Research

Dr. Hauk's home page 

As a plant systematist, I am interested in studying how plants evolve, and how understanding their evolutionary history can help us classify them in more meaningful ways. My research focuses on primitive ferns of the family Ophioglossaceae (adder's tongue ferns), and I use both whole organism and molecular methods. I employ DNA sequencing to help understand evolutionary relationships among species, and a PCR based technique (ISSR markers) to evaluate genetic variation within and among populations of closely related species. (For more information, click the link below.)

Dr. Homan's home page 

My research focuses on understanding the habitat requirements of pond-breeding amphibians, as well as on expanding the ways in which effects of habitat loss can be measured and monitored. Wetlands themselves have gained some protection in recent years, however many wetland organisms, including amphibians, rely heavily on the terrestrial upland. It is crucial to the protection of native wetland species that we understand both the quantity and quality of terrestrial habitat required to support a healthy population. Many pond-breeding amphibians, particularly Ambystoma species, can live for a decade or more, and this long life span can make traditional population studies challenging. Developing alternative techniques that can supplement, or in some time sensitive cases, replace traditional population studies may aid in the relatively rapid identification of at-risk populations, as well as enable the implementation of more effective management strategies. To that end, I am currently planning several experiments including a long-term population study of a pond-breeding salamander (A. maculatum) and several studies of potential rapid assessment techniques for identifying populations at risk of severe decline or extinction at local ponds. (For more information, click the link below)

Dr. Liebl's home page

I am using second-site modifier genetic screens in Drosophila to identify components of tyrosine kinase signaling pathways. Once novel genes are identified, they are characterized through classical and molecular genetic techniques. (For more information, click the link below.)

Dr. McCall's home page

I am a plant evolutionary ecologist interested in how organisms interact with their environment to shape functional traits and their underlying genetic architecture. In particular, I am interested in three main topics: 1) the effects of floral damage on pollination and mating system in plants, 2) The effects of inbreeding depression on plant resistance to herbivory and seed predation, and 3) how abiotic and biotic factors shape the realized niche of plants in patchy environments. Floral herbivory, or florivory, occurs on many different kinds of plants and can have large effects on both individuals and populations. Unfortunately, this type of damage has been relatively neglected in the ecological literature. One fascinating aspect of florivory is the way that plants may deter florivores. If a plant defends against these antagonists, it may also deter beneficial insects such as pollinating bees. Thus, the optimal amount of defense a plant dedicates to defense may be shaped by stabilizing selection. I am currently using the California annual plant Nemophila menziesii to answer questions about florivory. Inbreeding in plants is also widespread and can negatively affect populations. I am investigating whether inbreeding among close relatives can decrease resistance to both leaf herbivores and seed predators in the purple coneflower, Echinacea angustifolia. This work is being done in collaboration with Drs. Stuart Wagenius (Chicago Botanic Garden) and Ruth Shaw (University of Minnesota). I am currently looking for motivated students to work in my lab and in the field. If you are interested, please contact me at mccalla@denison.edu to set up a meeting! For more information, click the link below.

Dr. Mead's home page 

I am interested in the interactions between small-scale fluid dynamics and animal physiology, morphology, and behavior. One of my research interests (stemming from my Ph.D. work) examines how small-scale turbulence in the surf-zone affects fertilization of free-spawning organisms such as sea urchins, star stars, and mussels. Another research area addresses how crustaceans use odor cues to find food. Specifically, I am interested in how subtle differences in chemosensory seta morphology and in odor sampling strategies affect fluid flow through the setae and thus olfactory performance. Both research areas rely on a combination of methods including field measurements, experimental work in the laboratory, and physical and mathematical models to examine the effects of fluid flow on animal physiology, morphology, and behavior. I am concentrating on the latter line of inquiry, using crayfish as a model system. I currently have ongoing projects investigating the correlation between the flow habitat of the crayfish and its antennule design (with Amy Bruestle '03), the effects of size and gender on antennule structure (with Jimmy McCloskey '04), the effects of size on antennule sampling behavior (with Julie Hufnagel '04), crayfish odor choice maze behavior (with Hilary Stevenson '07), and the effects of antennule regeneration stage on olfactory sampling and search behavior. I typically like having 2-3 students in my lab. First years as well as seniors are welcome, as long as you are motivated and responsible. If you are interested, email me or come by my office. For more information, click the link below.

Dr. Rettig's home page 

I am interested in understanding the interactions between the different life stages of an organism (e.g., larva, juveniles, adults) and how these interactions, such as competition or predation, affect population dynamics. In addition I am interested in the effects each life stage has on the community in which it lives and the overall role the species plays in a community. I am an aquatic ecologist and to address these issues I use bluegill sunfish, a common fish in local lakes and ponds. Bluegill have four distinct life stages: egg, larval, juvenile, and adult. My research examines the interactions between larval and adult bluegill and the effects of larvae on their prey community (zooplankton, tiny crustaceans). I use a combination of field surveys and experiments to understand the factors that affect larval growth and survival, such as food availability (i.e., zooplankton), competition, or predation by invertebrates, and how adult bluegill may influence these factors, for instance by consuming animals that typically prey on larvae. (For further information, click the link below.)

Dr. Romano's home page 

A fundamental challenge in modern biology is to understand the molecular mechanisms underlying the evolution of morphological diversity. As a developmental biologist, I am seeking to identify changes at the molecular level that affect the morphological outcome of processes such as skeletogenesis. In recent years, researchers have discovered many of the genes that regulate skeletogenesis and other aspects of animal development. I hope to understand how developmental regulatory genes and the interactions between them have evolved to create morphological diversity both within and between species. My long-term goal is to understand how the genetic network underlying animal development has evolved in response to environmental factors. I am pursuing my research interests in evolutionary developmental biology using an invertebrate model system, the sea urchin. The sea urchin is widely used for studies in molecular, cellular, and developmental biology, and was recently selected by the US National Human Genome Research Institute for genome sequencing. For more information, click the link below.

Dr. Schultz's home page 

My scholarship involves two areas of research involving insects: the behavioral ecology of insect coloration, and the utility of insects as indicator taxa in bio-monitoring. As a behavioral ecologist, I am interested in how specific modes of color production are adaptive in thermoregulation, anti-predator defenses and intraspecific communication. I use spectroradiometry to study how insects produce color and reflect ambient light to either contrast with the visual background and provide conspicuous signals, or to blend with background noise to become cryptic. Much of my previous work has focused on how habitat preferences influence thermoregulatory behaviors and the evolution of defensive colorations in tiger beetles. Currently, I am exploring the intraspecific signals of damselflies in the context of the light environment of their preferred habitats. I am also frequently engaged in surveying and censusing specific insects that have utility as bioindicators. These studies contribute to long-term monitoring programs of local habitats, as well as investigate the proximate mechanisms of habitat dependence that underlie the utility of these insects as indicator taxa. For further information, click link below.

Dr. Smith's home page 

As an ecologist, my research focuses on extending our understanding of how the environment, in the broadest sense of the word, can influence individuals, populations, and communities. More specifically, my research at Denison seeks to understand how human alterations of the environment can affect populations and communities, and in particular, how they are affecting amphibian populations and communities. My current research can be divided into two major project lines: 1) studies examining factors that may influence amphibian individuals, populations, and communities, and 2) studies looking at what factors may influence the distributions and abundance of terrestrial salamanders. Both project lines seek to contribute to our understanding of the basic ecology of amphibians and to our understanding of human impacts on the environment. For more information, click the link below.

Dr. Thompson's home page 

My research interests revolve around mechanisms by which DNA is structurally and functionally organized within the nucleus of cells. Specifically, my lab is interested in the histone proteins, a family of highly conserved proteins that interact with DNA and other proteins to form chromatin. Chromatin can be arranged in a variety of structural conformations, which has implications for DNA accessibility and gene expression. I utilize a variety of genetic and molecular biology techniques to create mutations in the histone proteins and histone-associated factors in the yeast Saccharomyces cerevisiae in order to study the ways in which histones influence chromatin structure and function. We are working on a variety of projects to gain insight into the specific roles that the histones play in chromatin structure modulation, gene regulation, protection of DNA against mutagenic agents, and overall nuclear organization of the genome. For more information, click the link below.

Dr. Weingart's home page 

My research focuses on a bacterium that has the uncanny ability to cause disease in both onions and immunocompromised humans. My interest lies primarily in determining how this organism decides when it is appropriate to produce and release the factors necessary to cause disease. Many bacteria use a phenomenon called quorum sensing to survey their population and then release disease-causing factors when they have reached a quorum. Another tactic involves sensing environmental conditions such as oxygen content, pH, temperature, and salt concentration - all characteristics that can be linked to a specific environment such as the human body. Currently, we are studying both bacterial strategies - quorum sensing and environmental sensing - in order to reveal the mechanism that triggers this bacterium to release its disease-causing factors. Additionally, we are interested in uncovering the identities and functions of these released factors. For more information, click the link below.

Dr. Yoo's home page 

Cancer occurs when a combination of DNA mutations and abnormal gene expression in a cell leads to uncontrolled growth and invasion of surrounding tissues. It is critical to understand how mutations in individual genes, or more specifically, the series of events which occur as a result of those mutations, contribute to the development of tumors. My research focuses on a gene called Pten which is one of the most commonly mutated genes in human cancer. Previous work has shown that deletion or reduction in Pten function leads to increased cell proliferation, resistance to cell death, and heightened motility and invasiveness. I am interested in identifying the molecular changes which occur when Pten is mutated, and to elucidate the signaling pathways which are affected. In particular, I am studying the mechanism by which Pten deletion leads to increased cell size and the induction of the cyclin dependent kinase inhibitor p21. As a cell biologist, I use cell culture based methods in which Pten function can be reduced through the use of RNA interference, and assay for altered gene expression in candidate downstream pathways. I am also exploring the molecular basis for why certain tissues are much more susceptible than others to tumor development as a consequence of Pten mutation. For more information, click the link below.