Browsing by Author "Carrillo, Juli"

Now showing 1 - 6 of 6
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    A native plant competitor mediates the impact of above- and belowground damage on an invasive tree
    (Wiley, 2016) Carrillo, Juli; Siemann, Evan
    Plant competition may mediate the impacts of herbivory on invasive plant species through effects on plant growth and defense. This may predictably depend on whether herbivory occurs above or below ground and on relative plant competitive ability. We simulated the potential impact of above- or belowground damage by biocontrol agents on the growth of a woody invader (Chinese tallow tree,ﾠTriadica sebifera) through artificial herbivory, with or without competition with a native grass, little bluestem (Schizachyrium scoparium). We measured two defense responses ofﾠTriadicaﾠthrough quantifying constitutive and induced extrafloral nectar production and tolerance of above- and belowground damage (root and shoot biomass regrowth). We examined genetic variation in plant growth and defense across native (China) and invasive (United States)ﾠTriadicaﾠpopulations. Without competition, aboveground damage had a greater impact than belowground damage onﾠTriadicaﾠperformance, whereas with competition and above- and belowground damage impactedﾠTriadicaﾠsimilarly. Whole plant tolerance to damage below ground was negatively associated with tolerance to grass competitors indicating tradeoffs in the ability to tolerate herbivory vs. compete. Competition reduced investment in defensive extrafloral nectar (EFN) production. Aboveground damage inhibited rather than induced EFN production while belowground plant damage did not impact aboveground nectar production. We found some support for the evolution of increased competitive ability hypothesis for invasive plants as United States plants were larger than native China plants and were more plastic in their response to biotic stressors than China plants (they altered their root to shoot ratios dependent on herbivory and competition treatments). Our results indicate that habitat type and the presence of competitors may be a larger determinant of herbivory impact than feeding mode and suggest that integrated pest management strategies including competitive dynamics of recipient communities should be incorporated into biological control agent evaluation at earlier stages.
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    Does phylogeny matter? Assessing the impact of phylogenetic information in ecological meta-analysis
    (Blackwell Publishing Ltd/CNRS, 2012) Chamberlain, Scott A.; Hovick, Stephen M.; Dibble, Christopher J.; Rasmussen, Nick L.; Van Allen, Benjamin G.; Maitner, Brian S.; Ahern, Jeffrey R.; Bell-Dereske, Lukas P.; Roy, Christopher L.; Meza-Lopez, Maria; Carrillo, Juli; Siemann, Evan; Lajeunesse, Marc J.; Whitney, Kenneth D.
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    Facilitation and Competition among Invasive Plants: A Field Experiment with Alligatorweed and Water Hyacinth
    (Public Library of Science, 2012) Wundrow, Emily J.; Carrillo, Juli; Gabler, Christopher A.; Horn, Katherine C.; Siemann, Evan
    Ecosystems that are heavily invaded by an exotic species often contain abundant populations of other invasive species. This may reflect shared responses to a common factor, but may also reflect positive interactions among these exotic species. Armand Bayou (Pasadena, TX) is one such ecosystem where multiple species of invasive aquatic plants are common. We used this system to investigate whether presence of one exotic species made subsequent invasions by other exotic species more likely, less likely, or if it had no effect. We performed an experiment in which we selectively removed exotic rooted and/or floating aquatic plant species and tracked subsequent colonization and growth of native and invasive species. This allowed us to quantify how presence or absence of one plant functional group influenced the likelihood of successful invasion by members of the other functional group. We found that presence of alligatorweed (rooted plant) decreased establishment of new water hyacinth (free-floating plant) patches but increased growth of hyacinth in established patches, with an overall net positive effect on success of water hyacinth. Water hyacinth presence had no effect on establishment of alligatorweed but decreased growth of existing alligatorweed patches, with an overall net negative effect on success of alligatorweed. Moreover, observational data showed positive correlations between hyacinth and alligatorweed with hyacinth, on average, more abundant. The negative effect of hyacinth on alligatorweed growth implies competition, not strong mutual facilitation (invasional meltdown), is occurring in this system. Removal of hyacinth may increase alligatorweed invasion through release from competition. However, removal of alligatorweed may have more complex effects on hyacinth patch dynamics because there were strong opposing effects on establishment versus growth. The mix of positive and negative interactions between floating and rooted aquatic plants may influence local population dynamics of each group and thus overall invasion pressure in this watershed.
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    Herbivore-specific induction of indirect and direct defensive responses in leaves and roots
    (Oxford University Press, 2019) Xiao, Li; Carrillo, Juli; Siemann, Evan; Ding, Jianqing
    Herbivory can induce both general and specific responses in plants that modify direct and indirect defence against subsequent herbivory. The type of induction (local versus systemic induction, single versus multiple defence induction) likely depends both on herbivore identity and relationships among different responses. We examined the effects of two above-ground chewing herbivores (caterpillar, weevil) and one sucking herbivore (aphid) on indirect defence responses in leaves and direct defence responses in both leaves and roots of tallow tree, Triadica sebifera. We also included foliar applications of methyl jasmonate (MeJA) and salicylic acid (SA). We found that chewing herbivores and MeJA increased above-ground defence chemicals but SA only increased below-ground total flavonoids. Herbivory or MeJA increased above-ground indirect defence response (extrafloral nectar) but SA decreased it. Principal component analysis showed there was a trade-off between increasing total root phenolics and tannins (MeJA, chewing) versus latex and total root flavonoids (aphid, SA). For individual flavonoids, there was evidence for systemic induction (quercetin), trade-offs between compounds (quercetin versus kaempferitrin) and trade-offs between above-ground versus below-ground production (isoquercetin). Our results suggest that direct and indirect defence responses in leaves and roots depend on herbivore host range and specificity along with feeding mode. We detected relationships among some defence response types, while others were independent. Including multiple types of insects to examine defence inductions in leaves and roots may better elucidate the complexity and specificity of defence responses of plants.
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    Interactive effects of soils, local environmental conditions and herbivores on secondary chemicals in tallow tree
    (Oxford University Press, 2024) Xiao, Li; Huang, Wei; Carrillo, Juli; Ding, Jianqing; Siemann, Evan
    Plants produce secondary chemicals that may vary along with latitude due to changing abiotic and biotic stress gradients and local environmental conditions. Teasing apart the individual and combined effects of these different abiotic, such as soil nutrients, and biotic factors, such as soil biota and herbivores, on secondary chemicals is critical for understanding plant responses to changing environments. We conducted an experiment at different latitudes in China, using tallow tree (Triadica sebifera) seedlings sourced from a population at 31° N. These seedlings were cultivated in gardens located at low, middle and high latitudes, with either local soil or soil from the original seed collection site (origin soil). The seedlings were exposed to natural levels of aboveground herbivores or had them excluded. Plant secondary chemicals (both foliar and root), aboveground herbivores and soil characteristics were measured. Results showed that most leaf and root secondary metabolites depended on the interaction of the experimental site and soil type. Leaf and root phenolic and tannin concentrations were higher at the middle latitude site, especially in the origin soil. Root and foliar flavonoid concentrations increased when aboveground herbivores were excluded. Microbial communities depended strongly on soil treatment. The different responses of tannins versus flavonoids suggest that these two chemical classes differ in their responses to the varying abiotic and biotic factors in these sites along latitudes. Taken together, our results emphasize the importance of considering the interactive effects of local environmental conditions, soil properties and herbivory in regulating plant chemical defenses.
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    Specificity in the ecology and evolution of plant defense against herbivores: Identity and history
    (2013-12-04) Carrillo, Juli; Siemann, Evan; Dunham, Amy E.; Miller, Thomas E.; Bartel, Bonnie
    Biotic interactions can structure communities, drive succession, and account for patterns of biodiversity, yet we currently know little about how multiple biotic factors interact to influence traits in ecological and evolutionary time. Moreover, variation in biotic interactions among native and introduced plant ranges may account for the spectacular success of some invasive species. For example, in novel environments plants may experience ecological release from coevolved specialist enemies and may in turn evolve allocation away from costly defense towards competitive ability. This assumes that plants face a fundamental tradeoff between growth and defense, but we predict that this tradeoff depends on the biotic environment and specificity of plant responses to herbivores. I examined variation in growth and herbivore defense allocation in a model woody invader, using native and invasive populations of Triadica sebifera that differed in historic herbivore pressure. Greenhouse studies demonstrated that populations from the native range with a history of intense herbivory invested more in indirect herbivore resistance (extrafloral nectar production) than invasive populations. Additionally, the induction of indirect defense depended on herbivore feeding mode, suggesting tradeoffs among defenses against multiple herbivores. Further, I showed that even similarly feeding generalist herbivores can induce specific defense responses of plants, by demonstrating a loss of specificity in invasive populations compared to native populations, despite higher tolerance of herbivory overall. Together, these patterns suggest that selection for competitive ability may result in correlated selection for increased tolerance but decreased resistance of herbivory and reduced specificity of defense responses. I tested mechanisms causing this pattern of reallocation by examining the relative contributions of selection from herbivores and competitors in shaping herbivore defense in a different model plant species, common mustard. I used an experimental evolution approach to generate lines that differed in historical herbivore identity and competitive intensity. I detected that both herbivore and competitive history influence plant resistance to contemporary herbivores, and revealed a strong role for competitive history in contemporary plant defense. Understanding how variation in biotic interactions contributes to plant success is one way to predict the traits likely to evolve within a given selective environment and their ecological effects.