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1,186 results for “defensiveness”
Calcareous defense structures of prey mediate the effects of predation and biotic resistance towards the tropics
<p><span><span><span><span><span><span><span><span><span><span><span>Aims</span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span>The importance of biotic interactions in creating and maintaining diversity is expected to increase toward low latitudes. However, the way in which predation affects diversity, can depend on how predators mediate competitive interactions and also on defensive traits of prey. Here we assessed the role of physical defences of prey to escape predation and how the importance of predation on community structure and diversity changes across latitude.</span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span>Location</span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span>Six sites, in three regions distributed across 45 degrees of latitude in the Atlantic Ocean: a tropical region in Angola, a subtropical region in Brazil and a temperate region in Wales-UK.</span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span>Methods</span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span>We manipulated predation on marine sessile communities, using exclusion cages and assessed community parameters, including their susceptibility to biological invasion during early and advanced succession.</span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span>Results</span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span>Predation was more intense in the tropics and in advanced communities suggesting that predation effects increase through time. In the tropical region, predators reduced the number of co-occurring species and beta diversity, limited the occurrence of exotic species and promoted a change in the identity of the dominant organisms, replacing soft-bodied organisms with calcified animals. In the subtropical region, predation promoted a similar trait-mediated change in the identity of dominant prey, although it was not strong enough to affect diversity and did not prevent bioinvasion. In the temperate region other processes than predation seem to drive the community organization and resistance to invasion.</span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span>Main conclusions</span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span>Our results support both Biotic Interaction and Biotic Resistance Hypotheses, showing that the importance of predation to biodiversity increases toward the tropics. In addition, where predation is intense, morphological traits of prey drive the final structure and dominance in the community. Our results suggest that physical defences are the main traits preventing predation, perhaps explaining why calcified organisms are among the most common invasive species in coastal habitats.</span></span></span></span></span></span></span></span></span></span></span></p>
Single and mixed arbuscular mycorrhizal fungal species inocula have a different effect on the growth and oxidative stress defense in Lolium perenne exposed to phenol and polynuclear aromatic hydrocarbons
<p>Arbuscular mycorrhizal fungi (AMF) are ubiquitous mutualistic plant symbionts which promote plant growth and protect them from abiotic stresses. Studies on AMF-assisted phytoremediation have shown that AMF can increase plant tolerance to the presence of hydrocarbon contaminants by improving plant nutrition status and mitigating oxidative stress. This work aimed to evaluate the impact of single-species or mixed-species AMF inocula, obtained from the contaminated environment (<i>Funneliformis caledonium</i>, <i>Diversispora varaderana</i>, <i>Claroideoglomus walkeri</i>), on a growth, oxidative stress (DNA oxidation and lipid peroxidation) and activity of antioxidative enzymes (superoxide dismutase, catalase, peroxidase) in <i>Lolium perenne</i> cultured in a substrate contaminated with 0/0 - 30/120 mg phenol/polynuclear aromatic hydrocarbons (PAHs) kg<sup>-1</sup>. The assessment of AMF resistance to the presence of contaminants was based on mycorrhizal root colonization, spore production, the level of oxidative stress and antioxidative activity in AMF spores. In contrast to the mixed-species AMF inoculum, single AMF species significantly enhanced the growth of host plants cultured in the contaminated substrate. Their effect on the level of oxidative stress and the activity of antioxidative enzymes in plant tissues differed between the AMF species. Changes in the level of oxidative stress and the activity of antioxidative enzymes in AMF spores in response to contamination also depended on AMF species. Although, the concentration of phenol and PAHs had a negative effect on the production of AMF spores, low (5/20 mg phenol/PAHs kg<sup>-</sup>1) and substrate (15/60 mg phenol/PAHs kg<sup>-1</sup>) contamination stimulated the mycorrhizal colonization of roots. Among the studied AMF species, <i>F. caledonium</i> was the most resistant to phenol and PAHs and showed the highest potential in plant growth promotion. Adverse effects of mixed AMF inoculum on <i>L. perenne</i> growth might result from the competitive associations between the AMF species and excessive development of <i>C. walkeri</i>. Presented results might contribute to the development of functionally customized strategies of AMF-assisted phytoremediation with indigenous AMF inocula, adapted to form mycorrhizal associations in the presence of contaminants, which might enhance phytoremediation more effective than commercial AMF inocula.</p>
Hydroxyacetophenone defenses in white spruce against spruce budworm
<p>We review a recently discovered <span class="il">white</span> <span class="il">spruce</span> (Picea glauca) chemical defense <span class="il">against</span> <span class="il">spruce</span> <span class="il">budworm</span> (Choristoneura fumiferana) involving hydroxyacetophenones. These defense metabolites detected in the foliage accumulate variably as the aglycons, piceol and pungenol, or the corresponding glucosides, picein and pungenin. We summarize current knowledge of the genomic, molecular and biochemical as well as genetic underpinnings of this defense and its effects on C. fumiferana. We present an update with new results on the ontogenic variation and the phenological window of this defense, including analysis of transcript responses in P. glauca to C. fumiferana herbivory. We also discuss this chemical defense from an evolutionary and a breeding context.</p>
Data from: Dauer life stage of Caenorhabditis elegans induces elevated levels of defense against the parasite Serratia marcescens
Host-parasite research often focuses on a single host life stage, yet different life stages may exhibit different defenses. The nematode Caenorhabditis elegans has an alternate dispersal life stage, dauer. Despite dauer's importance in nature, we know little of how it responds to parasites. Previous research indicates that non-dauer C. elegans prefer to consume the virulent bacterial parasite, Serratia marcescens, when given a choice between the parasite and benign Escherichia coli. Here, we compared the preferences of dauer individuals from six strains of C. elegans to the preferences of other life stages. We found that dauer individuals exhibited reduced preference for S. marcescens, and dauers from some strains preferred E. coli to S. marcescens. In addition to testing food preference, a mechanism of parasite avoidance, we also measured host mortality rates after direct parasite exposure to determine if life stage also altered host survival. Overall, dauer individuals exhibited reduced mortality rates. However, dauer versus non-dauer larvae mortality rates also varied significantly by host strain. Collectively, we found evidence of dauer-induced parasite avoidance and reduced mortality in the presence of a parasite, but these effects were strain-specific. These results demonstrate the importance of host life stage and genotype when assessing infection dynamics.
Data from: Gape-limited predators as agents of selection on the defensive morphology of an invasive invertebrate
Invasive species have widespread and pronounced effects on ecosystems and adaptive evolution of invaders is often considered responsible for their success. Despite the potential importance of adaptation to invasion, we still have limited knowledge of the agents of natural selection on invasive species. Bythotrephes longimanus, a cladoceran zooplankton, invaded multiple Canadian Shield lakes over the past several decades. Bythotrephes have a conspicuous caudal process (tail spine) that provides a morphological defense against fish predation. We measured viability selection on the longest component of the Bythotrephes spine, the distal spine segment, through a comparison of the lengths of first and second instar Bythotrephes collected from lakes differing in the dominance of gape-limited predation (GLP) and non-gape-limited predation (NGLP) by fish. We found that natural selection varied by predator gape-limitation, with strong selection (selection intensity: 0.20-0.79) for increased distal spine length in lakes dominated by GLP, and no significant selection in lakes dominated by NGLP. Further, distal spine length was 17% longer in lakes dominated by GLP, suggesting the possibility of local adaptation. As all study lakes were invaded less than twenty years prior to our collections, our results suggest rapid divergence in defensive morphology in response to selection from fish predators.
Data from: Plant defense phenotypes determine the consequences of volatile emission for individuals and neighbors
Plants are at the trophic base of terrestrial ecosystems, and the diversity of plant species in an ecosystem is a principle determinant of community structure. This may arise from diverse functional traits among species. In fact, genetic diversity within species can have similarly large effects. However, studies of intraspecific genetic diversity have used genotypes varying in several complex traits, obscuring the specific phenotypic variation responsible for community-level effects. Using lines of the wild tobacco Nicotiana attenuata genetically altered in specific well-characterized defense traits and planted into experimental populations in their native habitat, we investigated community-level effects of trait diversity in populations of otherwise isogenic plants. We conclude that the frequency of defense traits in a population can determine the outcomes of these traits for individuals. Furthermore, our results suggest that some ecosystem-level services afforded by genetically diverse plant populations could be recaptured in intensive monocultures engineered to be functionally diverse.
Data from: Independent evolution of ancestral and novel defenses in a genus of toxic plants (Erysimum, Brassicaceae)
<p>Phytochemical diversity is thought to result from coevolutionary cycles as specialization in herbivores imposes diversifying selection on plant chemical defenses. Plants in the speciose genus <i>Erysimum</i> (Brassicaceae) produce both ancestral glucosinolates and evolutionarily novel cardenolides as defenses. Here we test macroevolutionary hypotheses on co-expression, co-regulation, and diversification of these potentially redundant defenses across this genus. We sequenced and assembled the genome of <i>E. cheiranthoides</i> and foliar transcriptomes of 47 additional <i>Erysimum</i> species to construct a phylogeny from 9,869 orthologous genes, revealing several geographic clades but also high levels of gene discordance. Concentrations, inducibility, and diversity of the two defenses varied independently among species, with no evidence for trade-offs. Closely related, geographically co-occurring species shared similar cardenolide traits, but not glucosinolate traits, likely as a result of specific selective pressures acting on each defense. Ancestral and novel chemical defenses in <i>Erysimum</i> thus appear to provide complementary rather than redundant functions.</p>
Data from: Personality, plasticity, and resource defense
In many animal taxa, behavior varies both among individuals (animal "personalities") and within individuals ("plasticity"). Personality and plasticity may co-vary if individuals differ in responsiveness to changes in their environment ("I × E" interaction). The nature and fitness implications of individual differences in behavioral plasticity in the wild are poorly understood. In territorial animals, fitness depends fundamentally on resource-defense behavior—their response to various threats from conspecific competitors. Such systems thus offer an ideal opportunity to investigate individual differences in behavioral plasticity. We used male superb fairy-wrens (Malurus cyaneus) to test for individual differences in the intensity and plasticity of territorial defense behavior. Using captive assays, we identified behavioral types on the basis of fast versus slow exploration of a novel environment (the "proactive–reactive" axis of behavior). Then we simulated territorial intrusions in the wild, using playback of experimentally manipulated songs that differed in trill length in a pair-wise design. Although previous work suggests that proactive individuals are more aggressive and less responsive than reactive individuals, we found no support for these differences in the context of territorial defense in the wild. Fast explorers (proactive) and slow explorers (reactive) responded equally aggressively to a simulated territorial intrusion overall. Furthermore, although fast explorers responded equally strongly to the two different playback stimuli, there was little evidence that slow explorers differentiated between the two stimuli, and this "I × E" interaction was not statistically significant. Further work is needed to determine the prevalence in the wild of personality-related differences in behavioral plasticity.
Data from: Parting ways: Parasite release in nature leads to sex-specific evolution of defense
We evaluate the extent to which males and females evolve along similar or different trajectories in response to the same environmental shift. Specifically, we use replicate experimental introductions in nature to consider how release from a key parasite (Gyrodactylus) generates similar or different defense evolution in male versus female guppies (Poecilia reticulata). After 8-12 generations of evolution, guppies were collected from the ancestral (parasite still present) and derived (parasite now absent) populations and bred for two generations in the laboratory to control for non-genetic effects. These F2 guppies were then individually infected with Gyrodactylus and infection dynamics were monitored on each fish. We found that parasite release in nature led to sex-specific evolutionary responses: males did not show much evolution of resistance, whereas females showed the evolution of increased resistance. Given that male guppies in the ancestral population had greater resistance to Gyrodactylus than did females, evolution in the derived populations led to reduction of sexual dimorphism in resistance. We argue that previous selection for high resistance in males constrained (relative to females) further evolution of the trait. We advocate more experiments considering sex-specific evolutionary responses to environmental change.
Data from: Socioecological predictors of immune defenses in wild spotted hyenas
Social rank can profoundly affect many aspects of mammalian reproduction and stress physiology, but little is known about how immune function is affected by rank and other socioecological factors in free-living animals. In this study, we examine the effects of sex, social rank and reproductive status on immune function in long-lived carnivores that are routinely exposed to a plethora of pathogens, yet rarely show signs of disease. Here, we show that two types of immune defences, complement-mediated bacterial killing capacity (BKC) and total IgM, are positively correlated with social rank in wild hyenas, but that a third type, total IgG, does not vary with rank. Female spotted hyenas, which are socially dominant to males in this species, have higher BKC, and higher IgG and IgM concentrations, than do males. Immune defences are lower in lactating than pregnant females, suggesting the immune defences may be energetically costly. Serum cortisol and testosterone concentrations are not reliable predictors of basic immune defences in wild female spotted hyenas. These results suggest that immune defences are costly and multiple socioecological variables are important determinants of basic immune defences among wild hyenas. The effects of these variables should be accounted for when attempting to understand disease ecology and immune function.
Data from: Dynamics of the continent-wide spread of a Drosophila defensive symbiont
Facultative symbionts can represent important sources of adaptation for their insect hosts and thus have the potential for rapid spread. Drosophila neotestacea harbors a heritable symbiont, Spiroplasma, that confers protection against parasitic nematodes. We previously found a cline in Spiroplasma prevalence across central Canada, ending abruptly at the Rocky Mountains. Resampling these populations nine years later revealed that Spiroplasma had increased substantially across the region, resembling a Fisherian wave of advance. Associations between Spiroplasma infection and host mitochondrial DNA indicate that the increase was due to local increase of Spiroplasma-infected flies. Finally, we detected Spiroplasma west of the Rocky Mountains for the first time and showed that defense against nematodes occurs in flies with a western genetic background. Because nematode infection is common throughout D. neotestacea's range, we expect Spiroplasma to spread to the Pacific coast.
Data from: Longevity and transposon defense, the case of termite reproductives
Social insects are promising new models in aging research. Within single colonies, longevity differences of several magnitudes exist that can be found elsewhere only between different species. Reproducing queens (and, in termites, also kings) can live for several decades, whereas sterile workers often have a lifespan of a few weeks only. We studied aging in the wild in a highly social insect, the termite Macrotermes bellicosus, which has one of the most pronounced longevity differences between reproductives and workers. We show that gene-expression patterns differed little between young and old reproductives, implying negligible aging. By contrast, old major workers had many genes up-regulated that are related to transposable elements (TEs), which can cause aging. Strikingly, genes from the PIWI-interacting RNA (piRNA) pathway, which are generally known to silence TEs in the germline of multicellular animals, were down-regulated only in old major workers but not in reproductives. Continued up-regulation of the piRNA defense commonly found in the germline of animals can explain the long life of termite reproductives, implying somatic cooption of germline defense during social evolution. This presents a striking germline/soma analogy as envisioned by the superorganism concept: the reproductives and workers of a colony reflect the germline and soma of multicellular animals, respectively. Our results provide support for the disposable soma theory of aging.
Data from: Evolutionary stability of antibiotic protection in a defensive symbiosis
The increasing resistance of human pathogens severely limits the efficacy of antibiotics in medicine, yet many animals, including solitary beewolf wasps, successfully engage in defensive alliances with antibiotic-producing bacteria for millions of years. Here, we report on the in situ production of 49 derivatives belonging to three antibiotic compound classes (45 piericidin derivatives, 3 streptochlorin derivatives, and nigericin) by the symbionts of 25 beewolf host species and subspecies, spanning 68 million years of evolution. Despite a high degree of qualitative stability in the antibiotic mixture, we found consistent quantitative differences between species and across geographic localities, presumably reflecting adaptations to combat local pathogen communities. Antimicrobial bioassays with the three main components and in silico predictions based on the structure and specificity in polyketide synthase domains of the piericidin biosynthesis gene cluster yield insights into the mechanistic basis and ecoevolutionary implications of producing a complex mixture of antimicrobial compounds in a natural setting.
Data from: Transgenerational effects alter plant defense and resistance in nature
Trichomes, or leaf hairs, are epidermal extensions that take a variety of forms and perform many functions in plants, including herbivore defense. In this study, I document genetically determined variation, within-generation plasticity, and a direct role of trichomes in herbivore defense for (Mimulus guttatus). After establishing the relationship between trichomes and herbivory, I test for transgenerational effects of wounding on trichome density and herbivore resistance. Patterns of inter-annual variation in herbivore density and the high cost of plant defense makes plant-herbivore interactions a system in which transgenerational phenotypic plasticity (TPP) is apt to evolve. Here, I demonstrate that parental damage alters offspring trichome density and herbivore resistance in nature. Moreover, this response varies between populations. This is among the first studies to demonstrate that TPP contributes to variation in nature, and also suggests that selection can modify TPP in response to local conditions.
Macroimmunology: the drivers and consequences of spatial patterns in wildlife immune defense
<p>1. Spatial variation in parasite pressure, abiotic and biotic conditions, and anthropogenic factors can all shape immune phenotypes across spatial scales. Identifying the most important spatial drivers of immunity could help preempt infectious disease risks, especially in the context of how large-scale factors such as urbanization affect defense by changing environmental conditions. 2. We provide a synthesis of how to apply macroecological approaches to the study of ecoimmunology (i.e., macroimmunology). We first review spatial factors that could generate spatial variation in defense, highlighting the need for large-scale studies that can differentiate competing environmental predictors of immunity and detailing contexts where this approach might be favored over small-scale experimental studies. We next conduct a systematic review of the literature to assess the frequency of spatial studies and to classify them according to taxa, immune measures, spatial replication and extent, and statistical methods. 3. We review 210 ecoimmunology studies sampling multiple host populations. We show that whereas spatial approaches are relatively common, spatial replication is generally low and unlikely to provide sufficient environmental variation or power to differentiate competing spatial hypotheses. We also highlight statistical biases in macroimmunology, in that few studies characterize and account for spatial dependence statistically, potentially affecting inferences for the relationships between environmental conditions and immune defense. 4. We use these findings to describe tools from geostatistics and spatial modeling that can improve inference about the associations between environmental and immunological variation. In particular, we emphasize exploratory tools that can guide spatial sampling and highlight the need for greater use of mixed-effects models that account for spatial variability while also allowing researchers to account for both individual- and habitat-level covariates. 5. We lastly discuss future research priorities for macroimmunology, including focusing on latitudinal gradients, range expansions, and urbanization as being especially amenable to spatial approaches. We highlight opportunities posed by assessing spatial variation in host tolerance, coupling large-scale field studies with small-scale field experiments and longitudinal approaches, and applying statistical tools from macroecology and meta-analysis to identify generalizable spatial patterns.</p>
Data from: Natural selection on immune defense: a field experiment
Predicting the evolution of phenotypic traits requires an understanding of natural selection on them. Despite its indispensability in the fight against parasites, selection on host immune defense has remained understudied. Theory predicts immune traits to be under stabilizing selection due to associated trade-offs with other fitness-related traits. Empirical studies, however, report mainly positive directional selection. This discrepancy could be caused by low phenotypic variation in the examined individuals and/or variation in host resource level that confounds trade-offs in empirical studies. In a field experiment where we maintained Lymnaea stagnalis snails individually in cages in a lake, we investigated phenotypic selection on two immune defense traits, phenoloxidase (PO)-like activity and antibacterial activity, in hemolymph. We used a diverse laboratory population and manipulated snail resource level by limiting their food supply. For six weeks, we followed immune activity, growth, and two fitness components, survival and fecundity of snails. We found that PO-like activity and growth were under stabilizing selection, while antibacterial activity was under positive directional selection. Selection on immune traits was mainly driven by variation in survival. The form of selection on immune defense apparently depends on the particular trait, possibly due to its importance for countering the present parasite community.
Data from: Macroevolution of leaf defenses and secondary metabolites across the genus Helianthus
Leaf defenses are widely recognized as key adaptations and drivers of plant evolution. Across environmentally diverse habitats, the macroevolution of leaf defenses can be predicted by the univariate trade-off model, which predicts that defenses are functionally redundant and thus trade off, and the resource availability hypothesis, which predicts that defense investment is determined by inherent growth rate and that higher defense will evolve in lower resource environments. Here, we examined the evolution of leaf physical and chemical defenses and secondary metabolites in relation to environmental characteristics and leaf economic strategy across 28 species of Helianthus (the sunflowers). Using a phylogenetic comparative approach, we found few evolutionary trade-offs among defenses and no evidence for defense syndromes. We also found that leaf defenses are strongly related to leaf economic strategy, with higher defense in more resource-conservative species, although there is little support for the evolution of higher defense in low-resource habitats. A wide variety of physical and chemical defenses predict resistance to different insect herbivores, fungal pathogens, and a parasitic plant, suggesting that most sunflower defenses are not redundant in function and that wild Helianthus represents a rich source of variation for the improvement of crop sunflower.
Data from: Water-borne defense induction of a rockweed in the wild
1. Laboratory-scale studies suggest that water-borne chemical cues released in grazing of marine macroalgae act as info-chemicals allowing the yet-undamaged conspecifics to increase their resistance before the actual herbivore attack. The relevance of this finding in natural populations has thus far remained unexplored. 2. We investigated spread of water-borne herbivore resistance in a field experiment using the littoral foundation species Fucus vesiculosus. We exposed algal genotypes for water-borne cues in the distances of 0.5 and 2 meters from the grazed cue-emitting genotypes. We measured herbivore resistance with preference experiments and recorded changes in the phlorotannin content. We recorded changes in biomass and length of the genotypes to test if water-borne resistance correlates with the grazing damage on the cue-emitter or incurs costs for the genotypes in terms of reduced growth. 3. In two of our four experimental blocks, induced resistance via water-borne cues took place and spread to undamaged neighbours that were two meters distance apart. This provides evidence of water-borne resistance induction in the wild as well as of small-scale spatial variation in the spread of induction. The undamaged neighbours induced resistance to a lesser extent than the directly grazed cue-emitters did, but resistance was consistently expressed among all 26 algal genotypes and independent of the amount of grazing damage on the cue-emitter. Herbivore resistance correlated negatively with the growth in the grazed cue-emitting genotypes while water-borne resistance was independent of the variation in growth. 4. Our results show, for the first time for marine macroalgae in a natural setting, that information about the increased risk of herbivory can be carried by water-borne cues and is used to prime or induce defences prior to an actual attack. The results we present furthermore indicate that water-borne resistance differs quantitatively and qualitatively from the resistance triggered by actively feeding herbivores. Ability to induce resistance prior the herbivore arrival may greatly influence the ability of littoral macroalgae to withstand the generally intense herbivory of marine benthic environments.
Data from: Transcriptional responses in a Drosophila defensive symbiosis
Inherited symbionts are ubiquitous in insects and can have important consequences for the fitness of their hosts. Many inherited symbionts defend their hosts against parasites or other natural enemies; however, the means by which most symbionts confer protection is virtually unknown. We examine the mechanisms of defence in a recently discovered case of symbiont-mediated protection, where the bacterial symbiont Spiroplasma defends the fly Drosophila neotestacea from a virulent nematode parasite, Howardula aoronymphium. Using quantitative PCR of Spiroplasma infection intensities and whole transcriptome sequencing, we attempt to distinguish between the following modes of defence: symbiont–parasite competition, host immune priming and the production of toxic factors by Spiroplasma. Our findings do not support a model of exploitative competition between Howardula and Spiroplasma to mediate defence, nor do we find strong support for host immune priming during Spiroplasma infection. Interestingly, we recovered sequence for putative toxins encoded by Spiroplasma, including a novel putative ribosome-inactivating protein, transcripts of which are up-regulated in response to nematode exposure. Protection via the production of toxins may be a widely used and important mechanism in heritable defensive symbioses in insects.
Data from: Strong but opposing effects of associational resistance and susceptibility on defense phenotype in an African savanna plant
The susceptibility of plants to herbivores can be strongly influenced by the identity, morphology, and palatability of neighboring plants. While the defensive traits of neighbors often determine the mechanism and strength of associational resistance and susceptibility, the effect of neighbors on plant defense phenotype remains poorly understood. We used field surveys and a prickle‐removal experiment in a semi‐arid Kenyan savanna to evaluate the efficacy of physical defenses against large mammalian herbivores in a common understory plant, Solanum campylacanthum. We then quantified the respective effects of spinescent Acacia trees and short‐statured grasses on browsing damage and prickle density in S. campylacanthum. We paired measurements of prickle density beneath and outside tree canopies with long‐term herbivore‐exclusion experiments to evaluate whether associational resistance reduced defense investment by decreasing browsing damage. Likewise, we compared defense phenotype within and outside pre‐existing and experimentally created clearings to determine whether grass neighbors increased defense investment via associational susceptibility. Removing prickles increased the frequency of browsing by ~25%, and surveys of herbivory damage on defended leaves suggested that herbivores tended to avoid prickles. As predicted, associational resistance and susceptibility had opposing effects on plant phenotype: individuals growing beneath Acacia canopies (or, analogously, within large‐herbivore exclosures) had a significantly lower proportion of their leaves browsed and produced ca 70–80% fewer prickles than those outside refuges, whereas plants in grass‐dominated clearings were more heavily browsed and produced nearly twice as many prickles as plants outside clearings. Our results demonstrate that associational resistance and susceptibility have strong, but opposing, effects on plant defense phenotype, and that variable herbivore damage is a major source of intraspecific variation in defense phenotype in this system.
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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.
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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.
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