Archives for November 2018

Impacts of Microbiomes on Mutualisms

November 16, 2018 by wpeeb

Jonathan Dickey, a graduate student in the Fordyce lab, investigates the mediation of pollinator network assembly by rhizospheric soil microbiota through reproductive plant traits and aboveground fitness consequences in the genus Salvia. He demonstrates this by sampling soil microbiomes of Salvia lyrata at various phenological stages of development while measuring traits like photosynthetic biomass and floral abundance.

“We have seen before that the main driver of pollinator visitation and community composition relative to ecoregion and soil context is driven by plant composition, floral traits, and rewards, but how do belowground communities influence plant distribution and relative attractiveness towards insects?” Jonathan says.

Jonathan plans to quantify soil microbial communities based on 16S rRNA gene abundance using Illumina next-generation sequencing for each plant replicate per phenological stage. Jonathan’s exploration of community assembly with Salvia lyrata is multidisciplinary and connects community ecology with population level, evolutionary processes like the phenotypic selection. Furthermore, he has been optimizing a protocol for seed sterilization and germination for the genus Salvia by repeated processes that include seed coat surface sterilization and heat treatments to remove all potential endophytic microbiota. Upon successful germination, Jonathan plans to use soil microbial slurries associated with juveniles and flowering individuals to measure flowering time, abundance, corolla tube length, and ultimately pollinator visitation rates.

Additionally, he uses species distribution modeling (SDMs) to inspect how nutrient based mutualisms can breakdown in future climate scenarios. Through this exploration, he explicitly states the spatial extent at which potential niche divergence could occur in Eastern North America and the implications for conservation and effects on higher trophic levels. From yet another avenue, Jonathan is writing an R package employing MuSSE, a phylogenetic method, to analyze population size as a trait dependent on the presence of a stress-tolerant gene. The utility of this package is versatile and can provide a nuanced look at community disassembly in light of climate change or various disturbance events.

“We’re just now beginning to fully appreciate the vital role that microbial communities play across levels of ecological organization,” Fordyce says. “Jonathan’s project, entirely of his own design, is timely and novel. I’m looking forward to seeing what he discovers.”

New Dimension of Plant Mating Systems

November 16, 2018 by wpeeb

In spring 2018, Daniel Malagon won the EEB Undergraduate Research Poster Contest as a junior. He has been conducting out-of-class research over the course of his undergraduate career. He has devoted as much of his time as possible into two labs – one led by Professor Susan Kalisz (EEB) and one led by Professor Matt Gray (FWF).

Using the genus Collinsia as a model, the Kalisz lab investigates the ecological causes and genetic and genomic consequences of mating system divergence between closely related sister species pairs. Daniel added a new dimension to ongoing studies on the evolution of plant mating systems. His research asked if senescence differed between outcrossing and selfing mating species using pollen performance as the metric. An outcrossing mating system relies on a vector to move pollen among flowers, while selfers autonomously move pollen within the same flower.

“Daniel arrived in our lab the first day of his freshman year on fire,” Kalisz says. “He was eager to learn the research ropes and do his own project. His research produced novel, surprising, and soon-to-be-published results: selfers pollen does not show senescent decline, while outcrossers do!”

In the UT Center for Wildlife Health (CWH), Daniel studies amphibian disease epidemiology. Currently, he is helping determine the potential impact a recently discovered fungal pathogen (Batrachochytrium salamandrivorans) may have on endemic salamander species. Using disease epidemiology models, the Gray-Miller Lab hopes to thwart invasion of this pathogen should it ever reach North America. Daniel’s senior thesis project focuses on the probability of disease transmission via direct contact between salamanders as the disease progresses.

“It has been a privilege to co-mentor Daniel with Dr. Debra Miller,” says Gray, associate director of the UT CWH. “We look at all undergraduate researchers as significant and important components of the CWH, capable of advancing the frontier of science.”

“I strongly encourage any motivated student to look into participating in undergraduate research with a professor whose research they find interesting,” Daniel says. “My participation in these two research labs has been the highlight of my undergraduate experience. I feel very privileged to have had this opportunity to engage with such an incredible faculty and staff. I hope to take everything that I have learned with me to graduate school next fall.”

What’s the Story?

November 16, 2018 by wpeeb

Anna Killeen Cameron is an undergraduate researcher who has worked in the Simberloff and Leppanen lab for the past year on a media analysis related to information about the management of the hemlock woolly adelgid.

The hemlock woolly adelgid (Adelges tsugae) is an invasive insect that is devastating hemlock populations (Tsuga canadensis and T. caroliniana) in eastern North America. Anna and fellow students in the lab analyzed the type and frequency of information presented by the media, including newspaper, radio, and television. In April 2018, they presented posters about their research at UT’s Exhibition of Undergraduate Research and Creative Achievement (EURēCA).

“Anna took the initiative to dig into a substantial dataset and helped us identify possible trends in literature about invasive species management,” says EEB’s Research Assistant Professor Christy Leppanen.

Anna also spent the summer conducting research with EEB PhD candidate Angela Chuang, Professor Leppanen, and EEB undergraduate Casey Fellhoelter. They studied the behavior of a parasitoid wasp and its interaction with the orb weaver spider, Cyrtophora citricola, which is invasive in Florida. The wasp (Philolema sp.) is a newly identified species, so the information gathered about the wasp will contribute to its future species description. Her work to understand the interactions between the wasp and the orb weaver spider are also important in determining whether the wasp could be used as a potential biological control of invasive C. citricola populations.

“Undergraduate research has been one of the best parts of my undergraduate experience. I’ve built great relationships with fellow students and with professors who I now consider to be mentors. It has challenged my way of thinking and has provided me with skills I would not have developed otherwise,” says Anna, who looks forward to her senior year at UT and hopes to continue to gain more field and research experience.

Leppanen C, Frank DM, Lockyer JJ, Fellhoelter CJ, Cameron AK, Smith LJ, Hardy BA, Clevenger MR, Simberloff D (2018) Media representation of hemlock woolly adelgid management risks: A case study of science communication and invasive species control. Biological Invasions.

Ants as Seed Dispersers

November 16, 2018 by wpeeb

Although it is likely most people have experienced ants at a picnic, they may not realize ants are important seed dispersers, a mutualism referred to by ecologists as myrmecochory. Seed dispersal by ants exists worldwide, but the eastern deciduous forests are a hotspot for this ant-plant interaction. Approximately 35 percent of the herbaceous plants in the understory of forests in eastern North America rely on ants for seed dispersal. Plant species that have coevolved myrmecochory have an oil-rich appendage, known as an elaiosome. The elaiosome attracts the ants with chemical cues. Ants pick up the seed by the elaiosome and return with it to their nest where they feed the elaiosome to their brood. The seed either remains in the nest or is taken outside of the nest. Thus, in myrmecochory, ants gain food, and seeds receive dispersal away from their parent plant, protection from seed predators, and a nutrient-rich germination site in or around ant nests.

Additional organisms likely play a role in this interaction. Microbes, such as bacteria and fungi, are abundant in soil and decaying wood environments where ants nest and seeds germinate. Some of these microbes are harmful to plants or ants, so ants and plants have defenses against these pathogens. Each partner in the ant seed dispersal mutualism has the potential to affect the other partner’s microbes. Chloe Lash, a graduate student in the Kwit Lab, is investigating the effects of chemicals and microbes in this mutualism for her dissertation.

Chloe uses advanced chemical identification techniques to investigate plant and ant chemicals and their potential antimicrobial properties. A combination of traditional and next generation sequencing techniques allows Chloe to understand the microbial loads that both ants and seeds encounter and how those microbial communities change when the partners interact with each other. This novel incorporation of chemical and microbial facets into myrmecochory will contribute to understanding the evolution and persistence of the myrmecochory mutualisms and can help scientists predict the consequences of global change-related disruptions.

An Untraditional Concentration

November 16, 2018 by wpeeb

Pursuing his DDS at Meharry Medical College in Nashville, Tennessee, John Patrick (J.P.) Carney (’13) begins his fourth and final year of dental school this fall. He will graduate May 2019. A graduate from the University of Tennessee, Knoxville, Carney received his BS in biological sciences with a concentration in ecology and evolutionary biology. Before he began his first year at UT, Carney knew he wanted to become a dentist.

Although biochemistry and cellular and molecular biology and chemistry are two of the traditional pre-dental majors, Carney declared his major in biological sciences with a concentration in EEB. He decided on an untraditional concentration after becoming acquainted with other pre-health students in his prerequisite classes. With most of the requirements completed, Carney discovered his niche, electing to focus his studies in the area that would allow him to stand out during the intensely competitive environment of dental school admissions. The experience of EEB allowed Carney to master the art of communication, which contributes to his success in dental school. Likewise, the correlation of lecture topics with weekly field trips to places like Ijams Nature Center and the Knoxville Zoo allowed members of the EEB department to find balance in real world application of knowledge.

The study of ecology and evolutionary biology is a prime example of the way people can benefit from having diversity in the classroom and in life. Carney found an environment of great diversity waiting for him at Meharry Medical College, a school that welcomes all to its campus and exemplifies the concept of diversity. The diversity among dental students created an inclusive atmosphere that facilitated the treatment of patients from all around the world. This level of diversity taught Carney an important concept in healthcare: cultural competency, a factor that can impact overall patient satisfaction and quality of care. More diversity in the classroom or a healthcare setting can ultimately lead to substantially improved interprofessional collaboration, which can help reduce medical errors, improve the quality of care, and meet the needs of diverse populations. Taking in different perspectives on problems facing the healthcare industry is key to finding solutions and providing patients with optimal care and satisfaction.

Carney looks forward to utilizing the lessons he learned in EEB in his future practice. As a general dentist, he plans to further his knowledge in implant dentistry to provide patients the highest standard of dental care. Knoxville will always be home sweet home, and he knows that the future is bright on Rocky Top.

Invisible Organisms with an Enormous Impact

November 16, 2018 by wpeeb

Understanding the distributions and functions of microscopic fungi and bacteria is what drives new Assistant Professor Stephanie Kivlin’s research.

“Microbes can sometimes get a bad reputation, causing disease, food spoilage, etc.,” Kivlin says. “But, people are often surprised to learn that most microorganisms are beneficial for humans; increasing crop yields, purifying water, and recycling nutrients from dead plants back into soils.”

Because there are more than 1,000,000,000 microorganisms in a scoop of soil, determining exactly where, when, and how microbes perform these beneficial functions is still an open line of research. These questions motivated Kivlin to follow a career in microbial ecology after being trained as a microbiologist. She has since pursued research to connect the function of these tiny organisms (< 0.01mm) to whole ecosystem scale resource dynamics.

Kivlin’s research occurs in locations near and far from Knoxville. She spends her summers assessing microbial response to the 2016 Chimney Tops 2 fire in the Great Smoky Mountains National Park and elevational patterns of microorganisms and the soil resources they affect in the western Colorado Rockies at the Rocky Mountain Biological Laboratory. The rest of year, she models microbial biogeography and ecosystem resource cycling at regional to global scales.

Students participate in a long-term warming experiment at the RMBL collecting fungal endophytes from grass leaves for metabolic analysis.

Kivlin is especially thrilled to be joining the UT EEB faculty. “I have always valued and encouraged collaborative science. The unique opportunity to collaborate with plant and soil ecologists, mycologists and spatial ecologists in the UT EEB department combined with associations with ecosystem modelers at the Oak Ridge National Lab is the perfect fit for my research program.”

Kivlin’s field site view from Rosy Point, Gothic, Colorado.

Kivlin is no stranger to the excellent microbial and ecosystem ecology group already established in the department. To start her lab, Kivlin brought on recent UT EEB PhD graduates Jessica Moore and Leigh Moorhead, with expertise in ecosystem modeling and response to disturbance, as postdoctoral researchers. Moore and Moorhead took advantage of the UT-ORNL connection by conducting their PhD research at ORNL.

“The unique opportunity to collaborate with leading ecosystem experts at ORNL enticed me to select UT for graduate school, and I’m excited to further my ORNL collaborations throughout my post-doc,” Moore says.

“Ecosystem and microbial ecology have always been a strength of the UT EEB department, so I was exceptionally fortunate to attract two postdoctoral researchers whose graduate careers I had been tracking over the last five years,” Kivlin says. “We are all looking forward to building intra- and inter-departmental scientific synergies!”

The Geography of Ecology

November 16, 2018 by wpeeb

What’s the difference? How is it that a pest or pathogen can kill its host in one place but not another? Research Assistant Professor Christy Leppanen wants to know.

Leppanen is looking for differences that explain why an invasive insect, the hemlock woolly adelgid (Adelges tsugae or HWA), kills North American eastern hemlocks (Tsuga canadensis) and Carolina hemlocks (T. caroliniana), but not hemlocks from its native range in Asia.

“Simply speaking, I am interested in identifying mechanisms responsible for different outcomes when communities are considered the same,” Leppanen says. “For example, a particular insect pest or biocontrol agent kills its host plant in one location, but not another. We increase the likelihood of success and reduce the risk of negative non-target effects when management takes these mechanisms into account.”

Easier said than done. Including these considerations seems intuitive, but discerning differences in communities is challenging. Populations are influenced by direct and indirect interactions, such as with predators, competitors, pathogens, and microbial communities, or host resistance, all influenced by variation in nutrients, phenology, and climate.

“Difficulty transferring population control mechanisms from one location to another might reflect the fact that differences in these systems might not be inconsequential.”

For instance, in eastern North America, hemlock woolly adelgid (HWA) biocontrol using natural enemies translocated from HWA’s native range has not yet proven successful. HWA infests different hemlock species in its native range. Evidence suggests host resistance influences infestations, and while this does not preclude some role of natural enemies, vulnerability in eastern North American hemlocks might override possible population level control by natural enemies.

Leppanen comes from a multidisciplinary research, management, and regulatory background in environmental toxicology, conservation biology, and pest management. Her work with HWA falls within her larger interests to improve pest control, mitigate associated harmful non-target effects, and increase sustainable practices.

“The HWA problem embodies many challenges we face managing nature,” Leppanen says. “We have not confirmed which mechanisms control HWA populations in its native range, but specificity associated with effective biocontrol means its interactions and role in population control must be precisely understood. We sometimes feel pressured, however, to implement before we understand. Additionally, approaches sometimes counter one another; for example, chemical control that is often broad spectrum can have broad non-target impacts, even to natural enemies.”

Leppanen is confident scientists will find solutions.

“Collectively, we’ll keep at it. This is interesting and important work, with new tools and technologies and an enthusiastic and engaged group of participants.”

At UT, Leppanen teaches courses in environmental toxicology and invasion biology, the latter with Professor Daniel Simberloff. She is also the author of an award-winning mock scientific journal. The Bulletin of ZOMBIE Research (BOZR) is a collection of deadpan post-apocalyptic articles that uses popular culture to lure readers into learning about research and technical literature, dissolving barriers to accessing and understanding science.

Illustration by Steven Lee (graphiko.com)

A Rare Collection of Fish Specimens

November 16, 2018 by wpeeb

The UT Etnier Ichthyology Collection (UTEIC) was established in 1965 when Professor David A. Etnier started collecting fish specimens from throughout the state for teaching and research purposes. At the time, little was known about fish diversity in the region, which made identification challenging. The need for a collection became apparent to Etnier, so he began sampling fishes from the many river systems in Tennessee. The UTEIC now holds approximately 425,000 specimens, a staggering number for a young collection, gathered from nearly all 50 states, Gulf of Mexico, Mexico, South America, Africa, Australia, New Zealand, Antarctica, Russia, and the Atlantic and Pacific oceans.

With more than 40,000 jars of specimens, it is the largest fish collection in the state of Tennessee and one of the most valuable in the southeastern United States. It has become a highly celebrated, nationally renowned biological archive. In fact, many southeastern US specimens in the collection have prompted the discovery of new species and have been used to study the effects of climate change and water quality on aquatic communities. The UTEIC is considered the most comprehensive tool enabling researchers to identify and predict changes in where fishes live and the size of their populations throughout Tennessee.

While UTEIC contains collections from all over the world, the bulk of its holdings come from east of the Rocky Mountains in North America, most notably from biological hotspots in the Southeastern region. Over the years, the UTEIC has served as a critical repository, possessing substantial inventories, such as samples from regional monitoring surveys spanning more than 50 years provided by the Tennessee Valley Authority and the Tennessee Wildlife Resources Agency. Among these holdings is a significant representation of southeastern jeopardized species.

The collection has also served as an invaluable resource for researchers, private agencies, and governmental organizations. The loan program processes hundreds of outgoing fish and tissue biopsies for DNA extraction each year. Requests for data associated with the specimens are constant. Since its establishment, the studies of at least 45 PhD and MSc students incorporated existing data or produced new data from the collection. Fish specimens used in more than 100 publications embodying the research of Etnier and his students are vouchered in the UTEIC, including 269 lots (2,995 specimens) of designated paratypes. The UTEIC is an invaluable resource for teaching purposes, providing specimens for classes in both ichthyology and vertebrate biology. Additionally, undergraduate students complete independent research projects using UTEIC specimens and data from the collection.

Natural history collections such as the UTEIC are becoming increasingly important as researchers become more interested in how organisms are related, interact with each other, and respond to largely human-caused and relatively rapid changes in global environments. In these areas, the UTEIC is very much an active and growing collection. Our current curator, Benjamin Keck, has described new species, including the Tennessee Logperch (Percina apina). He works with other EEB faculty to examine how land use patterns are associated with fish communities and serves on advisory committees for US Fish and Wildlife Service reviews of endangered species, including the famous snail darter (Percina tanasi).

UTEIC’s new and vibrant online presence expands contribution to knowledge about aquatic resources. Researchers at other institutions and government agencies can quickly access the data, request loans, predict occurrences for survey work, and generally increase the number of studies possible. In the future, staff would also like to develop teaching modules for a broad range of educators based on the data. For instance, a community ecology lesson could allow students to pick a local creek or river, use UTEIC data to determine which species occur there, and then explore the ecology of the individual species to predict community interactions.

Several years ago, Professor Etnier created the Etnier Ichthyology Collection Endowment. The endowment provides financial resources to help maintain and improve the collection. The endowment pays for the bulk of the supplies necessary for maintenance and collaboration efforts (alcohol, glassware, shipping materials, and fees). The ultimate goal, however, is to increase the endowment to the level necessary to support the growth of EEB outreach programs, facilitate critical storage improvements and, eventually, endow the UTEIC curator position.

Alumni and friends who support the endowment will help ensure the viability of this valuable collection. For more information about the Collection and the Endowment, contact Jennifer Brummett at 865-974-1948 or email her at jparris@utk.edu.

Natural History of the Great Smoky Mountains

November 16, 2018 by wpeeb

Want to take a field course immersed in the natural beauty and ecological complexity of one the world’s biodiversity hotspots?

The Great Smoky Mountains National Park is a UNESCO World Heritage Site, an International Biosphere Reserve, a Biodiversity Hotspot, and a naturalist’s paradise. The Smokies also are at our own backdoor. Since 2016, EEB has offered a field course, EEB 480: Natural History of the Great Smoky Mountains, that allows students to explore the plant and animal communities, geology, geography, and human history of our nation’s most visited national park. Over a two-week period in the summer mini-term, students immerse themselves in the natural history of our Southern Appalachians.

The first week is taught on campus, where students dig into the outstanding biodiversity collections maintained by EEB and the McClung Museum, learn about plant and animal communities in the Smokies, and identify species in these communities. Students also learn about the human history and ecological threats to the Smokies, including invasive species, changing environmental conditions, and human impacts.

The second week is devoted to field-based exploration of the Great Smoky Mountains. Students and faculty stay at the EEB Field Station, just outside of the Greenbrier entrance to the Great Smoky Mountains National Park. They live and work in a community environment, staying in an open-air camping area with modern kitchen and bathroom facilities. They get up early, stay up late, get wet and dirty, and eat well. Fieldwork involves a lot of hiking. Each day they explore a different part of the park, investigating plant and animal communities and identifying species in the wild. The course winds up with students each making presentations on a research topic that they choose while immersed in the natural wonders of the Park.