Louis J. Guillette, Jr.

personal site

Associate Dean for Research, CLAS
Distinguished Professor of Zoology
Ph.D.   University of Colorado, 1981


528 Bartram
Box 118525
Gainesville, FL
32611-8525
Voice: (352) 392-1098   Fax: (352) 392-3704
ljg@zoology.ufl.edu

Research Interests

The mechanisms by which environmental factors influence the evolution of reproduction in vertebrates has been, and continues to be, the focus of my research. Specifically, I have examined the physiological and anatomical modifications required for the evolution of viviparity in amniote vertebrates. This has included studying the endocrine basis of gestation maintenance and the anatomical modifications of the oviduct required for successful placentation. I also have active research programs examining (1) the influence of contaminants on the developmental and reproductive biology of wildlife and (2) endangered/threatened species reproduction. Below I briefly describe these study areas.Gestation Maintenance

Students Currently Supervised

Dieldrich Bermudez
http://www.zoology.ufl.edu/ljg/Graduate/dbermudez.htm
"Phenotypic plasticity in thyroid function of American alligators exposed to contaminants." Summer 2000 - present. I am interested in the role of xenobiotics or xenopollutents as possible endocrine disrupters. Primarily, I plan to look at the mechanisms of disruption down to the cellular/subcelluar level. Are contaminants altering gene expression, cellular mechanisms, and if so, how? What is the mechanism by which signaling is altered? Currently, I am investigating the role of nutrient pollution (nitrates) on the endocrine system.

Teresa Bryan
http://www.zoology.ufl.edu/ljg/Graduate/tbryan.htm
"Endocrine - gene interactions during the development of external genitalia in alligators." Summer 2001 - present. My research interests lie in elucidating the effects of environmental compounds on alligator phallic development. Currently, I am documenting the developmental differences during embryological growth of external genitalia in alligators reared at both male and female incubation temperatures. Proposed endpoints include morphometrics at the cellular and tissue levels and steroid receptor prevalence in tissues from animals of different ages. I plan to use this information in researching potential variation in alligators from contaminated and reference lakes in Florida. Ultimately, I’d like to identify to what degree, if any, reproductive anomalies in wildlife (and their causes) can be paralleled with those of humans (i.e., cryptorchidism, hypospadias, decreased sperm count, etc.). Additionally, I am studying alligator eggshell variation within and between different Florida lakes.

Krista McCoy (PhD through SNRE, cosponsored with Colette St. Mary)
http://zoology.ufl.edu/kristam
I study questions regarding how endocrine disrupting chemicals (EDCs) interact with natural stressors, and how these effects scale up from genes through individuals to populations. Many natural stressors influence endocrine system function; therefore these stressors may interact with endocrine disrupting chemicals (EDCs) to induce unpredictable effects on wildlife. Endocrine disrupting pollutants may play an important role in modulating population dynamics because they can influence homeostasis, survival, and reproductive success. Although we know much about the effects of particular contaminants on organisms, one limitation of traditional eco-toxicological studies is that these effects and their mechanisms are not studied within an ecological context. For example, it is not clear how the effects of EDCs change relative to competition, predation, and density. Knowing how ecological factors influence an organism's response to EDCs, and other pollutants, will help us predict the effects of pollutants in the wild and will advance our understanding of how to restore polluted habitats.

Brandon Moore
http://www.zoology.ufl.edu/bmoore/
"Nutrition, leptin and alligator reproduction". Fall 2002 - present.

Representative Publications

GUILLETTE, L. J. JR. 1982. The evolution of viviparity and placentation in the high elevation, Mexican lizard Sceloporus aeneus. Herpetologica 38:94-103.

GUILLETTE, L. J. JR. 1987. The evolution of viviparity in fishes, amphibians, and reptiles: An endocrine perspective. In: Hormones and Reproduction in Fishes, Amphibians, and Reptiles. D. O. Norris and R. E. Jones, eds. Plenum Press, N. Y., pp. 523-562.

GUILLETTE, L. J., JR. 1992. Morphology of the reproductive tract in a lizard (Sphenomorphus fragilis) exhibiting incipient viviparity and its implications for the evolution of the reptilian placenta. Journal of Morphology 212: 163-173.

GUILLETTE, L. J., JR. 1993. The evolution of viviparity in lizards. Bioscience43: 742-751.

GIRLING, J.E., A. CREE AND L.J. GUILLETTE, JR. 1998. Oviducal structure in four species of gekkonid lizard differing in parity mode and eggshell structure. Reproduction, Fertility and Development 10:139-154.