James Vonesh - Academia.edu (original) (raw)
Papers by James Vonesh
Biological Invasions
The Comparative Functional Response Approach (CFRA) was developed to provide a practical methodol... more The Comparative Functional Response Approach (CFRA) was developed to provide a practical methodology by which short-term experiments can be used to forecast the longer-term impacts of a potential invading consumer. The CFRA makes inferences about potential invader impact based on comparisons of the functional responses of invader and native consumers on native resources in a common experimental venue. Application of the CFRA and derivative approaches have proliferated since it was introduced in 2014. Here we examine the conceptual foundations of the CFRA within the context of basic Lotka–Volterra consumer-resource theory. Our goals are to assess whether core predictions of the CFRA hold within this framework, to consider the relative importance of background mortality and consumer assimilation efficiency in determining predator impact, and to leverage this conceptual framework to expand the discussion regarding stability and long term consumer and resource dynamics. The CFRA asserti...
Students investigate questions of community ecology and biogeography using data from an urban roc... more Students investigate questions of community ecology and biogeography using data from an urban rock pool ecosystem. Using ArcGIS 10, students learn to create effective maps, calculate landscape attributes, and perform introductory spatial analysis.
Functional Ecology, 2021
Warming can impact consumer-resource interactions through multiple mechanisms. For example, warmi... more Warming can impact consumer-resource interactions through multiple mechanisms. For example, warming can both alter the rate at which predators consume prey and the rate prey develop through vulnerable life stages. Thus, the overall effect of warming on consumer-resource interactions will depend upon the strength and asymmetry of warming effects on predator and prey performance. Here, we quantified the temperature dependence of both 1) density-dependent predation rates for two dragonfly nymph predators on a shared mosquito larval prey, via the functional response, and 2) the development rate of mosquito larval prey to a predator-invulnerable adult stage. We united the results of these two empirical studies using a temperature- and density-dependent stage-structured predation model. Warming accelerated both larval mosquito development and increased dragonfly consumption. Model simulations suggest that differences in the magnitude and rate of predator and prey responses to warming determined the change in magnitude of the overall effect of predation on prey survival to adulthood. Specifically, we found that depending on which predator species prey were exposed to in the model, the net effect of warming was either an overall reduction or no change in predation strength across a temperature gradient. Our results highlight a need for better mechanistic understanding of the differential effects of temperature on consumer-resource pairs to accurately predict how warming affects food web dynamics.
Ecology and Evolution, 2015
![Research paper thumbnail of Effects of hatching timing on red-eyed treefrog tadpoles: relative vulnerability varies among predators but not with hatchling age-structure, growth varies with the presence of more vulnerable tadpoles [poster]](https://attachments.academia-assets.com/97517302/thumbnails/1.jpg)
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Oecologia, 2009
Anthropogenic chemical contamination is an important issue for conservation of aquatic ecosystems... more Anthropogenic chemical contamination is an important issue for conservation of aquatic ecosystems. While recent research highlights that community context can mediate the consequences of contaminant exposure, little is known about how contaminants themselves might determine this context by altering habitat selection and thus initial community composition. Here we show that the insecticide carbaryl and its commercial counterpart Sevin can affect aquatic community composition by differentially altering oviposition and colonization of experimental pools by amphibians and insects. On average, contaminated pools received 20-fold more adult beetle and heteropteran colonists and 12-fold more Culex mosquito and chironomid midge egg masses. On the other hand, ovipositing Anopheles mosquitoes and cricket frogs showed no preference and we have shown previously that gray treefrogs strongly avoid contaminated pools. Overall, initial richness doubled in contaminated pools compared with controls. By affecting colonizing taxa differently and increasing richness, the contaminant may alter the ecological context under which subsequent effects of exposure will unfold. Given that community context is important for evaluating toxicity effects, understanding the net effects of contaminants in natural systems requires an understanding of their effects on community assembly via shifts in habitat selection.
As organisms with complex life cycles transition between life-stages, trade-offs in risks and opp... more As organisms with complex life cycles transition between life-stages, trade-offs in risks and opportunities focus selection from two sequential, potentially variable environments. Plasticity in the timing of life history switch points, such as hatching and metamorphosis, is phylogenetically widespread and allows organisms to optimize transitions. The short-term effects of plasticity on individual survival and other fitness correlates are better understood than long-term consequences for individuals or effects on population-level processes, ...
For organisms with complex life histories, environments encountered early in ontogeny may substan... more For organisms with complex life histories, environments encountered early in ontogeny may substantially alter densities or phenotypes transitioning into subsequent habitats. These differences in initial conditions could arise via a number of processes, including differences in maternal investment or habitat selection, abiotic factors, or the lethal and phenotypic effects of predators earlier in ontogeny. In this study we employ a simulation based approach to extend the 'minimize mortality (μ)/growth (g)'framework of Werner and Gilliam ...
Resource subsidies can strongly affect food web structure and dynamics. Along with habitat shape ... more Resource subsidies can strongly affect food web structure and dynamics. Along with habitat shape and boundary permeability, relative productivities of donor and recipient habitats have been suggested to influence when and where subsidies are important. Yet, empirical support for this spatial framework is lacking. We suggest that efforts to test these predictions are hindered in part by the absence of a universally used definition of resource subsidy that clearly assigns the source of production. In particular, when whole organisms comprise ...
![Research paper thumbnail of Non-lethal effects of dragonfly predators on the interactions between the tadpoles of two Neotropical hylid frogs [poster]](https://attachments.academia-assets.com/81121703/thumbnails/1.jpg)
](![Research paper thumbnail of The Ecology of Fear: Colonization and Oviposition in Aquatic Systems [poster]](https://attachments.academia-assets.com/81121701/thumbnails/1.jpg)
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Freshwater Science, 2021
Connectivity and patch size are important landscape characteristics that drive patterns of abunda... more Connectivity and patch size are important landscape characteristics that drive patterns of abundance and diversity across scales. However, responses to connectivity and patch size are dependent on species traits. Riverine landscapes are highly dynamic both spatially and temporally, with hydrologic connectivity being a major driver of abundance and diversity. Here we modeled the densities of 2 taxa that differ in life history and dispersal ability, the Virginia River Snail (Elimia virginica) and skimmer dragonfly larvae (Pantala spp.), as a function of flooding, patch area, and season in >300 riverine rock pools. We found key differences in how each taxon responded to these predictors. Specifically, increasing pool flood height had a strong negative effect on snail densities, whereas dragonfly nymph densities increased as pools became isolated from the river channel for longer durations of time. Increasing pool surface area had a positive effect on snail densities, whereas dragonf...
![Research paper thumbnail of The Cost of Hatching Early: Vulnerability and Exposure to Predators [poster]](https://attachments.academia-assets.com/81121697/thumbnails/1.jpg)
](![Research paper thumbnail of Behavior and development of red-eyed treefrogs during metamorphosis [poster]](https://attachments.academia-assets.com/81121695/thumbnails/1.jpg)
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![Research paper thumbnail of Regional and scale-specific effects of land use on amphibian diversity [poster]](https://attachments.academia-assets.com/81121690/thumbnails/1.jpg)
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Biological Invasions
The Comparative Functional Response Approach (CFRA) was developed to provide a practical methodol... more The Comparative Functional Response Approach (CFRA) was developed to provide a practical methodology by which short-term experiments can be used to forecast the longer-term impacts of a potential invading consumer. The CFRA makes inferences about potential invader impact based on comparisons of the functional responses of invader and native consumers on native resources in a common experimental venue. Application of the CFRA and derivative approaches have proliferated since it was introduced in 2014. Here we examine the conceptual foundations of the CFRA within the context of basic Lotka–Volterra consumer-resource theory. Our goals are to assess whether core predictions of the CFRA hold within this framework, to consider the relative importance of background mortality and consumer assimilation efficiency in determining predator impact, and to leverage this conceptual framework to expand the discussion regarding stability and long term consumer and resource dynamics. The CFRA asserti...
Students investigate questions of community ecology and biogeography using data from an urban roc... more Students investigate questions of community ecology and biogeography using data from an urban rock pool ecosystem. Using ArcGIS 10, students learn to create effective maps, calculate landscape attributes, and perform introductory spatial analysis.
Functional Ecology, 2021
Warming can impact consumer-resource interactions through multiple mechanisms. For example, warmi... more Warming can impact consumer-resource interactions through multiple mechanisms. For example, warming can both alter the rate at which predators consume prey and the rate prey develop through vulnerable life stages. Thus, the overall effect of warming on consumer-resource interactions will depend upon the strength and asymmetry of warming effects on predator and prey performance. Here, we quantified the temperature dependence of both 1) density-dependent predation rates for two dragonfly nymph predators on a shared mosquito larval prey, via the functional response, and 2) the development rate of mosquito larval prey to a predator-invulnerable adult stage. We united the results of these two empirical studies using a temperature- and density-dependent stage-structured predation model. Warming accelerated both larval mosquito development and increased dragonfly consumption. Model simulations suggest that differences in the magnitude and rate of predator and prey responses to warming determined the change in magnitude of the overall effect of predation on prey survival to adulthood. Specifically, we found that depending on which predator species prey were exposed to in the model, the net effect of warming was either an overall reduction or no change in predation strength across a temperature gradient. Our results highlight a need for better mechanistic understanding of the differential effects of temperature on consumer-resource pairs to accurately predict how warming affects food web dynamics.
Ecology and Evolution, 2015
Oecologia, 2009
Anthropogenic chemical contamination is an important issue for conservation of aquatic ecosystems... more Anthropogenic chemical contamination is an important issue for conservation of aquatic ecosystems. While recent research highlights that community context can mediate the consequences of contaminant exposure, little is known about how contaminants themselves might determine this context by altering habitat selection and thus initial community composition. Here we show that the insecticide carbaryl and its commercial counterpart Sevin can affect aquatic community composition by differentially altering oviposition and colonization of experimental pools by amphibians and insects. On average, contaminated pools received 20-fold more adult beetle and heteropteran colonists and 12-fold more Culex mosquito and chironomid midge egg masses. On the other hand, ovipositing Anopheles mosquitoes and cricket frogs showed no preference and we have shown previously that gray treefrogs strongly avoid contaminated pools. Overall, initial richness doubled in contaminated pools compared with controls. By affecting colonizing taxa differently and increasing richness, the contaminant may alter the ecological context under which subsequent effects of exposure will unfold. Given that community context is important for evaluating toxicity effects, understanding the net effects of contaminants in natural systems requires an understanding of their effects on community assembly via shifts in habitat selection.
As organisms with complex life cycles transition between life-stages, trade-offs in risks and opp... more As organisms with complex life cycles transition between life-stages, trade-offs in risks and opportunities focus selection from two sequential, potentially variable environments. Plasticity in the timing of life history switch points, such as hatching and metamorphosis, is phylogenetically widespread and allows organisms to optimize transitions. The short-term effects of plasticity on individual survival and other fitness correlates are better understood than long-term consequences for individuals or effects on population-level processes, ...
For organisms with complex life histories, environments encountered early in ontogeny may substan... more For organisms with complex life histories, environments encountered early in ontogeny may substantially alter densities or phenotypes transitioning into subsequent habitats. These differences in initial conditions could arise via a number of processes, including differences in maternal investment or habitat selection, abiotic factors, or the lethal and phenotypic effects of predators earlier in ontogeny. In this study we employ a simulation based approach to extend the 'minimize mortality (μ)/growth (g)'framework of Werner and Gilliam ...
Resource subsidies can strongly affect food web structure and dynamics. Along with habitat shape ... more Resource subsidies can strongly affect food web structure and dynamics. Along with habitat shape and boundary permeability, relative productivities of donor and recipient habitats have been suggested to influence when and where subsidies are important. Yet, empirical support for this spatial framework is lacking. We suggest that efforts to test these predictions are hindered in part by the absence of a universally used definition of resource subsidy that clearly assigns the source of production. In particular, when whole organisms comprise ...
Freshwater Science, 2021
Connectivity and patch size are important landscape characteristics that drive patterns of abunda... more Connectivity and patch size are important landscape characteristics that drive patterns of abundance and diversity across scales. However, responses to connectivity and patch size are dependent on species traits. Riverine landscapes are highly dynamic both spatially and temporally, with hydrologic connectivity being a major driver of abundance and diversity. Here we modeled the densities of 2 taxa that differ in life history and dispersal ability, the Virginia River Snail (Elimia virginica) and skimmer dragonfly larvae (Pantala spp.), as a function of flooding, patch area, and season in >300 riverine rock pools. We found key differences in how each taxon responded to these predictors. Specifically, increasing pool flood height had a strong negative effect on snail densities, whereas dragonfly nymph densities increased as pools became isolated from the river channel for longer durations of time. Increasing pool surface area had a positive effect on snail densities, whereas dragonf...