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Climate and ant diversity explain the global distribution of ant-plant mutualisms

Biotic interactions play an important role in shaping species geographic distributions and diversity patterns. However, the role of mutualistic interactions in shaping global plant diversity patterns remains poorly understood, particularly with respect to interactions with invertebrates. It is unclear how the nature of different mutualisms interacts with abiotic drivers and affects the distribution of mutualistic organisms. Here, we present a global-scale biogeographic analysis of three distinct ant-plant mutualisms, differentiating between plants bearing domatia, extrafloral nectaries (EFNs), and elaiosomes, based on comprehensive geographic distributions of ~19,000 flowering plants and ~13,000 ant species. Domatia and extrafloral nectaries involve indirect plant defences provided by ants, while elaiosomes attract ants to disperse seeds. Our results reveal distinct biogeographic patterns of different ant-plant mutualisms, with domatium- and EFN-bearing plant diversity decreasing sharply from the equator towards the poles, while elaiosome-bearing plants prevail at mid-latitudes. Present climate, especially mean annual temperature and precipitation, emerge as the strongest predictors of ant-associated plant diversity. In hot and moist regions, typically the tropics, the representation of EFN-bearing plants increases with the proportion of potential ant partners while domatium-bearing plants show no correlation with ants. In dry regions, plants with elaiosomes are strongly linked to interacting ant seed dispersers. Our results suggest that ants in combination with climate drive the spatial variation of plants bearing domatia, extrafloral nectaries, and elaiosomes, highlighting the importance of mutualistic interactions for understanding plant biogeography.

Data from: A mosaic of endogenous and plant-derived courtship signals in moths

Insects rely on olfaction to guide a wide range of adaptive behaviors, including mate- and food-localization, mate choice, oviposition site selection, kin recognition and predator avoidance. In nocturnal insects, such as moths and cockroaches, mate finding is stimulated predominantly by long-range species-specific sex pheromones, typically emitted by females. During courtship, at close-range, males in most moth species emit a blend of pheromone compounds from an everted, often large, pheromone gland. While long-distance communication with sex pheromones has been remarkably well characterized in thousands of moth species, close-range chemosensory sexual communication remains poorly understood. We reveal that in the moth Chloridea virescens, the male pheromone consists of three distinct classes of compounds: de novo biosynthesized alcohols, aldehydes, acetates and carboxylic acids that resemble the female's emissions, and newly identified compounds that are unique to the male pheromone: aliphatic polyunsaturated hydrocarbons and sequestered plant secondary compounds and hormone derivatives, including methyl salicylate (MeSA). Thus, males employ a mosaic pheromone blend of disparate origins that may serve multiple functions during courtship. We show that two olfactory receptors in female antennae are tuned to MeSA, which facilitates female acceptance of the male. Because MeSA is emitted by plants attacked by pathogens and herbivores, the chemosensory system of female moths was likely already tuned to this plant volatile, and males appear to exploit the female's preadapted sensory bias. Interestingly, while female moths (largely nocturnal) and butterflies (diurnal) diverged in their use of sensory modalities in sexual communication, MeSA is used by males of both lineages.

EPDM microplastic and earthworm effects on plants

Soil microplastic pollution can have negative effects on organisms, including plants, but the underlying mechanisms are not fully understood. We tested whether structural or chemical properties of a microplastic cause its effects on plant above- and belowground growth and whether these effects can be influenced by earthworms. We conducted a factorial experiment in a greenhouse with seven common Central European grassland species. Microplastic granules of the synthetic rubber ethylene propylene diene monomer (EPDM), a frequently used infill material of artificial turfs, and cork granules with a comparable size and shape to the EPDM granules were used to test for structural effects of granules in general. To test for chemical effects, EPDM-infused fertilizer was used, which should have contained any leached water-soluble chemical components of EPDM. Two Lumbricus terrestris individuals were added to half of the pots, to test whether these earthworms modify effects of EPDM on plant growth. As response parameters aboveground, belowground, and total biomass, as well as several root traits were measured, and further parameters derived from the measured values. EPDM granules had a clear negative effect on plant growth, but since cork granules had a negative effect of similar magnitude, with an average decrease in biomass of 37 % in presence of granules, this is likely due to the structural properties of granules (i.e., size and shape). For some belowground plant traits, EPDM had a stronger effect than cork, which shows that there must be other factors playing into the effects of EPDM on plant growth. The EPDM-infused fertilizer did not have any significant effect on plant growth by itself, but it had in interaction with other treatments. Earthworms had an overall positive effect on plant growth and mitigated most of the negative effects of EPDM. These results show that EPDM microplastic can have negative effects on plant growth, and that these might be more related to its structural than to its chemical properties.

The plant toxin 4-methylsulfinylbutyl isothiocyanate decreases herbivore performance and modulate cellular and humoral immunity

Insect herbivores frequently encounter plant defense molecules, but the physiological and ecological consequences for their immune systems are not fully understood. The majority of studies attempting to relate levels of plant defensive chemistry to herbivore immune responses have used natural population or species-level variation in plant defensive chemistry. Yet, this potentially confounds the effects of plant defense chemistry with other potential traits that may affect the expression of herbivore immunity such as development time and nutritional quality. We have used an artificial diet containing known quantities of a plant toxin (4-methylsulfinylbutyl isothiocyanate; 4MSOB-ITC or ITC), an isothiocyanate present in many plants in the genus Brassica, to explicitly explore the effects of a plant toxin on the cellular and humoral immune responses of the generalist herbivore Trichoplusia ni (Lepidoptera: Noctuidae) that frequently feeds on glucosinolate-containing plants. Caterpillars feeding on diets with high concentrations of ITC experienced reduced survivorship and growth rates. High concentrations of ITC suppressed the appearance of several types of hemocytes and melanization activity, which are critical defenses against parasitic Hymenoptera and microbial pathogens. In terms of T. ni humoral immunity, only the antimicrobial peptide (AMP) genes lebocin and gallerimycin were significantly upregulated in caterpillars fed on diets containing high levels of 4MSOB-ITC relative to caterpillars that were provided with ITC-free diet. Surprisingly, challenging caterpillars with a non-pathogenic strain of Escherichia coli resulted in the upregulation of the AMP gene cecropin. Feeding on high concentrations of plant toxins hindered caterpillar development and decreased cellular immunity but conferred mixed effects on humoral immunity. Our findings provide novel insights into the effects of herbivore diet composition on insect performance demonstrating the role of specific plant defense toxins that shape herbivore immunity and trophic interactions.

Data for: A unique C-terminal domain contributes to the molecular function of restorer-of-fertility proteins in plant mitochondria

Restorer-of-fertility (Rf) genes have practical applications in hybrid seed production as a means to control self-pollination. They encode pentatricopeptide repeat (PPR) proteins that are targeted to mitochondria where they specifically bind to transcripts that induce cytoplasmic male sterility and repress their expression. We have identified a unique domain, RfCTD (Restorer-of-fertility C-terminal domain), which discriminates Restorer-of-fertility-like (RFL) proteins from hundreds of PPR proteins encoded in plant genomes. Using the sequence of this domain from hundreds of plant species, we have constructed a sequence profile that can quickly and accurately identify RfCTD sequences in plant genomes or transcriptomes. This data set contains PPR genes identified in 213 plant genomes (as summarised in accompanying table).

Data from: Soil microbes mediate the effects of resource variability on plant invasion

A fundamental question in ecology is which species will prevail over others amid changes in both environmental mean conditions and their variability. Although the widely accepted fluctuating resource hypothesis predicts that increases in mean resource availability and variability therein will promote non-native plant invasion, it remains unclear to what extent these effects might be mediated by soil microbes. We grew eight invasive non-native plant species as target plants in pot-mesocosms planted with five different synthetic native communities as competitors and assigned them to eight combinations of two nutrient-fluctuation (constant vs pulsed), two nutrient-availability (low vs high) and two soil-microbe (living vs sterilized) treatments. We found that when plants grew in sterilized soil, nutrient fluctuation promoted the dominance of non-native plants under overall low nutrient availability, whereas the nutrient fluctuation had minimal effect under high nutrient availability. In contrast, when plants grew in living soil, nutrient fluctuation promoted the dominance of non-native plants under high nutrient availability rather than under low nutrient availability. Analysis of the soil microbial community suggests that this might reflect that nutrient fluctuation strongly increased the relative abundance of the most dominant pathogenic fungal family or genus under high nutrient availability, while decreasing it under low nutrient availability. Our findings are the first to indicate that besides its direct effect, environmental variability could also indirectly affect plant invasion via changes in soil microbial communities.

Late instar monarch caterpillars sabotage milkweed to acquire toxins, not to disarm plant defense

Sabotaging milkweed by monarch caterpillars (Danaus plexippus) is a famous textbook example of disarming plant defense. By severing leaf veins or petioles, monarchs are thought to prevent the flow of toxic latex to their feeding site. Here we show that sabotaging by monarch caterpillars is not only an avoidance strategy. While young caterpillars appear to avoid latex, late-instar caterpillars actively ingest exuding latex, presumably to increase sequestration of toxic latex cardenolides used for defense against predators. Comparisons with caterpillars of the related but non-sequestering common crow butterfly (Euploea core) revealed three lines of evidence supporting our hypothesis. First, monarch caterpillars sabotage inconsistently and therefore the behavior is not obligatory to feed on milkweed, whereas sabotaging precedes each feeding event in Euploea caterpillars. Second, monarch caterpillars shift their behavior from latex avoidance in younger stages to eager drinking in later stages, whereas Euploea caterpillars consistently avoid latex and spit it out during sabotaging. Third, monarchs reared on detached leaves without latex, sequestered more cardenolides when caterpillars imbibed latex offered with a pipette. Thus, we conclude that monarch caterpillars have transformed the 'sabotage to avoid' strategy of their relatives into a 'sabotage to consume' strategy implying a novel behavioral adaptation to increase sequestration of cardenolides for defense.

Long-term livestock exclusion increases plant richness and reproductive capacity in arid woodlands

Aim Herbivore exclusion is implemented globally to recover ecosystems from grazing by introduced and native herbivores, but evidence for large-scale biodiversity benefits is inconsistent in arid ecosystems. We examined the effects of livestock exclusion on dryland plant richness and reproductive capacity. Location Central Australia. Methods We collected data on plant species richness and seeding (reproductive capacity), rainfall, vegetation productivity and cover, soil health, and herbivore grazing intensity from 68 sites across 6500 km2 of arid Georgina gidgee (Acacia georginae) woodlands between 2017 and 2020. Sites were on an actively grazed cattle station and two destocked conservation reserves. We used structural equation modelling to examine indirect (via soil or vegetation modification) versus direct (herbivory) effects of grazing intensity by two introduced herbivores (cattle, camels) and a native herbivore (red kangaroo), on seasonal plant species richness and seeding. Results Soil health and rainfall were the strongest drivers of variation in richness and seeding. Cattle and camel grazing indirectly led to lower seasonal richness and seeding by reducing soil health. Kangaroos had a small but negative direct impact on richness, but no impact on soil health. Both introduced and native herbivores reduced annual chenopod shrub richness and seeding, whereas only cattle directly reduced perennial shrub richness and seeding. Camels indirectly reduced perennial shrub richness by impacting shrub abundance. Introduced herbivores reduced native grass richness and seeding indirectly via impacts on soil health, whereas forbs responded positively to cattle and camel activity. Main conclusion Considering indirect impacts improves evaluations of the effects of disturbances on biodiversity, as focusing only on direct effects can mask critical mechanisms of change. Our results indicate substantial biodiversity benefits from excluding livestock and controlling camels in drylands. Reducing introduced herbivore impacts will improve soil and vegetation condition, ensure reproduction and seasonal persistence of species, and protect native plant diversity.

Warmer springs increase potential for temporal reproductive isolation among habitat patches in subalpine flowering plants

<ol> <li>Flowering phenology can vary considerably even at fine spatial scales, potentially leading to temporal reproductive isolation among habitat patches. Climate change could alter flowering synchrony, and hence temporal isolation, if plants in different microhabitats vary in their phenological response to climate change. Despite the importance of temporal isolation in determining patterns of gene flow, and hence population genetic structure and local adaptation, little is known about how changes in climate affect temporal isolation within populations.</li> <li>Here, we use flowering phenology and floral abundance data of 50 subalpine plant species over 44 years to test whether temporal isolation between habitat patches is affected by spring temperature. For each species and year, we analyzed temporal separation in peak flowering and flowering overlap between habitat patches separated by 5 to 950 m.</li> <li>Across our study species, warmer springs were associated with more temporal differentiation in flowering peaks among habitat patches, and less flowering overlap, increasing potential for temporal isolation within populations.</li> <li> Synthesis. By reducing opportunities for mating among plants in nearby habitat patches, our results suggest that warmer springs may reduce opportunities for gene flow within populations, and, consequently, the capacity of plant populations to adapt to environmental changes.</li> </ol>

opencc-by-4.0Jul 2023View details →

Raw data accompanying the manuscript "Uptake of microplastics and impacts on plant traits of savoy cabbage"

These are the raw datasets used to generate Figure 1 for the manuscript entitled "Uptake of microplastics and impacts on plant traits of savoy cabbage". The folders contain all raw CARS and SRS data that are needed to reproduce Figure 1 (TIFF format).

Data from: Soil nutrient heterogeneity alters productivity and diversity of experimental plant communities under multiple global change factors

Plant communities in nature are often challenged by multiple global change factors (GCFs) and also ubiquitously encountered with soil nutrient heterogeneity. So far, however, we know little about the interactive effect of multiple GCFs and soil nutrient heterogeneity on plant communities. We conducted an outdoor mesocosm experiment in which a plant community was either grown in heterogeneous soils consisting of high- and low-nutrient patches, or in homogeneous soils where the same amount of nutrients was evenly distributed. These plant communities were exposed to none (control), single, or a combination of two or four GCFs (i.e., drought, nitrogen deposition, microplastic and cadmium). Biomass of the plant community exposed to drought and nitrogen deposition were greater in heterogeneous than in homogeneous soils, but evenness of the plant community exposed to microplastics was lower. Increasing the number of GCFs increased community biomass more in heterogeneous than in homogeneous soils, but it generally reduced community evenness, independent of soil nutrient heterogeneity. These contrasting responses were related to changing competitive hierarchies and root foraging responses under different treatments. Our results suggest that soil nutrient heterogeneity can alter community productivity and diversity via changing competitive interactions of the component species, depending on both the identity and the number of GCFs acting on the community. These results have important implications for the maintenance of ecosystem functions and services under rapid and complex ongoing global changes.

Activity of tjakura (great desert skinks) at burrows in relation to plant cover and predators

Increased predation where ground cover is reduced after severe wildfire is increasingly implicated as a factor causing decline of vulnerable prey populations. In arid central Australia, one species detrimentally affected by repeated wildfire is the great desert skink or tjakura (Liopholis kintorei), a distinctive lizard of the central Australian arid zone that constructs and inhabits multi-entranced communal burrows. We aimed to test whether tjakura or predator activity at burrow entrances varied with cover and how tjakura respond to predator presence. Using time-lapse photography, we monitored tjakura and predator activity at the largest entrance of 12 burrows ranging from high (>70 %) to low (<50 %) cover and at multiple entrances of two other burrows. Overall activity did not vary between burrows with high and low cover. Within burrow systems, tjakura were more active at sparsely vegetated entrances, often sitting wholly or partly inside the burrow. However, consistent between and within burrow systems, skinks spent proportionally more time fully outside where cover was higher. Predators – mostly native – were detected at most burrows, with no apparent relationship between predator activity and cover. Skinks also did not appear to modify their activity in response to predator visits. Our results indicate that tjakura may spend more time outside burrow entrances when cover is higher, but there was no direct evidence that this related to perceived or real predation risk. Differences in food availability, thermoregulatory opportunities, and opportunities for ambush foraging associated with differences in vegetation cover or composition are other factors likely to be important in determining the activity of tjakura at burrows. Our research demonstrates the usefulness of camera traps for behavioural studies of ectothermic burrowing animals. The complex relationships between tjakura activity and vegetation cover were thereby revealed, suggesting outcomes of fire-mediated habitat change on predator-prey interactions are not easily predictable.

Recolonizing native wildlife facilitates exotic plant invasion into Singapore's rain forests: Data and R script

Halting biological invasions and rewilding extirpated fauna are conservation interventions to bolster biodiversity, species interactions, and ecosystems. These actions are often considered separately and the potential for reintroduced wildlife to facilitate invasive plants has been largely overlooked. Here, we investigate the role of Singapore's recolonizing native wild pigs (Sus scrofa) in facilitating an invasive weed Miconia crenata into tropical rain forests, which are normally highly resistant to invasion. We conducted line-transect surveys in 11 Singaporean rain forests and used generalized linear mixed models to consider the contribution of pigs' soil disturbances, human forest paths, and other environmental covariates, on the density of M. crenata. We found that M. crenata was more abundant at forest edges and invasion into forest interior was facilitated by pigs, paths, and canopy gaps, but that these effects were all additive, not synergistic (i.e. not multiplicative). These results highlight how modern invasions are driven by multiple disturbances as well as propagule pressure (e.g. urban birds dispersing seeds at forest edges where they establish in pig soil disturbances). Singapore's extensive native forest restoration efforts may have provided plentiful edge and secondary forests that are well suited to pigs and M. crenata, which in turn undermine the aims of fostering later-successional native plant communities. To prevent negative externalities, we suggest that plant restoration and rewilding projects consider the potential role of wildlife in facilitating non-native plants, and couple these actions with preliminary screening of unintended consequences and continued monitoring, as well as limiting human-mediated weed invasion to minimize propagule sources.

A nutrition-defense tradeoff drives diet choice in a toxic plant generalist

Plant toxicity shapes the dietary choices of herbivores. Especially when herbivores sequester plant toxins, they may experience a tradeoff between gaining protection from natural enemies and avoiding toxicity. The availability of toxins for sequestration may additionally trade off with the nutritional quality of a potential food source for sequestering herbivores. We hypothesized that diet mixing might allow a sequestering herbivore to balance nutrition and defense (via sequestration of plant toxins). Accordingly, here we address diet mixing and sequestration of large milkweed bugs (Oncopeltus fasciatus) when they have differential access to toxins (cardenolides) in their diet. In the absence of toxins from a preferred food (milkweed seeds), large milkweed bugs fed on nutritionally adequate non-toxic seeds, but supplemented their diet by feeding on nutritionally poor, but cardenolide-rich milkweed leaf and stem tissues. This dietary shift corresponded to reduced insect growth but facilitated sequestration of defensive toxins. Plant production of cardenolides was also substantially induced by bug feeding on leaf and stem tissues, perhaps benefitting this cardenolide-resistant herbivore. Thus, sequestration appears to drive diet mixing in this toxic plant generalist, even at the cost of feeding on nutritionally poor plant tissue.

Pan trap and plant-flower visitor observation data for: Multi-species crop mixtures increase insect biodiversity in an intercropping experiment

<ol> <li>Recent biodiversity declines require action across sectors such as agriculture. The situation is particularly acute for arthropods, a species-rich taxon providing important ecosystem services. To counteract negative consequences of agricultural intensification, creating a less hostile agricultural "matrix" through growing crop mixtures can reduce harm for arthropods without yield losses. </li> <li>While grassland biodiversity experiments showed positive plant biodiversity effects on arthropods, experiments manipulating crop diversity and agrochemical input use to study arthropods are lacking. </li> <li>Here, we experimentally manipulated crop diversity (1–3 species, fallows), crop species (wheat, faba bean, linseed, oilseed rape) and agrochemical input (high vs. low) and studied responses of arthropod biodiversity. We tested if arthropod responses were affected by crop diversity, mixtures and management. Additionally, we measured crop biomass.</li> <li>Crop biomass increased with crop diversity under high-input mangement, while under low management intensity, biomass was highest in two-species mixtures.</li> <li>Increasing crop diversity positively affected arthropod abundance and diversity, both under low- and high-input management. Crop mixtures containing faba bean, linseed or oilseed rape had particularly high arthropod diversity.</li> <li>Mass-flowering crops attracted more arthropods than legumes or cereals. Integrating intercropping into agricultural systems could increase flower visits by insects up to 15 million per hectare, thus likely also supporting pollination and pest-control ecosystem services.</li> <li>Flower-visitor network complexity increased in mixtures containing linseed and faba bean, and under low-input management.</li> <li>Intercropping can counteract insect declines in farmland by creating beneficial matrix habitat without compromising crop yield.</li> </ol>

opencc-by-4.0Aug 2023View details →

Dataset and R-script for Article: Increased heat tolerance of geothermal plants comes at the cost of reduced performance under cooler conditions

Dataset and R-script for Article "Increased heat tolerance of geothermal plants comes at the cost of reduced performance under cooler conditions" to be published in the Journal "Ecology and Evolution"

opencc-by-4.0Aug 2023View details →

Evaluation of local movement of Bemisia tabaci MEAM1 and tomato severe rugose virus transmission to tomato plants using labeled and unlabeled whiteflies

The data presents the effects of two types of labels on whiteflies' behavior. Besides, it shows the flight distances at close range and ToSRV transmission.

opencc-zeroAug 2023View details →

Quantifying the complexity of plant reproductive structures reveals a history of morphological and functional integration

Vascular plant reproductive structures have become more complex through time, evolving differentiated parts that interact in specialized ways. But quantifying these patterns at broad scales is challenging because lineages produce disparate reproductive structures that cannot readily be compared. We develop a novel approach for analyzing interactions within reproductive structures using networks, treating component parts as nodes and a suite of physical and functional interactions among parts as edges. We apply this approach to the plant fossil record, showing that interactions have generally increased through time and that the concentration of these interactions has shifted towards differentiated surrounding organs, resulting in more compact, functionally integrated structures. Such transference of function and morphological differentiation are widespread across plant lineages, but their extent and timing vary with reproductive biology; seed-producing structures show them more strongly than spore or pollen-producing structures. More broadly, our results demonstrate that major reproductive innovations like the origin of seeds and angiospermy were associated with increased integration and interactions among parts. However, they also reveal that for certain lineages, such as Mesozoic gymnosperms, millions of years elapsed between the origin of a reproductive innovation and a measurable increase in the integration and interaction among parts within their reproductive structures.

opencc-by-4.0Aug 2023View details →

Plant invasion and fertilizer addition alter soil biota and their functions: A global meta-analysis

Datasets used for meta-analysis on plant invasion and fertilizer addition effects on soil biota and their functions.