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opencc-zeroMay 2024View details →

Data from: Mycorrhizal-herbivore interactions and the competitive release of subdominant tallgrass prairie species

Plant-microbial-herbivore interactions play a crucial role in the structuring and maintenance of plant communities and biodiversity, yet these relationships are complex. In grassland ecosystems, herbivores have the potential to greatly influence the survival, growth, and reproduction of plants. However, few studies examine interactions of above- and belowground grazing and AM mycorrhizal symbiosis on plant community structure. We established experimental mesocosms containing an assemblage of eight tallgrass prairie grass and forb species in native prairie soil, maintained under mycorrhizal and nonmycorrhizal conditions, with and without native herbivorous soil nematodes, and with and without grasshopper herbivory. Using factorial analysis of variance and principal component analysis, we examined: a) the independent and interacting effects of above- and belowground herbivores on AM symbiosis in tallgrass prairie mesocosms, b) independent and interacting effects of above- and belowground herbivores and mycorrhizal fungi on plant community structure, and c) potential influences of mycorrhizal responsiveness of host plants on herbivory tolerance, and concomitant shifts in plant community composition. Treatment effects were characterized by interactions between AM fungi and both aboveground and belowground herbivores, while herbivore effects were additive. The dominance of mycorrhizal-dependent C4 grasses in the presence of AMF symbiosis was increased (p < 0.0001) by grasshopper herbivory but reduced (p < 0.0001) by nematode herbivory. Cool-season C3 grasses exhibited a competitive release in the absence of AMF symbiosis but this effect was largely reversed in the presence of grasshopper herbivory. Forbs showed species-specific responses to both AM fungal inoculation and the addition of herbivores. Biomass of the grazing-avoidant, facultatively mycotrophic forb Brickellia eupatorioides increased (p < 0.0001) in the absence of AMF symbiosis and with grasshopper herbivory, while AMF-related increases in the aboveground biomass of mycorrhizal-dependent forbs Rudbeckia hirta and Salvia azurea were eradicated (p < 0.0001) by grasshopper herbivory. In contrast, nematode herbivory enhanced (p = 0.001) the contribution of Salvia azurea to total biomass. Synthesis: Our research indicates that AM symbiosis is the key driver of the dominance of C4 grasses in the tallgrass prairie, with foliar and root herbivory being two mechanisms for the maintenance of plant diversity.

opencc-zeroJun 2024View details →

Interacting effects of surface water and temperature on wild and domestic large herbivore aggregations and contact rates

Earth's climate is rapidly changing, bringing forth questions of how domestic and wild animals will alter their behavior in response to increasing temperatures and dryland expansion. Dwindling water availability will likely impact animal behavior and water foraging, potentially increasing animal aggregations and interspecific contacts. These interspecific contacts are especially important for competition, predation, and disease transmission among wildlife and domestic animals. In this study, we analyzed interspecific wildlife and cattle contacts using two years of camera trap data at an experimental water manipulation site at a conservancy in central Kenya. We found that on average, the hourly probability of any interspecific contact was approximately 3.4 times higher at water sources versus drained water sources, and 18 times higher than surrounding matrix areas, and that this relationship was amplified by dry and hot conditions. Species-specific analyses revealed variation in the magnitude of responses across wildlife and domestic cattle, although all animals had approximately 2-3 times higher interspecific contact probability with other species at water in hot conditions versus other conditions. Notably, we observed the largest behavioral changes for relatively water-independent species, such as giraffe, which had 3.6 times higher interspecific contact probability at water sources in hot versus other conditions. Synthesis and applications: These findings show how elevated temperatures that will become increasingly common with future climate changes can increase interspecific contacts around critical water resources. In mixed wildlife-livestock systems, maintaining wildlife-only water sources may be a practical management tool to mitigate human-wildlife conflict and disease transmission at this interface, especially during dry and hot conditions.

opencc-by-4.0Dec 2015View details →

Fig. 6 in Large Herbivore Abundance, Distribution And Winter Pasture Quality In Two Game Farms In North Kazakhstan

Fig. 6. Siberian roe deer wintering concentration places in "Zerenda" game farm.

opencc-by-4.0Dec 2015View details →

Fig. 1 in Large Herbivore Abundance, Distribution And Winter Pasture Quality In Two Game Farms In North Kazakhstan

Fig. 1. Moose wintering concentration places in "Bulandy" game farm.

opencc-by-4.0Dec 2015View details →

Fig.4 in Large Herbivore Abundance, Distribution And Winter Pasture Quality In Two Game Farms In North Kazakhstan

Fig.4. Moose wintering concentration places in "Zerenda" game farm.

opencc-zeroJul 2024View details →

Ungulate herbivores promote beta diversity and drive stochastic plant community assembly by selective defoliation and trampling: From a four-year simulation experiment

Ungulate herbivores shape grassland plant communities at multiple scales, ultimately affecting ecosystem function. However, ungulates have complex effects on grasslands, including defoliation, trampling, excreta return, and their interactions. Moreover, the effects of ungulate density on grasslands are regulated by these three mechanisms. Nevertheless, how these three mechanisms affect biodiversity at multiple scales and community assembly remains poorly understood. Here, we conducted a 4-year novel field experiment to disentangle the effects of defoliation, trampling, and excreta return by ungulates on plant community assembly in a temperate grassland in Inner Mongolia, China. This experiment set two different scenarios: moderate ungulate density (Moderate, characterised by selective defoliation and moderate trampling) and high ungulate density (Intense, characterised by non-selective defoliation and heavy trampling), including different combinations of defoliation, trampling, and excreta return in each scenario. We found that defoliation and trampling increased stochasticity in community assembly and promoted alpha and beta diversity under both scenarios. Specifically, defoliation promoted the coexistence of species with multiple resource acquisition strategies (higher functional trait diversity) by reducing interspecific competition; trampling tended to facilitate random species colonisation. Conversely, excreta return favoured grasses, promoting deterministic assembly and impacting species coexistence. Notably, selective defoliation in the moderate scenario led to a dominance of stochastic processes during community assembly, whereas non-selective defoliation still did not change the dominance of deterministic processes. Further, communities subject to selective defoliation were insensitive to changes in soil properties caused by trampling and excreta return, maintaining a high-level beta diversity and the stochastic of community assembly. Synthesis: Our study provides important insights into the mechanisms by which ungulate herbivores influence plant community assembly, suggesting that defoliation and trampling have the potential to drive stochastic processes, while excreta return plays the opposite role. Our study also suggests that selective foraging by ungulates acts as stronger stochastic forces during community assembly compared to non-selective defoliation. These results imply that considering ungulate feeding preferences and foraging behaviour in grassland management will help prevent biodiversity loss and biotic homogenisation.

opencc-by-4.0Sep 2024View details →

PHENOLOGICAL INDICATORS OF RESOURCES OFFERED TO LEAF HERBIVORES IN RESTINGA COMMUNITIES

Dataset from the second chapter of the doctoral thesis entitled “HERBIVORY PATTERNS, ANTI-HERBIVORY DEFENSES AND INSECT GUILD OCCURRENCE IN ATLANTIC FOREST COMMUNITIES.”

opencc-zeroNov 2019View details →

Data from: Mismatches between the resources for adult herbivores and their offspring suggest invasive Spartina alterniflora is an ecological trap

1. Plant invasions can alter the behavior and performance of native herbivorous insects because the insects are evolutionarily naïve to the novel plants. An ecological trap results when native insects prefer invasive plants over their native hosts but suffer reduced fitness on the invaders. Although such traps are predicted to occur frequently given the prevalence of invasive plants, empirical support for ecological traps and their underlying mechanisms remains sparse. 2. We examined the potential for the invasive plant Spartina alterniflora to act as an ecological trap for the native moth Laelia coenosa, which previously fed mainly on the indigenous plant Phragmites australis in a Chinese saltmarsh. We surveyed Laelia egg densities on Spartina and Phragmites in the field, and determined adult oviposition preference and offspring development on the two plant species. To investigate the causes of adult preference and offspring performance patterns, we compared resource abundance in the field, plant-odor attractiveness, and leaf nutritional and defensive traits between Spartina and Phragmites. 3. We found that Laelia egg density and female preference for ovipositing were higher on Spartina than Phragmites. However, performance of offspring was poorer on Spartina than Phragmites. Spartina dominated a larger area and had greater leaf biomass than Phragmites in the field, and volatile odors released by Spartina were more attractive to Laelia females than those released by Phragmites. Although leaf C, C:P ratio, and terpenoid content did not differ significantly between the two plant species, Spartina leaves were tougher and more waxy, had lower N, and had higher concentrations of alkaloids and phenolics than Phragmites leaves. 4. Synthesis: Our data suggest that invasive Spartina can create an ecological trap for the native insect Laelia. This trap appears to result from environmental cues (resource availability and leaf odors) that attract the herbivore to the plant, but do not reliably predict the dietary qualities (nutrition and defenses) that negatively affect herbivore offspring performance. These findings reveal an important negative effect of plant invasions on resident herbivores and highlight the roles of resource availability and plant traits at different life stages of the insect.

The burden of size and growth for the juveniles of large mammalian herbivores: structural and functional constraints in the feeding biology of juveniles relative to adults in red kangaroos, Osphranter rufus

Juvenile mammals in their post weaning developmental stages face many challenges in transitioning to adulthood. Among large grazing species such as ruminant bovids and cervids an overarching challenge is acquiring and processing sufficient nutrients to survive and grow, with a gut that may not yet be fully developed. Marsupial kangaroos of Australia face similar challenges; they also digest vegetation by fermentation in a large foregut. In red kangaroos, Osphranter rufus (= Macropus rufus), the dominant species of Australia's arid interior, females may breed continuously; however, juvenile recruitment to the adult population is irregular and coincident with sporadic rainfall. As compared with adult females the nutritional requirements of juvenile O. rufus are high in relation to their body mass (BM), largely due to the cost of their rapid growth. We examined processes that juveniles have in their morphology, physiology and behaviours to meet their elevated nutritional needs, by comparing recently weaned juveniles of both sexes and adult female O. rufus in their desert habitat. Features studied include relative body sizes, relative dimensions and capacities of principal gut regions, the foregut, small intestine, caecum and large intestine with rectum. Also examined were digesta attributes and rates of digesta excretion. Additionally, the rates of change in skull parameters and dental characteristics to maturity were assessed. Field determinations of diet choice were made for both age classes. In juveniles the content masses of major gut structures were related to body mass (BM), as were those of adult females, i. e. ~BM1.0. In both age classes the digesta mass of the foreguts exceeded 75 % of the total digesta mass. Diets of both juvenile and adult O. rufus largely focused on grasses. Juveniles had higher rates of digesta excretion while foraging than adults. In addition, the foregut contents in juveniles occupies proportionally less of the total gut than in adult females. Together, the higher excretion rate and smaller relative foregut of juveniles suggests that they necessarily focus on forage that can be rapidly digested, such as young, green grasses or herbage. Comparison of the skulls of juveniles and adults revealed how this harvest can occur. Relative to BM juveniles had skulls of larger volume than adults. Additionally, during growth the skull lengthens proportionally faster than increasing. By weaning the dimensions of the incisor bite of juveniles neared those of adult females. The area of wear on premolars/molars increased only slowly relative to the development of incisors, further pointing to juveniles selecting more digestible forage than adults. The intermittent availability of such forage, principally young grasses, appears key to the significant recruitment into the O. rufus population in their arid habitat.

Data from: Chemical novelty facilitates herbivore resistance and biological invasions in some introduced plant species

Ecological release from herbivory due to chemical novelty is commonly predicted to facilitate biological invasions by plants, but has not been tested on a community scale. We used metabolomics based on mass spectrometry molecular networks to assess the novelty of foliar secondary chemistry of 15 invasive plant species compared to 46 native species at a site in eastern North America. Locally, invasive species were more chemically distinctive than natives. Among the 15 invasive species, the more chemically distinct were less preferred by insect herbivores and less browsed by deer. Finally, an assessment of invasion frequency in 2,505 forest plots in the Atlantic coastal plain revealed that, regionally, invasive species that were less preferred by insect herbivores, less browsed by white-tailed deer, and chemically distinct relative to the native plant community occurred more frequently in survey plots. Our results suggest that chemically-mediated release from herbivores contributes to many successful invasions.

opencc-zeroDec 2020View details →

Intra-specific variation in plant associated herbivore communities is phylogenetically structured in Brassicaceae

As a result of co-evolution between plants and herbivores, related plants often interact with similar herbivore communities. Variation in plant-herbivore interactions is determined by variation in underlying functional traits and by ecological and stochastic processes. Hence, typically only a subset of possible interactions is realized on individual plants. We show that insect herbivore communities assembling on individual plants are structured by plant phylogeny among twelve species in two phylogenetic lineages of Brassicaceae. This community sorting to plant phylogeny was retained when splitting the community according to herbivore feeding guilds. Relative abundance of herbivores as well as the size of the community structured community dissimilarity among plant species. Importantly, the amount of intra-specific variation in realized plant-herbivore interactions is also phylogenetically structured. We argue that variability in realized interactions that is not directly structured by plant traits is ecologically relevant and must be considered in the evolution of plant defences.

opencc-zeroDec 2019View details →

Data from: Life history variation in an invasive plant is associated with climate and recent colonization of a specialist herbivore

Premise: Spatial variation in selective pressures can lead to intraspecific variation in life history, favoring some life histories and constraining others depending on the vulnerability of life stages. We examined how spatial variation in herbivory and climate influences flowering size and the occurrence of semelparity (reproducing once) versus iteroparity (reproducing multiple times) in the introduced range of an invasive plant, houndstongue (Cynoglossum officinale). Houndstongue is a short-lived semelparous perennial in its native range. In its introduced range, we previously documented increased rates of iteroparity and a higher median threshold flowering size compared to the native range. We hypothesized that the recent introduction of a specialist biocontrol insect (a root-boring weevil, Mogulones crucifer) would decrease threshold flowering size, and reduce the proportion of iteroparous plants, because M. crucifer preferentially attacks large individuals and may reduce overwinter survival. Methods: We surveyed 24 sites across the northwestern United States to quantify the frequency of semelparity versus iteroparity and to estimate weevil abundance, and used demographic data collected from six sites to estimate median threshold flowering size. Key Results: We found that sites with greater winter precipitation and no weevils had a greater proportion of iteroparous plants. Sites with higher weevil attack had a lower median threshold flowering size. Conclusions: The variation in frequency of flowering and threshold flowering size that we documented in North American houndstongue populations and the relationships between this variation and herbivory and climate provide evidence for how selective pressures covary with the life histories of invasive plants.

Large herbivores suppress liana infestation in an African savanna

African savannas are the last stronghold of diverse large-mammal communities, and a major focus of savanna ecology is to understand how these animals affect the relative abundance of trees and grasses. However, savannas support diverse plant life-forms, and human-induced changes in large-herbivore assemblages—declining wildlife populations and their displacement by livestock—may cause unexpected shifts in plant community composition. We investigated how herbivory affects the prevalence of lianas (woody vines) and their impact on trees in an East African savanna. Although scarce (<2% of tree canopy area) and defended by toxic latex, the dominant liana, Cynanchum viminale (Apocynaceae), was eaten by 15 wild large-herbivore species and was consumed in bulk by native browsers during experimental cafeteria trials. In contrast, domesticated ungulates rarely ate lianas. When we experimentally excluded all large herbivores for periods of 8 to 17 years (simulating extirpation), liana abundance increased dramatically, with up to 75% of trees infested. Piecewise exclusion of different-sized herbivores revealed functional complementarity among size classes in suppressing lianas. Liana infestation reduced tree growth and reproduction, but herbivores quickly cleared lianas from trees after the removal of 18-year-old exclosure fences (simulating rewilding). A simple model of liana contagion showed that, without herbivores, the long-term equilibrium could be either endemic (liana-tree coexistence) or an all-liana alternative stable state. We conclude that ongoing declines of wild large-herbivore populations will disrupt the structure and functioning of many African savannas in ways that have received little attention and that may not be mitigated by replacing wildlife with livestock.

Data from: Insectivorous birds can see and smell systemically herbivore‐induced pines

Several studies have shown that insectivorous birds are attracted to herbivore-damaged trees even when they cannot see or smell the actual herbivores or their faeces. However, it often remained an open question whether birds are attracted by herbivore-induced changes in leaf odour or in leaf light reflectance or by both types of changes. Our study addressed this question by investigating the response of great tits (Parus major) and blue tits (Cyanistes caeruleus) to Scots pine (Pinus sylvestris) damaged by pine sawfly larvae (Diprion pini). We released the birds individually to a study booth, where they were simultaneously offered a systemically herbivore-induced and a non-infested control pine branch. In the first experiment, the birds could see the branches, but not smell them, because each branch was kept inside a transparent, air-tight cylinder. In the second experiment, the birds could smell the branches, but not see them, because each branch was placed inside a non-transparent cylinder with a mesh lid. The results show that the birds were more attracted to the herbivore-induced branch in both experiments. Hence, either type of the tested cues, the herbivore-induced visual plant cue alone as well as the olfactory cues per se, is attractive to the birds.

opencc-zeroAug 2021View details →

Animal personality drives individual dietary specialisation across multiple dimensions in a mammalian herbivore

1. Animal personality influences how individuals perceive and react to different stimuli, such as food quality and predation risk, thereby shaping foraging behaviour. As a consequence, animal personality is predicted to influence the diet and dietary specialisation of individuals within a population, but animal personality and dietary specialisation have yet to be linked. 2. Here, we tested whether individual diet and dietary specialisation are a function of animal personality, using an arboreal herbivore, the common brushtail possum, as a model species. We hypothesised that pro-active individuals have more diverse foraging opportunities than reactive individuals. We therefore predicted that pro-active animals (more exploratory, bold and more active) would be less specialised, with a broader and higher-quality diet than their reactive counterparts. We quantified the personality traits and dietary niche using proportional similarity index and specialisation categories of possums (n = 30) in a population flanking native eucalypt woodland and residential gardens in suburban Sydney, Australia. 3. We found that personality traits were related to the breadth and quality of the realised diets of individual possums. As predicted, proactive individuals had a broad, high-quality diet with less individual dietary specialisation than reactive individuals. Highly exploratory individuals had a more diverse diet than less exploratory individuals, and bold individuals were more likely than shy individuals to consume plants on the ground. 4. Our study demonstrates an important link between animal personality and individual dietary specialisation. The finding that the personality of individuals is associated with different diet choices within the same landscape is fundamentally significant. First, personality as a driver of niche partitioning likely reduces within-species competition and hence could contribute to adaptive capacity. Second, the strength of ecological processes arising from interactions (e.g. predator-prey and plant-herbivore interactions) could differ among individuals according to their personality traits. 5. Our findings are also relevant for effectively managing both threatened native, and invasive species. Management strategies will be improved by incorporating knowledge of individual traits and their ecological consequences, plus the ecological context of food- and fear-scapes.

opencc-by-nc-4.0Apr 2019View details →

Figure 3 in Spatiotemporal ecology of two Neotropical herbivorous mammals

Figure 3. Activity density pattern of the spotted paca (A) and tapeti (B) during the rainy and dry seasons, at a forest fragment, IFS, São Cristóvão, SE, Brazil. The X-axis shows the time of the day. During the rainy season, the average sunrise time was at 06:15 and average sunset time at 17:45. For the dry season, the average sunrise time was at 05:45 and the average sunset time was at 18:15.

opencc-by-nc-4.0Apr 2019View details →

Figure 2 in Spatiotemporal ecology of two Neotropical herbivorous mammals

Figure 2. Individual distributions of spotted paca and tapeti at a forest fragment at IFS, São Cristóvão, SE, Brazil.We collected the data through camera traps records at 33 sample sites from July 2015 to August 2017. The presence of each species was inferred from species camera trap records from each sample site, while the absence of the species was inferred by the lack of these records.

opencc-by-nc-4.0Apr 2019View details →

Figure 1 in Spatiotemporal ecology of two Neotropical herbivorous mammals

Figure 1. Forest Fragment location at the Federal Institute of Sergipe (IFS), São Cristóvão, SE. The insertion at the top-right hand corner represents the Brazilian territory with a highlight to Sergipe state (on dark gray).

opencc-zeroAug 2021View details →

Siliceous and non-nutritious: nitrogen limitation increases anti-herbivore silicon defenses in a model grass

Silicon (Si) accumulation alleviates a diverse array of environmental stresses in many plants, including conferring physical resistance against insect herbivores. It has been hypothesised that grasses, in particular, utilise 'low metabolic cost' Si for structural and defensive roles under nutrient limitation. While carbon (C) concentrations often negatively correlate with Si concentrations, the relationship between nitrogen (N) status and Si is more variable. Moreover, the impacts of N limitation on constitutive physical Si defences (e.g. silica and prickle cells) against herbivores are unknown. We determined how N limitation affected Si deposition in the model grass Brachypodium distachyon and how changes in these constitutive defences impacted insect herbivore (Helicoverpa armigera) growth rates. We used scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry in conjunction with X-ray mapping (XRM) to quantify physical structures on leaves and determine Si deposition patterns. We also determined how N limitation and Si supply impacted the jasmonic acid (JA) pathway, the master-regulator of induced defences against arthropod herbivores. N limitation reduced shoot growth by over 40%, but increased root mass (+21%), leaf Si concentrations (+50%) and the density of silica (+28%) and flattened prickle (+76%) cells. EDS and XRM established that Si was being deposited in these structures, together with hooked prickle cells and macro-hairs. Herbivore relative growth rates (RGR) were more than 115% lower in Si supplied plants compared to plants without Si supply and negatively correlated with leaf Si concentration and silica cell density. RGR was further reduced by N limitation and positively correlated with leaf N concentrations. Increases in JA concentrations following induction of the JA pathway were at least doubled by N limitation. Si accumulation and deposition were highly regulated by N availability, with N limitation promoting both constitutive Si physical defences and induction of the JA defensive pathway, in line with the resource availability hypothesis. These results indicate that grasses use 'low cost Si' when resources are limited and suggests that plant productivity may benefit from optimising conventional fertilisers and Si fertilisation.