|
|
RESEARCH INTERESTS
Comparative physiology of vertebrates
PUBLICATIONS
Although all research questions in evolutionary biology are highly related, research in my laboratory focuses on the following fundamental questions about organismal adaptation:
The evolution of integrated phenotypes - Natural and sexual selection act on phenotypes that are an amalgamation of morphological, physiological, and behavioral characters. To understand the evolution of organisms requires integrative approaches rather than the study of isolated traits. We are particularly interested in identifying and understanding on a broad scale - from the ecological to the genetic - patterns of evolution in correlated suites of traits. Across the animal Kingdom, the evolution of parental care behaviors and sociality are frequently correlated with (although generally convergently acquired) the evolution of specific traits, for example an expanded aerobic capacity, elaborated mechanisms for communication (e.g., keen hearing and vocalization), an aggressive disposition, and the evolution of venom or toxins. We are examining the ecological factors that favor the evolution of these suites of characters, the physiological mechanisms that control and coordinate their functions, and the genetic architecture that appears to predispose the correlation of these phenotypes.
The study of large scale patterns of diversity in time - New evidence of paleoclimatic conditions and from paleontological explorations of the past 50 years has elucidated many large-scale evolutionary patterns and is providing insight into the question of what drives major replacements in the history of life. Profound mass extinctions related to climate change - rising levels of carbon dioxide, global warming, and plummeting levels of oxygen - occurred in the Late Permian when more than 85% of marine species and approximately 70% of land species died out. Atmospheric hypoxia (low oxygen) persisted throughout the Mesozoic. Although the dominant terrestrial vertebrate assemblages declined at this time, such as most of the mammal-like reptiles, a new group appeared, the Archosauroformes, which gave rise to one of the greatest lineages of terrestrial vertebrates ever known. The lineage was exceptional in its extraordinary number of orders, in its extreme morphological diversity, but especially in its absolute dominance of large body size niches over a period of approximately 150 million years, any terrestrial vertebrate fossil found from this period that is longer than a meter is an archosaur. Archosaurs declined at the end of the Cretaceous and the synapsids (mammals) once again came to occupy these large body size niches. Was the ascendancy and success of the archosaur radiation due to an ability to outcompete their rivals or did they simply take advantage of ecological niches left vacant by the mass extinctions? We are using neontological studies of American alligators to examine the former hypothesis.
Applied evolution - Amphibians are more threatened and declining more rapidly than either birds or mammals. Many species have been driven to extinction and hundred of others now face extinction, especially species that inhabit Neotropical montane steams. Of the 6,000 known species it is thought that at least 168 have gone extinct and 2,469 (43%) are declining. Although a variety of factors are contributing to this decline - such as endocrine disruption, habitat loss and fragmentation, and competition with introduced species - the spread of the fungus Chytrid (Batrachochytrium dendrobatidis) is a significant contributor to the decline. We are applying evolutionary principles and molecular techniques to develop strategies to tackle the spread Chytrid with the aim of stemming the loss of this heritage.
| |
|
|
