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Gary W Felton - One of the best experts on this subject based on the ideXlab platform.
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Insect Eggs Can Enhance Wound Response in Plants: A Study System of Tomato Solanum lycopersicum L. and
2016Co-Authors: Helicoverpa Zea Boddie, John F Tooker, Consuelo M De Moraes, Douglas S Luthe, Jinwon Kim, Gary W FeltonAbstract:Insect oviposition on plants frequently precedes herbivory. Accumulating evidence indicates that plants recognize insect oviposition and elicit direct or indirect Defenses to reduce the pressure of future herbivory. Most of the oviposition-triggered plant Defenses described thus far remove eggs or keep them away from the host plant or their desirable feeding sites. Here, we report induction of Antiherbivore Defense by insect oviposition which targets newly hatched larvae, not the eggs, in the system of tomato Solanum lycopersicum L., and tomato fruitworm moth Helicoverpa zea Boddie. When tomato plants were oviposited by H. zeamoths, pin2, a highly inducible gene encoding protease inhibitor2, which is a representative Defense protein against herbivorous arthropods, was expressed at significantly higher level at the oviposition site than surrounding tissues, and expression decreased with distance away from the site of oviposition. Moreover, more eggs resulted in higher pin2 expression in leaves, and both fertilized and unfertilized eggs induced pin2 expression. Notably, when quantified daily following deposition of eggs, pin2 expression at the oviposition site was highest just before the emergence of larvae. Furthermore, H. zea oviposition primed the wound-induced increase of pin2 transcription and a burst of jasmonic acid (JA); tomato plants previously exposed to H. zea oviposition showed significantly stronger induction of pin2 and higher production of JA upon subsequent simulated herbivory than without oviposition. Our results suggest that tomato plants recognize H. zea oviposition as a signal of impending future herbivory and induce Defenses to prepare for thi
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Priming of Antiherbivore defensive responses in plants
Insect science, 2012Co-Authors: Jinwon Kim, Gary W FeltonAbstract:Defense priming is defined as increased readiness of Defense induction. A growing body of literature indicates that plants (or intact parts of a plant) are primed in anticipation of impending environmental stresses, both biotic and abiotic, and upon the following stimulus, induce Defenses more quickly and strongly. For instance, some plants previously exposed to herbivore-inducible plant volatiles (HIPVs) from neighboring plants under herbivore attack show faster or stronger Defense activation and enhanced insect resistance when challenged with secondary insect feeding. Research on priming of Antiherbivore Defense has been limited to the HIPV-mediated mechanism until recently, but significant advances were made in the past three years, including non-HIPV-mediated Defense priming, epigenetic modifications as the molecular mechanism of priming, and others. It is timely to consider the advances in research on Defense priming in the plant- insect interactions.
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insect eggs can enhance wound response in plants a study system of tomato solanum lycopersicum l and helicoverpa zea boddie
PLOS ONE, 2012Co-Authors: John F Tooker, Consuelo M De Moraes, Douglas S Luthe, Gary W FeltonAbstract:Insect oviposition on plants frequently precedes herbivory. Accumulating evidence indicates that plants recognize insect oviposition and elicit direct or indirect Defenses to reduce the pressure of future herbivory. Most of the oviposition-triggered plant Defenses described thus far remove eggs or keep them away from the host plant or their desirable feeding sites. Here, we report induction of Antiherbivore Defense by insect oviposition which targets newly hatched larvae, not the eggs, in the system of tomato Solanum lycopersicum L., and tomato fruitworm moth Helicoverpa zea Boddie. When tomato plants were oviposited by H. zea moths, pin2, a highly inducible gene encoding protease inhibitor2, which is a representative Defense protein against herbivorous arthropods, was expressed at significantly higher level at the oviposition site than surrounding tissues, and expression decreased with distance away from the site of oviposition. Moreover, more eggs resulted in higher pin2 expression in leaves, and both fertilized and unfertilized eggs induced pin2 expression. Notably, when quantified daily following deposition of eggs, pin2 expression at the oviposition site was highest just before the emergence of larvae. Furthermore, H. zea oviposition primed the wound-induced increase of pin2 transcription and a burst of jasmonic acid (JA); tomato plants previously exposed to H. zea oviposition showed significantly stronger induction of pin2 and higher production of JA upon subsequent simulated herbivory than without oviposition. Our results suggest that tomato plants recognize H. zea oviposition as a signal of impending future herbivory and induce Defenses to prepare for this herbivory by newly hatched neonate larvae.
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Indigestion is a plant's best Defense
Proceedings of the National Academy of Sciences of the United States of America, 2005Co-Authors: Gary W FeltonAbstract:Over three decades ago, Green and Ryan (1) reported that insect herbivory induces the accumulation of proteinase inhibitors (PIs) in tomato leaves, a discovery that initiated the concept that plant Defenses were dynamic processes. Their seminal finding also showed that a key mechanism of plant Defense was targeted at limiting an herbivore's ability to digest and use essential nutrients from its host plant. More recently, microarray-based approaches have shown that scores of genes are up-regulated by herbivory and/or the wound signal jasmonic acid (JA); yet very few gene products definitively have been shown to play a role in Antiherbivore Defense. In this issue of PNAS, Chen et al. (2) elegantly demonstrate that two tomato plant enzymes mediate antinutritive Defenses against an insect herbivore ( Manduca sexta ). In the broader context, this article demonstrates a new level of coordination and complementation of plant Defenses heretofore not fully appreciated. Chen et al. use a novel proteomics/mass spectrophotometry approach to identify plant proteins that are stable (or undigested) in the herbivore's digestive system (i.e., midgut). The midgut of many caterpillars, including the Manduca sexta used in this study, is a hostile environment for …
Marc T. J. Johnson - One of the best experts on this subject based on the ideXlab platform.
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Predicting the strength of urban-rural clines in a Mendelian polymorphism along a latitudinal gradient.
Evolution letters, 2020Co-Authors: James S. Santangelo, Ken A. Thompson, Beata Cohan, Jibran Syed, Rob W. Ness, Marc T. J. JohnsonAbstract:Cities are emerging as models for addressing the fundamental question of whether populations evolve in parallel to similar environments. Here, we examine the environmental factors that drive the evolution of parallel urban-rural clines in a Mendelian trait-the cyanogenic Antiherbivore Defense of white clover (Trifolium repens). Previous work suggested urban-rural gradients in frost and snow depth could drive the evolution of reduced hydrogen cyanide (HCN) frequencies in urban populations. Here, we sampled over 700 urban and rural clover populations across 16 cities along a latitudinal transect in eastern North America. In each population, we quantified changes in the frequency of genotypes that produce HCN, and in a subset of the cities we estimated the frequency of the alleles at the two genes (CYP79D15 and Li) that epistatically interact to produce HCN. We then tested the hypothesis that cold climatic conditions are necessary for the evolution of cyanogenesis clines by comparing the strength of clines among cities located along a latitudinal gradient of winter temperature and frost exposure. Overall, half of the cities exhibited urban-rural clines in the frequency of HCN, whereby urban populations evolved lower HCN frequencies. Clines did not evolve in cities with the lowest temperatures and greatest snowfall, supporting the hypothesis that snow buffers plants against winter frost and constrains the formation of clines. By contrast, the strongest clines occurred in the warmest cities where snow and frost are rare, suggesting that alternative selective agents are maintaining clines in warmer cities. Some clines were driven by evolution at only CYP79D15, consistent with stronger and more consistent selection on this locus than on Li. Together, our results demonstrate that urban environments often select for similar phenotypes, but different selective agents and targets underlie the evolutionary response in different cities.
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Predicting the strength of urban-rural clines in a Mendelian polymorphism along a latitudinal gradient
2019Co-Authors: James S. Santangelo, Ken A. Thompson, Beata Cohan, Jibran Syed, Rob W. Ness, Marc T. J. JohnsonAbstract:Abstract Cities are emerging as models for addressing the fundamental question of whether populations evolve in parallel to similar environments. Here, we examine the environmental factors that drive parallel evolutionary urban-rural clines in a Mendelian trait — the cyanogenic Antiherbivore Defense of white clover (Trifolium repens). We sampled over 700 urban and rural clover populations across 16 cities along a latitudinal transect in eastern North America. In each population, we quantified the frequency of genotypes that produce hydrogen cyanide (HCN), and in a subset of the cities we estimated the frequency of the alleles at the two genes (CYP79D15 and Li) that epistatically interact to produce HCN. We then tested the hypothesis that winter environmental conditions cause the evolution of clines in HCN by comparing the strength of clines among cities located along a gradient of winter temperatures and frost exposure. Overall, half of the cities exhibited urban-rural clines in the frequency of HCN, whereby urban populations evolved lower HCN frequencies. The weakest clines in HCN occurred in cities with the lowest temperatures but greatest snowfall, supporting the hypothesis that snow buffers plants against winter frost and constrains the formation of clines. By contrast, the strongest clines occurred in the warmest cities where snow and frost are rare, suggesting that alternative selective agents are maintaining clines in warmer cities. Additionally, some clines were driven by evolution at only CYP79D15, consistent with stronger and more consistent selection on this locus than on Li. Together, our results demonstrate that both the agents and targets of selection vary across cities and highlight urban environments as large-scale models for disentangling the causes of parallel evolution in nature. Impact Summary Understanding whether independent populations evolve in the same way (i.e., in parallel) when subject to similar environments remains an important problem in evolutionary biology. Urban environments are a model for addressing the extent of parallel evolution in nature due to their convergent environments (e.g. heat islands, pollution, fragmentation), such that two distant cities are often more similar to one another than either is to nearby nonurban habitats. In this paper, we used white clover (Trifolium repens) as a model to study the drivers of parallel evolution in response to urbanization. We collected >11,000 plants from urban and rural habitats across 16 cities in eastern North America to examine how cities influence the evolution of a Mendelian polymorphism for an Antiherbivore Defense trait – hydrogen cyanide (HCN). This trait had previously been shown to exhibit adaptive evolution to winter temperature gradients at continental scales. Here we tested the hypothesis that winter environmental conditions cause changes in the frequency of HCN between urban and rural habitats. We found that half of all cities had lower frequency of HCN producing genotypes relative to rural habitats, demonstrating that cities drive parallel losses of HCN in eastern North America. We then used environmental data to understand why cities vary in the extent to which they drive reduction in HCN frequencies. The warmest cities showed the greatest reductions in HCN frequencies in urban habitats, while colder, snowier cities showed little change in HCN between urban and rural habitats. This suggests that snow weakens the strength of natural selection against HCN in cities. However, it additionally suggests alternative ecological or evolutionary mechanisms drive the strong differences in HCN between urban and rural habitats in the warmest cities. Overall, our work highlights urban environments as powerful, large-scale models for disentangling the causes of parallel and non-parallel evolution in nature.
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Antiherbivore Defenses alter natural selection on plant reproductive traits.
Evolution; international journal of organic evolution, 2016Co-Authors: Ken A. Thompson, Marc T. J. JohnsonAbstract:While many studies demonstrate that herbivores alter selection on plant reproductive traits, little is known about whether Antiherbivore Defenses affect selection on these traits. We hypothesized that Antiherbivore Defenses could alter selection on reproductive traits by altering trait expression through allocation trade-offs, or by altering interactions with mutualists and/or antagonists. To test our hypothesis, we used white clover, Trifolium repens, which has a Mendelian polymorphism for the production of hydrogen cyanide-a potent Antiherbivore Defense. We conducted a common garden experiment with 185 clonal families of T. repens that included cyanogenic and acyanogenic genotypes. We quantified resistance to herbivores, and selection on six floral traits and phenology via male and female fitness. Cyanogenesis reduced herbivory but did not alter the expression of reproductive traits through allocation trade-offs. However, the presence of cyanogenic Defenses altered natural selection on petal morphology and the number of flowers within inflorescences via female fitness. Herbivory influenced selection on flowers and phenology via female fitness independently of cyanogenesis. Our results demonstrate that both herbivory and Antiherbivore Defenses alter natural selection on plant reproductive traits. We discuss the significance of these results for understanding how Antiherbivore Defenses interact with herbivores and pollinators to shape floral evolution.
Ian T. Baldwin - One of the best experts on this subject based on the ideXlab platform.
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Determination of 15N‑Incorporation into Plant Proteins and their Absolute Quantitation: A New Tool to Study Nitrogen Flux Dynamics and Protein Pool Sizes Elicited by Plant–Herbivore Interactions
2016Co-Authors: Lynn Ullmann-zeunert, Ian T. Baldwin, Alexander Muck, Natalie Wielsch, Franziska Hufsky, Mariana A. Stanton, Stefan Bartram, Sebastian Böcker, Karin Groten, Aleš SvatošAbstract:Herbivory leads to changes in the allocation of nitrogen among different pools and tissues; however, a detailed quantitative analysis of these changes has been lacking. Here, we demonstrate that a mass spectrometric data-independent acquisition approach known as LC–MSE, combined with a novel algorithm to quantify heavy atom enrichment in peptides, is able to quantify elicited changes in protein amounts and 15N flux in a high throughput manner. The reliable identification/quantitation of rabbit phosphorylase b protein spiked into leaf protein extract was achieved. The linear dynamic range, reproducibility of technical and biological replicates, and differences between measured and expected 15N-incorporation into the small (SSU) and large (LSU) subunits of ribulose-1,5-bisphosphate-carboxylase/oxygenase (RuBisCO) and RuBisCO activase 2 (RCA2) of Nicotiana attenuata plants grown in hydroponic culture at different known concentrations of 15N-labeled nitrate were used to further evaluate the procedure. The utility of the method for whole-plant studies in ecologically realistic contexts was demonstrated by using 15N-pulse protocols on plants growing in soil under unknown 15N-incorporation levels. Additionally, we quantified the amounts of lipoxygenase 2 (LOX2) protein, an enzyme important in Antiherbivore Defense responses, demonstrating that the approach allows for in-depth quantitative proteomics and 15N flux analyses of the metabolic dynamics elicited during plant–herbivore interactions
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Variation in Antiherbivore Defense Responses in Synthetic Nicotiana Allopolyploids Correlates with Changes in Uniparental Patterns of Gene Expression
Plant physiology, 2010Co-Authors: Samir Anssour, Ian T. BaldwinAbstract:We examined the expression of Nicotiana attenuata (Na) and Nicotiana obtusifolia (No) herbivore-induced genes in synthetic autopolyploids (NaT and NoT) and five independent allopolyploid Nicotiana × obtusiata (N×o) lines to understand how the expression of genes regulating complex polygenetic Defense traits is altered in the early stages of allopolyploid hybridization. In Na, applying Manduca sexta oral secretions (OS) to wounds rapidly increased the transcript accumulation of wound-induced protein kinase (WIPK), lipoxygenase 3 (LOX3), nonexpressor of pathogenesis-related 1 (NPR1), and jasmonate-resistant 4 (JAR4) genes; these were correlated with increases in accumulation of jasmonic acid (JA), jasmonate-isoleucine, and trypsin protease inhibitors (TPIs). In No, OS elicitation reduced NPR1 transcripts and increased the level of salicylic acid (SA) that appeared to antagonize JA and JA-mediated Defenses. OS elicited N×o lines, accumulated high levels of the uniparental transcript of WIPK, LOX3, JAR4, and TPI, but low levels of both parental NPR1 transcripts that in turn were correlated with an increase in SA and a decrease in JA levels, suggesting SA/JA antagonism in the allopolyploid crosses. Methyl jasmonate treatment of N×o lines elicited transcripts of both parental LOX3, JAR4, and TPIs, demonstrating that the uniparental pattern observed after OS elicitation was not due to gene inactivation. TPIs were induced at different levels among N×o lines; some lines expressed high levels comparable to Na, others low levels similar to No, suggesting that synthetic neoallopolyploids rapidly readjust the expression of their parental defensive genes to generate diverse Antiherbivore responses. Changes in the expression of key genes and posttranscriptional events likely facilitate adaptive radiations during allopolyploid speciation events.
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Jasmonate-Dependent and -Independent Pathways Mediate Specific Effects of Solar Ultraviolet B Radiation on Leaf Phenolics and Antiherbivore Defense
Plant physiology, 2009Co-Authors: Patricia V. Demkura, Ian T. Baldwin, Guillermina Irene Abdala, Carlos L. BallaréAbstract:Ultraviolet B (UV-B) radiation, a very small fraction of the daylight spectrum, elicits changes in plant secondary metabolism that have large effects on plant-insect interactions. The signal transduction pathways that mediate these specific effects of solar UV-B are not known. We examined the role of jasmonate signaling by measuring responses to UV-B in wild-type and transgenic jasmonate-deficient Nicotiana attenuata plants in which a lipoxygenase gene (NaLOX3) was silenced (as-lox). In wild-type plants, UV-B failed to elicit the accumulation of jasmonic acid (JA) or the bioactive JA-isoleucine conjugate but amplified the response of jasmonate-inducible genes, such as trypsin proteinase inhibitor (TPI), to wounding and methyl jasmonate, and increased the accumulation of several phenylpropanoid derivatives. Some of these phenolic responses (accumulation of caffeoyl-polyamine conjugates) were completely lacking in as-lox plants, whereas others (accumulation of rutin and chlorogenic acid) were similar in both genotypes. In open field conditions, as-lox plants received more insect damage than wild-type plants, as expected, but the dramatic increase in resistance to herbivory elicited by UV-B exposure, which was highly significant in wild-type plants, did not occur in as-lox plants. We conclude that solar UV-B (1) uses jasmonate-dependent and -independent pathways in the elicitation of phenolic compounds, and (2) increases sensitivity to jasmonates, leading to enhanced expression of wound-response genes (TPI). The lack of UV-B-induced Antiherbivore protection in as-lox plants suggests that jasmonate signaling plays a central role in the mechanisms by which solar UV-B increases resistance to insect herbivores in the field.
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jasmonic acid signalling and herbivore resistance traits constrain regrowth after herbivore attack in nicotiana attenuata
Plant Cell and Environment, 2006Co-Authors: Jorge A Zavala, Ian T. BaldwinAbstract:Because traits conferring resistance on herbivores can reduce fitness-associated traits, trade-offs may occur between tolerance and resistance responses. We examined these trade-offs in genotypes of Nicotiana attenuata that were transformed to silence trypsin proteinase inhibitor (TPI) production (AS-Natpi), an Antiherbivore Defense associated with (14%) reductions in seed production, and the jasmonate signal cascade that elicits these Defenses (AS-Nalox3), by measuring stalk and axillary branch growth and seed production after two defoliation regimes and Manduca sexta larval attack to bottom or middle and top stalk leaves. Larval attack and defoliation at middle and top leaves depressed seed production and increased axillary branching more than at bottom leaves. AS-Nalox3 and AS-Natpi plants produced significantly longer (two- to fourfold) branches than did wild-type (WT) plants, results that are consistent with resource-based trade-offs between resistance and regrowth. Methyl jasmonate (MeJA) treatment of AS-Nalox3 plants restored WT branch growth, suggesting that jasmonic acid (JA) signalling suppresses regrowth and contributes to apical dominance. These results are consistent with the existence of JA- and resource-mediated trade-offs between regrowth and herbivore resistance traits.
Ken A. Thompson - One of the best experts on this subject based on the ideXlab platform.
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Predicting the strength of urban-rural clines in a Mendelian polymorphism along a latitudinal gradient.
Evolution letters, 2020Co-Authors: James S. Santangelo, Ken A. Thompson, Beata Cohan, Jibran Syed, Rob W. Ness, Marc T. J. JohnsonAbstract:Cities are emerging as models for addressing the fundamental question of whether populations evolve in parallel to similar environments. Here, we examine the environmental factors that drive the evolution of parallel urban-rural clines in a Mendelian trait-the cyanogenic Antiherbivore Defense of white clover (Trifolium repens). Previous work suggested urban-rural gradients in frost and snow depth could drive the evolution of reduced hydrogen cyanide (HCN) frequencies in urban populations. Here, we sampled over 700 urban and rural clover populations across 16 cities along a latitudinal transect in eastern North America. In each population, we quantified changes in the frequency of genotypes that produce HCN, and in a subset of the cities we estimated the frequency of the alleles at the two genes (CYP79D15 and Li) that epistatically interact to produce HCN. We then tested the hypothesis that cold climatic conditions are necessary for the evolution of cyanogenesis clines by comparing the strength of clines among cities located along a latitudinal gradient of winter temperature and frost exposure. Overall, half of the cities exhibited urban-rural clines in the frequency of HCN, whereby urban populations evolved lower HCN frequencies. Clines did not evolve in cities with the lowest temperatures and greatest snowfall, supporting the hypothesis that snow buffers plants against winter frost and constrains the formation of clines. By contrast, the strongest clines occurred in the warmest cities where snow and frost are rare, suggesting that alternative selective agents are maintaining clines in warmer cities. Some clines were driven by evolution at only CYP79D15, consistent with stronger and more consistent selection on this locus than on Li. Together, our results demonstrate that urban environments often select for similar phenotypes, but different selective agents and targets underlie the evolutionary response in different cities.
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Predicting the strength of urban-rural clines in a Mendelian polymorphism along a latitudinal gradient
2019Co-Authors: James S. Santangelo, Ken A. Thompson, Beata Cohan, Jibran Syed, Rob W. Ness, Marc T. J. JohnsonAbstract:Abstract Cities are emerging as models for addressing the fundamental question of whether populations evolve in parallel to similar environments. Here, we examine the environmental factors that drive parallel evolutionary urban-rural clines in a Mendelian trait — the cyanogenic Antiherbivore Defense of white clover (Trifolium repens). We sampled over 700 urban and rural clover populations across 16 cities along a latitudinal transect in eastern North America. In each population, we quantified the frequency of genotypes that produce hydrogen cyanide (HCN), and in a subset of the cities we estimated the frequency of the alleles at the two genes (CYP79D15 and Li) that epistatically interact to produce HCN. We then tested the hypothesis that winter environmental conditions cause the evolution of clines in HCN by comparing the strength of clines among cities located along a gradient of winter temperatures and frost exposure. Overall, half of the cities exhibited urban-rural clines in the frequency of HCN, whereby urban populations evolved lower HCN frequencies. The weakest clines in HCN occurred in cities with the lowest temperatures but greatest snowfall, supporting the hypothesis that snow buffers plants against winter frost and constrains the formation of clines. By contrast, the strongest clines occurred in the warmest cities where snow and frost are rare, suggesting that alternative selective agents are maintaining clines in warmer cities. Additionally, some clines were driven by evolution at only CYP79D15, consistent with stronger and more consistent selection on this locus than on Li. Together, our results demonstrate that both the agents and targets of selection vary across cities and highlight urban environments as large-scale models for disentangling the causes of parallel evolution in nature. Impact Summary Understanding whether independent populations evolve in the same way (i.e., in parallel) when subject to similar environments remains an important problem in evolutionary biology. Urban environments are a model for addressing the extent of parallel evolution in nature due to their convergent environments (e.g. heat islands, pollution, fragmentation), such that two distant cities are often more similar to one another than either is to nearby nonurban habitats. In this paper, we used white clover (Trifolium repens) as a model to study the drivers of parallel evolution in response to urbanization. We collected >11,000 plants from urban and rural habitats across 16 cities in eastern North America to examine how cities influence the evolution of a Mendelian polymorphism for an Antiherbivore Defense trait – hydrogen cyanide (HCN). This trait had previously been shown to exhibit adaptive evolution to winter temperature gradients at continental scales. Here we tested the hypothesis that winter environmental conditions cause changes in the frequency of HCN between urban and rural habitats. We found that half of all cities had lower frequency of HCN producing genotypes relative to rural habitats, demonstrating that cities drive parallel losses of HCN in eastern North America. We then used environmental data to understand why cities vary in the extent to which they drive reduction in HCN frequencies. The warmest cities showed the greatest reductions in HCN frequencies in urban habitats, while colder, snowier cities showed little change in HCN between urban and rural habitats. This suggests that snow weakens the strength of natural selection against HCN in cities. However, it additionally suggests alternative ecological or evolutionary mechanisms drive the strong differences in HCN between urban and rural habitats in the warmest cities. Overall, our work highlights urban environments as powerful, large-scale models for disentangling the causes of parallel and non-parallel evolution in nature.
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Antiherbivore Defenses alter natural selection on plant reproductive traits.
Evolution; international journal of organic evolution, 2016Co-Authors: Ken A. Thompson, Marc T. J. JohnsonAbstract:While many studies demonstrate that herbivores alter selection on plant reproductive traits, little is known about whether Antiherbivore Defenses affect selection on these traits. We hypothesized that Antiherbivore Defenses could alter selection on reproductive traits by altering trait expression through allocation trade-offs, or by altering interactions with mutualists and/or antagonists. To test our hypothesis, we used white clover, Trifolium repens, which has a Mendelian polymorphism for the production of hydrogen cyanide-a potent Antiherbivore Defense. We conducted a common garden experiment with 185 clonal families of T. repens that included cyanogenic and acyanogenic genotypes. We quantified resistance to herbivores, and selection on six floral traits and phenology via male and female fitness. Cyanogenesis reduced herbivory but did not alter the expression of reproductive traits through allocation trade-offs. However, the presence of cyanogenic Defenses altered natural selection on petal morphology and the number of flowers within inflorescences via female fitness. Herbivory influenced selection on flowers and phenology via female fitness independently of cyanogenesis. Our results demonstrate that both herbivory and Antiherbivore Defenses alter natural selection on plant reproductive traits. We discuss the significance of these results for understanding how Antiherbivore Defenses interact with herbivores and pollinators to shape floral evolution.
Phyllis D. Coley - One of the best experts on this subject based on the ideXlab platform.
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Is extrafloral nectar production induced by herbivores or ants in a tropical facultative ant–plant mutualism?
Oecologia, 2010Co-Authors: Ryan J. Bixenmann, Phyllis D. Coley, Thomas A. KursarAbstract:Many plants use induced Defenses to reduce the costs of Antiherbivore Defense. These plants invest energy in growth when herbivores are absent but shunt energy to Defense when herbivores are present. In contrast, constitutive Defenses are expressed continuously regardless of herbivore presence. Induction has been widely documented in temperate plants but has not been reported from tropical plants. Most tropical plants have higher, more constant herbivore pressure than temperate plants. In this situation, it is hypothesized that constitutive Defenses rather than induced Defense would be favored. Using natural herbivores of four species of Inga saplings on Barro Colorado Island, Panama, herbivore presence was crossed with ant presence to determine their effects on extrafloral nectar production. Analysis of nectar samples revealed that Inga species do not induce nectar production in response to herbivores. This result is not due to an inability of the plants to respond, as the plants in this study increased nectar production in response to light and ant presence. Contrary to most induction experiments with temperate ecosystem plants, these results demonstrate that tropical plants do not induce one type of Defense, and they suggest that the most adaptive Defense strategies are different for the two ecosystems.
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herbivores promote habitat specialization by trees in amazonian forests
Science, 2004Co-Authors: Italo Mesones, Paul V A Fine, Phyllis D. ColeyAbstract:In an edaphically heterogeneous area in the Peruvian Amazon, clay soils and nutrient-poor white sands each harbor distinctive plant communities. To determine whether a trade-off between growth and Antiherbivore Defense enforces habitat specialization on these two soil types, we conducted a reciprocal transplant study of seedlings of 20 species from sixgenera of phylogenetically independent pairs of edaphic specialist trees and manipulated the presence of herbivores. Clay specialist species grew significantly faster than white-sand specialists in both soil types when protected from herbivores. However, when unprotected, white-sand specialists dominated in white-sand forests and clay specialists dominated in clay forests. Therefore, habitat specialization in this system results from an interaction of herbivore pressure with soil type.
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Delayed greening in tropical leaves: an Antiherbivore Defense?
Biotropica, 1992Co-Authors: Thomas A. Kursar, Phyllis D. ColeyAbstract:Many tropical species flush entire canopies of red, white, or light green young leaves. In these species, there is a delay of the normal greening process until after leaves have fully expanded and have begun to toughen. Delayed greening involves a delay in the input of chlorophyll, rubisco, nitrogen, and energy. Photosynthetic capacity is therefore lower than in species with normal greening. At full expansion, leaves begin to toughen quickly, and rates of herbivory drop by a factor of 4. We suggest that delayed greening has evolved as a mechanism for minimizing losses to herbivores by delaying input of valuable resources until after the leaf is fully expanded and better protected by toughness. These benefits outweigh the costs of forfeited photosynthesis in the shaded understory but not in the high light treefall gaps. This cost evaluation suggests that, in the face of herbivory, it is advantageous to have delayed greening in the shade and normal development in the sun. Data from 175 of the most common tree species on Barro Colorado Island confirm that delayed greening is extremely common in shade tolerant species and rare in gap specialists.