M. Deane Bowers

M. Deane Bowers
University of Colorado Boulder | CUB · Department of Ecology and Evolutionary Biology (EBIO)

Ph.D.

About

160
Publications
18,768
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6,472
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Introduction

Publications

Publications (160)
Article
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Defense against natural enemies constitutes an important driver of herbivore host range evolution in the wild. Populations of the Baltimore checkerspot butterfly, Euphydryas phaeton (Nymphalidae), have recently incorporated an exotic plant, Plantago lanceolata (Plantaginaceae), into their dietary range. To understand the tritrophic consequences of...
Article
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Sequestration of plant secondary metabolites by herbivores can vary across both host plant phenology and herbivore ontogeny, but few studies have explored how they concurrently change in the field. We explored variation in iridoid glycoside concentration and composition in white turtlehead, Chelone glabra, as well as sequestration of iridoid glycos...
Article
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The checkerspot butterfly, Euphydryas anicia (Nymphalidae), specializes on plants containing iridoid glycosides and has the ability to sequester these compounds from its host plants. This study investigated larval preference, performance, and sequestration of iridoid glycosides in a population of E. anicia at Crescent Meadows, Colorado, USA. Althou...
Article
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The impacts of predators on bee foraging behavior are varied, but have been suggested to depend on both the type of predator (namely their hunting strategy) and also risk assessment by the prey (i.e., ability to perceive predators and learn to avoid them). However, nearly all studies have explored these impacts using social bees, despite the fact t...
Article
Full-text available
Many insect herbivores are dietary specialists capable of sequestering the secondary metabolites produced by their host plants. These defensive compounds have important but complex implications for tritrophic interactions between plants, herbivores, and natural enemies. The sequestration of host plant secondary metabolites defends herbivores from a...
Article
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The amount of damage that herbivorous insects impose on plants varies as a function of plant ontogenetic trajectories in tissue quality and defenses, and the herbivores’ own developmental trajectories in body size, mandible shape and detoxification enzymes, among others. However, little is known about how host plant and herbivore ontogeny interact....
Article
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Plants produce a variety of secondary metabolites that function as a defense against their natural enemies. Production of these secondary metabolites is genetically controlled, but is also phenotypically plastic and varies in response to both biotic and abiotic factors. Therefore, plant species may vary widely in their chemical defenses and such va...
Article
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Many insect species sequester compounds acquired from their host plants for defense against natural enemies. The distribution of these compounds is likely to affect both their efficacy as defenses, and their costs. In this study we examined the distribution of sequestered iridoid glycosides (IGs) in two congeneric species of nymphalid butterfly, Eu...
Article
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Changes in the chemical composition of plant defense compounds during herbivory can impact herbivore resource allocation patterns and thereby herbivore survival, growth, and immune response against endoparasitoid infection. Few studies have investigated folivore responses to changes in plant chemistry that occur under outbreak conditions in mature...
Article
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Habitat modification by invasive species places numerous butterfly species at risk of extinction. Grass-specific herbicides, graminicides, are a sought-after tool to reduce invasive grasses, augment forbs and enhance butterfly populations. However, possible non-target effects raise concern. We investigated non-target effects of graminicides on thre...
Article
Plants produce an array of secondary metabolites which play important ecological roles as anti-herbivore and anti-pathogen defenses. Many herbivores experience physiological costs when they consume secondary metabolites, yet some also benefit, for example when these chemicals confer resistance to parasites and predators. Secondary metabolites are o...
Article
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Both the physiological efficiency (PE) hypothesis and the preference–performance (PP) hypothesis address the complex interactions between herbivores and host plants, albeit from different perspectives. The PE hypothesis contends that specialists are better physiologically adapted to their host plants than generalists. The PP hypothesis predicts tha...
Chapter
I remember v-e-r-y slowly putting my hand through the fence into my neighbor’s yard to capture my first black female tiger swallowtail; no net available. I was nine. It was awesome! I still have the specimen with its sewing pin through the thorax (thankfully not the abdomen, as I was pretty inept in those days) and a label the size of a business ca...
Article
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Non-native plants introduced to new habitats can have significant ecological impact. In many cases, even though they interact with the same community of potential herbivores as their new native competitors, they regularly receive less damage. Plants produce secondary metabolites in their leaves that serve a range of defensive functions, including r...
Article
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Aims: Ripe, fleshy fruits generally function as rewards to attract mutual-istic seed dispersers, but many fruits also contain high concentrations of toxic secondary metabolites. These compounds may serve a variety of adaptive roles in seed dispersal or as a defense against non-dispersing seed predators or pathogens. We tested the effects of iridoid...
Article
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Although fleshy fruits function primarily to attract seed dispersers, many animal-dispersed fruits contain potentially toxic secondary metabolites. These metabolites can provide defense against seed predators and pathogens, but their effects on dispersers are still poorly understood. In some cases plants may experience a tradeoff, where the metabol...
Article
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The majority of insect species consume plants, many of which produce chemical toxins that defend their tissues from attack. How then are herbivorous insects able to develop on a potentially poisonous diet? While numerous studies have focused on the biochemical counter-adaptations to plant toxins rooted in the insect genome, a separate body of resea...
Article
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Herbivorous insects use several different defenses against predators and parasites, and tradeoffs among defensive traits may occur if these traits are energetically demanding. Chemical defense and immune response potentially can interact, and both can be influenced by host plant chemistry. Two closely related caterpillars in the lepidopteran family...
Article
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Yellow monkeyflower [Mimulus guttatus DC., (Phyrmaceae)] has long been a model plant species for studies in genetics, evolution, and ecology, including plant-animal interactions. Nonetheless, exceedingly little is known about its secondary chemistry. We have discovered that the foliage of yellow monkeyflower contains a diverse suite of phenylpropan...
Article
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Natural enemies often cause significant levels of mortality for their prey and thus can be important agents of natural selection. It follows, then, that selection should favor traits that enable organisms to escape from their natural enemies into "enemy-free space" (EFS). Natural selection for EFS was originally proposed as a general force in struc...
Conference Paper
The U.S. Department of Energy projects that millions of acres of croplands will be converted to new bioenergy crops in coming years. Such shifts in crop production are expected to alter the agricultural landscape, potentially affecting organisms inhabiting these agroecosystems. In particular, there is growing concern about how bees will respond to...
Conference Paper
The catalpa sphinx, Ceratomia catalpae (Lepidoptera: Sphingidae), occurs in the eastern US and feeds exclusively on Catalpa spp., which contain iridoid glycosides, a class of secondary metabolites, consisting mainly of catalpol and catalposide. Many catalpa trees are heavily infested and defoliated by catalpa sphinx caterpillars each year whereas o...
Article
The diet breadth of insect herbivores influences their response to variation in plant quality, and these bitrophic interactions have implications for the higher-level trophic interactions between herbivores and their natural enemies. In this comparative study, we examined the role of host plant species and plant secondary chemistry on the potential...
Article
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Physiological and morphological constraints during plant ontogeny affect the expression of numerous plant traits relevant to higher trophic levels, such as nutritional content and physical and chemical defenses. Yet we know little about how temporal variation in these traits can directly and/or indirectly mediate tri-trophic interactions, such as t...
Article
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Intra-specific variation in host-plant quality affects herbivore foraging decisions and, in turn, herbivore foraging decisions mediate plant fitness. In particular, variation in defenses against herbivores, both among and within plants, shapes herbivore behavior. If variation in defenses is genetically based, it can respond to natural selection by...
Conference Paper
Background/Question/Methods Plants produce an array of chemical compounds that may be deterrent or toxic to herbivores, termed plant secondary metabolites. These compounds are also present in plant parts attractive to mutualists, including floral nectar. The presence of secondary metabolites in nectar could be an unavoidable consequence of plant...
Conference Paper
Background/Question/Methods Escape from coevolved specialist enemies is hypothesized to be a central driver of invader success. Evidence for the importance of enemy escape is substantial, leading to the important question: do invaders evolve to become locally adapted to these different enemy regimes? In plants, trade-offs between defenses against...
Article
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Although ripe, fleshy fruits function primarily to attract seed dispersers, they must also be defended against diverse communities of seed predators and pathogens. For some plants, the concentration and diversity of secondary metabolites in fruits can exceed that of leaves and other plant parts, but little is known about the functional significance...
Conference Paper
The Bees' Needs is a citizen science project designed to study the abundance and diversity of solitary wood-nesting bees and wasps in Colorado's Northern Front Range and to explore relationships of these metrics to surrounding landscape attributes. The large volunteer workforce behind this project not only allows us to survey a greater study area a...
Article
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Little is known about the evolution, diversity, and functional significance of secondary metabolites in reproductive plant parts, particularly fruits and seeds of plants in natural ecosystems. We compared the concentration and diversity of amides among six tissue types of Piper reticulatum: leaves, roots, flowers, unripe fruit pulp, ripe fruit pulp...
Article
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Abstract Although the primary function of fleshy fruits is to attract seed dispersers, many ripe fruits contain toxic secondary compounds. A number of hypotheses have been proposed to explain this evolutionary paradox, most of which describe the potential adaptive role that secondary compounds may play in seed dispersal. However, some authors have...
Article
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The introduction of exotic plants, animals, and pathogens into non-native ecosystems can have profound effects on native organisms. Plantago lanceolata, narrow-leaf or ribwort plantain (Plantaginaceae), is a weed that was introduced to North America from Eurasia approximately 200 years ago and that has been incorporated into the diet of a variety o...
Article
Plant defensive compounds can have sometimes severe deleterious effects on both herbivores and their natural enemies. Iridoid glycosides (IGs) are defensive compounds that are well established as deterrent to several generalist herbivores and generalist predators. Trichoplusia ni Hübner (Lepidoptera: Noctuidae) is exceptional among generalist herbi...
Article
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Chemical defenses are thought to contribute to the invasion success and impacts of many introduced plants; however, for most of these species, little is known about these compounds and how they vary in natural environments. Plant allelochemical concentrations may be affected by a variety of abiotic and biotic factors, including soil nutrients and h...
Conference Paper
Background/Question/Methods The application of plant hormones known to elicit systemic changes in defense compounds has been shown to result in higher plant fitness, increased abundance of natural enemies, and decreased herbivore attacks. According to optimal defense theory, defenses against herbivores are costly to plants and hence should be all...
Article
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The search for general patterns in the production and allocation of plant defense traits will be facilitated by characterizing multivariate suites of defense, as well as by studying additional plant taxa, particularly those with available genomic resources. Here, we investigated patterns of genetic variation in phytochemical defenses (phenylpropano...
Article
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Background and Aims The lack of studies assessing the simultaneous expression of tolerance and resistance traits during seedling development and overall seedling defences as compared with adult plants, in general, constitutes a significant research need that can greatly improve our understanding of overall investment in defences during plant ontoge...
Article
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Interspecific hybridization among non-native plant species can generate genotypes that are more reproductively successful in the introduced habitat than either parent. One important mechanism that may serve as a stimulus for the evolution of invasiveness in hybrids is increased variation in secondary metabolite chemistry, but still very little is k...
Article
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Plants use a diverse mix of defenses against herbivores, including multiple secondary metabolites, which may affect herbivores synergistically. Chemical defenses also can affect natural enemies of herbivores via limiting herbivore populations or by affecting herbivore resistance or susceptibility to these enemies. In this study, we conducted larval...
Article
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We compared variation in butterfly communities across 3 years at six different habitats in a temper-ate ecosystem near Boulder, Colorado, USA. These habitats were classified by the local Open Space consortium as Grasslands, Tallgrass, Foothills Grasslands, Foothills Riparian, Plains Riparian, and Montane Woodland. Rainfall and temperature varied co...
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Determining the magnitude of climate change patterns across elevational gradients is essential for an improved understanding of broader climate change patterns and for predicting hydrologic and ecosystem changes. We present temperature trends from five long-term weather stations along a 2077-meter elevational transect in the Rocky Mountain Front Ra...
Data
Climate data for the RMFR transect weather stations (1953–2008) with flagged corrections and additions. (ODS)
Article
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Unlabelled: • Premise of the study: Human nitrogen (N) inputs to terrestrial ecosystems have greatly increased in recent years and may have important consequences for plant growth, reproduction, and defense. Although numerous studies have investigated the effects of nitrogen addition on plants, few have examined both above- and belowground respo...
Conference Paper
Background/Question/Methods The genus Lonicera (Caprifoliaceae) includes approximately 200 species worldwide, with 18 native and 16 introduced species in North America. Several Asiatic Lonicera species have become some of most problematic woody plant invasives in the United States (e.g., L. maackii, L. tatarica, and L. japonica), while native Lon...
Conference Paper
Background/Question/Methods Despite being the principal constituents of conifers, the role of monoterpenes as defensive compounds against defoliating insects remains controversial. Few studies have determined how herbivory alters foliar monoterpene levels in conifers, and less have asked how altered concentrations affect herbivores. Due to the vo...
Article
Full-text available
Optimal defense theory posits that plants with limited resources deploy chemical defenses based on the fitness value of different tissues and their probability of attack. However, what constitutes optimal defense depends on the identity of the herbivores involved in the interaction. Generalists, which are not tightly coevolved with their many host...
Article
1. Nitrogen enrichment is an important driver of environmental change. In the present study, plant-mediated effects of increased nitrogen on a specialist herbivore, Calophasia lunula Hufnagel, which sequesters antirrhinoside, an iridoid glycoside produced by its host plants, were examined. 2. Caterpillars were reared on Linaria dalmatica plants gr...
Article
Herbivores with polyphagous feeding habits must cope with a diet that varies in quality. One of the most important sources of this variation in host plant suitability is plant secondary chemistry. We examined how feeding on plants containing one such group of compounds, the iridoid glycosides, might affect the growth and enzymatic activity in a pol...
Article
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Post-introduction evolution of increased growth or reproduction has been observed in many species of invasive plants; however, it is not consistently associated with a loss of defense, as predicted by the influential evolution of increased competitive ability (EICA) hypothesis. Inconsistent support for the EICA hypothesis likely reflects the fact t...
Article
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Plant secondary chemistry can vary among plant tissues, individuals, and populations, and this variation has population-level consequences for upper trophic levels. In this study, we examined the multi-trophic consequences of variation in iridoid glycosides, which are a component of plant defense against generalist herbivores and also contribute to...
Article
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Numerous empirical studies have examined ontogenetic trajectories in plant defenses but only a few have explored the potential mechanisms underlying those patterns. Furthermore, most documented ontogenetic trajectories in plant defenses have generally concentrated on aboveground tissues; thus, our knowledge regarding whole plant trends in plant def...
Article
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Herbivore-induced plant responses can significantly change as a function of plant developmental stage and previous history of damage. Yet, empirical tests that assess the combined role of multiple damage events and age-dependent constraints on the ability of plants to induce defenses within and among tissues are scarce. This question is of particul...
Conference Paper
Background/Question/Methods Optimal defense theory predicts that plant parts that have the highest fitness value, such as flowers and fruits, should be protected with high levels of chemical defense, but that, in animal-dispersed fruits, these defenses should diminish upon ripening. Changes in fruit chemistry with ripening that match these predic...
Conference Paper
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Background/Question/Methods Soil nitrogen availability plays a key role in plant resource allocation to growth, reproduction, and defense. Human nitrogen inputs in terrestrial ecosystems have dramatically increased in recent years and these inputs may alter plant allocation patterns, plant defense, and plant-herbivore interactions. Although a num...
Article
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Although the loss of species is often attributed to reductions in habitat area, heterogeneity and connectivity, species specific traits and taxonomic relatedness can be important in explaining which species groups may be most impacted by the fragmentation process. In this study, using urban grassland fragments within the Front Range of northern Col...
Article
This study compared different methods of tissue preparation for extraction of iridoid glycosides sequestered by three species of lepidopteran larvae. Junonia coenia is a specialist on plant species that produce iridoid glycosides, while the arctiids Estigmene acrea and Spilosoma congrua are both polyphagous and will eat plants that produce iridoid...
Article
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We considered the effects of plant secondary metabolites on the immune response, a key physiological defense of herbivores against pathogens and parasitoids. We tested the effect of host plant species and ingested iridoid glycosides on the immune response of the grazing, polyphagous caterpillar, Grammia incorrupta (Arctiidae). Individuals of G. inc...
Article
Iridoid glycosides are secondary plant compounds that have deterrent, growth reducing or even toxic effects on non-adapted herbivorous insects. To investigate the effects of iridoid glycoside containing plants on the digestive metabolism of a generalist herbivore, larvae of Spilosoma virginica (Lepidoptera: Arctiidae) were reared on three plant spe...