Ecology and Evolutionary Biology Archives

Undergrad Research – Abe Stone Functional Forest Fungus

Published June 18, 2024

Undergraduate

Abe Stone is an undergraduate majoring in ecology and evolutionary biology. He came to Michigan Tech’s Biological Sciences Department, already with a great interest in learning more about and working with fungus. Once he enrolled at MTU, he decided to get involved in undergraduate research and start down his fungus research path.

Abe Stone in forest working with invasive buckthorn and propagated fungus. — Abe Stone in the field.

Through his research, Stone found a way to effectively and practically propagate silver leaf disease—a fungal forest pathogen—and use it as an herbicide to attack the invasive tree species, buckthorn, while sparing native species. Stone has been working with Biological Sciences’ Dr. Erika Hersch-Green to learn more about how plants and fungi interact with each other, as well as advisors in the College of Forest Resources and Environmental Science (CFRES).

To learn more about Abe Stone, how he began this journey, and his work, visit Abe’s “Fungus Among Us…” story—featured on MTU’s Unscripted Research Blog.

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In Print: Erika Hersch-Green and Angela Walczyk

Published September 13, 2023

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Congratulations to Dr. Angela Walczyk (recent Ph.D. from Biological Sciences) and her advisor Dr. Erika Hersch-Green for their two new publications! You can access the papers here:

1. Exciting findings that genome size can affect resource requirements and genomic/transcriptomic functional trait trade-offs.

Abstract

Premise: Increased genome-material costs of N and P atoms inherent to organisms with larger genomes have been proposed to limit growth under nutrient scarcities and to promote growth under nutrient enrichments. Such responsiveness may reflect a nutrient-dependent diploid versus polyploid advantage that could have vast ecological and evolutionary implications, but direct evidence that material costs increase with ploidy level and/or influence cytotype-dependent growth, metabolic, and/or resource-use trade-offs is limited.

Methods: We grew diploid, autotetraploid, and autohexaploid Solidago gigantea plants with one of four ambient or enriched N:P ratios and measured traits related to material costs, primary and secondary metabolism, and resource-use.

Results: Relative to diploids, polyploids invested more N and P into cells, and tetraploids grew more with N enrichments, suggesting that material costs increase with ploidy level. Polyploids also generally exhibited strategies that could minimize material-cost constraints over both long (reduced monoploid genome size) and short (more extreme transcriptome downsizing, reduced photosynthesis rates and terpene concentrations, enhanced N-use efficiencies) evolutionary time periods. Furthermore, polyploids had lower transpiration rates but higher water-use efficiencies than diploids, both of which were more pronounced under nutrient-limiting conditions.

Conclusions: N and P material costs increase with ploidy level, but material-cost constraints might be lessened by resource allocation/investment mechanisms that can also alter ecological dynamics and selection. Our results enhance mechanistic understanding of how global increases in nutrients might provide a release from material-cost constraints in polyploids that could impact ploidy (or genome-size)-specific performances, cytogeographic patterning, and multispecies community structuring.

2. Finding that tetraploid Giant Goldenrods may be pre-adapted to be good invaders but that polyploidy per se does not increase phenotypic plasticity.

Abstract

Polyploidy commonly occurs in invasive species, and phenotypic plasticity (PP, the ability to alter one’s phenotype in different environments) is predicted to be enhanced in polyploids and to contribute to their invasive success. However, empirical support that increased PP is frequent in polyploids and/or confers invasive success is limited. Here, we investigated if polyploids are more pre-adapted to become invasive than diploids via the scaling of trait values and PP with ploidy level, and if post-introduction selection has led to a divergence in trait values and PP responses between native- and non-native cytotypes. We grew diploid, tetraploid (from both native North American and non-native European ranges), and hexaploid Solidago gigantea in pots outside with low, medium, and high soil nitrogen and phosphorus (NP) amendments, and measured traits related to growth, asexual reproduction, physiology, and insects/pathogen resistance. Overall, we found little evidence to suggest that polyploidy and post-introduction selection shaped mean trait and PP responses. When we compared diploids to tetraploids (as their introduction into Europe was more likely than hexaploids) we found that tetraploids had greater pathogen resistance, photosynthetic capacities, and water-use efficiencies and generally performed better under NP enrichments. Furthermore, tetraploids invested more into roots than shoots in low NP and more into shoots than roots in high NP, and this resource strategy is beneficial under variable NP conditions. Lastly, native tetraploids exhibited greater plasticity in biomass accumulation, clonal-ramet production, and water-use efficiency. Cumulatively, tetraploid S. gigantea possesses traits that might have predisposed and enabled them to become successful invaders. Our findings highlight that trait expression and invasive species dynamics are nuanced, while also providing insight into the invasion success and cyto-geographic patterning of S. gigantea that can be broadly applied to other invasive species with polyploid complexes.

New Funding: Amy Marcarelli and Michelle Kelly

Published September 8, 2023

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Amy Marcarelli is the principal investigator (PI) on a project that has received a $300,000 research and development grant from the National Science Foundation.

The project is titled “MSA: Quantifying whole-stream denitrification and nitrogen fixation with integrated modeling of N2 and O2 fluxes.”

Michelle Kelly is a co-PI on this potential two-year project.

Amy is an ecosystem ecologist with interests in energy and biogeochemical cycles in freshwaters. Her research program blends basic and applied research and integrates across aquatic habitats, including streams, rivers, wetlands, lake littoral zones, and the nearshore regions of the Great Lakes. Dr. Marcarelli’s past and future research trajectory is governed by an interest in understanding the role of small, poorly quantified fluxes or perturbations on ecosystem processes and in linking those ecosystem processes to the underlying structure of microbial, algal, macrophyte, and animal communities.

Congratulations Dr. Marcarelli and Michelle Kelly!

Amy Marcarelli is the recipient of MTU’s 2023 Distinguished Teaching Award in the Associate Professor/Professor category

Published June 20, 2023

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Amy Marcarelli is a professor of biological sciences and an ecosystem ecologist with an interest in energy and biogeochemical cycles in freshwater bodies. She received her bachelor’s in biology from Colgate University and her Ph.D. in ecology from Utah State. She is the director of both the Ecosystem Science Center and the Aquatic Analysis (AQUA) shared facility at Michigan Tech. Her research applies across aquatic habitats, including streams, rivers, wetlands, lake littoral zones — the sloping area where sunlight reaches from the lake’s surface all the way to the sediment, located between the shore and deeper water — and the nearshore regions of the Great Lakes.

“Amy Marcarelli is a true example of the teacher-scholar model. She maintains an active research program studying ecology of aquatic ecosystems and has administrative duties as the director of our Ecosystem Science Center on campus. Yet she also devotes vast time and talent to doing an outstanding job in the classroom, introducing our students to the remarkable ecology of Lake Superior, involving them by the dozens in research in her laboratory, and preparing students for graduate school and careers. Michigan Tech is fortunate to have Dr. Marcarelli on our faculty.”
David Hemmer, Dean of the Michigan Tech College of Sciences and Arts

Click to read the full article

O-fish-ally Fin-tastic Research!

Published April 26, 2023

By Riley Powers

Tessa Tormoen is a fourth-year student majoring in ecology and evolutionary biology with a minor in fish biology. She is one of the most adventurous people you’ll ever meet. You can often find her cross-country skiing on the Swedetown and Tech Trails. Not only is she a fan of heart-racing adventures, but her curiosity has also led to her getting involved in undergraduate research. Throughout Tessa’s classes, she learned the basic skills and processes needed in the lab. Her confidence grew. She was ready to put these skills into practice and take on an independent project. In the fall of 2021, she discussed her interest with Dr. Kristin Brzeski, assistant professor at Michigan Tech.

A picture of Tessa in the lab using a pipette to transfer a sample. — Tessa in the lab

Fishing for DNA

Dr. Brzeski put Tessa to work observing Golden and Blueline Tilefish. She extracted DNA from the digestive tracts of predator fish and constructed what the taxonomic group looks like by using a method called Metabarcoding, which is a process of DNA sequencing and identification. Using this technique she was able to characterize the dietary composition of the two different tilefish species to better determine the species’ niche breadth (or use of food resources in this case) and degree of similarity. This is one factor showing how the two species co-exist.

Like any craft, it’s a continual learning process. Working alongside graduate students and mentors, she developed her independent problem-solving and management technique. Learning the ins and outs of research was a steep learning curve, but Tessa was able to gain valuable skills and knowledge during her time as a researcher. “It’s a joy to have an undergraduate like Tessa in the lab. She brings passion, intelligence, and a genuine interest in research and natural resource conservation to every interaction,” said Dr. Brzeski.

Tessa exhibited her research at the 2023 Undergraduate Research Symposium, winning the third place GLRC award. She also won a merit award at the Ecosystem Science Center poster session. And she presented her findings at the Wildlife Society National Conference in Spokane, Washington with others in her lab.

Tessa is presenting her research to an audience by referring to a poster. The audience is pictured from behind. — Tessa presents her research “Using DNA Metabarcoding to Evaluate Dietary Resource Partitioning Between Two Sympatric Tilefish” at the 2023 Undergraduate Research Symposium

A Close-Net-Bunch

Tessa believes that her experiences in research have helped shape the future for the better. “I’m a lucky person. I’ve had an incredible four years. Jill Olin and Kristin Brzeski [have] built me into an independent scientist. They taught me how to solve problems, how to be independent and confident in my abilities,” she says. She credits both graduate and undergraduate colleagues in the lab with perpetuating the culture Drs Brzeski and Olin cultivated. “It was a welcoming and hopeful atmosphere.”

That feeling extends to the department. “Everyone is extremely kind, no matter who you talk to! All of my professors throughout my coursework have been very approachable and extremely passionate about what they study. I love that the biological sciences department is so personal and you can build relationships with the faculty. It truly makes the department’s environment so incredible. The support I have received from my advisor and my professors has been a valuable part of my education. I also love how the biological sciences department is a bit smaller compared to other departments like engineering. Each semester I recognize many familiar faces. I’ve been able to create great relationships with my peers through this,” Tessa said.

The Water is Just Right at Michigan Tech

Like many before her, Tessa chose to study ecology and evolutionary biology at Michigan Tech because she fell in love with this area. “I realized that I have a passion for understanding the world around me and this is a beautiful place to do that,” she said. “Plus, the experiences you’re able to have in this degree are fantastic, and I was compelled by the sheer amount of opportunities available to me.”

Tessa appreciated the flexibility the ecology and evolutionary biology degree program offered. “A lot of the coursework is electives that you get to choose from, so you can tailor your education to what you are most interested in. Thus, I was able to take courses like Mammalogy, Tropical Island Biology, Valuing the Great Lakes, Botany, and more!” Tessa said. “Sometimes you get to go outside for classes; one of my biggest memories from my degree is my Tropical Island Biology course, where we stayed in the Bahamas over Spring Break. This degree program has given me such a strong foundation and a whole list of interests that I can build upon with secondary education and post-education work experience.”

Tessa Tormoen enjoys the views of Portage Lake from the Biological Sciences Lounge

In addition to research and the degree program, Tessa took advantage of other opportunities on campus. She served as vice president of the Ski and Snowboard Club. Tessa also coordinated activities as part of the Women’s Leadership Council.

Leaving the School: Tessa’s Post-Graduation Plan

Following commencement this month, Tessa plans to “go with the flow.” This summer, you’ll find her on Isle Royale working as a fisheries technician, performing limnological assessments and fish surveys on their inland lakes. “I’m excited about this opportunity as it honestly feels like a dream job,” she said.

After taking one year to work in the field and gain more experience, Tessa wants to return to school for her master’s degree and potentially a Ph.D. “I think my experience at Michigan Tech has helped me greatly in understanding the opportunities available to me after graduation. I think that my education, research experience, and relationships at Tech have set me up for success once I leave,” she said.

We are certain her future will go swimmingly well!

Saving the Brook Trout by Restoring their Spawning Habitat

Published September 1, 2022

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News

Professor Casey Huckins has been studying the ecology of coaster brook trout for nearly 20 years. He started out investigating these migratory fish’s population ecology and life history. His research now focuses on analyzing the movement patterns of coaster brook trout due to human impact on the watershed. He is also focusing on ways to restore them and the habitat they need to spawn. Recently, with funding from the Michigan Departments of Environment, Great Lakes and Energy (EGLE) and the Department of Natural Resources, his lab has been actively restoring its critical habitat. “Human actions have turned these iconic heritage species of Lake Superior into a conservation concern by overharvesting them and disturbing their habitat,” Huckins explains.

Casey using a tool in a stream — Casey Huckins working in the field

His team is actively studying the two coaster brook trout populations still known to exist along the south-central shore of Lake Superior.

These migratory coaster brook trout live in Lake Superior. However, they return to their rivers of origin to breed in the same spots where they were spawned. Due to disturbances in the watersheds, like logging and road use, the spawning habitat of these creatures has been buried. This has altered the critical dynamic of erosion and sedimentation, leading to a buildup of fine sand. The sand present here is responsible for covering larger sediment particles like cobbles and pebbles. Cobbles are small rocks that have been rounded by water flow. These pebbles serve as the spawning habitat and also as the home for the brook trout’s food and aquatic insects.

With his recent state funding, Huckins says his goal is to restore the critical spawning habitat. He will do this by removing excess sand and studying the impacts on the habitat and the brook trout population. His team has installed in-stream sand collectors that passively collect sand as it flows over them. The researchers then routinely operate pumps to move the sand out of the floodplain.

Huckins’ team is now investigating whether the community of stream insects that are key food items for the brook trout also increases in abundance, diversity, and community structure. He hopes to see a site with natural, free-flowing cobble-based cold-water habitat. Huckins found this at the site when he started studying it with his graduate students nearly two decades ago.

His next goal is to acquire additional funding to automate the sand collectors to operate independently. Huckins’ goal is to eliminate the need for researchers to manually pump sand at the site, saving them time and fuel expenses. The team is currently expanding their efforts to implement this system in various streams and rivers. Their equipment is being utilized to rehabilitate other waterways that have suffered from erosion due to flooding, land use, or other factors that cause sand to flow downstream. As our climate changes, we expect to see more extreme events that will have outcomes we need to address to restore and maintain these critical aquatic ecosystems.

This blog post initially appeared in the Fall 2022 Biological Sciences Newsletter. Read this article and others like it today.

Erika Hersch-Green Receives NSF CAREER Award

Published September 1, 2022

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Erika Hersch-Green, plant evolutionary ecologist and associate professor of Biological Sciences, received a National Science Foundation CAREER Award. She will investigate how specific attributes of plants, such as their genome size, influence community biodiversity responses to increased nitrogen and phosphorus availability. Hersch-Green’s approach combines molecular, cytological, physiological, and phylogenetic techniques.

Hersch-Green is conducting her research on three fronts. First, she is currently gathering fresh data and merging it with information from experimental grassland sites around the world. These sites have plots with different nutrient treatments, allowing her to examine how response patterns vary depending on climate conditions. Second, she is conducting controlled greenhouse studies to better understand mechanisms that focus on two common grassland plants: fireweed and goldenrod, both of which she has studied before. Lastly, she developed a new research site at Churning Rapids, north of Hancock and south of McClain State Park. There she is extending her research to look at how disturbance patterns affect levels of biodiversity.

She is also exploring ways to improve students’ scientific literacy and engagement in research. To accomplish this, she is incorporating students in grades 6 through 12 and undergraduates in research, enhancing research involvement in the classroom, facilitating effective scientific communication skills of graduate students, and promoting collaboration among undergraduate students and faculty in the Departments of Biological Sciences and Humanities. These students will produce video content that will be used to enhance education and public understanding of biological science and ecology.

To summarize, Hersch-Green aims to provide a system-level understanding of how nutrient eutrophication—the increasingly dense growth of particular plants at the expense of other species—and landscape disturbances affect individual organisms and multi-species communities by looking at their interactions.

Although she is passionate about her research, Hersch-Green is also deeply committed to the educational component of her CAREER award. Her educational goals are to increase both scientific literacy and engagement of high school and university students on critical topics related to nutrient eutrophication, biodiversity, evolutionary adaptation, and awareness of related STEM (science, technology, engineering, and math) career pathways.