Michelle Hersh

AB, Bryn Mawr College. PhD, Duke University. Postdoctoral Research Associate, Bard College, Cary Institute of Ecosystem Studies. Community ecologist with a special interest in the connections between biodiversity and disease. Author of articles on how fungal seedling pathogens maintain tree diversity in temperate forests and how animal diversity alters the risk of tickborne diseases. Recipient of grants from the National Science Foundation. Previously taught at Bard College and Eastern Michigan University. SLC, 2013–

Current undergraduate courses

Disease Ecology

Fall

Interactions between hosts and pathogens have consequences not only at the individual level but also cascading up through populations, communities, and ecosystems. In this course, we will look at infectious disease through the lens of ecology. We will consider infected hosts as ecosystems, focusing on ecological interactions within hosts both between microorganisms and between pathogens and the host immune system. Further, we will investigate disease dynamics within and between populations, including the emergence of new diseases and the dynamics of vector-borne disease systems. Mathematical models of disease transmission and spread will be introduced. Finally, we will explore the larger impacts of disease on biological communities and entire ecosystems, considering topics such as the relationship between disease and biodiversity and the surprising ways in which disease can affect ecosystem structure and function. Examples will be drawn from plant, wildlife, and human disease systems.

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Related Cross-Discipline Paths

General Biology Series: Ecology

Fall

The natural world can be beautiful and inspiring but also can be challenging to understand mechanistically. Ecology is the scientific study of how organisms interact with the environment. Ecologists might ask questions about how plant growth responds to climate change, how squirrel population size or behavior changes in response to acorn availability, or how nutrients such as nitrogen and phosphorous cycle in rivers and streams. In this course, students will develop a strong foundational understanding of the science of ecology on the individual, population, community, and ecosystem scales. Throughout the course, emphasis will be placed on how carefully-designed experiments and data analysis can help us find predictable patterns despite the complexity of nature. Students will be expected to design and carry out a field experiment in small groups. The course will include a weekly lab section, with most labs held outdoors at local parks and field stations.

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Giving, Taking, and Cheating: The Ecology of Symbiosis

Spring

From gut flora of animals to fungi living in tree roots, symbioses are important and widespread throughout the natural world. We can broadly define symbiosis as different species living together in a close association of any nature, from mutualism to parasitism. In this seminar course, we will explore how symbioses are developed, maintained, and broken down and consider the scientific challenges to understanding the function of such associations. We will read and discuss papers from the primary literature exploring a broad range of taxonomic groups, including fungus-farming ants, bioluminescent bacteria living in squid, figs and their wasp pollinators, parasitic butterflies, and sloths and the moths that live in their fur. We will place a special emphasis on mutualisms, or interactions in which both partners benefit—unless, of course, one cheats. We will also think carefully about how to design scientific experiments to understand the nature of symbioses and design and carry out class experiments on mutualisms between plants and nitrogen-fixing bacteria.

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Related Cross-Discipline Paths

Global Change Biology

Spring

Climate change. Biodiversity loss. Nutrient pollution. Invasive species. Global ecosystems are being altered in dramatic ways due to human activities. In order to address these challenges, we first need to understand them scientifically. This course will explore the impacts of global environmental change through the lens of the biological sciences. Should humans assist with tree migration so that slow-migrating plants can catch up to changing temperature conditions? How are invasive predators like Burmese pythons in Florida affecting mammal populations? How can the extensive use of fertilizers upstream in a large river affect biological communities downstream? How has overfishing altered marine biodiversity? How could urbanization and habitat loss alter the risk of disease spillover from wildlife to humans? We will use the scientific journal articles and other primary sources to address these kinds of questions and more in this seminar course.

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Related Cross-Discipline Paths

Previous courses

Evolutionary Biology

Spring

What biological processes led to the development of the incredible diversity of life that we see on Earth today? The process of evolution, or a change in the inherited traits in a population over time, is fundamental to our understanding of biology and the history of life on Earth. This course will introduce students to the field of evolutionary biology. We will interpret evidence from the fossil record, molecular genetics, systematics, and empirical studies to deepen our understanding of evolutionary mechanisms. Topics covered include the genetic basis of evolution, phylogenetics, natural selection, adaptation, speciation, coevolution, and the evolution of behavior and life history traits.

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First-Year Studies: Urban Ecology

FYS

Ecology is a scientific discipline that studies interactions between living organisms and their environment and processes governing how species are distributed, how they interact, and how nutrients and energy cycle through ecosystems. Although we may think of these processes occurring in “natural” areas with little to no human development, all of these processes still take place in environments heavily modified by humans, such as cities. This course will cover fundamental concepts in the discipline of ecology and then further explore how these patterns and processes are altered (sometimes dramatically) in urban environments. We will use examples from our local environment—the New York City metropolitan area—to understand ecological concepts in light of urbanization. Special attention will be paid to the ecology of the Hudson River, including field trips and work involving the Sarah Lawrence Center for the Urban River at Beczak.

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General Biology II: Organismal and Population Biology

Spring

In this class, we will apply the building blocks of biology from General Biology I—molecules, cells, genetics, and evolution—to better understand the organization, structure, and function of earth’s staggering levels of biological diversity. From the microscopic to the macroscopic scale, we will introduce and discuss the diversity of life, including viruses, bacteria, protozoa, fungi, plants, and animals. We will also explore topics in ecology, considering how organisms interact with the environment and each other. Readings and lectures will be supplemented with peer-reviewed journal articles, and the process of biological inquiry, hypothesis testing, and experimental design will be discussed. In addition, students will participate in weekly laboratory work, including field trips.

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Microbiology

Fall

Humans are bathing in a sea of microbes; microbes coat our environments, live within our bodies, and perform functions both beneficial and detrimental to human wellbeing. This course will explore the biology of microorganisms, broadly defined as bacteria, archaea, viruses, and single-celled eukaryotes. We will study microbes at multiple scales, including the individual cell, the growing population, and populations interacting with one another or their environments. Microbial physiology, genetics, diversity, and ecology will be covered in depth. Particular emphasis will be given to the role of microbes in ecological processes and microbes that cause infectious disease in humans.

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Selected Publications

“When is a parasite not a parasite? Effects of larval tick burdens on white-footed mouse survival”

Co-authors: Michelle H. Hersh Shannon L. LaDeau M. Andrea Prevital Richard S. Ostfeld