A central aspect of any reproductive study is understanding the reproductive cycle of the species under study. In collaboration with numerous colleagues from various countries, my students and I has described the reproductive cycle and biology of a number of Mexican high elevation lizards and snakes, the tuatara and several geckos of New Zealand, and the American alligator. These studies have help demonstrate the great diversity that exists in reproductive cyclicity and have also provide important clues to the evolution of the reproductive system in amniotes. In addition to the work on reptiles, I also have an interest in reproduction in various other vertebrates and my graduate students have worked on fish, amphibians, birds and mammals. The reproductive biology of the high elevation Mexican lizard Barisia imbricata .
Alligators provide evidence for the evolution of an archosaurian mode of oviparity.
Identification and characterization of proteins synthesized de novo and secreted by the reproductive tract of the American alligator, Alligator mississippiensis . The effects of contaminants on wildlife have been studied for more than 30 years, especially since the publication of Rachel Carson's Silent Spring. During the last seven years, new data has reminded us of Carson's original focus, the effects of environmental contamination on the development of various organ systems, especially the reproductive system. For the last seven years, I have examined the developmental biology of the reproductive system in control and contaminated populations of fish and alligators. Our data indicate that environmental contaminants are endocrine disruptors capable of causing a wide spectrum of effects, from embryonic death to subtle, but detrimental changes in reproductive anatomy and function.