number, only a single QTL could be mapped, suggesting that multiple other loci each make a small contribution to trichome patterning. Thus, the genetic architecture of intraspecific variation and interspecific differences exhibit similarities and differences that may reflect differences between short-term and long-term evolutionary processes.

Trait-modulated decline of carabid beetle occurrence along elevation gradients across the European Alps

Aim: To assess how species traits modulate the responses of carabids to elevation gradients, and how consistent these relationships are across different Alpine regions. Location: Italian Alps. Taxon: Coleoptera, Carabidae (ground beetles) Methods: Carabid communities were sampled using pitfall traps along elevation gradients (697-2840 m) in 416 study sites comprising a range of habitat types. The probability of carabid occurrence was modelled in relation to elevation and its interaction with two key traits, body size and wing development, using a mixed-modelling framework. The consistency of these associations was then assessed across three geographically separated regions. Results: Carabid occurrence declined with increasing elevation, although this relationship was modulated by both body size and wing development. Smaller species were less likely to occur than larger-bodied species at lower elevations. There was a steep decline in occurrence of larger species from low to high elevation, but a slight increase in smaller species, when considering all regions combined. All wing development types declined with elevation, most notably for brachypterous (reduced wings) species. However, these patterns also varied regionally, especially for wing development, indicating that trait-elevation interactions are not geographically consistent. Habitat could not explain the differences between regions for body size, but was likely an important driver of regional differences in the role of wing development on carabid occurrence. Main conclusions: Species traits are important in explaining the distribution of carabids along elevation gradients in mountains, and they may help to identify the species that are the most vulnerable, and the most resilient, to future environmental change. Increased probability of occurrence of smaller species at higher elevations suggests that they may be particularly vulnerable to environmental change in the future. However, the difference in responses to elevation between regions has important implications for modelling species distributions, as it suggests low model transferability, i.e. a trait-based model derived from one region cannot necessarily be used to project relative elevational shifts in a wider area.

Divergent responses of forest dominant trees species to the manipulated canopy and understory nitrogen additions in terms of foliage stoichiometric, economic and hydraulic traits

Nitrogen (N) deposition effects on the stoichiometric balance and photosynthetic and hydraulic couplings in subtropical forests has drawn wide attentions. The previously adopted understory application of N fertilization is criticized because it might ignore foliar N retention for different species. This paper reports a fertilizing application from the canopy (CAN) and under the canopy (UAN) in a phosphorus (P) limited ecosystem. Foliage stoichiometric, photosynthetic and hydraulic traits of six dominant species were measured and analyzed. Both treatments equally enhanced foliage N and N/P, but not foliage P, who was highly species-specific depending on tree height, which implied enhanced P limitation. Decreased isotope abundance of 15N (δ15N) that approaching to the level in the urea fertilizer under CAN suggested the existence of canopy retention of N. Besides, N response sensitivity of N, P and δ15N that positively related to tree height (H) under CAN indicated different exposure to the added N, which promoted stoichiometric imbalance among species. The photosynthetic traits represented by net photosynthesis (An) increased under both treatments. A divergent foliar photosynthetic and hydraulic traits varations was identified by signifcant decreased stomatal conductance (gs) and An /gs for CAN treatments, which induced the elevated isotope abundance of 13C (δ13C). Correspondingly, foliage hydraulic traits that shifted to water use efficiency axis were identified only under CAN in principal component analysis. Overall, our results proved that the canopy obsorbtion and species heterogeneity should be considered regarding foliar safety vs efficiency trade-off in response to nitrogen additions in the future.

Data from: An identification of invariants in life history traits of amphibians and reptiles

While many morphological, physiological, and ecological characteristics of organisms scale with body size, some do not change under size transformation. They are called invariant. A recent study recommended five criteria for identifying invariant traits. These are based on that a trait exhibits a unimodal central tendency and varies over a limited range with body mass (type I), or that it does not vary systematically with body mass (type II). We methodologically improved these criteria and then applied them to life history traits of amphibians, Anura, Caudata (eleven traits), and reptiles (eight traits). The numbers of invariant traits identified by criteria differed across amphibian orders and between amphibians and reptiles. Reproductive output (maximum number of reproductive events per year), incubation time, length of larval period, and metamorphosis size were type I and II invariant across amphibians. In both amphibian orders, reproductive output and metamorphosis size were type I and II invariant. In Anura, incubation time and length of larval period and in Caudata, incubation time were further type II invariant. In reptiles, however, only number of clutches per year was invariant (type II). All these differences could reflect that in reptiles body size and in amphibians, Anura, and Caudata metamorphosis (neotenic species go not through it) and the trend towards independence of egg and larval development from water additionally constrained life history evolution. We further demonstrate that all invariance criteria worked for amphibian and reptilian life history traits, although we corroborated some known and identified new limitations to their application.

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Supplementary material 1 from: Bustamante RO, Alves L, Goncalves E, Duarte M, Herrera I (2020) A classification system for predicting invasiveness using climatic niche traits and global distribution models: application to alien plant species in Chile. NeoBiota 63: 127-146. https://doi.org/10.3897/neobiota.63.50049

Table S1. Exotic species located in Quadrant 1 (see Figure 3) and impacts on biodiversity, agriculture and cattle raisng

Herbivory of a biocontrol agent on a native plant causes an indirect trait-mediated non-target effect on a native insect

Identifying food web linkages between biocontrol agents of invasive plants and native species is crucial for predicting indirect non-target effects. Biocontrol insects can integrate into food webs within recipient habitats and influence native insects through apparent competition (altering shared natural enemies) or density-mediated exploitation competition (changing density of native plants). However, whether and how trait-mediated exploitation competition (modifying native plant chemical defenses and volatiles profiles) can produce indirect non-target effects remains largely overlooked, despite plant phenotypic responses to insect herbivory being common and widely documented. The beetle Agasicles hygrophila was introduced into China for management of weedy Alternanthera philoxeroides, but it also attacks the native congener A. sessilis, which may have indirect non-target effects on the native beetle Cassida piperata that also feeds on A. sessilis. Here, we examined the relationships among the abundance of A. hygrophila and C. piperata, and A. sessilis coverage in the field. Then, we investigated the impact of A. hygrophila herbivory on C. piperata development and oviposition, as well as A. sessilis primary metabolites and leaf volatiles. Cassida piperata abundance was not related to A. sessilis coverage, but C. piperata was less abundant on plants with more A. hygrophila in the field survey and on plants with more prior A. hygrophila damage in the field cage experiment. Cassida piperata development was inhibited by prior A. hygrophila herbivory in bioassays in enemy-free conditions and they preferred to oviposit on A. sessilis plants that had experienced little or no A. hygrophila damage. Agasicles hygrophila herbivory decreased A. sessilis foliar glucose and protein, and substantially changed its leaf volatile blend. Synthesis. Our results show that A. hygrophila has its major indirect non-target effects on C. piperata through trait-mediated exploitation competition, rather than apparent competition or density-mediated exploitation competition. Our results demonstrate a new mechanism for indirect non-target effects of biocontrol agents. Furthermore, our results indicate that minor and temporary negative impacts on non-target plants might propagate to higher trophic levels and such negative impacts can strengthen with increasing intensity of the direct non-target effect.

Human mediated land use change drives intraspecific plant trait variation

In the Anthropocene, more than three quarters of ice-free land has experienced some form of human driven habitat modification, with agriculture dominating 40% of the Earth's surface. This land use change alters the quality, availability, and configuration of habitat resources, affecting the community composition of plants and insects, as well as their interactions with each other. Landscapes dominated by agriculture are known to support a lower abundance and diversity of pollinators and frequently larger populations of key herbivore pests. In turn, insect communities subsidized by agriculture may spill into remaining natural habitats with consequences for wild plants persisting in (semi) natural habitats. Adaptive responses by wild plants may allow them to persist in highly modified landscapes; yet how landscape-mediated variation in insect communities affects wild plant traits related to reproduction and defense remains largely unknown. We synthesize the evidence for plant trait changes across land use gradients and propose potential mechanisms by which landscape-mediated changes in insect communities may be driving these trait changes. Further, we present results from a common garden experiment on three wild Brassica species demonstrating variation in both defensive and reproductive traits along an agricultural land use gradient. Our framework illustrates the potential for plant adaptation under land use change and predicts how defense and reproduction trait expression may shift in low diversity landscapes. We highlight areas of future research into plant population and community effects of land use change.