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Community-level direct and indirect impacts of an invasive plant favour exotic over native species

1. Indirect interactions mediated by shared enemies or mutualists (i.e., apparent competition) can influence whether invasive plants harm or benefit co-occurring species. However, studies to date have largely examined single pairwise interactions, limiting our understanding of the interplay among different types of interactions and whether indirect impacts systematically favour native or exotic species. Predicting indirect interaction strength has also proven challenging, and it remains unclear whether the strengths of different indirect interactions are correlated. 2. We conducted a field experiment in a grassland invaded by Scotch broom (Cytisus scoparius) to compare the strength of its indirect impacts, via both soil fungi or herbivores, on 21 native and exotic legume species growing in pots buried in the ground. Direct interactions of plants with soil fungi were controlled using nylon mesh pot windows of differing porosity (1 or 38 µm) to prevent or allow soil fungi hyphal growth. Arthropod herbivores were controlled through spraying pyrethrum pesticide. To assess indirect impacts, interactions were compared between plants adjacent to or 50 m away from an extensive Scotch broom invasion. We measured plant performance (survival, height, and biomass), arthropod and hare herbivory, and rhizobia nodulation. 3. Despite increasing arthropod herbivory of both native and exotic plant species, Scotch broom had a net positive impact on their survival and growth, through sheltering them from abiotic stress, and indirectly via beneficial soil fungi and release from hare browsing. Soil fungi also increased arthropod herbivory, decreased rhizobia nodulation, and disproportionately promoted the growth of exotic plants. Overall, exotic plants experienced stronger interactions, which favoured them with beneficial soil fungi and rhizobia but not hare browsing. Finally, indirect interaction strength was not correlated among indirect interactions mediated by different interaction partners. 4. Synthesis: We demonstrate that invaders affect their competitors through multiple interacting indirect pathways that were stronger than direct 'nurse plant' effects, emphasising the importance of a community-level approach to studying biological invasions. Exotic species experienced stronger positive and negative impacts than natives, but were facilitated overall, potentially contributing to exotic dominance in communities.

Data from: Plant-pollinator interactions along an urbanization gradient from cities and villages to farmland landscapes

Urbanization affects pollinator diversity and plant-pollinator networks by changing resource availability locally and in the surrounding landscape. We experimentally established (N = 12) standardized plant communities in farmland, villages and cities to identify the relative role of local and landscape effects on plant-pollinator communities along this urbanization gradient. We found that the number of flower visits by solitary bees, but not bumblebees, were highest in cities and lowest in farmland, with villages being intermediate, whereas syrphid flies exhibited lowest numbers in cities. Villages supported the richest pollinator communities, as they appeared to benefit from both farmland and city communities. Plant-pollinator network metrics such as robustness, interaction evenness and interaction diversity decreased with increasing urbanization, although local plant richness increased towards urban areas. In conclusion, pollinator communities were most diverse and stable in farmland and village sites, despite the high plant richness in cities. The different composition of pollinator communities along the urbanization gradient suggests considering all three landscape types for conservation schemes.

Data from: The effect of root-associated microbes on plant growth and chemical defence traits across two contrasted elevations,

1. Ecotypic differences in plant growth and anti-herbivore defence phenotypes are determined by the complex interactions between the abiotic and the biotic environment. 2. Root-associated microbes (RAMs) are pervasive in nature, vary over climatic gradients, and have been shown to influence the expression of multiple plant functional traits related to biomass accumulation and biotic interactions. We addressed how variation in climatic conditions between lowland and sub-alpine habitats in the Alps and RAMs can independently or interactively affect plant growth and anti-herbivore defence trait expression. 3. To address the contribution of climate and RAMs on growth and chemical defences of high- and low-elevation Plantago major ecotypes, we performed a full-factorial reciprocal transplant field experiment at two elevations. We coupled it with plant functional trait measurements and metabolomics analyses. 4. We found that local growing climatic conditions mostly influenced how the ecotypes grew, but we also found that the high- and low-elevation ecotypes improved biomass accumulation if in the presence of their own-elevation RAMs. Second, we found that while chemical defence expression was affected by climate, they were also more highly expressed when plants were inoculated with low elevation RAMs. 5. Synthesis – Our research demonstrated that RAMs from contrasted elevations impact how plants grow or synthesize toxic secondary metabolites. At low elevation, where biotic interactions are stronger, RAMs enhance plant biomass accumulation and the production of toxic secondary metabolites.

Interspecific variation and elevated CO2 influence the relationship between plant chemical resistance and regrowth tolerance

To understand how comprehensive plant defense phenotypes will respond to global change, we investigated the legacy effects of elevated CO2 on the relationships between chemical resistance (constitutive and induced via mechanical damage) and regrowth tolerance in four milkweed species (Asclepias). We quantified potential resistance and tolerance tradeoffs at the physiological level following simulated clipping/mowing, which are relevant to milkweed ecology and conservation. We examined the legacy effects of elevated CO2 on four hypothesized tradeoffs between: 1) plant growth rate and constitutive chemical resistance (foliar cardenolide concentrations), 2) plant growth rate and mechanically induced chemical resistance, 3) constitutive resistance and regrowth tolerance, and 4) regrowth tolerance and mechanically induced resistance. We observed support for one tradeoff between plant regrowth tolerance and mechanically induced resistance traits that was, surprisingly, independent of CO2 exposure. Across milkweed species, mechanically induced resistance increased by 28% in those plants previously exposed to elevated CO2. In contrast, constitutive resistance, and the diversity of mechanically induced chemical resistance traits declined in response to elevated CO2 in two out of four milkweed species. Finally, previous exposure to elevated CO2 uncoupled the positive relationship between plant growth rate and regrowth tolerance following damage. Our data highlight the complex and dynamic nature of plant defense phenotypes under environmental change and question the generality of physiologically-based defense tradeoffs.

opencc-zeroApr 2021View details →

High water use in desert plants exposed to extreme heat

Many plant water use models predict leaves maximize carbon assimilation while minimizing water loss via transpiration. Alternate scenarios may occur at high temperature, including heat avoidance, where leaves increase water loss to evaporatively cool regardless of carbon uptake; or heat failure, where leaves non-adaptively lose water also regardless of carbon uptake. We hypothesized that these alternative scenarios are common in species exposed to hot environments, with heat avoidance more common in species with high construction-cost leaves. Diurnal measurements of leaf gas exchange and temperature for 11 Sonoran Desert species revealed 37% of these species increased transpiration in the absence of increased carbon uptake. High leaf mass per area partially predicted this behavior (r2=0.39). These data are consistent with heat avoidance and heat failure, but failure is less likely given the ecological dominance of the focal species. These behaviors are not yet captured in any extant plant water use model.

Independent evolutionary changes in fine-root traits among main clades during the diversification of seed plants

Rationale: Changes in fine-root morphology are typically associated with transitions from the ancestral arbuscular mycorrhizal (AM) to the alternative ectomycorrhizal (ECM) or non-mycorrhizal (NM) associations. However, the modifications in root morphology may also coincide with new modifications in leaf hydraulics and growth habit during angiosperm diversification. These hypotheses have not been evaluated concurrently, which limits our understanding of the causes of fine-root evolution. Methods: To explore the evolution of fine-root systems, we assembled a 600+ species database to reconstruct historical changes in seed plants over time. We utilize ancestral reconstruction approaches together with phylogenetically informed comparative analyses to test whether changes in fine-root traits were most strongly associated with mycorrhizal affiliation, leaf hydraulics or growth form. Key Results: Our findings show significant shifts in root diameter, specific root length and root tissue density as angiosperms diversified, largely independent from leaf changes or mycorrhizal affiliation. Growth form was the only factor associated with fine-root traits in statistical models including mycorrhizal association and leaf venation, suggesting substantial modifications in fine-root morphology during transitions from woody to non-woody habits. Conclusion: Divergences in fine-root systems were crucial in the evolution of seed plant lineages, with important implications for ecological processes in terrestrial ecosystems.

Data from: Attack and aggregation of a major squash pest: parsing the role of plant chemistry and beetle pheromones across spatial scales

1. Successful management of insect crop pests requires an understanding of the cues and spatial scales at which they function to affect rates of attack of preferred and non-preferred host plants. A long-standing conceptual framework in insect-plant ecology posits that there is hierarchical structure spanning host location, acceptance, and attack that could be exploited for integrated pest management. 2. We investigated how plant- and insect-derived chemical cues affect successive decisions of host choice in aggregating insects, and tested predictions in the Cucurbita pepo - Acalymma vittatum system. Acalymma vittatum is an aggregating specialist beetle pest that strongly prefers zucchini (C. p. pepo) to summer squash (C. p. ovifera), two independent domesticates of C. pepo. We hypothesized that subspecies-specific plant traits, especially volatile cues, interact with the male-produced aggregation pheromone to amplify beetle preference for C. p. pepo. 3. Differential beetle attack of C. pepo subspecies in the field is not determined by plant traits that affect host finding or differential aggregation due to pheromones: across two years, beetles had strong density-dependent attraction to both subspecies when male beetles were feeding, and no interactions between plant volatiles and the male-produced pheromone were detected. In absence of male pheromone emission, beetles were equally unattracted to plants with or without beetle feeding. 4. In contrast, plant traits that mediate insect acceptance appear to underlie differences in preference. At a local scale, beetles did not accept and emigrated from C. p. ovifera compared to C. p. pepo. Distinct volatile emissions were observed between subspecies, but further work is needed to identify if these volatiles promote emigration. 5. Synthesis and applications: By dissecting pest preference during successive host choice decisions, we isolated a trait with implications for pest management. Beetles on cucurbits can be managed by employing cultivars with differential susceptibility (e.g. trap cropping), and the mechanistic knowledge presented here informs best practices and limitations for on-farm applications. More broadly, pest management in diversified cropping systems can be enhanced through understanding how plant preference gradients affect herbivore movement and behavior, and plant breeders can target traits to reduce herbivory in such systems.

Latitudinal pattern in community-wide herbivory does not match the pattern in herbivory averaged across common plant species

1. The latitudinal herbivory hypothesis (LHH) predicts that plant losses to herbivores decrease from low to high latitudes. Although the LHH is a community-level hypothesis, it has been rarely tested with data on community-wide herbivory, i.e. the percentage of annual production of foliar biomass consumed by insects from all plant species at a given site. Therefore, we asked whether community-wide leaf herbivory follows the same latitudinal pattern as observed for an unweighted average of herbivory across common plant species. 2. We selected ten study sites in boreal forests from 60°N to 69°N along 1000 km long latitudinal gradient in NW Russia. We measured relative foliar losses to insect herbivores in seven woody plant species (jointly comprising over 95% of the community-wide aboveground biomass) and estimated their current-year foliar biomass. We averaged leaf herbivory for all seven species and calculated community-wide leaf herbivory by weighting the relative foliar losses of each plant species against the contribution of that species to the annual foliar biomass production. 3. Leaf herbivory was five-fold higher in deciduous species than in conifers. Latitudinal patterns in herbivory varied from a significant poleward decrease in all deciduous species to a significant poleward increase in Norway spruce. Herbivory values, averaged across seven plant species, decreased with latitude and followed the pattern observed in deciduous plants due to their higher foliar losses compared with conifers. By contrast, community-wide herbivory did not change with latitude. This discrepancy emerged because the proportion of deciduous plant foliage in the community increased with increasing latitude, and this increase counterbalanced the simultaneous poleward decrease in losses of these species to insects. 4. Synthesis The herbivory measured by averaging relative losses of individual plant species and the community-wide herbivory are likely to show different latitudinal patterns in various plant communities. The contributions of plant species to the total foliar biomass production should be taken into account in studies of spatial patterns of herbivory which test community-level hypotheses. This approach may provide new insight into macroecological research on biotic interactions and improve our understanding of the role of insect herbivores in ecosystem-level processes.

opencc-zeroDec 2019View details →

Agricultural intensification reduces plant taxonomic and functional diversity across European arable systems.

1. Agricultural intensification is one of the main drivers of species loss worldwide, but there is still a lack of information about its effect on functional diversity of arable weeds communities. 2. Using a large scale pan European study including 786 fields within 261 farms from eight countries, we analysed differences in the taxonomic and functional diversity of arable weeds assemblages across different levels of agricultural intensification in. We estimated weed species frequency in each field, and collected species' traits (vegetative height, specific leaf area and seed mass) from the TRY plant trait database. With this information we estimated taxonomic (species richness), functional composition (community weighted means) and functional diversity (functional richness, evenness, divergence and redundancy). We used indicators of agricultural management intensity at the individual field scale (e.g. yield, inputs of nitrogen fertilizer and herbicides, frequency of mechanical weed control practices) and at the landscape scale surrounding the field (i.e. number of crop types, mean field size and proportion of arable land cover within a radius of 500m from the sampling points). 3. The effects of agricultural intensification on species and functional richness at the field scale were stronger than those of intensification at the landscape scale, and we did not observe evidence of interacting effects between the two scales. Overall, assemblages in more intensified areas had fewer species, a higher prevalence of species with ruderal strategies (low stature, high leaf area, light seeds), and lower functional redundancy. 4. Maintaining the diversity of Europe's arable weed communities requires some simple management interventions, for example, reducing the high intensity of field-level agricultural management across Europe, which could be complemented by interventions that increase landscape complexity.

Data from: The functional roles of species in metacommunities, as revealed by metanetwork analyses of bird-plant frugivory networks

Understanding how biodiversity and interaction networks change across environmental gradients is a major challenge in ecology. We integrated metacommunity and metanetwork perspectives to test species' functional roles in bird-plant frugivory interactions in a fragmented forest landscape in Southwest China, with consequences for seed dispersal. Availability of fruit resources both on and under trees created vertical feeding stratification for frugivorous birds. Bird-plant interactions involving birds feeding only on the tree or both on and under the tree (shared) had a higher centrality and contributed more to metanetwork organization than interactions involving birds feeding only under the tree. Moreover, bird-plant interactions associated with large-seeded plants disproportionately contributed to metanetwork organization and centrality. Consequently, on-the-tree and shared birds contributed more to metanetwork organization whereas under-the-tree birds were more involved in local processes. We would expect that species' roles in the metanetwork will translate into different conservation values for maintaining functioning of seed-dispersal networks.

opencc-zeroDec 2019View details →

Data from: The contribution of hybridization to range‐wide population genetic structure in a Pacific coastal dune plant

Premise of the study: Interspecific hybridization can cause genetic structure across species ranges if the mating system and degree of sympatry/parapatry with close relatives varies geographically. The coastal dune endemic Camissoniopsis cheiranthifolia (Onagraceae) exhibits genetic subdivisions across its range, some of which are associated with shifts in mating system from outcrossing to selfing, while others are not. For instance, strong differentiation between large-flowered, self-incompatible (LF-SI) and large-flowered, self-compatible (LF-SC) populations occurs without much reduction in outcrossing or obvious barriers to gene flow. We hypothesized that LF-SI diverged from LF-SC via hybridization with the predominantly inland SI sister species C. bistorta. Methods: We analyzed spatial proximity using 1460 herbarium records, and genetic variation at 12 microsatellites assayed for 805 and 404 individuals from 32 C. cheiranthifolia and 18 C. bistorta populations, respectively. We also assayed nine chloroplast microsatellites for 124 and 111 individuals from 27 and 19 populations, respectively. Key results: Closer parapatry was associated with unexpectedly high genetic continuity between LF-SI C. cheiranthifolia and C. bistorta. LF-SI genotypes clustered with C. bistorta exclusive of other C. cheiranthifolia genotypes. Similarly, pairwise FST among SI C. cheiranthifolia and C. bistorta, adjusted for geographic proximity, was not higher between heterospecific than conspecific populations. Conclusions: The lack of genetic differentiation between LF-SI C. cheiranthifolia and C. bistorta populations, even those located away from the zone of parapatry, suggests that LF-SI C. cheiranthifolia instead of hybridizing with C. bistorta is rather an ecotype of C. bistorta that has adapted to coastal dune habitat independent of other lineages in C. cheiranthifolia proper.

Data for: Relatively rare root endophytic bacteria drive plant resource allocation patterns and tissue nutrient concentration in unpredictable ways

Premise of Study Plant endophytic bacterial strains can influence plant traits such as leaf area and root length. Yet, the influence of more complex bacterial communities in regulating overall plant phenotype is less explored. Here, we conducted two complementary experiments to test if we can predict plant phenotype response to changes in microbial community composition. Methods In the first study, we inoculated a single genotype of Populus deltoideswith individual root endophytic bacteria and measured plant phenotype. Next, single inoculation data were used to predict phenotypic traits in mixed three-member community inoculations, which we tested in the second experiment. Key Results When in isolation, each bacterial endophyte significantly but weakly altered plant phenotype relative to non-inoculated plants. In mixture, bacterial strain BurkholderiaBT03, constituted at least 98% of community relative abundance. Yet, plant resource allocation and tissue nutrient concentrationswere disproportionately influenced by Pseudomonas sp.GM17, GM30, and GM41. We found a 10% increase in leaf mass fraction and a 11% decrease in root mass fraction when replacingPseudomonas GM17 with GM41 in communities containing both Pseudomonas GM30 and BurkholderiaBT03. Conclusions Our results indicate that interactions among endophytic bacteria may drive plant phenotype over the contribution of each strain individually. Additionally, we have shown that low-abundant strains contribute to plant phenotype challenging the assumption that the dominant strains will drive plant function.

Data from: Edge effects and mating patterns in a bumblebee-pollinated plant

Researchers have long assumed that plant spatial location influences plant reproductive success and pollinator foraging behavior. For example, many flowering plant populations have small, linear, or irregular shapes that increase the proportion of plants on the edge, which may reduce mating opportunities through both male and female function. Additionally, plants that rely on pollinators may be particularly vulnerable to edge effects if those pollinators exhibit restricted foraging and pollen carryover is limited. To explore the effects of spatial location (edge vs. interior) on siring success, seed production, pollinator foraging patterns, and pollen-mediated gene dispersal, we established a square experimental array of 49 Mimulus ringens (monkeyflower) plants. We observed foraging patterns of pollinating bumblebees and used paternity analysis to quantify male and female reproductive success and mate diversity for plants on the edge vs. interior. We found no significant differences between edge and interior plants in the number of seeds sired, mothered, or the number sires per fruit. However, we found strong differences in pollinator behavior based on plant location, including 15% lower per flower visitation rates and substantially longer interplant moves for edge plants. This translated into 40% greater pollen-mediated gene dispersal for edge than for interior plants. Overall, our results suggest that edge effects are not as strong as is commonly assumed, and that different plant reproduction parameters respond to spatial location independently.

opencc-zeroDec 2019View details →

Data from: Spatial scale, neighbouring plants and variation in plant volatiles interactively determine the strength of host-parasitoid relationships

Species-specific responses to the environment can moderate the strength of interactions between plants, herbivores and parasitoids. However, the ways in which characteristics of plants, such as genotypic variation in herbivore induced volatiles (HIPVs) that attract parasitoids, affect trophic interactions in different contexts of plant patch size and plant neighbourhood is not well understood. We conducted a factorial field experiment with white cabbage (Brassica oleracea) accessions that differ in the attractiveness of their HIPVs for parasitoids, in the context of different patch sizes and presence or absence of surrounding Brassica nigra plants. Parasitism rates of experimentally introduced Pieris brassicae caterpillars and the presence of naturally occurring Pieris spp. caterpillars in the plots were assessed throughout the growing season. The abundance of Pieris caterpillars was neither affected by cabbage accession nor plot size. Later in the season, when B. nigra plants had senesced, fewer caterpillars were found on cabbage plants in plots with a B. nigra border. Parasitism rates fluctuated over the season, and were not affected by plot size. However, the B. nigra border negatively affected parasitism rates on the accession that is less attractive to the parasitoid Cotesia glomerata, but not on the more attractive accession. Our results show that plant variation in HIPVs can differentially influence herbivores and parasitoids depending on characteristics of the surrounding vegetation context. These findings underscore the importance of considering the interaction between focal plant traits and neighbourhood context to reliably predict trophic cascades.

Data from: Climate warming drives Himalayan alpine plant growth and recruitment dynamics

<ul> <li>Understanding how climate influences plant reproduction and growth at contrasting range limits is crucial for predicting how species' ranges may shift in response to ongoing climate change. Trees and shrubs have shown warming-induced increases in performance at upper elevation limits but reduced performance at lower distributional limits due to warming-driven drought limitation. Whether these differential responses are also valid for alpine forbs exposed to accelerated warming remains largely unknown. </li> <li>We examined climate signal recorded in annual growth and recruitment over the past sixty years in the alpine forb Potentilla pamirica in Western Himalayas, and tested whether the responses to recent climate warming differ between dry steppe, wet alpine and cold subnival zone within the species 5250-5900 m elevation range. We reconstructed recruitment and growth chronologies from 1019 individuals spanning 1-73 years, and more than 21,500 annual growth rings.</li> <li>We identified contrasting climatic controls of recruitment and growth at opposite elevation range margins, as well as contrasting demographic trends identified from age distributions. In lower-elevation steppes, recruitment increased with high late-winter snowfall and decreased with high summer temperatures, while growth increased with high summer precipitation. Conversely, warm winters and summers in higher-elevation alpine and subnival zones support growth and recruitment, while snowy winters reduce them, especially at their upper elevation limit. The age distribution revealed greater numbers of younger individuals, indicating healthy growing populations, in the alpine habitat, while evidence of ageing plant populations was observed in steppe and subnival zones.</li> <li>Accelerated warming since the 1990s reduced growth and recruitment in dry steppes while supporting plant performance in the alpine habitat. The recruitment in the subnival zone did not peak during the past warmest decade due to concomitant extreme snowfall events. </li> <li>Synthesis: Our results bring novel information on population-specific climate dependency of plant recruitment, growth, and population dynamics, suggesting a high vulnerability of high elevation Himalayan ecosystems to climate change. This is partly balanced by high species longevity and slow radial growth securing a long-term population persistence. Continuing trends of extreme snowfall events at higher elevations and droughts at lower elevations may lead to species range contraction.</li> </ul>

Data from: Savannas after afforestation: assessment of herbaceous community responses to wildfire versus native tree planting

Afforestation and fire exclusion are pervasive threats to tropical savannas. In Brazil, laws limiting prescribed burning hinder the study of fire in the restoration of Cerrado plant communities. We took advantage of a 2017 wildfire to evaluate the potential for tree cutting and fire to promote the passive restoration of savanna herbaceous plant communities after destruction by exotic tree plantations. We sampled a burned pine plantation (Burned Plantation); a former plantation that was harvested and burned (Harvested & Burned); an unburned former plantation that was harvested, planted with native trees, and treated with herbicide to control invasive grasses (Native Tree Planting); and two old-growth savannas which served as reference communities. Our results confirm that herbaceous plant communities on post-afforestation sites are very different from old-growth savannas. Among post-afforestation sites, Harvested & Burned herbaceous communities were modestly more similar in composition to old-growth savannas, had slightly higher richness of savanna plants (3.8 species per 50-m2), and supported the greatest cover of native herbaceous plants (56%). These positive trends in herbaceous community recovery would be missed in assessments of tree cover: whereas canopy cover in the Harvested & Burned site was 6% (less than typical of savannas of the Cerrado), the Burned Plantation and Native Tree Planting, supported 34% and 19% cover, respectively. By focusing on savanna herbaceous plants, these results highlight that tree cutting and fire, not simply tree planting and fire exclusion, should receive greater attention in efforts to restore savannas of the Cerrado.

Data from: Foundation species promote local adaptation and fine-scale distribution of herbaceous plants

1) Interactions among neighbors can alter demography and traits of commingled species via adaptation or plasticity in phenotypic expression and understanding these two mechanisms in diverse communities is important for determining the ecological and evolutionary consequences of plant–plant interactions. 2) We reciprocally transplanted perennial species (Arenaria armerina and Festuca indigesta) among patches of two foundation shrub species and open ground to assess whether origin microsite (defined as the spatially distinct abiotic and biotic conditions associated with the two shrubs and open ground) determines germination, recruitment and growth that, in turn, promotes fine-scale distribution of species among microsites. In addition, we tested the effect of origin microsite on traits, competitive ability, drought tolerance and outlier loci to assess whether origin microsite conditions drove differences in traits, strategies and adaptive loci. 3) Germination was consistently greater for seeds planted back into their origin microsite relative to seeds sourced from foreign microsites, although this effect was weakened for recruitment. Plant growth was best in open sites regardless of origin microsite. In the greenhouse, A. armerina had conserved traits within origin microsite but distinct trait values among microsite conditions, specifically for plants originating from the most productive microsite (e.g. sufficient light and high nutrients and water availability). Festuca indigesta had conserved trait responses among microsites while within microsite, individuals had significant trait plasticity to different environmental conditions. The combined field and greenhouse results suggest that fine-scale distributions are supported by local adaptation among microsites of A. armerina and phenotypic plasticity of F. indigesta. Synthesis Adaptation or plasticity in phenotypic expression have different implications for demographic rate and persistence of species in changing environments. Local adaptation to neighbors suggests that reductions in foundation species diversity could concomitantly lead to reduced genetic diversity of commingled species while a plastic response indicates a more robust and broad response to changing climatic and biotic conditions.

Data from: Specialized breeding in plants affects diversification trajectories in Neotropical frogs

Many animals breed exclusively in plants that accumulate rainwater (phytotelma; e.g., bromeliad, bamboo, fruit husk, and tree hole), to which they are either physiologically or behaviorally specialized for this microhabitat. Of the numerous life-history modes observed in frogs, few are as striking or potentially consequential as the transition from pond- or stream-breeding to the deposition of eggs or larvae in phytotelmata. Such specialization can increase offspring survivorship due to reduced competition and predation, representing potential ecological opportunity for adaptive radiation, yet few lineages of phytotelma-breeding frogs appear to have diversified extensively after such a transition, at least in the New World. We use a phylogeny of Neotropical frogs and data on breeding microhabitat to understand the evolutionary transitions involved with specialized phytotelma-breeding. First, we find that phytotelma-breeding is present in at least 168 species in 10 families of frogs. Across the phylogeny, we estimate 14 origins of phytotelma-breeding and 115 reversals, showing that phytotelma-breeding is a highly labile character. Second, phytotelma-breeding lineages overall have higher net diversification than non-phytotelma-breeding ones. This specialization represents an ecological opportunity resulting in increased diversification in most families with phytotelma-breeding lineages, whereas phytotelma-breeding toads have restricted diversification histories.

Data from: Norway and Sweden Green Roof (GF) plant data

Standard succulent vegetation mixes developed mostly in temperate climates are being increasingly used on green roofs in different climate zones with uncertain outcome regarding vegetation survival and cover. We investigated vegetation on green roofs at nine temperate, cold and/or wet locations in Norway and Sweden covering wide ranges of latitude, mean annual temperature, annual precipitation, frequencies of freeze-thaw cycles and longest annual dry period. The vegetation on the roofs were surveyed in two consecutive years, and weather data were compiled from meteorological databases. At all sites we detected a significant decline in species compared to originally intended (planted/sown) species. Both the survival rate and cover of the intended vegetation were positively related to the mean annual temperature. Contrary to a hypothesis, we found that intended vegetation cover was negatively rather than positively related to mean annual precipitation. Conversely, the unintended (spontaneous) vegetation was favoured by high mean annual precipitation, and low mean annual temperature, possibly by enabling it to colonise bare patches and outcompete the intended vegetation. When there is high mortality and variation in cover of the intended vegetation, predicting the strength of ecosystem services the vegetation provides on green roofs is difficult. The results highlight the needs for further investigation on species traits and the local factors driving extinction and colonisations in order to improve survivability and ensure a dense vegetation throughout the successional stages of a green roof.

Species identity and diversity effects on invasion resistance of tropical freshwater plant communities

Biotic resistance mediated by native plant diversity has long been hypothesized to reduce the success of invading plant species in terrestrial systems in temperate regions. However, still little is known about the mechanisms driving invasion patterns in other biomes or latitudes. We help to fill this gap by investigating how native plant community presence and diversity, and the presence of native phylogenetically closely related species to an invader, would affect invader Hydrilla verticillata establishment success in tropical freshwater submerged plant communities. The presence of a native community suppressed the growth of H. verticillata, but did not prevent its colonisation. Invader growth was negatively affected by native plant productivity, but independent of native species richness and phylogenetic relatedness to the invader. Native plant production was not related to native species richness in our study. We show that resistance in these tropical aquatic submerged plant communities is mainly driven by the presence and biomass of a native community independent of native species diversity. Our study illustrates that resistance provided by these tropical freshwater submerged plant communities to invasive species contrasts to resistance described for other ecosystems. This emphasizes the need to include understudied systems when predicting patterns of species invasiveness and ecosystem invasibility across biomes.