Arthur R. Marshall, Jr., Ecological Sciences Laboratory

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Department of Biology

Mail: Department of Biology
111 Bartram Hall, PO Box 118525
Gainesville, FL 32611-8525

Robert D. Holt
Professor and Arthur R. Marshall, Jr., Chair in Ecology
Ph.D., Harvard University

111 Bartram Hall


Picture of Robert D. Holt 

   My core personal research focuses on theoretical and conceptual issues at the population and community levels of ecological organization, and on the task of linking ecology with evolutionary biology. In addition to basic research, I am interested in bringing modern ecological theory to bear on significant applied problems, particularly in conservation biology. I have also carried out large-scale experiments on habitat fragmentation. My students include both theoreticians and empirical, experimental ecologists. I have historically collaborated with many faculty at a wide range of institutions, both inside and outside the USA. Web page with links to publications and research interests.

Mary Christman
Courtesy Associate Professor
Ph.D., George Washington University

110 Bartram Hall


Picture of Mary Christman 

    My background and interests are at the intersection of statistical methodology and environmental and ecological research. My current interests include development and application of statistical methods for spatial modeling of community structure and species abundances; accounting for uncertainty and sampling error in models of population dynamics; analyses when data are zero-inflated; developing sampling designs and estimators for rare and elusive species; linear and non-linear mixed models; hierarchical modeling; and sampling strategies for spatial data analysis. I collaborate and consult with scientists across many disciplines, including agriculture and natural resources, zoology, ecology, human nutrition, fisheries, and wildlife conservation. Curriculum vitae.

Robert Ulanowicz
Professor Emeritus of Theoretical Ecology, University of Maryland
Ph.D., Johns Hopkins University

110 Bartram Hall

Picture of Bob Ulanowicz 

 I have spent my career on Chesapeake Bay creating quantitative methods to analyze networks of trophic transfers. I have developed methods that quantify indirect effects, trophic hierarchies, domains of recycling and whole system indexes of ecosystem organization and flexibility. In the process, I have reached the conclusion that the dynamics of ecosystems are hardly mechanical, but rather dual and dialectic-like. Consequently, I have proposed a perspective on nature that is predicated on processes rather than on objects and laws. My current interest is in promulgating the necessity of indeterminacy for ecosystem sustainability. In economic terms, the implication is that parallel, alternative currencies are likely required to impart sustainability to local and national economies. More than anyone ever wanted to know about me can be found at

Michael Barfield
Assistant Scientist
Ph.D., University of Kansas

111 Bartram Hall


Picture of Michael Barfield

    I have worked at the Ecological Sciences Laboratory doing research on theoretical population biology since 2001. Publications are available through the link below, and include research on adaptation in source-sink systems (Holt et al. 2003, 2004a, 2004b, 2005; Holt and Barfield 2008, 2009b), infectious disease ecology (Orive et al. 2005; Holt and Barfield 2006; Wayne et al. 2011), effects of temporal variation on populations (Holt and Barfield 2003; Holt et al. 2003, 2004b; Roy et al. 2005), evolution (Knight et al. 2008; Barfield et al. 2011), species ranges (Holt et al. in 2011; Holt and Barfield 2011; Filin et al. 2008) and arctic lake ecology (O'Brien et al. 2004, 2005).  Web page with links to publications.

Cristina Gonçalves
Postdoctoral Associate 
Ph.D., Universidade Estadual Paulista Júlio de Mesquita Filho, UNESP, Brazil.

110 Bartram Hall


Picture of Cristina Goncalves

 I am a biologist formed in Zoology, and I am interested in freshwater fish biology and ecology. Currently, my research is focused on stream fishes of the Atlantic forest in a conservation area located on the southern coast of the state of São Paulo (Brazil).

We know that stream fish populations are spatially organized due different habitat requirements to complete their life cycles, and that many factors have a strong influence on the structure of fish populations, such as habitat heterogeneity, spatial scale and the dispersal of species between available environments. I am interested in verifying the influence of environmental factors (e.g., pH, conductivity, dissolved oxygen, substrate type, depth, etc.) and landscape (e.g., elevation, isolation, geomorphology, etc.) on the organization of the fish fauna of the Atlantic coastal streams. Personal website:

Kristen Sauby
Ph.D. Candidate, Biology
M.S., Mississippi State

110 Bartram Hall


Picture of Kristen Sauby


Vitrell Sherif
Lab Manager

111 Bartram Hall


Picture of Vitrell Sherif

Vitrell is the administrative lab manager for the Arthur R. Marshall, Jr., Laboratory. 

Previous Personnel
(Names link to old Marshall lab web pages.)

Visiting Faculty

Luiz Dos Anjos, here for 2008, Londrina State U., Londrina, Brazil.
Leticia Aviles, Spring 2011, University of British Columbia. 
Mark Taper, September 2011-February 2012, Montana State U.


Tiffany Knight, postdoc 2003-4, now at Washington U. in St. Louis. Her website there.
Nicholas Friendenberg, postdoc 2003. His website.
Manojit Roy, postdoc 2004-2010, now at the University of Michigan.
Ricardo Holdo, postdoc 2005-2010, now at the University of Missouri.
Taal Levi, postdoc 2013-2014, now at Oregon State University.

Graduate Students

Tristan Kimbrell, Ph.D. 2007.
Tania Kim, M.S. 2006.
Gabriela Blohm, M.S. 2008, now Ph.D. student here.
Connie Clark, Ph.D. 2009.
Cedric Worman, Ph.D. 2012.
Smriti Bhotika, Ph.D. 2012.

Student Assistants

David J. Hall.
Vanessa Trujillo.
Yaneke (Yani) Paulay.

Recent Visitors

Colleen Webb, Colorado State U.
Richard Gomulkiewicz, Washington State U.
Jeannine Cavender-Bares, U. of Minnesota.
Carolina Murcia, Science Director for the Organization of Tropical Studies.
Jin Yao, New Mexico State U.
Ido Filin, U. of Helsinki.
James Estes, U. of California, Santa Cruz.
Michael Rosenzweig, U. of Arizona.
Sam Scheiner, Program Director, Division of Environmental Sciences, National Science Foundation.
Val Smith, U. of Kansas.
Michael Bonsall, U. of Oxford.
Per Lundberg, U. of Lund, Sweden.
Leticia Aviles, U. of British Columbia.
Lev Ginzburg, Stony Brook University.
Roger Arditi, University Pierre et Marie Curie, Paris.

Page last updated May 14, 2014.