Mentors and Project Descriptions
Dr. Jill Anderson and Dr. Thomas Mitchell-Olds, Duke University
We seek to understand the evolutionary, ecological, and historical forces influencing adaptation to local environments in Boechera stricta (Brassicaceae), a genetically tractable plant species closely related to Arabidopsis. We perform reciprocal transplant experiments, using quantitative trait locus (QTL) mapping: 1) to identify the chromosomal regions (and ultimately the individual genes) responsible for ecologically important trait variation and 2) to quantify the fitness consequences of molecular variation within and among popuations. These field experiments focus on three fitness-related traits: resistance to herbivory, age at first reproduction (flowering time), and drought tolerance, which are well-characterized at the molecular level. In 2010, we will initiate an experiment to assess natural selection on flowering time, using individuals that we have manipulated to flower early, at the average time, and late in relation to endogenous populations. We will also maintain ongoing field experiments testing for local adaptation. There are many opportunities for students to develop independent projects associated with our overall objectives, including studies on: 1) the population density and species composition of the herbivore community that attacks B. stricta; 2) the movement of pollen within populations; and 3) local adaptation in ecologically-relevant traits, especially drought tolerance. Experimental studies would need to be coordinated in advance of the field season to ensure the availability of experimental plants. The student working with us will also need to arrive at the very beginning of June and may leave in late July or early August.
Dr. Daniel T. Blumstein, University of California at Los Angeles
Vocal individuality. We know that species make unique sounds and that individuals within species make unique sounds, but we don't have a general understanding of the information content of these individually-specific vocalizations. As part of a larger program developing hardware and software to acoustically census species, the REU-fellow will record bird and marmot vocalizations, and calculate information statistics to quantify individuality. The ability to start early (late May--while birds are singing to defend territories) would be a bonus.
Risk-taking in yellow-bellied marmots. This project will be co-mentored with Dr. Raquel Monclus
We know that marmots that enter hibernation in poor body condition are less likely to survive a harsh winter and breed the next year. What we don't know is how an individuals' propensity to take risks influences this. We will conduct a simple experiment to quantify risk-taking in yellow-bellied marmots. By establishing feeding stations different distances from their burrows, we will study the trade-off marmots make between foraging and anti-predator vigilance and how exposure (estimated as distance to the burrow) influnences it. We naturally see animals take greater risks in years with late summer droughts--they forage far from their burrows. What we don't know is the degree to which marmots can compensate for these risks and therefore how vulnerable marmots will be to a drier, hotter, sub-alpine community.
Interspecific alarm communication. Prey should respond to whatever cues about predation they can acquire from the environment. In the past, we've noticed that mule deer with fawns are particularly attentive to alarm calls produced by yellow-bellied marmots. We will test this experimentally by broadcasting marmot alarm calls, predator sounds, and control sounds to mule deer with and without fawns.
Olfactory predator recognition. See Price et al., below, for a description of this collaborative project.
Dr. Alison Brody, University of Vermont
I am broadly interested in the suite of interactions among plants, their mutualist pollinators and antagonists such as herbivores and seed predators. The interactions among these multiple species affect both the ecology, i.e., abundance and distribution, of plants as well as the evolution of floral traits. Most recently, I’ve been investigating how the interactions among plants and their pollinators, pre-dispersal seed predators and herbivores, affect the stability of plant sex-ratios. In some species, e.g., sticky Polemonium, plants produce hermaphroditic or perfect flowers, as well as flowers that function only as females and produce little or no pollen. One might imagine that the two sex morphs interact differently with pollinators looking for floral rewards in nectar and pollen, and seed predators looking for food (i.e., seeds) for their offspring. The relative strength of these interactions will provide selective feed-backs affecting sex-ratios within and among populations. A second, on-going project is to examine the role of vertebrate herbivores in the life-history of long-lived perennial plants. Much attention is paid to how vertebrate herbivores affect plants when they browse inflorescences. However, we know less about how herbivory in earlier life-history stages affects the longevity and reproduction of plants. My work provides students the opportunity to address questions about plant-animal interactions from ecological and evolutionary perspectives.
Amanda Buchanan, Florida State University
Interactions among plants, herbivores, and pollinators.
Plant traits often reflect conflicting environmental pressures: a plant that requires animal pollinators must attract those pollinators while simultaneously repelling herbivores. This conflict may cause plant traits like floral display size or chemical defenses to be constrained by its ecological costs. I use a clonal, perennial host plant (Chamerion angustifolium, fireweed) to explore the following questions, using a combination of field manipulations and population observations.
(1) The effects of herbivore damage and pollination on plant growth and reproduction (for example, how high levels of herbivory affect flower production, or how low levels of pollination affect clonal stem number).
(2) Plant-mediated indirect interactions between herbivores and pollinators (for example, how herbivore-induced changes in flower production affect pollinator foraging).
(3) Correlations among damage, pollination, and reproductive traits across plant populations.
I expect students to develop a project related to some aspect of plant-herbivore interactions, plant defenses, plant-pollinator interactions, herbivore behavior, pollinator behavior, or plant allocation costs. This project can be on the Chamerion system I use, or another plant-insect system.
Dr. Diane Campbell, University of California at Irvine
Behavioral responses of pollinators to floral trait associations.
Our work at RMBL focuses on plant-pollinator interactions, plant hybrid zones, and speciation. Current projects are diverse. They include: field reciprocal transplant studies to examine local adaptation of related species and their hybrids, genetic and ecological studies of floral traits, and physiological studies of photosynthetic traits important to the fitness of plant hybrids. For 2010, a potential student project would examine behavioral responses of pollinators to associations of floral traits. The idea that animal pollinators respond to suites of floral traits (e.g. flower shape, color, rewards, scent) is at the heart of pollination ecology. Yet few studies have examined the relative importance of specific floral traits to specific pollinator types, and especially whether those traits have additive or interactive effects on the rate at which insects and other pollinators (e.g. hummingbirds) visit flowers. Experimental manipulations of floral traits could be used to address these questions with a variety of local flower species within the phlox family. This project is best suited to students interested in the evolutionary aspects of plant-animal interactions. There will also be the chance to collaborate on other ongoing projects in the lab.
Daniel Erickson, Vanderbilt University and Dr. Ian Billick, RMBL
What are the realized niches of the anti-parasitoid bacterial symbionts of aphids?
“Key-stone” mutualisms between plants and microbes have been shown to affect surrounding species diversity on all trophic levels, but little is known regarding the realized niches of insect-microbe mutualisms and their consequent effect on community dynamics. Secondary endosymbionts of aphids are well characterized for providing beneficial phenotypes that protect aphids against high temperatures, and predation by fungi and parasitoid wasps. The lysogenic bacteriophage APSE in the bacteria Hamiltonella defensa produces toxins that increase survivorship of aphids by killing developing parasitoid wasps within aphids in laboratory environments.
However, our understanding of the ecological niches of these defensive microbes in a natural setting is limited to infection prevalence in sparse ecological settings with little correlation to ecological parameters. In my research, I study the effect of biotic and abiotic factors on the incidence of aphid infection by H. defensa. I expect that interested students will help me pursue research topics related to the questions below:
(a) If aphids are already protected by ant mutualists against parasitoids, is defense conferred to aphids by H. defensa redundant and how then does the bacteria persist in aphid populations?
(b) If infected aphids are highly migratory and parasitoid wasps are ubiquitous, what confines H. defensa infections to particular geographic locations?
(c) Do infected aphids increase apparent competition and generalist parasitoid predation on other aphid species?
Dr. Chris Floyd, University of Wisconsin at Eau Claire
I study ecological factors determining habitat selection by red-naped sapsuckers (Sphyrapicus nuchalis). These woodpeckers excavate their cavity nests in aspens (Populus tremuloides), which are the dominant tree of montane woodlands in the Rocky Mountains of Colorado. The nest cavities are not reused by the sapsuckers and, thus, eventually become available for several species of cavity-nesting birds that cannot excavate their own nests, such as chickadees (Poecile sp.) and swallows (Tachycineta sp.). The sapsuckers also excavate sap wells in aspens and willows (Salix sp.), creating a food resource for many species of insects and vertebrates. Because of their prolific nest cavity and sap well excavation, sapsuckers are considered a keystone engineering species. However, there is a third important component: the aspen heart rot fungus, Phellinus tremulae, which promotes cavity excavation by softening the heartwood. Sapsuckers nest almost strictly in aspens infected with this fungus. Since the summer of 2005 my students and I have been studying multivariate relationships between sapsucker nest site location and habitat variables such as fungal prevalence, willow proximity, aspen stand characteristics, and elevation. I am interested in mentoring students who want to study this system or some other ecological aspect of the cavity-nest associated community in the East River Valley.
Josh Grinath, Florida State University
Studying ant/honeydew mutualisms in a community context
I study the role of positive interspecific interactions in ecological communities. Mutualisms occur when two species interact to reciprocally benefit one another; and though positive interactions are ubiquitous in nature, they remain understudied in comparison with negative interactions such as competition and predation. My work focuses on mutualisms among ants and honeydew-producing bugs, and how these species interact with their arthropod communities and the plants on which they live. In this kind of mutualism, honeydew-producing bugs such as aphids or membracids feed on plant phloem and excrete drops of sugar-rich honeydew as a waste product. Ants feed on this honeydew and provide protection for the honeydew-producer by aggressively deterring predators and competitors. To understand this mutualism in a community context, I use a combination of field experimentation and statistical techniques to construct interaction webs that quantify the relative strengths of both positive and negative interspecific interactions within manipulated communities of insects on individual host plants. Generally, I am interested in mentoring students who want to study the community-level relationships among insects and their host plants. More specifically, I expect students to conduct experiments on the plants, ants, honeydew-producers, or other arthropods in my field site to build upon the knowledge of this meadow community. Potential research projects include analyzing the competitive relationships among ants and spiders that use different hunting modes, assessing how ants can benefit larval lepidopterans when tending honeydew-producers on the same plant, or comparing the effects of different host plant species on the strength of ant/honeydew mutualisms.
Dr. John Harte, University of California at Berkeley
Student research will be supervised in two interrelated areas:
1. The macroecology of disturbed sites.
2. The ecological effects of climate change on subalpine/alpine ecosystems.
1. Macroecology is the study of the abundance and distribution of species across multiple spatial scales. It is an essential component in the science of biodiversity. Among the patterns that macroecologists study are species-area relationships, abundance distributions, and relationships between adult body size and abundance across species. They seek to understand the processes that generate the patterns. Most prior macroecological studies, both empirical and theoretical, have been designed for relatively undisturbed ecosystems. Areas of disturbance, such as heavily eroded sites, avalanche slopes, post fire sites, and habitats that are experiencing rapid climate change, have been neglected. We have recently begun a study of “disturbance macroecology”, trying to answer the question of whether field data in disturbed sites in the vicinity of RMBL reveal macroecolgical patterns that are similar to the patterns that are both observed, and are explained by recent theory, in undisturbed sites.
2. We are conducting a long term (it is now in its 20th -year) meadow warming experiment at RMBL. Many changes have been documented in the heated plots relative to the controls, including loss of soil carbon and a shift in plant species composition from forb dominance to shrub dominance, but many questions remain. Are shrubs doing better because competing forbs are doing worse, or are forbs doing worse because competing shrubs are doing better, or is neither of hypotheses correct? Biogeochemical theory suggests that the soil carbon decline should reverse in the coming years, with the soil carbon levels recovering back to pre-heated values: is that theory descriptive of our experimental plots?
Changes in phenology—i.e., seasonal biological events like flowering, leaf fall, and migrations—are among the most sensitive biological responses to climate change. At RMBL, we have some of the best long-term records describing these changes and how they are affecting the plant and animal communities. In addition, the lab has recently installed a network of weather stations that provide much-needed data on weather in this complex mountain landscape. We would like to work with a student to integrate phenology monitoring into the standard observations at these weather stations. This work will provide direct links between the weather station network and other cutting-edge phenology research taking place at RMBL. It will help to identify specific drivers of phenological changes taking place, answer whether these changes vary substantially across an elevational gradient, and inform projections of ecological responses to future climate change. The project is a part of a collaboration between RMBL and the USA National Phenology Network, and we hope that it will lay the foundation for a long-term monitoring program that could be replicated at other biological field stations.
Dr. Rebecca Irwin, Dartmouth College
The relationship between flowering phenology and solitary bee phenology in subalpine Colorado. Solitary bees are important and diverse pollinators worldwide, but the factors that affect the distribution and abundance of solitary bees are not well explored. The goal of this study is to test whether there is a relationship between flowering phenology and abundance and solitary bee phenology and abundance. The study will use pan traps, nesting blocks, and netting to assess the phenology and abundance of solitary bees. Students interested in pollination biology and bee taxonomy will be most suited to this project.
Hummingbird behavior in response to nectar robbing. Hummingbirds must make foraging decisions about which patches, plants, and individual flowers to visit for nectar rewards. The goal of this study is to test hypotheses for how hummingbirds respond to variation in nectar rewards and the mechanisms involved. The project will focus on hypotheses concerning how hummingbird pollinators avoid nectar-robbed plants and flowers. Students interested in animal (bird) behavior will be most suited to this project.
Nectar and pollen rewards in native and invasive plants. Invasive species are a leading component of environmental change and a second leading cause of biodiversity loss worldwide. There is growing recognition that invasive plants can affect native plants by luring away shared pollinators; however, the mechanisms driving such changes in pollinator behavior are not well explored. The goal of this project is to survey the nectar and pollen reward structure of native and invasive plants to assess how floral rewards may influence pollinator behavior in invaded communities. Students interested in plant ecology will be most suited to this project.
The ecological and conservation consequences of pollinator flight distances. See Stang and Irwin, below, for a description of this collaborative project.
Dr. Kailen Mooney, University of California at Irvine
The evolutionary and community ecology of plant- insect interactions, including investigations of the factors that may influence the outcomes of ant-hemipteran interactions including, but not limited to:
1. Predators and parasitoids: By studying the effects of ants on hemipterans open to and protected from predators and parasitoids, the student would determine to what extent the effect of ants on hemipterans is through ant deterrence of hemipteran enemies.
2. Ant species: By comparing the effects of differing ants species on hemipterans the student would determine whether ant species identity is an important factor mediating the benefits received by those hemipterans.
3. Foraging by insectivorous birds: By characterizing ant-hemipteran interactions on Aspen (P. tremuloides) branches with (control) and without (exclusion) of insectivorous birds the student would determine how vertebrate predators mediate the interactions between ants, hemipterans, and the arthropod predators and parasitoids of those hemipterans.
4. Ant reproductive status: The student would measure the effects of ants on hemipterans associated with mounds that did and did not include queens and brood in order to determine the effects of ant colony reproductive status and nutritional needs on ant-hemipteran interactions.
Dr. Mary Price and Dr. Nick Waser, University of California at Riverside and University of Arizona
Dr. Dan Blumstein, University of California at Los Angeles
Dr. David Inouye, University of Maryland at College Park
Mule deer sightings, rare before the 1980s, are now an everyday part of RMBL life. It is not uncommon for five does to fawn in the willows of the townsite and to browse unconcernedly a few meters from people. The increase in deer activity is of interest to plant ecologists, because deer-preferred plants seem to be declining in abundance at the RMBL. It is also of interest to behavioral ecologists, because the increased activity may be due to changes in behavior, not just to changes in population density: deer may congregate in the townsite because predators are less common there. We will involve two research students in a collaborative study to see if individually-marked deer respond behaviorally to predator scent, and to evaluate the consequences of deer for plant communities.
The first question we propose to address is, Are deer particularly common in the RMBL townsite? Our initial data suggest the answer is yes, but we need to collect more information, by walking standard transects from the RMBL townsite into surrounding habitats, and recording sightings of deer.
The second question, assuming the first is answered in the affirmative, is to ask why. Possible answers, not mutually exclusive, are that the cattle-exclusion fence that was installed in the 1980s has improved forage for deer in the townsite because cattle no longer graze there; and that deer have learned that coyotes avoid the townsite, thus creating a “safe haven” for fawns. We propose to explore the second possibility by deploying depots of coyote urine at replicated sites within the townsite, and by marking deer individually, to see if deer activity and behavior are different near vs. far from scent stations.
The third question is, What are the consequences of high deer activity for plant communities in the RMBL townsite? We propose to answer this by linking the rates of browsing on deer-preferred plant species (such as Colorado’s State flower, blue columbine) to any gradients in deer activity that are produced by scent stations.
Both research students will be involved in the exact design of this project. Both will contribute to transect surveys and maintenance of scent stations. Although we will encourage students to participate in all parts of the project, we propose that one student focus more on the deer behavior question, and the other more on the question of consequences for plants.
Dr. Graham Pyke, The Australian Museum
1. Using Optimal Foraging Theory to understand the distribution and behaviour of bumblebees visiting flowers. Optimal Foraging Theory has proven to be a powerful tool in understanding how animals forage and how they integrate foraging into other aspects of their lives. The optimal foraging approach has been used in a number of RMBL-based studies of foraging by nectar-feeding animals and pollination-ecology of the plants they visit. It remains possible, however, to expand upon these studies to further our understanding in these areas. Potential projects could investigate foraging and predation risk to nectar-feeding animals, spatial distribution of bumblebees, and plants as patches for foraging bumblebees.
2. Long-term climate changes around RMBL. There are long-term weather data for the area around RMBL from a variety of sources. This project will be computer-based and will involve statistical analyses of these available weather data. One aim will be to determine spatial and temporal patterns at various scales. Another will be to evaluate these patterns in relation to theories re how climate is determined and observed long-term climate changes from regional to global spatial scales.
3. Effects of climate change on bumblebees and the flowers they visit
Surveys around RMBL in 1974 and 2007 of bumblebees and the flowers they visit and contemporary local weather records provide a basis for considering possible biological effects of climate change. This project would aim to further our understanding of such effects through repeating part of these surveys in summer 2009.
4. Understanding the nature and extent of population decline in the bumblebee Bombus occidentalis. The bumblebee Bombus occidentalis has apparently declined throughout much of its original distribution. It is now almost extinct along the west coast of the U.S. and has declined around RMBL, at least below about 9,500ft. The aim of this project would be to further our understanding of the nature and extent of these declines around RMBL and to increase our understanding of the mechanisms involved. The project would involve surveys targeted at this bumblebee species and records of various aspects of the habitat such as the abundance of particular flower species and general flower abundance.
Projects 3 and 4 would extend from mid-June until the end of August. They could be carried out by a team of students working together, so long as the team had access to a vehicle. In addition, the team would have to quickly learn the local bumblebee fauna (~15 spp) and the local flora, be able to develop and maintain a computerised database for incoming data, and be adept at using computer-software to manipulate and analyse data.
Students will gain an improved understanding of methods used to manage and analyse data, but should be familiar with computerised spreadsheets and have previously completed an undergraduate-level introductory course in statistics.
Dr. Jennifer Rudgers, Rice University
My research program uses plants, arthropods, and microbes to explore how mutualistic species interactions affect population dynamics, community structure, and the evolution of species traits. Mutualistic microbes, in particular, contribute an important, but often overlooked, layer of diversity in ecosystems, and their inclusion in ecological research can increase the realism of both experiments and theory.
Fungal endophytes in cool season grasses grow in the intercellular spaces of aboveground plant tissues. In economically important forage and turf grasses, these fungi are known to increase host resistance to herbivory and drought, in part through the production of fungal alkaloids. However, we are just beginning to understand the ecological consequences of endophyte symbioses in natural ecosystems.
(1) Does symbiont frequency decline with altitude? How does endophyte presence affect host performance along an altitudinal gradient? Few studies have examined ecological factors that correlate with the frequency of fungal endophytes in nature. This project would involve surveys of fungal endophyte frequency in Rocky Mountain grasses combined with a reciprocal transplant experiment that assess the consequences of endophyte presence/absence for host plant growth.
(2) Does drought stress increase the frequency of symbiotic endophytes in host populations? Given that endophytes are known to improve drought resistance in agronomic grasses, we expect increases in the frequency of symbiotic plants under increased drought stress. This project would involve planting small mesocosms consisting of 50:50 mixtures of endophyte-symbiotic and endophyte-free seeds. We will manipulate water availability and track changes in the frequency of symbiotic plants through one growing season.
Dr. Rosemary Smith, Idaho State University
This research project focuses on the behavior and ecology of a very interesting, large, colorful, and stinky beetle. The burying beetle (Coleoptera: Silphidae: Nicrophorus) belongs to a family of beetles that breed on carrion. In the case of Nicrophorus, the carrion consists primarily of small mammals (voles, deer mice, jumping mice). Once the beetles locate a carcass they have intense fights, the largest M-F pair usually wins, and they begin the process of carcass preparation: burial, fur removal, and shaping into a ball. When the brood chamber is complete, the larvae hatch and are fed and tended by both parents. The larvae consume the entire carcass in about 14 days, then stay in the soil until they pupate the following summer. The parents leave and may breed again. Possible student projects include ecological studies: competition among beetles or interspecific competitors (ants, flies, other beetles), population density, habitat selection, or activity periods. Behavioral projects include competition and intruders at carcasses, parental care, larval competition, alternative mating strategies, and communication. Experiments can include both a field and a captive/lab component. Students must be willing to work with live animals in an ethical manner, pay attention to details, and collaborate with others in the same lab.
Dr. Martina Stang, University of Leiden, The Netherlands
Flower choice of butterflies
Many butterfly species depend as adults on floral nectar as their main energy source. These butterflies differ considerably in the number of plant species visited. Little is known about the factors determining nectar plant choice at the level of a community. Why do some butterfly species visit many plant species and others only few? The main questions in this project are (1) does butterfly morphology influence how many and how often plant species are visited, and (2) does flower morphology and abundance influence butterfly choice? Students interested in behavior, morphological diversity of flowers and butterflies, and community ecology are most suited for this project.
Nectar production and flower visitation
Nectar is an important food resource for flower visiting insects. It is often hidden in floral tubes and differs considerably in volume and concentration across plant species. Surprisingly little is known about how much nectar the species in a community produce and how nectar production rate is related to flower morphology. However, this information is crucial to understand floral choice of flower visiting insects and the structure of plant - pollinator interaction webs. The main questions of this project are (1) is nectar production rate related to flower morphology and (2) is nectar production rate and flower morphology related to flower visitation rate. This study is suited for students interested in flower morphology, plant - insect interactions and community ecology.
The ecological and conservation consequences of pollinator flight distances
Honey bees can fly up to several kilometers to find flowering plants to forage on. The flight distances of solitary bees and bumble bees may be shorter, but in most cases are unknown. However, there are indications that flight distance is related to body size and influenced by the size and isolation of the meadows where the food plants grow. Understanding pollinator flight distances has importance consequences for land-use management and conservation of native bees. The goals of this project are to (a) learn more about the flight distances of bees in relation to body size and (b) estimate how a potential decline of bee diversity and abundance in one meadow (e.g., due to sampling for research) could affect bee activity in adjacent meadows. Students interested in entomology and conservation would be most suited to this project.
Dr. Brad Taylor, Dartmouth University
1) How do extinctions of freshwater invertebrates caused by mining and invasive species affect nutrient cycling rates in stream ecosystems?
Freshwater invertebrates are highly threatened and as sentinel species they are used to detect human impacts. This project will discover how nutrient recycling by stream invertebrates is altered by the loss of particular species due to invasive species (the alga, Didymosphenia geminata) or acid mine drainage. The project is ideal for a student interested in learning how to identify aquatic insects, measure nutrient excretion by animals (e.g., ammonium and phosphorus), and combine data from excretion rates, species diversity and abundance into a model predicting the impacts of species losses on stream nutrient cycling. I will assist a student with field and lab work and provide equipment and supplies, but the ability to work independently is required. The goal of this project is to produce a publication showing how changes in aquatic insect diversity due to human impacts alter the amount and type of nutrients recycled by stream invertebrates. The focus on mining or invasive species will depend on logistics and the student’s preference. The start date is in mid June and the end date is mid August.
2) The influence of hydrology and temperature changes on a nuisance alga, Didymosphenia geminata.
The alga Didymosphenia geminata (or rock snot) is an emerging nuisance organism that is blooming in rivers worldwide, particularly in the Rocky Mountains. My research on this organism shows that this stalk-forming diatom is susceptible to bed-scouring disturbance and blooms in streams with warmer water. These factors may be linked to climate change, an increase in beavers and their dams, or both. Data suggest that this alga may prefer large or stable substrates and areas in streams with particular flow characteristics, such as, below dams. This project is ideal for a student interested in linking hydrologic properties or the effects of changing temperatures on the proliferation of a nuisance species. Students should have an interest in mastering the use of scientific instruments, wading in rivers, and working independently. The ideal student will use an acoustic doppler velocity meter to quantify turbulence, color dyes to quantify stream water residence times, various methods to estimate algal biomass, and experimental manipulations of water temperature in flow-through tanks. The start date is in late June and the end date is late August.
Dr. Noah Whiteman, University of Arizona
Our research at the RMBL focuses on understanding the molecular, ecological and evolutionary basis of host-parasite interactions using ecological, genetic and genomic approaches. Parasites comprise most lineages of Eukaryotic life on the planet, dominate food web links and regulate population dynamics of their hosts. We are interested in understanding how hosts resist persistent parasites and how parasites cope with host defenses.
We are initiating a long-term project at the RMBL on co-evolutionary interactions between an ecologically important host plant (the beautiful Cardamine cordifolia) and its natural enemies, including insect herbivores and plant pathogenic bacteria. Importantly, the host plant, the most important herbivore of this plant (a leafmining fly) and its plant pathogens are closely related to genetic or genomic model plants that we study in the laboratory. Our specific research goal is to test whether host resistance and toxin pathways, parasite detoxification pathways and outcomes of interactions between multiple parasite species gleaned from laboratory studies are actually important in the field.
Specific projects in 2010 will involve field and laboratory research at the RMBL and could include, but are not limited to the following:
(1) A particular parasite of C. cordifolia, a leafmining fly, typically attacks the lowest leaves of plants. These leaves are the oldest and first to appear in the growing season and they also contain among the lowest concentrations of plant defense compounds known as mustard oils, or glucosinolates. Do female flies oviposit in these leaves because they are the first available or because they have the lowest glucosinolate concentrations (or both or neither)? This experiment will involve laboratory and field experiments.
(2) A relative of the leafmining fly that attacks C. cordifolia has been shown to perform better on mustard plants that have been engineered to produce no mustard oils, suggesting that mustard oils impose a fitness cost on the leafminers. Is this true for the leafminers at the RMBL? This experiment will involve laboratory and field experiments.
(3) What defense pathways are important in C. cordifolia against leafminer attack? This will involve infecting naïve plants with leafminers and sampling leaves for gene expression studies. It will also involve pre-treating plants with plant hormones that induce resistance against herbivores and pathogens, and then conducting leafminer performance assays in the laboratory and field.
(4) Is there evidence of local adaptation of parasites to host clonal genotypes in this system? We will perform a laboratory experiment where parasites from different geographic locations are placed in plants from allopatric or sympatric populations to test the hypothesis that parasites are locally adapted to common host genotypes. We will also sample plants and leafminers from several locations around the RMBL and elsewhere in Colorado and preserve tissue that will later be used to quantify reciprocal natural selection on host resistance genes and parasite detoxification genes across the landscape.
(5) Does pathogen infection influence susceptibility to leafminer attack? We will experimentally infect plants with plant pathogenic bacteria in the laboratory and field and test whether this increases or decreases resistance against plant pathogens.
(6) Is climate change affecting the leafminer-C. cordifolia interaction? To establish a baseline, we will temporally monitor populations of C. cordifolia along an altitudinal transect and quantify plant growth, leafminer prevalence/development and glucosinolate levels.
My research focuses on evolutionary ecology of plants, with current research projects on the effects of hybridization in plants, on effects of genetic diversity in plants, and on interactions between plants and seed dispersers, pollinators, and herbivores. I will work closely with students to develop projects in these areas. Possible projects include, but aren't limited to:
1) Assembly of plant communities as mediated by plant-pollinator interactions. What determines which flowering plants are present in an area? Are species with certain floral traits are excluded from some communities because they are too similar to existing species, and/or are they under natural selection to shift their morphology (size, shape, color, scent, etc)? What role does evolutionary history (phylogeny) play in structuring communities?
2) Plant hybridization. Does exchange of genes between species allow more rapid adaptation? Several complexes of hybridizing species exist in the RMBL area and work is needed to characterize these hybrids and their ecological attributes.
3) Herbivory and phylogeny. Preliminary data from RMBL indicate that the amount of leaf damage (folivory) a plant gets is predicted by how closely it is related to the rest of the species in the flora, with distantly-related species getting less damage. This may be because chemical defenses become more divergent as species share less evolutonary history. Does this pattern hold up for other types of damage (e.g. damage to seeds or flowers)? Does it explain why some invasive species perform so well?
Jamie Winternitz, University of Georgia
Infectious diseases have been shown to threaten small populations and populations with low genetic diversity. This study looks to understand the mechanisms that maintain genetic diversity in immune genes in populations that go through repeated bottlenecks. I work on the charismatic and elusive montane vole to examine how the relationship between parasites and immune genes (the major histocompatibility complex; MHC) is affected by fluctuations in population density.
Through a combination of observational field studies and experiments, my goal is to investigate whether MHC heterozygosity and allelic diversity change non-randomly over time, and how that is influenced by the selection pressures arising from mate choice and pathogen resistance. Potential 2010 undergraduate projects could include:
1) mate preference experiments to determine if female infection status influence the strength or direction of her mate preference
2) Inter-individual variation in parasite load over time
3) Population cycle analysis (analyzing time series to determine if montane vole populations are actually cyclic)
4) Condition and infection status- are animals in poorer condition more likely to acquire parasites?
Dr. Scott Wissinger, Allegheny College
We study aquatic ecosystems, and in particular the population and community ecology of lakes, ponds, and wetlands in the vicinity of RMBL. Much of our work is focused on the 60+ subalpine (elev. 3400 m) aquatic habitats at the Mexican Cut Nature Reserve, which is owned by The Nature Conservancy and managed for research by RMBL. Long-term ( 20 yrs) data collected with Dr. Howard Whitman reveal dramatic fluctuations in the density of salamanders, the top predators in the ponds. We are interested in understanding how those fluctuations affect prey communities and pond ecosystem function. Independent projects for summer 2010 could be tailored to the following:
1) Primary sources of energy in alpine ponds. The low levels of nutrients (N & P) in the ponds suggest there should be low levels of primary production. To better understand the trophic basis of animal production, we need to compare live-plant sources of energy and nutrients to those of detritus (dead plant material from the edges of the ponds). The next questions we need to ask include a) what are the standing-crop biomasses of phytoplankton and benthic algae, and how do they vary seasonally and spatially among habitats, and 2) How much detritus enters these ponds, and what is the fate of that detritus?
2) Detritus processing by caddisfly larvae. We know that caddisflies are the dominant macro-detritivores in our ponds, and that salamander-driven fluctuations in their densities should modulate the re-entry of detrital nutrients and energy into consumer food webs. The next questions we need to address are a) do caddisflies benefit twice from processing detritus; first when they eat the detritus, and second when they graze algae growth stimulated by the nutrients the caddisflies excrete. b) to what extent are the results of our previous experiments on caddisfly detritus processing relevant at the whole pond level. c) Do temporary-habitat caddisflies have similar impacts on detritus processing as those we have measured for permanent-pond caddisflies.
3) Salamander – aquatic invertebrate predator-prey interactions. Long-term monitoring documents that several groups of large-bodied invertebrates predators (caddisflies, dragonflies, damselflies), exhibit coupled population fluctuations with those of the salamanders. The next questions that we need to address are 1) what do these large invertebrate eat, and therefore, what are the most likely cascading effects on lower trophic levels. 2) do the species that appear to react most to changes in salamander population size have different behavioral or morphological adaptations for avoiding salamander predation.
The start date for these projects would likely be later in June.