Roberto Brenes

Ph.D. Candidate






My research is building from previous UTIA studies that examined the relative susceptibility of amphibians to the emerging pathogen, ranavirus. In 2008 and 2009, Dr. Jason Hoverman, Dr. Matt Gray and Dr. Debra Miller tested 19 amphibian species from eastern North America and determined that susceptibility differed among taxonomic species, families and orders (Hoverman et al. in review).My research is expanding this foundational work and testing the relative susceptibility of an additional 21 amphibian species from other regions of North America. Using the collective data set, I will perform phylogenetic analyses that relate ranavirus susceptibility to evolutionary lineages and ecological characteristics of the host species so that generalizations can be made regarding trends in susceptibility to ranavirus among North American amphibians.Iím also performing a second series of experiments that is examining community level interactions of different host species exposed simultaneously to ranavirus and measuring the concomitant changes in aquatic ecosystem trophic structure following a ranaviral disease die-off.This series of experiments will determine if the outcome of ranavirus epizootic events is driven by the amphibian species that are present in an aquatic ecosystem.Finally, Iím exploring the possibility that ranaviruses are transmitted among amphibians, reptiles and fish.Die-offs in the wild and captivity suggest that ranaviruses with very similar genomes appear to cause ranaviral disease in each of these groups.The occurrence of pathogen transmission among three vertebrate classes is unknown in double-stranded DNA viruses, and has major implications for the persistence of this pathogen in aquatic ecosystems.I will be challenging amphibian, turtle, and fish species with three ranaviruses isolated from a bullfrog, box turtle, and pallid sturgeon.If transmission occurs, I will subsequently assemble an aquatic community in outdoor mesocosms with one species from each vertebrate class, and test whether transmission occurs under more natural conditions.


The objectives of my doctoral research are to:


1)          Identify host characteristics that are linked to susceptibility to ranavirus,

2)          Determine the effect of community composition on the likelihood of ranavirus emergence, and

3)          Examine the possibility of interclass transmission of ranavirus among amphibians, reptiles and fish.


Collaborators:  UT AgResearch, UT East Tennessee Research and Education Center, UT College of Veterinary Medicine, and UT Center of Excellence in Livestock Diseases and Human Health.††







I grew up in a small town near San Jose, Costa Rica.  I graduated with a B.S. in Biology from Universidad de Costa Rica.I met Dr. Gray in 1999 and worked with him as a visiting research scholar for 2 years during his doctoral research at Texas Tech University.Thereafter, I studied the natural history of Necturus beyeri under Dr. Neil Ford at University of Texas-Tyler, and secured a M.S. in Biology in 2003.For the next 5 years, I worked on research in Panama examining ecosystem effects of amphibian die-offs associated with chytridiomycosis.In 2009, I accepted a life science instructor position at Turtle Mountain Community College in North Dakota.In 2010, I started my Ph.D. in the UT Center for Wildlife Health with Dr. Gray and Dr. Miller.†††††





Colon-Gaud, C., M. R. Whiles, K. R. Lips, C. M. Pringle, S.S. Kilham, R. Brenes, and S.D. Peterson. Stream invertebrate responses to a catastrophic decline in consumer diversity. Journal of the North American Benthological Society 20(4):1185-1198


Colon-Gaud, C., M. R. Whiles, R. Brenes, S.S. Kilham K. R. Lips, C. M. Pringle, S. Connelly , and S.D. Peterson. 2010. Functional redundancy and resource facilitation between tadpoles and insect grazers. Freshwater Biology 55: 2077- 2088


Connelly, S., C. M. Pringle, R. J. Bixby, R. Brenes, M. R. Whiles, K. R. Lips, S. Kilham, and A. Huryn. Changes in stream primary communities resulting from large-scale catastrophic amphibian declines: can small-scale experiments predict effects of tadpole loss? Ecosystems 11:1262-1276.


Brenes, R. and Neil, B. Ford. 2006 Seasonality and movements of the Gulf Coast Waterdog (Necturus beyeri) in East Texas. Southwestern Naturalist 51(2):1-6.


Lips, K. R., F. Brem, R. Brenes, J. D. Reeve, R. A. Alford, J. Voyles, C. Carey, L. Livo, A. P., Pessier, and J. P. Collins. 2006. Emerging infectious disease and the loss of biodiversity in a Neotropical amphibian community. Proceedings of the National Academy of Sciences 103 (9):3165-3170.


Whiles, M., K. R., Lips, C. Pringle, S. S., Kilham, R. J. Bixby, R. Brenes, S. Connelly, J. C. Colon Gaud, M. Hunte-Brown, A. D. Huryn, C. Montgomery, and S. Peterson. 2006. The Consequences of Amphibian Population Declines to the Structure and Function of Neotropical Stream Ecosystems. Frontiers in Ecology 4(1): 27-34


Gray, M. J., L. M. Smith, and R. Brenes. 2004. Effects of agricultural cultivation on demographics of southern high plains amphibians. Conservation Biology 18.1386-1377.


Contact Information



Phone: 865-974-3897


(Research in Texas playa lakes)



UT Wetlands Program


UT Center for Wildlife Health


UT Department of Forestry, Wildlife and Fisheries