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1,187 results for “herbivores”
Data from: Herbivores safeguard plant diversity by reducing variability in dominance
1. Reductions in community evenness can lead to local extinctions as dominant species exclude subordinate species; however, herbivores can prevent competitive exclusion by consuming otherwise dominant plant species, thus increasing evenness. While these predictions logically result from chronic, gradual reductions in evenness, rapid, temporary pulses of dominance may also reduce species richness. Short pulses of dominance can occur as biotic or abiotic conditions temporarily favor one or a few species, manifested as increased temporal variability (the inverse of temporal stability) in community evenness. Here, we tested whether consumers help maintain plant diversity by reducing the temporal variability in community evenness. 2. We tested our hypothesis by reducing herbivore abundance in a detailed study of a developing, tallgrass prairie restoration. To assess the broader implications of the importance of herbivory on community evenness as well as potential mechanisms, we paired this study with a global herbivore-reduction experiment. 3. We found that herbivores maintained plant richness in a tallgrass prairie restoration by limiting temporary pulses in dominance by a single species. Dominance by an annual species in a single year was negatively associated with species richness, suggesting that short pulses of dominance may be sufficient to exclude subordinate species. 4. The generality of this site-level relationship was supported by the global experiment in which inter-annual variability in evenness declined in the presence of vertebrate herbivores over timeframes ranging in length from 2-5 years, preventing declines in species richness. Furthermore, inter-annual variability of community evenness was also negatively associated with pre-treatment species richness. 5. Synthesis: A loss or reduction of herbivores can destabilize plant communities by allowing brief periods of dominance by one or a few species, potentially triggering a feedback cycle of dominance and extinction. Such cycles may not occur immediately following the loss of herbivores, being delayed until conditions allow temporary periods of dominance by a subset of plant species.
Data from: Museum specimens provide novel insights into changing plant-herbivore interactions
Mounting evidence shows that species interactions may mediate how individual species respond to climate change. However, long-term anthropogenic effects on species interactions are poorly characterized due to a lack of data. Insect herbivory is a major ecological process that represents the interaction between insect herbivores and their host plants, but historical data on insect damage to plants is particularly sparse. Here, we suggest that museum collections of insects and plants can fill key gaps in our knowledge on changing trophic interactions, including proximate mechanisms and the net outcomes of multiple global change drivers across diverse insect herbivore-plant associations. We outline theory on how global change may affect herbivores and their host plants and highlight the unique data that could be extracted from museum specimens to explore their shifting interactions. We aim to provide a framework for using museum specimens to explore how some of the most diverse co-evolved relationships are responding to climate and land use change.
Data from: Climatic variation modulates the indirect effects of large herbivores on small-mammal habitat use
Large mammalian herbivores (LMH) strongly shape the composition and architecture of plant communities. A growing literature shows that negative direct effects of LMH on vegetation frequently propagate to suppress the abundance of smaller consumers. Indirect effects of LMH on the behaviour of these consumers, however, have received comparatively little attention despite their potential ecological significance. We sought to understand (i) how LMH indirectly shape small-mammal habitat use by altering the density and distribution of understorey plants; (ii) how these effects vary with climatic context (here, seasonality in rainfall); and (iii) the extent to which behavioural responses of small mammals are contingent upon small-mammal density. We tested the effects of a diverse LMH community on small-mammal habitat use using 4 years of spatially explicit small-mammal trapping and vegetation data from the UHURU Experiment, a replicated set of LMH exclosures in semi-arid Kenyan savanna. Small-mammal habitat use was positively associated with tree density and negatively associated with bare (unvegetated) patches in all plots and seasons. In the presence of LMH, and especially during the dry season, small mammals consistently selected tree cover and avoided bare patches. In contrast, when LMH were excluded, small mammals were weakly associated with tree cover and did not avoid bare patches as strongly. These behavioural responses of small mammals were largely unaffected by changes in small-mammal density associated with LMH exclusion. Our results show that LMH indirectly affect small-mammal behaviour, and that these effects are influenced by climate and can arise via density-independent mechanisms. This raises the possibility that anthropogenic LMH declines might interact with changing patterns of rainfall to alter small-mammal distribution and behaviour, independent of numerical responses by small mammals to these perturbations. For example, increased rainfall in East Africa (as predicted in many recent climate-model simulations) may relax constraints on small-mammal distribution where LMH are rare or absent, whereas increased aridity and/or drought frequency may tighten them.
Data from: Large scale variation in birth timing and synchrony of a large herbivore along the latitudinal and altitudinal gradients
<p>1. Hopkins' Bioclimatic Law predicts geographic patterns in phenological timing by establishing a correspondence between latitudinal and altitudinal gradients. First proposed for key phenological events of plants, such as leaf sprouting or flowering dates, this law has rarely been used to assess the geographical equivalence of key life history traits of mammals.</p> <p>2. We hypothesize that (H1) parturition dates of European roe deer (Capreolus capreolus) are delayed and more synchronized at higher latitudes and altitudes, (H2) parturition timing varies along latitudinal and altitudinal gradients in a way that matches the Hopkins' Bioclimatic Law, and (H3) females adjust parturition timing to match the period of high energy demand with peak resource availability.</p> <p>3. We used parturition dates of 7,444 European roe deer from Switzerland to assess altitudinal variation in birth timing and synchrony from 288 to 2,366 m a.s.l. We then performed a literature survey to compare altitudinal results with those from different populations along the species' latitudinal range of distribution. Finally, we performed spatial analysis combining our highly resolved altitudinal data on parturition dates with plant phenology data.</p> <p>4. As expected, parturition dates were delayed with increasing latitude and altitude. This delay matched the Bioclimatic Law, as the effect of 1º increase in latitude was similar to 120 m increase in altitude. However, while parturitions were more synchronized with increasing altitude, we did not detect any trend along the latitudinal gradient. Finally, plant phenology explained altitudinal variation in parturition timing better than a linear effect of altitude.</p> <p>5. Our findings clearly demonstrate the ability of a large herbivore to match parturition timing with phenological conditions across the altitudinal gradient, even at the smallest spatial scales. </p>
Data from: Changes in behavior are unable to disrupt a trophic cascade involving a specialist herbivore and its food plant
Changes in ecological conditions can induce changes in behavior and demography of wild organisms, which in turn may influence population dynamics. Black brant (Branta bernicla nigricans) nesting in colonies on the Yukon–Kuskokwim Delta (YKD) in western Alaska have declined substantially (~50%) since the turn of the century. Black brant are herbivores that rely heavily on Carex subspathacea (Hoppner's sedge) during growth and development. The availability of C. subspathacea affects gosling growth rates, which subsequently affect pre‐ and postfledging survival, as well as size and breeding probability as an adult. We predicted that long‐term declines in C. subspathacea have affected gosling growth rates, despite the potential of behavior to buffer changes in food availability during brood rearing. We used Bayesian hierarchical mixed‐effects models to examine long‐term (1987–2015) shifts in brant behavior during brood rearing, forage availability, and gosling growth rates at the Tutakoke River colony. We showed that locomotion behaviors have increased (β = 0.05, 95% CRI: 0.032–0.068) while resting behaviors have decreased (β = −0.024, 95% CRI: −0.041 to −0.007), potentially in response to long‐term shifts in forage availability and brood density. Concurrently, gosling growth rates have decreased substantially (β = −0.100, 95% CRI: −0.191 to −0.016) despite shifts in behavior, mirroring long‐term declines in the abundance of C. subspathacea (β = −0.191, 95% CRI: −0.355 to −0.032). These results have important implications for individual fitness and population viability, where shifts in gosling behavior putatively fail to mitigate long‐term declines in forage availability.
Data from: Will like replace like? linking thermal performance to ecological function across predator and herbivore populations
The inability of species to adapt to changing climate may cause ecological communities to disassemble and lose ecological functioning. However, theory suggests that communities may be resilient whenever populations within species exhibit variation in thermal plasticity or adaptation whereby thermally tolerant populations replace thermally sensitive ones. But will they maintain the functional roles of the populations being replaced? This study evaluated whether "like replaces like" functionally by measuring how four populations of a grasshopper herbivore and its co-occurring spider predator cope with environmental warming. The study occurred across a latitudinal gradient bounded by southerly, warmer Connecticut and northerly, cooler New Hampshire, USA. The study compared the survival rates, thermal performance, habitat usage, and food chain interactions of each grasshopper and spider population between its home field site (field of origin) and a Connecticut transplant site, and the native Connecticut population. Three grasshopper populations exhibited physiological plasticity by adjusting metabolic rates. The fourth population selected cooler habitat locations. Spider populations did not alter their metabolism, and instead selected cooler habitat locations thereby altering spatial overlap with their prey and food chain interactions. Grasshopper populations that coped physiologically consumed plants in different ratios than the fourth population and the Connecticut population. Hence "like may not replace like" whenever populations adapt physiologically to warming.
Parasitoids of leaf herbivores enhance plant fitness and do not alter caterpillar-induced resistance against seed beetles
<p>1. Organisms of the third trophic level can indirectly interact with plants. However, whether parasitoids of herbivores have a positive effect on plant fitness has been controversial. In addition to possible effects on plant fitness, parasitoid-mitigated herbivory can modify plant physiological responses and thereby alter the plant-mediated indirect interactions between different herbivore species. These types of indirect multitrophic interactions remain largely unexplored. Thus, to understand the full effect of the third trophic level on plants, it is necessary to consider the context of the community of interacting species, both herbivores and their enemies.</p> <p>2. Here, we investigated if parasitoids of leaf-feeding caterpillars affect plant fitness (seed quantity and quality) and the consequences for seed-dwelling insects at the second and third trophic levels through plant mediated effects. To test this, we exposed lima bean plants (<i>Phaseolus lunatus</i>), under controlled field conditions, to unparasitized caterpillars (<i>Spodoptera latifascia</i>) or caterpillars that were parasitized by the parasitoid species <i>Cotesia marginiventris</i>. Later in the season, we measured seed production and infestation by seed beetles and their parasitoids.</p> <p>3. We found that parasitoids significantly reduced the leaf damage inflicted by the caterpillars, such that the plants suffered no loss in seed production. Yet, parasitoids had no effect on the emergence of seed beetles (<i>Zabrotes subfasciatus</i> and <i>Acanthoscelides obtectus</i>), which was equally reduced in plants attacked by unparasitized and by parasitized caterpillars. Seeds from undamaged plants were significantly more attacked by <i>Z. subfasciatus</i> beetles. Parasitism rates of seed beetle larvae were similar for all treatments.</p> <p>4. Although parasitized caterpillars did not damage the plants enough to reduce seed production (unlike unparasitized caterpillars), the damage they inflicted induced resistance against other herbivores. Taken together, these results reveal how parasitoids can indirectly enhance plant fitness in the context of the local ecological networks. These findings have significant implications for natural and agricultural systems since they reveal that the indirect interaction between plants and parasitoids can be beneficial in communities with multiple herbivore species.</p>
Data from: Herbivores and plant defenses affect selection on plant reproductive traits more strongly than pollinators
Pollinators and herbivores can both affect the evolutionary diversification of plant reproductive traits. However, plant defenses frequently alter antagonistic and mutualistic interactions and therefore variation in plant defenses may alter patterns of herbivore- and pollinator-mediated selection on plant traits. We tested this hypothesis by conducting a common garden field experiment using 50 clonal genotypes of white clover (Trifolium repens) that varied in a Mendelian inherited chemical antiherbivore defense—the production of hydrogen cyanide (HCN). To evaluate whether plant defenses alter herbivore- and/or pollinator-mediated selection, we factorially crossed chemical defense (25 cyanogenic and 25 acyanogenic genotypes), herbivore damage (herbivore suppression) and pollination (hand-pollination). We found that herbivores weakened selection for increased inflorescence production, suggesting that large displays are costly in the presence of herbivores. In addition, herbivores weakened selection on flower size but only among acyanogenic plants, suggesting that plant defenses reduce the strength of herbivore-mediated selection. Pollinators did not independently affect selection on any trait, although pollinators weakened selection for later flowering among cyanogenic plants. Overall, cyanogenic plant defenses consistently increased the strength of positive directional selection on reproductive traits. Herbivores and pollinators both strengthened and weakened the strength of selection on reproductive traits, although herbivores imposed ~2.7× stronger selection than pollinators across all traits. Contrary to the view that pollinators are the most important agents of selection on reproductive traits, our data show that selection on reproductive traits is driven primarily by variation in herbivory and plant defenses in this system.
Data from: Spatial transitions in tree cover are associated with soil hydrology, but not with grass biomass, fire frequency, or herbivore biomass in Serengeti savannahs
1. Although there is a well-known association between tree cover and soil texture in savannahs, the hydrological drivers of tree cover variation have not been systematically explored, particularly in parallel with factors such as fire, herbivory, and tree-grass interactions. The relationship between hydrological factors and tree cover is important for resolving the relative contribution of bottom-up vs. top-down factors in structuring savannah vegetation. 2. We quantified soil moisture dynamics across eight 1-km transects spanning tree cover gradients from open to woody savannah in Serengeti National Park in Tanzania using soil moisture sensors coupled with dataloggers. We mapped tree cover at two spatial scales through supervised classification of high-resolution satellite imagery. We simultaneously produced water retention curves in open and woody habitats within each transect to compare soil hydrological properties and to convert volumetric water content (θ) from dataloggers to plant-available water over the course of an annual cycle. We also quantified grass biomass at 100 locations per transect, estimated fire frequency from MODIS satellite data, and quantified herbivore occupancy with paired camera traps situated in open and woody habitats within each transect. 3. We found a positive relationship between tree cover and soil moisture drainage rate, and found that open habitats had more negative water potentials than woody habitats for a given value of θ. In contrast, we found no evidence for a consistent relationship between grass biomass or fire frequency and tree cover. We found evidence for higher browser occupancy in woody than open habitats, but no habitat effects on herbivores as a group (browsers plus grazers), suggesting that herbivory is unlikely to be the dominant factor explaining variation in tree cover. 4. Our results suggest that variation in tree cover is partly driven by hydrological (edaphic) factors unrelated to fire, herbivory, tree-grass interactions or mean annual precipitation at these spatial scales in Serengeti. We contrast our findings with previous work attributing tree cover shifts in Serengeti to precipitation gradients.
Data from: Latitudinal patterns of herbivore pressure in a temperate herb support the biotic interactions hypothesis
The longstanding biotic interactions hypothesis predicts that herbivore pressure declines with latitude, but the evidence is mixed. To address gaps in previous studies, we measured herbivory and defense in the same system, quantified defense with bioassays, and considered effects of leaf age. We quantified herbivory and defense of young and mature leaves along a continental gradient in eastern North America in the native herb Phytolacca americana. Herbivory in the field declined with latitude and was strongly correlated with Lepidopteran abundance. Laboratory bioassays revealed that leaf palatability was positively correlated with latitude of origin. Young leaves were more damaged than mature leaves at lower latitudes in the field, but less palatable in bioassays. Both defense and palatability displayed non-linear latitudinal patterns, suggesting potential mechanisms based on biological or climatic thresholds. In sum, observational and experimental studies find patterns consistent with high herbivore pressure and stronger plant defenses at lower latitudes.
Data from: The greenscape shapes surfing of resource waves in a large migratory herbivore
The Green Wave Hypothesis posits that herbivore migration manifests in response to waves of spring green-up (i.e. green-wave surfing). Nonetheless, empirical support for the Green Wave Hypothesis is mixed, and a framework for understanding variation in surfing is lacking. In a population of migratory mule deer (Odocoileus hemionus), 31% surfed plant phenology in spring as well as a theoretically perfect surfer, and 98% surfed better than random. Green-wave surfing varied among individuals and was unrelated to age or energetic state. Instead, the greenscape, which we define as the order, rate and duration of green-up along migratory routes, was the primary factor influencing surfing. Our results indicate that migratory routes are more than a link between seasonal ranges, and they provide an important, but often overlooked, foraging habitat. In addition, the spatiotemporal configuration of forage resources that propagate along migratory routes shape animal movement and presumably, energy gains during migration.
A non-vector herbivore indirectly increases the transmission of a vector-borne virus by reducing plant chemical defenses
<ol> <li><span><span>Vectors and viruses </span><span><span>exist</span></span><span> in communities consisting of many interacting species. Although the cascading effects of predators or parasitoids on disease spread via direct effects on vectors have been investigated, little is known about the effects of other free-living species in communities on the transmission of vector-borne viruses via </span><span><span>indirect (host-plant mediated) effects</span></span><span> on vectors.</span></span></li> <li><span><span>In the present study, we used a food web consisting of tomato plants (</span><i><span>Solanum lycopersicum</span></i><span>), two tomato herbivores (the vector whitefly,</span><i><span> Bemisia tabaci</span></i><span>, and the non-vector two-spotted spider mite, </span><i><span>Tetranychus urticae</span></i><span>), and a whitefly-vectored plant virus (</span><i><span>Tomato yellow leaf curl virus</span></i><span>, TYLCV) to study how </span><i><span>T. urticae</span></i><span> may affect TYLCV transmission by </span><i><span>B. tabaci</span></i><span> via </span><span><span>host-plant</span></span><span> </span><span><span>mediated effects</span></span><span><span> on </span><i><span>B. tabaci</span></i></span><span>.</span></span></li> <li><span><span>We found that </span><i><span>T. urticae</span></i><span> infestation promoted </span><i><span>B. tabaci</span></i><span> feeding and thereby increased TYLCV transmission to tomato plants. These increases were </span><span><span>associated with</span></span><span> </span><i><span>T. urticae</span></i><span>-induced reductions in two flavonoids (rutin and quercetin trisaccharide) of tomato plants. Elevation of rutin and quercetin trisaccharide levels in </span><i><span>T. urticae</span></i><span>-infested plants via exogenous stem applications reduced </span><i><span>B. tabaci</span></i><span> feeding and TYLCV transmission. Therefore, suppression of these flavonoids by </span><i><span>T. urticae</span></i><span> infestation was </span><span><span>the most likely explanation for the observed changes in </span></span><i><span><span>B. tabaci</span></span></i><span><span> feeding behavior and TYLCV transmission</span></span><span>.</span></span></li> <li> <span>Our results show that by reducing flavonoids in tomato plants, a non-vector herbivore can indirectly increase the transmission of a vector-borne plant virus. These findings indicate that species that are far removed from the direct vector–virus interactions can indirectly affect vector–borne virus transmission by altering the </span><span><span>chemical defenses</span></span><span> of the shared host plant.</span> </li> </ol>
Data from: Temperature alters the toxicological impacts of plant terpenoids on the polyphagous model herbivore Vanessa cardui
<p>Terpenes are a major class of secondary metabolites present in all plants, and long hypothesized to have diversified in response to specific plant-herbivore interactions. Herbivory is a major biotic interaction that plays out across broad temporal and spatial scales that vary dramatically in temperature regimes, both due to climatic variation across geographic locations as well as the effect of seasonality. In addition, there is an emerging understanding that global climate change will continue to alter the temperature regimes of nearly every habitat on Earth over the coming centuries. Regardless of source, variation in temperature may influence herbivory, in particular via changes in the efficacy and impacts of plant defensive chemistry. This study aims to characterize temperature-driven variation in toxicological effects across several structural classes of terpenes in the model herbivore Vanessa cardui, the painted lady butterfly. We observed a general increase in monoterpene toxicity to larvae, pupa, and adults at higher temperatures, as well as an increase in development time as terpene concentration increased. Results obtained from this study yield insights into possible drivers of seasonal variation in plant terpene production as well as inform effects of rising global temperatures on plant-insect interactions. In the context of other known effects of climate change on plant-herbivore interactions like carbon fertilization and compensatory feeding, temperature-driven changes in plant chemical defense efficacy may further complicate the prediction of climate change impacts on the fundamental ecological process of herbivory.</p>
Crop diversity and within field multi-species interactions mediate herbivore abundances in cotton fields
<p>Insect herbivore abundances in agricultural fields partly depend on surrounding landscape compositional heterogeneity (e.g., landscape complexity). Landscape complexity can directly (e.g., dilution of host crops) and indirectly (promoting herbivore biocontrol) regulate herbivores in agricultural fields. While much is known about direct (e.g., resource concentration) and indirect effects (i.e., promoting biocontrol) of landscape complexity on herbivore populations, more work is needed to study whether landscape complexity can regulate herbivore populations by mediating within field multi-species interactions among herbivores and their shared natural enemies. During 2019 and 2020, we estimated <em>Bemisia tabaci </em>and<em> Aphis gossypii</em> abundances, their dominant predators (coccinellids, spiders, <em>Orius </em>spp., and <em>Geocoris </em>spp.), and their interaction (using molecular analysis) in 38 cotton fields along a gradient of landscape diversity across Georgia, USA. Within cotton fields, we assessed the effect of predator abundances, their frequency of feeding on herbivores, and the correlation between herbivore abundances (<em>B. tabaci </em>and <em>A. gossypii</em>) on the <em>B. tabaci</em> and <em>A. gossypii</em> abundance. At the landscape scale, crop diversity and different cover types influenced the abundance of <em>B. tabaci</em> and <em>A. gossypii</em> within cotton fields. We found a complex interaction among pests at the field scale, with higher aphid abundance correlated with decreased whitefly abundance. Our results support crop diversification for improving suppression of generalist pests in cotton landscapes through promoting biocontrol and diluting host crop area. Our result further suggests that the landscape complexity effect on whiteflies can indirectly mediate aphid abundance in cotton fields, indicating the importance of within field species interactions.</p>
Data for: Horizontal viewsheds of large herbivores as a function of woodland structure
<p>This dataset contains values of tree stem density per hectare of different size classes (Sapling: > 0.3m, < 1.3m height, Small stem: >=1.3m height, < 10cm DBH, Medium stem: 10-20cm DBH, Large: 21-30cm DBH, Very large: >=31cm DBH), Viewshed Coefficient values (vc), Leaf Area Index (LAI) values for 0.75 - 1.5m above the ground and average percentage cover of bramble (<em>Rubus frutocisus agg.</em>). These data have come from 71 circular 15m-radius sampling plots (four-character codes in plotID column across ten woodland sites (three-character codes in site column). </p> <p>The "raw_data" tab contains the untransformed, unscaled raw data. The "transformed_scaled_data" tab contains the transformed, scaled data that were used in the modelling approach in the associated manuscript.</p>
Data from: Disparate home range dynamics reflect nutritional inadequacies on summer range for a large herbivore
<p>The spatial distribution of animals has consequences for nutrition, predator-prey dynamics, spread of diseases, and population dynamics in general. Animals must establish a home range to secure adequate resources to fuel their energetic needs. Home ranges, therefore, are temporally and spatially dynamic given the changing requirements of an animal and the availability of resources on the landscape. We used data from two populations of bighorn sheep with contrasting population dynamics following pneumonia epizootics and different habitat quality on their summer range to test the hypothesis that the distribution and size of home ranges are influenced by environmental conditions and reproductive status. We used a combination of data from 768 vegetation transects and remotely sensed metrics to index forage quality of consecutive biweekly home ranges for 27 bighorn sheep, June–August 2019–2021. There were population differences in space use that were consistent with resource limitations in the population declining in abundance. Animals in both populations increased the area of their space use through the summer in association with declining forage quality indexed by plant phenology. Furthermore, animals in the Whiskey Mountain population without live offspring used areas more than twice the size of animals with offspring, whereas there were no differences in the area of space use between animals with and without offspring in Jackson. We demonstrated that limitations young offspring impose on space use of a mother may have consequences for animals living where larger home ranges are needed to secure adequate resources—sheep in Whiskey Mountain had to travel 1,000 m from escape terrain to access the same amount of biomass that the Jackson sheep could access directly adjacent to escape terrain. Forage quality and availability influence movement and home range dynamics. In the presence of disease, movement and home range dynamics may influence pathogen transmission and persistence. Thus, forage availability may play an indirect role in population dynamics in the presence of disease, which is another line of evidence for how environmental and nutritional conditions may influence population dynamics of populations coping with disease.</p>
Native herbivore browsing alters plant physical and chemical traits in a eucalypt forest understory
<p>Macropods exhibit selective herbivory on plant traits within and between species and hence can alter plant trait variation. In this study we asked, what are the effects of macropod herbivory on intraspecific variation in plant traits of forest understorey species? We tested the effects of herbivory by macropods on eight plant traits, in nine understorey species using a herbivore exclusion experiment. Generalised linear mixed models were used to test for differences between herbivory treatments in trait means as well as variation within species and at the community level. Macropod herbivory resulted in differences in either the mean trait value or trait variance within a species for seven of the eight tested plant traits. Macropod exclusion resulted in larger dimensions of size for most species, as well as changes in specific leaf area, moisture content, and carbon content of leaves. Further, community-weighted means of specific leaf area, moisture content, and leaf nitrogen were lower in the presence of macropods. Plant trait variance was altered for three of the seven community weighted traits. This study demonstrates a mechanism through which macropods can drive changes in the traits of understorey plant species. Plant traits have been linked to various larger scale ecological processes including ecosystem flammability, nutrient cycling, response to global change and habitat suitability for other organisms. Therefore, herbivore-induced changes in plant trait variation and community composition could have important flow on effects for other environmental processes and hence should be considered in management decisions regarding fire-prone ecosystems.</p>
Data from: navigating uncertainty: managing herbivore communities enhances savanna ecosystem resilience under climate change
<p>Savannas are characterized by water scarcity and degradation, making them highly vulnerable to increased uncertainties in water availability resulting from climate change. This poses a significant threat to ecosystem services and rural livelihoods that depend on them. In addition, the lack of consensus among climate models on precipitation change makes it difficult for land managers to plan for the future. Therefore, savanna rangeland management needs to develop strategies that can sustain savanna resilience and avoid tipping points under an uncertain future climate. Our study aims to analyze the impacts of climate change and rangeland management on degradation in savanna ecosystems of southern Africa, providing insights for the management of semi-arid savannas under uncertain conditions worldwide. To achieve this, we simulated the effects of projected changes in temperature and precipitation, as predicted by ten global climate models, on water resources and vegetation (cover, functional diversity, tipping points (transition from grass-dominated to shrub-dominated vegetation)). We simulated three different rangeland management options (herbivore community dominated by grazers, by browser and by mixed-feeders), each with low and high animal densities using the ecohydrological model EcoHyD. Our results identified intensive grazing as the primary contributor to the increased risk of degradation in response to changing climatic conditions across all climate change scenarios. This degradation encompassed a reduction in available water for plant growth within the context of predicted climate change. It also entails a decline in the overall vegetation cover, the loss of functionally important plant species, and the inefficient utilization of available water resources, leading to earlier tipping points. Our findings underscore that in the face of climate uncertainty, farmers' most effective strategy for securing their livelihoods and ecosystem stability is to integrate browsers and apply management of mixed herbivore communities. This management approach not only significantly delays or averts tipping points but also maintained greater plant functional diversity, fostering a more robust and resilient ecosystem that acts as a vital buffer against adverse climatic conditions.</p>
Trait-based mechanistic approach highlights global patterns and losses of herbivore biomass functional diversity
<ol> <li>Mammalian herbivores play a pivotal role in Earth System processes by affecting biogeochemical cycles and ecosystem functioning, potentially leading to significant repercussions on atmosphere-biosphere feedbacks. Global dynamic models of mammalian populations can improve our understanding of their ecological role at large scales and the consequences of their extinctions. However, such models are still lacking and mammals are poorly integrated in Earth System science.</li> <li>We developed a mechanistic global model of terrestrial herbivore populations simulated with 37 functional groups defined through the analysis of eco-physiological traits across all extant herbivores (2599 species). We coupled this model with a global vegetation model to predict herbivores' maximum potential biomass in pre-industrial and at present-day and to study the environmental drivers explaining the distribution of herbivore biomass. Present-day biomass was estimated by accounting for anthropogenic activity causing habitat and range losses.</li> <li>We show that natural ecosystems could have sustained a potential wild herbivore wet biomass of 330 Mt [95% CI 245–417], comprised of 193 Mt [95% CI 177–208] by large species (body mass > 1–10 kg, depending on functional group) and 138 Mt [95% CI 68-209] by small species. We estimate that the remaining present-day large herbivores biomass is 82 Mt [95% CI 32–133], reduced by 57% due to anthropogenic activity; consequently, small herbivores currently dominate global herbivore biomass with 98 Mt (95% CI 91–106, -29%). Losses vary greatly across climatic zones and functional groups, suggesting that size is not the only discriminant feature of biomass decline.</li> <li>Actual evapotranspiration is the most important driver of total, large, and small herbivore biomass and explains 64%, 59%, and 49% of its variation, respectively. Distribution of modeled and observed large herbivores' biomass suggested a high dependency on energy and water with more biomass in hot and wet areas. These results challenge the notion that large herbivore biomass peaks primarily in ecosystems with intermediate precipitation levels such as savannas.</li> <li>Outside Africa and the Tropics, pre-industrial biomass hotspots occur in areas today dominated by humans; this could undermine the recovery of larger species biomass in certain areas. These herbivore biomass estimates provide a quantitative benchmark for setting conservation and rewilding goals at large spatial scales. The herbivore model and functional classification create new opportunities to integrate mammals into Earth System science and models.</li> </ol>
Local habitat complexity and its effects on herbivores and predators in urban agroecosystems
<p>In urban community gardens, cultivated vegetation provides variable levels of habitat complexity, which can suppress pests by promoting predator diversity and improving pest control. In this study, we examine three components of the structural complexity of garden vegetation (cover, diversity, and connectivity) to investigate whether higher garden vegetation complexity leads to fewer herbivores, more predators, and higher predation. We worked in eight community gardens where we quantified vegetation complexity, sampled the arthropod community, and measured predation on cornworm eggs. We found that plots with high vegetation cover supported higher species richness and greater abundance of predatory insects. High vegetation cover also supported a greater abundance and richness of spiders. In contrast, high vegetation diversity was negatively associated with predator abundance. While high predator abundance was positively associated with egg predation, greater predator species richness had a negative impact on egg predation, suggesting that antagonism between predators may limit biological control. Community gardeners may thus manipulate vegetation cover and diversity to promote higher predator abundance and diversity in their plots. However, the species composition of predators and the prevalence of interspecific antagonism may ultimately determine subsequent impacts on biological pest control.</p>
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.