16 research outputs found

    Temperature Tolerance and Stress Proteins as Mechanisms of Invasive Species Success

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    Invasive species are predicted to be more successful than natives as temperatures increase with climate change. However, few studies have examined the physiological mechanisms that theoretically underlie this differential success. Because correlative evidence suggests that invasiveness is related to the width of a species' latitudinal range, it has been assumed – but largely untested – that range width predicts breadth of habitat temperatures and physiological thermotolerances. In this study, we use empirical data from a marine community as a case study to address the hypotheses that (1) geographic temperature range attributes are related to temperature tolerance, leading to greater eurythermality in invasive species, and (2) stress protein expression is a subcellular mechanism that could contribute to differences in thermotolerance. We examined three native and six invasive species common in the subtidal epibenthic communities of California, USA. We assessed thermotolerance by exposing individuals to temperatures between 14°C and 31°C and determining the temperature lethal to 50% of individuals (LT50) after a 24 hour exposure. We found a strong positive relationship between the LT50 and both maximum habitat temperatures and the breadth of temperatures experience across the species' ranges. In addition, of the species in our study, invasives tended to inhabit broader habitat temperature ranges and higher maximum temperatures. Stress protein expression may contribute to these differences: the more thermotolerant, invasive species Diplosoma listerianum expressed higher levels of a 70-kDa heat-shock protein than the less thermotolerant, native Distaplia occidentalis for which levels declined sharply above the LT50. Our data highlight differences between native and invasive species with respect to organismal and cellular temperature tolerances. Future studies should address, across a broader phylogenetic and ecosystem scope, whether this physiological mechanism has facilitated the current success of invasive species and could lead to greater success of invasives than native species as global warming continues

    Data from: Spartina alterniflora genotypic identity affects plant and consumer responses in an experimental marsh community

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    1. Competition and herbivory are ubiquitous processes known to interactively shape plant performance, distribution and community assembly. Likewise, plant genetic variation and associated trait differences can impact both plant-plant and plant-herbivore interactions individually, yet few studies have explored these interactions simultaneously. 2. Salt marsh communities are an ideal system to study these questions, as they are dominated along the Atlantic and Gulf coasts of the United States by a foundation plant species, Spartina alterniflora, with high levels of genetically-based trait variation. Furthermore, consumer pressure and plant competitors are known to influence both the distribution and production of Spartina. We manipulated Spartina genetic identity, neighbor identity (needlerush, Juncus roemerianus), and consumer presence (snail, Littoraria irrorata) in a one-year field experiment in St. Joseph Bay, FL to test how the strength and direction of neighbor and consumer interactions vary by plant genotype. 3. Consumer effects on Spartina were generally stronger and more variable than those of the plant neighborhood, and these effects were generally consistent across Spartina genotypes. However, genotype-specific variation in morphology, phenology, and palatability significantly influenced both consumer and neighbor responses to Spartina: the consumer Littoraria was more likely to climb palatable Spartina genotypes, and neighboring Juncus had shorter stems in the presence of highly productive Spartina genotypes. 4. Synthesis. Our results add to the growing list of examples highlighting the role of intraspecific variation in species interactions, and suggest that variation in these interactions may promote the maintenance of plant genetic variation and community composition

    Zerebeckietal_1-5

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    Zerebeckietal_1-5.zip contains 5 consecutively numbered csv files which contain the data presented in the manuscript and appendices

    Data from: Consumer trait variation influences tri-trophic interactions in salt marsh communities

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    The importance of intraspecific variation has emerged as a key question in community ecology, helping to bridge the gap between ecology and evolution. Although much of this work has focused on plant species, recent syntheses have highlighted the prevalence and potential importance of morphological, behavioral, and life history variation within animals for ecological and evolutionary processes. Many small-bodied consumers live on the plant that they consume, often resulting in host plant-associated trait variation within and across consumer species. Given the central position of consumer species within tritrophic food webs, such consumer trait variation may play a particularly important role in mediating trophic dynamics, including trophic cascades. In this study, we used a series of field surveys and laboratory experiments to document intraspecific trait variation in a key consumer species, the marsh periwinkle Littoraria irrorata, based on its host plant species (Spartina alterniflora or Juncus roemerianus) in a mixed species assemblage. We then conducted a 12-week mesocosm experiment to examine the effects of Littoraria trait variation on plant community structure and dynamics in a tritrophic salt marsh food web. Littoraria from different host plant species varied across a suite of morphological and behavioral traits. These consumer trait differences interacted with plant community composition and predator presence to affect overall plant stem height, as well as differentially alter the density and biomass of the two key plant species in this system. Whether due to genetic differences or phenotypic plasticity, trait differences between consumer types had significant ecological consequences for the tritrophic marsh food web over seasonal time scales. By altering the cascading effects of the top predator on plant community structure and dynamics, consumer differences may generate a feedback over longer time scales, which in turn influences the degree of trait divergence in subsequent consumer populations

    Appendix A. Supplementary methods for the fouling community census and mesocosm experiments.

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    Supplementary methods for the fouling community census and mesocosm experiments

    Appendix B. Predicted change in abundance over time of species at +4.5°C increase relative to ambient temperature.

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    Predicted change in abundance over time of species at +4.5°C increase relative to ambient temperature

    Appendix C. Change in relative proportion of native species during the survival experiment.

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    Change in relative proportion of native species during the survival experiment

    Snail morphological trait variation

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    Variation in shell morphology of Littoraria irrorata snails from Spartina alterniflora or Juncus roemerianus host plant

    Snail stable isotope variation

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    Variation in C and N stable isotopes for Littoraria irrorata snails from Spartina alterniflora or Juncus roemerianus host plant
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