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1,187 results for “herbivores”
Data from: Plant – herbivorous beetle networks: molecular characterization of trophic ecology within a threatened steppic environment
DNA barcoding facilitates many evolutionary and ecological studies, including the examination of the dietary diversity of herbivores. In this study, we present a survey of ecological associations between herbivorous beetles and host plants from seriously threatened European steppic grasslands. We determined host plants for the majority (65%) of steppic leaf beetles (55 species) and weevils (59) known from central Europe using two barcodes (trnL and rbcL) and two sequencing strategies (Sanger for mono/oligophagous species and Illumina for polyphagous taxa). To better understand the ecological associations between steppic beetles and their host plants, we tested the hypothesis that leaf beetles and weevils differ in food selection as a result of their phylogenetic relations (within genera and between families) and interactions with host plants. We found 224 links between the beetles and the plants. Beetles belonging to seven genera feed on the same or related plants. Their preferences were probably inherited from common ancestors and/or resulted from the host plant's chemistry. Beetles from four genera feed on different plants, possibly reducing intrageneric competition and possibly due to an adaptation to different plant chemical defences. We found significant correlations between the numbers of leaf beetle and weevil species feeding on particular plants for polyphagous taxa, but not for nonpolyphagous beetles. Finally, we found that the previous identifications of host plants based on direct observations are generally concordant with host plant barcoding from insect gut. Our results expand basic knowledge about the trophic relations of steppic beetles and plants and are immediately useful for conservation purposes.
Data from: Soil fertility and parasitoids shape herbivore selection on plants
1. Although plants and herbivores interact under varying soil resources and natural enemy effects, little is known about how these factors influence plant-herbivore interactions and shape the evolution of plant and herbivore traits. Here we ask whether soil fertility and parasitoids shape selection on fruit number imposed by a seed predator (SP) on the perennial herb Ruellia nudiflora. 2. We used a common garden where half the plants of 14 genetic families were fertilized, and recorded the abundance of cleistogamous (CL) fruits and seeds, SPs, and parasitoids. We calculated relative fitness per family based on CL seed number under the following three scenarios: Three trophic levels (accounting for SP and parasitoid effects), two trophic levels (accounting for SP but not parasitoid effects), and one trophic level (fitness in absence of SPs), and compared selection strength on fruit number between trophic scenarios and fertility environments. 3. In unfertilized conditions, SPs selected for increased CL fruit number, whereas parasitoids dampened (but did not eliminate) this selective impact. With fertilization, however, selection by SPs was reduced and unaffected by parasitoids. 4. Synthesis: Overall, we show that parasitoids can shape herbivore selection on plants, but that both herbivore and parasitoid selective impacts depend upon the abiotic environment. These findings underscore how linkages between abiotic factors and trophic complexity influence the ecological and evolutionary outcomes of species interactions.
Data from: Geographic mosaic of plant evolution: extrafloral nectary variation mediated by ant and herbivore assemblages
Herbivory is an ecological process that is known to generate different patterns of selection on defensive plant traits across populations. Studies on this topic could greatly benefit from the general framework of the Geographic Mosaic Theory of Coevolution (GMT). Here, we hypothesize that herbivory represents a strong pressure for extrafloral nectary (EFN) bearing plants, with differences in herbivore and ant visitor assemblages leading to different evolutionary pressures among localities and ultimately to differences in EFN abundance and function. In this study, we investigate this hypothesis by analyzing 10 populations of Anemopaegma album (30 individuals per population) distributed through ca. 600 km of Neotropical savanna and covering most of the geographic range of this plant species. A common garden experiment revealed a phenotypic differentiation in EFN abundance, in which field and experimental plants showed a similar pattern of EFN variation among populations. We also did not find significant correlations between EFN traits and ant abundance, herbivory and plant performance across localities. Instead, a more complex pattern of ant–EFN variation, a geographic mosaic, emerged throughout the geographical range of A. album. We modeled the functional relationship between EFNs and ant traits across ant species and extended this phenotypic interface to characterize local situations of phenotypic matching and mismatching at the population level. Two distinct types of phenotypic matching emerged throughout populations: (1) a population with smaller ants (Crematogaster crinosa) matched with low abundance of EFNs; and (2) seven populations with bigger ants (Camponotus species) matched with higher EFN abundances. Three matched populations showed the highest plant performance and narrower variance of EFN abundance, representing potential plant evolutionary hotspots. Cases of mismatched and matched populations with the lowest performance were associated with abundant and highly detrimental herbivores. Our findings provide insights on the ecology and evolution of plant–ant guarding systems, and suggest new directions to research on facultative mutualistic interactions at wide geographic scales.
Data from: Mechanisms of a locally adaptive shift in allocation among growth, reproduction, and herbivore resistance in Mimulus guttatus
Environmental gradients can drive adaptive evolutionary shifts in plant resource allocation among growth, reproduction, and herbivore resistance. However, few studies have attempted to connect these adaptations to underlying physiological and genetic mechanisms. Here, we evaluate potential mechanisms responsible for a coordinated locally adaptive shift between growth, reproduction, and herbivore defense in the yellow monkeyflower, Mimulus guttatus. Through manipulative laboratory experiments we found that gibberellin (GA) growth hormones may play a role in the developmental divergence between perennial and annual ecotypes of M. guttatus. Further, we detected an interaction between a locally adaptive chromosomal inversion, DIV1, and GA addition. This finding is consistent with the inversion contributing to the evolutionary divergence between inland annual and coastal perennial ecotypes by reducing GA biosynthesis/activity in perennials. Finally, we found evidence that the DIV1 inversion is partially responsible for a coordinated shift in the divergence of growth, reproduction, and herbivore resistance traits between coastal perennial and inland annual M. guttatus. The inversion has already been established to have a substantial impact on the life-history shift between long-term growth and rapid reproduction. Here, we demonstrate that the DIV1 inversion also has sizable impacts on both the total abundance and composition of phytochemical compounds involved in herbivore resistance.
Data from: Evolutionary dynamics of specialisation in herbivorous stick insects
Understanding the evolutionary dynamics underlying herbivorous insect mega-diversity requires investigating the ability of insects to shift and adapt to different host plants. Feeding experiments with nine related stick insect species revealed that insects retain the ability to use ancestral host plants after shifting to novel hosts, with host plant shifts generating fundamental feeding niche expansions. These expansions were however not accompanied by expansions of the realized feeding niches, as species on novel hosts are generally ecologically specialized. For shifts from angiosperm to chemically challenging conifer hosts, generalist fundamental feeding niches even evolved jointly with strong host plant specialization, indicating that host plant specialization is not driven by constraints imposed by plant chemistry. By coupling analyses of plant chemical compounds, fundamental and ecological feeding niches in multiple insect species, we provide novel insights into the evolutionary dynamics of host range expansion and contraction in herbivorous insects.
Data from: Extreme precipitation variability, forage quality and large herbivore diet selection in arid environments
Nutritional ecology forms the interface between environmental variability and large herbivore behaviour, life history characteristics, and population dynamics. Forage conditions in arid and semi-arid regions are driven by unpredictable spatial and temporal patterns in rainfall. Diet selection by herbivores should be directed towards overcoming the most pressing nutritional limitation (i.e. energy, protein [nitrogen, N], moisture) within the constraints imposed by temporal and spatial variability in forage conditions. We investigated the influence of precipitation-induced shifts in forage nutritional quality and subsequent large herbivore responses across widely varying precipitation conditions in an arid environment. Specifically, we assessed seasonal changes in diet breadth and forage selection of adult female desert bighorn sheep Ovis canadensis mexicana in relation to potential nutritional limitations in forage N, moisture and energy content (as proxied by dry matter digestibility, DMD). Succulents were consistently high in moisture but low in N and grasses were low in N and moisture until the wet period. Nitrogen and moisture content of shrubs and forbs varied among seasons and climatic periods, whereas trees had consistently high N and moderate moisture levels. Shrubs, trees and succulents composed most of the seasonal sheep diets but had little variation in DMD. Across all seasons during drought and during summer with average precipitation, forages selected by sheep were higher in N and moisture than that of available forage. Differences in DMD between sheep diets and available forage were minor. Diet breadth was lowest during drought and increased with precipitation, reflecting a reliance on few key forage species during drought. Overall, forage selection was more strongly associated with N and moisture content than energy content. Our study demonstrates that unlike north-temperate ungulates which are generally reported to be energy-limited, N and moisture may be more nutritionally limiting for desert ungulates than digestible energy.
Data from: Scatterhoarders drive long- and short-term population dynamics of a nut-producing tree, while pre-dispersal seed predators and herbivores have little effect
1.Both seed predators and herbivores can have profound effects on individual plant growth, reproduction and survival, but their population level effects are less well understood. While most plants interact with a suite of seed predators and herbivores over their life cycle, few studies incorporate the effects of multiple interacting partners and multiple life stages on plant population growth. 2.We constructed a matrix model using six years of data from a rare, seed-producing population of American chestnut (Castanea dentata). We combined field demographic data with published experimental results on the effects of pre-dispersal seed predators (weevils) and post-dispersal seed predators (scatter-hoarding vertebrates) and incorporated the effect of vertebrate herbivores estimated from the field data. We explored the impact of these three different animal interactions for short-term (transient) and long-term (asymptotic) tree population growth. In addition, we used the model to explore the conditions under which scatter-hoarding would function as a mutualism. 3.Seed predators had greater effect on both short- and long-term population growth than herbivores. Although weevil infestation can greatly reduce the probability of germination, pre-dispersal seed predators had smaller effects on both short- or long-term population growth than post-dispersal predators. The elasticities of weevil-related parameters were also small. The effect of browsers on both the short- and long-term population growth rate were the smallest of the effects studied. Post-dispersal seed predation affected population growth the most of the interactions studied. The probability of seed removal was amongst the largest elasticities, similar in magnitude to survival of large trees. 4.Synthesis Our results indicate that neither weevils nor the intensity of browse damage observed at our study site are likely to hinder tree regeneration or reintroduction, though both reduced population growth. Although researchers and forest managers often assume that seeds are unimportant for long-lived tree populations, our test of this assumption shows that scatterhoarders and other post-dispersal seed consumers can significantly limit natural regeneration. Forest management that alters scatterhoarder behaviour could have significant effects on tree population dynamics that are largely unexplored.
Herbivore phenology can predict response to changes in plant quality by livestock grazing
<p>Livestock grazing can have a strong impact on herbivore abundance, distribution and community. However, not all species of herbivores respond the same way to livestock grazing, and we still have a poor understanding of the underlying mechanisms driving these differential responses. Here, we investigate the effect of light intensity cattle grazing on the abundance of two grasshoppers (<i>Euchorthippus cheui</i> and <i>E. unicolor</i>) that co-occur in the same grasslands and feed on the same food plant (the dominant grass <i>Leymus chinensis</i>). The two grasshopper species differ in phenology so that their peak abundances are separated into early- and late-growing seasons. We used an exclosure experiment to monitor grasshopper abundance and food quality in the field under grazed and ungrazed conditions, and performed feeding trials to examine grasshopper preference for grazed or ungrazed food plants in the laboratory. We found that the nitrogen content of <i>L. chinensis</i> leaves continuously declined in the ungrazed areas, but was significantly enhanced by cattle grazing over the growing season. Cattle grazing facilitated the early-season grasshopper <i>E. cheui, </i>whereas it suppressed<i> </i>the late-season grasshopper <i>E. unicolor</i>. Moreover, feeding trials showed that <i>E. cheui</i> preferred <i>L. chinensis</i> from grazed plots, while <i>E. unicolor</i> preferred the leaves from ungrazed plots. We conclude that livestock grazing has opposite effects on the two grasshopper species, and that these effects may be driven by grazing-induced chagnes in plant nutrient content and the unique nutritional niches of the grasshoppers. These results suggest that insects that belong to the same guild can have opposite nutrient requirements, related to their distinct phenologies, and that this can ultimately affect their response to cattle grazing. Our results show that phenology may link insect physiological needs to local resource availabilities, and should be given more attention in future work on interactions between large herbivores and insects.</p>
Data from: Nutrient presses and pulses differentially impact plants, herbivores, detritivores and their natural enemies
Anthropogenic nutrient inputs into native ecosystems cause fluctuations in resources that normally limit plant growth, which has important consequences for associated food webs. Such inputs from agricultural and urban habitats into nearby natural systems are increasing globally and can be highly variable, spanning the range from sporadic to continuous. Despite the global increase in anthropogenically-derived nutrient inputs into native ecosystems, the consequences of variation in subsidy duration on native plants and their associated food webs are poorly known. Specifically, while some studies have examined the effects of nutrient subsidies on native ecosystems for a single year (a nutrient pulse), repeated introductions of nutrients across multiple years (a nutrient press) better reflect the persistent nature of anthropogenic nutrient enrichment. We therefore contrasted the effects of a one-year nutrient pulse with a four-year nutrient press on arthropod consumers in two salt marshes. Salt marshes represent an ideal system to address the differential impacts of nutrient pulses and presses on ecosystem and community dynamics because human development and other anthropogenic activities lead to recurrent introductions of nutrients into these natural systems. We found that plant biomass and %N as well as arthropod density fell after the nutrient pulse ended but remained elevated throughout the nutrient press. Notably, higher trophic levels responded more strongly than lower trophic levels to fertilization, and the predator/prey ratio increased each year of the nutrient press, demonstrating that food web responses to anthropogenic nutrient enrichment can take years to fully manifest themselves. Vegetation at the two marshes also exhibited an apparent tradeoff between increasing %N and biomass in response to fertilization. Our research emphasizes the need for long-term, spatially diverse studies of nutrient enrichment in order to understand how variation in the duration of anthropogenic nutrient subsidies affects native ecosystems.
Data from: Seasonally dependent relationship between insect herbivores and host plant density in Jatropha nana, a tropical perennial herb
The fact that plant spatial aggregation patterns shape insect herbivore communities in a variety of ways has resulted in a large body of literature on the subject. The landmark resource concentration hypothesis predicts that density of insect-herbivores per plant will increase as host plant density increases. I examined this prediction across temporal samplings using Jatropha nana and the associated specialist insect-herbivores as a system. Through 12 field samplings, I modelled the effect of host plant density on insect-herbivore loads. The initial samplings (2-3) provided evidence for the resource concentration hypothesis with insect loads increasing with increasing host plant density, whereas the later samplings (4-5, 7-11) showed the opposite- a resource dilution pattern with decline of insect loads with increasing host plant density. These patterns also depend on the biology of the herbivores and have important implications on J. nana population dynamics.
Data from: Land abandonment and intensification diminish spatial and temporal β-diversity of grassland plants and herbivorous insects within paddy terraces
1. Although traditional land-use and management practices are known to enhance environmental heterogeneity in agricultural lands, loss of heterogeneity resulting from recent land-use changes can lead to spatiotemporal β-diversity losses (biotic homogenization). However, patterns and causes of β-diversity loss, especially at a within-field scale, have remained unexplored. 2. We examined β-diversity declines in plants, butterflies and orthopterans resulting from land abandonment and intensification in semi-natural grasslands on paddy margins at a within-field scale in relation to changes in disturbance frequency and surrounding landscapes by surveying eight abandoned, thirteen traditional and ten intensive paddy terraces. Three indices, the additive partitioning of species richness (βadd) and the turnover (βtu) and nestedness (βne) components of Jaccard dissimilarity of plants and herbivores, were used to evaluate different aspects of β-diversity. We hypothesized that biotic homogenization due to abandonment and intensification would be expressed as low spatiotemporal βadd and βtu, low spatial βne and high temporal βne. 3. The spatial and temporal βadd of plants and herbivores were higher in traditional terraces than in others. Changes in mowing frequency caused direct declines in butterfly βadd and indirectly decreased herbivore βadd through diminished plant βadd in abandoned and intensified terraces. 4. Neighbouring forests increased plant spatial and butterfly temporal βadd and βtu. Abandoned terraces had higher orthopteran spatial and plant temporal βtu than traditional terraces. Mowing frequency generally did not influence spatial and temporal βtu of plants and herbivores. In intensive terraces, temporal βne of plants were higher than in traditional terraces, suggesting dominance by plant species sharing similar phenologies. 4. Synthesis and applications. These results suggest that traditional mowing practices are essential for maintaining plant and herbivore βadd, and consequently, species pools within terraces. The higher spatial or temporal species turnover of plants and orthopterans in abandoned terraces and higher temporal plant nestedness in intensive than in traditional terraces were not due to increases in species pools within terraces. Because within-terrace environmental heterogeneity is thought to remain in abandoned and intensive terraces, we recommend reduction in mowing frequency in intensive terraces and reintroduction of mowing in abandoned terraces for biodiversity restoration.
Data from: Varying the spatial arrangement of synthetic herbivore-induced plant volatiles and companion plants to improve conservation biological control
1.Conservation biological control aims to control pests by promoting wild populations of natural enemies. One challenge is to attract and retain efficient natural enemies in crop fields, which often are a suboptimal environment. Towards this goal, the attract-and-reward strategy relies on combining attractive synthetically produced herbivore-induced plant volatiles (HIPVs) with companion plants (non-crop plants which provide alternative resources to the targeted natural enemies). Although severely overlooked, the spatial arrangement of HIPV dispensers and rewards inside crop fields may strongly influence the foraging behaviour and persistence of natural enemies and thus the success of this pest management strategy. 2.We tested the impact of two contrasting spatial arrangements of HIPV dispensers and rewards, alternatively inside and around a block of target apple trees, on the efficacy of the biological control of Aphis citricola populations by the common predatory ladybird Propylea japonica in apple orchards in northern China. We used synthetic methyl salicylate (MeSA) as an attractant and the companion plant Calendula officinalis as a reward. To better understand how the spatial arrangement of MeSA dispensers and companion plants affected the attraction and foraging behaviour of adult ladybirds, we conducted indoor experiments in a flight mill, an olfactometer and a wind-tunnel. 3.Blocks of target trees treated with MeSA dispensers inside and companion plants around provided the most efficient pest control in orchards, compared with the opposite spatial arrangement. 4.The synthetic MeSA dispenser and the companion plant synergistically attracted ladybirds in the olfactometer and enhanced their flight activity in the flight mill. In the wind-tunnel, MeSA served as a spatial cue for ladybirds to find nearby prey, while companion plants were sought in the absence of prey. 5.Synthesis and applications. The present study will help further improvements of aphid control in apple orchards through a careful spatial arrangement of herbivore-induced plant volatiles dispensers (HIPVs) and rewards (companion plants) in optimized attract-and-reward strategies. Without such assessment, these strategies may be hazardous even with well-identified targeted natural enemies. Associated lab experiments highlight that HIPVs and companion plants interactively influence ladybird foraging pattern, and that their spatial arrangement can modulate the ability of such key predators to find their prey.
Data from: Linking niche theory to ecological impacts of successful invaders: insights from resource fluctuation-specialist herbivore interactions
1. Theories of species coexistence and invasion ecology are fundamentally connected and provide a common theoretical framework for studying the mechanisms underlying successful invasions and their ecological impacts. Temporal fluctuations in resource availability and differences in life-history traits between invasive and resident species are considered as likely drivers of the dynamics of invaded communities. Current critical issues in invasion ecology thus relate to the extent to which such mechanisms influence coexistence between invasive and resident species, and to the ability of resident species to persist in an invasive-dominated ecosystem. 2. We tested how a fluctuating resource and species traits differences may explain and help predict long-term impacts of biological invasions in forest specialist insect communities. We used a simple invasion system comprising closely related invasive and resident seed-specialized wasps (Hymenoptera: Torymidae) competing for a well-known fluctuating resource, and displaying divergent diapause, reproductive and phenological traits. 3. Based on extensive long-term field observations (1977-2010), we developed a combination of mechanistic and statistical models aiming to (i) obtain a realistic description of the population dynamics of these interacting species over time, and (ii) clarify the respective contributions of fluctuation-dependent and fluctuation-independent mechanisms to long-term impact of invasion on the population dynamics of the resident wasp species. 4. We showed that a fluctuation-dependent mechanism was unable to promote coexistence of the resident and invasive species. Earlier phenology of the invasive species was the main driver of invasion success, enabling the invader to exploit an empty niche. Phenology also had the greatest power to explain the long-term negative impact of the invasive on the resident species, through resource preemption. 5. This study provides strong support for the critical role of species differences in interspecific competition outcomes within animal communities. Our mechanisticstatistical approach allows disentangling the critical drivers of the dynamics of coexistence and exclusion within novel species assemblages, following both intentional and non-intentional species introductions.
Data from: Remotely-sensed primary productivity shows that domestic and native herbivores combined are overgrazing Patagonia
1. Carrying capacity is the maximum density of animals an area can sustain without a deterioration of its resources. Overgrazing degraded Patagonia grasslands in the past, but sheep stocks decreased in the last three decades and gave way to a mixed system with cattle, goats and guanacos (native wild camelids). 2. The objective of this paper was to develop a method to estimate carrying capacity based on remotely sensed data, and to assess wild and domestic herbivore numbers to establish if combined grazing stocks have evolved to a balance with carrying capacity. 3. Net Primary Productivity (NPP) MOD17/A3 images and Aerial Net Primary Productivity (ANPP) data of 66 sites were linearly regressed (R2= 0.83, P<0.01), and the slope 0.236 was used to convert MOD17/A3 NPP to ANPP. The proportion of ANPP that can be sustainably consumed (Harvest index) was HI=-5.71+0.72 ANPP0.5. Consumable forage was CF =ANPP.HI and carrying capacity CC =CF.EAC-1, where EAC is an estimate of annual consumption: 500, 3200 and 750 kg DM.head-1.year-1 for sheep or goats, cattle and guanacos, respectively. 4. Regional ANPP±SD (2000-2015) was 758±52 kg DM ha-1.yr-1; HI= 13.7±0.6% and CF= 104±12 kg DM ha-1yr-1 resulting in regional carrying capacity of 14.8±1.6 M sheep or goats, 2.3±0.3 M cattle or 9.9±1.2 M guanacos. 5. Domestic stock was high from 1920 to 1980, but declined thereafter and remained mostly within ±1SD of carrying capacity in this century. Annual mean provincial stocks and carrying capacity (2000-2015) correlated well (R²= 0.94, p<0.01) with a slope close to 1. 6. Guanacos increased from 0.5 M to 2 M between 2000 and 2015, driving linearly combined grazing pressures 36 and 62% above carrying capacity in southern Patagonia provinces in 2015. 7. Synthesis and applications: Herbivore de-stocking is necessary to restore grazing balance in south Patagonia. Guanacos are capable of grazing low-quality food and maintain production during dry periods, and their meat and fibre may be incorporated and combined with sheep production. Management of population of guanacos in mixed grazing systems with adjusted stocks may prevent further rangeland degradation, farm abandonment, and loss of ecosystem services of these rangelands.05-Apr-2019
Data from: Lagged effects of early-season herbivores on valley oak fecundity
The seasonal match between folivore and leaf phenology affects the annual success of arboreal folivore populations because many folivores exploit developing leaves, which are an ephemeral resource. One strategy for folivores to exploit early-season leaves is to anticipate their emergence. The consequence of this behavior for trees is that individuals that set leaves earlier may experience greater rates of folivore damage, with potential negative fitness consequences. To test this hypothesis, we surveyed the early-season phenology, insect folivore damage, and acorn crop of a population of valley oaks (Quercus lobata) over a 3-year period. We found that trees that set leaves earlier experienced greater rates of folivore damage than trees that set leaves later in the season. In addition, we observed a lagged effect of folivore damage on acorn production, whereby trees with greater leaf damage produced fewer acorns in the subsequent year. These results indicate potential negative fitness consequences of earlier leaf phenology. Our study suggests that folivore pressure may be one factor that affects the optimal timing of leaf set in oaks.
Data from: Numbers and population trends of large herbivores in Mole National Park, Ghana
<p>Mole National Park (MNP) is Ghana's oldest and largest wildlife preserve. Eight large herbivores were counted in four different seasons in 2013/2014 on transects covering 4.7% of the park to estimate their population sizes and trends after changes in park management; all species were more abundant than previously reported. Averaging counts across seasons, and including all age classes, gave an estimated population of 1595 elephants, which is likely to be a substantial proportion of the west African elephant population. Kob were the most abundant herbivore, with an estimated population of 9092, followed by bushbuck (6758), warthog (6247) and hartebeest (6039). Roan, buffalo and waterbuck population estimates were 4382, 4272 and 4140 respectively. The impact of widespread burning on herbivore populations is currently unknown, but probably helps maintain both numbers and diversity. While all herbivore populations were higher than previously estimated, it was hard to determine the extent of recent increases due to methodological limitations of earlier aerial surveys. However, the distribution of large herbivores seems to be little changed, suggesting that both numbers and distribution are still limited by poaching and seasonal water availability.</p>
Data from: Mechanisms and implications of a type IV functional response for short-term intake rate of dry matter in large mammalian herbivores
1. The functional response (i.e. the relationship between consumers' intake rate and resource density) is central in plant-herbivore interactions. Its shape and the biological processes leading to it have significant implications for both foraging theory and ecology of grazing systems. 2. A type IV functional response (i.e. dome-shaped relationship) of short-term intake rate of dry matter (intake while grazing) has rarely been reported for large herbivores and the conditions that can lead to it are poorly understood. 3. We report a type IV functional response observed in heifers grazing monocultures of Cynodon sp. and Avena strigosa. The mechanisms and consequences of this type of functional response for grazed system dynamics are discussed. 4. Intake rate was higher at intermediate than at short or tall sward heights in both grass species. The type IV functional response resulted from changes in bite mass instead of a longer time needed to encounter and process bites. Thus, the decrease of intake rate of dry matter in tall swards is not explained by a shift from process 3 (potential bites are concentrated and apparent) to process 2 (potential bites are apparent but dispersed, Spalinger & Hobbs 1992). Bite mass was smaller in tall than in intermediate swards due to a reduction of bite volume possibly caused by the greater proportion of stem and sheath acting as a physical barrier to bite formation. 5. It is generally accepted that potential bites are abundant and apparent in most grassland and meadow systems, as they were in the present experiments. Therefore, a type IV response of intake rate not directly related to digestive constraints may determine the dynamics of intake and defoliation under a much larger set of conditions than previously thought. These results have implications for foraging theory and stability of grazing systems. For example, if animals prefer patches of intermediate stature that yield the highest intake rate, grazing should lead to the widely observed bimodal distribution of plant mass per unit area, even when tall patches are not of significantly lower digestive quality than the pasture average.
Data from: Pleiotropic effect of the Flowering Locus C on plant resistance and defence against insect herbivores
1. Plants vary widely in the extent to which they defend themselves against herbivores. Because the resources available to plants are often site-specific, variation among sites dictates investment into defence, and may reveal a growth-defence trade-off. Moreover, plants that have evolved different life-history strategies in different environments may situate themselves on this trade-off curve differently. For instance, plants that flower later have a longer vegetative lifespan, and may accordingly defend themselves differently than those that flower earlier. 2. Here, we tested whether late-flowering plants, with a longer vegetative lifespan, invest more in defence than early-flowering plants, using recombinant genotypes of the annual herb Cardamine hirsuta that differ in flowering time as a result of differences in the activity of the major floral repressor Flowering Locus C (FLC). 3. We found that variation at FLC was mainly responsible for regulating flowering time and allocation to reproduction, but this partially depended on where the plants grew. We also found that variation at FLC mediated plant allocation to defence, with late-flowering plants producing higher levels of total glucosinolates and stress-related phytohormones. Nonetheless, plant growth and the qualitative values of plant defence and plant resistance against specialist herbivores were mainly independent from FLC. 4. Synthesis - Our results highlight pleiotropic effects associated with flowering-time genes that might influence plant defence and plant-herbivore interactions.
Data from: Attracting mutualists and antagonists: plant trait variation explains the distribution of specialist floral herbivores and pollinators on crops and wild gourds
PREMISE OF THE STUDY: Floral traits play important roles in pollinator attraction and defense against floral herbivory. However, plants may experience trade-offs between conspicuousness to pollinators and herbivore attraction. Comparative studies provide an excellent framework to examine the role of multiple traits shaping mutualist and antagonist interactions. METHODS: To assess whether putative defensive and attractive traits predict species interactions, we grew 20 different Cucurbitaceae species and varieties in the field to measure interactions with pollinators and herbivores and in the greenhouse to assess trait variation. Cucurbits are characterized by the production of cucurbitacins, bitter nonvolatile terpenoids that are effective against generalist herbivores but can attract specialist beetles. We determined whether plant traits such as cucurbitacins predict herbivore resistance and pollinator attraction using an information-theoretic approach. KEY RESULTS: Mutualists and floral antagonists were attracted to the same cucurbit varieties once they flowered. However, rather than cucurbitacin concentration, we found that the size of the flower and volatile emissions of floral sesquiterpenoids explained both pollinator and floral herbivore visitation preference across cucurbit taxa. This pattern held across cucurbit taxa and within the Cucurbita genus. CONCLUSIONS: Surprisingly, floral sesquiterpenoid volatiles, which are associated with direct defense, indirect defense, and attraction, rather than defense traits such as cucurbitacins, appeared to drive interactions with both pollinators and floral herbivores across cucurbit taxa. Identifying the relevant plant traits for attraction and deterrence is important in this economically valuable crop, particularly if pollinators and floral herbivores use the same plant traits as cues.
Data from: Identifying native plants for coordinated habitat management of arthropod pollinators, herbivores and natural enemies
1. Providing non-crop flowering resources in agricultural landscapes is widely promoted as a strategy to support arthropods that deliver pollination and pest control services. However, management options have largely been developed separately for pollinators and natural enemies, whereas possible effects on insect herbivores, such as crop pests, have often been overlooked. A first critical step for design and implementation of multifunctional plantings that promote beneficial arthropods while controlling insect pests is to identify suitable plant species to use. 2. We aimed to identify California native plants and, more generally, plant traits suitable for the coordinated management of pollinators (wild bees and honey bees), insect herbivores and arthropod natural enemies (predators and parasitic wasps). We established 43 plant species in a common garden experiment and sampled arthropods by weekly netting (wild bees), observations (honey bees) or vacuum sampling (insect herbivores, arthropod predators and parasitic wasps) during peak bloom of each plant species over two years. 3. Plant species differed in attractiveness for each arthropod functional group. Floral area of the focal plant species positively affected honey bee, predator and parasitic wasp attractiveness. Later bloom period was associated with lower numbers of parasitic wasps. Flower type (actinomorphic, composite or zygomorphic) predicted attractiveness for honey bees, which preferred actinomorphic over composite flowers and for parasitic wasps, which preferred composite flowers over actinomorphic flowers. 4. Across plant species, herbivore, predator and parasitic wasp abundances were positively correlated, and honey bee abundance correlated negatively to herbivore abundance. 5. Synthesis and applications. We use data from our common garden experiment to inform evidence-based selection of plants that support pollinators and natural enemies without enhancing potential pests. We recommend selecting plant species with a high floral area per ground area unit, as this metric predicts the abundances of several groups of beneficial arthropods. Multiple correlations between functionally important arthropod groups across plant species stress the importance of a multifunctional approach to arthropod habitat management.
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Allen Brain Atlas
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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.
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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.