RONALD G. OLDFIELD, PHD
Lecturer
Research Interests
My primary area of interest could be called evolutionary ecology, or integrative evolutionary biology. I use diverse approaches to analyze and compare character states within monophyletic groups of species of fishes in order to better understand evolutionary patterns and processes. Traditionally, comparative studies of evolution have been largely restricted to analyses of anatomical structures. However, increasing data and technology are beginning to make it possible to analyze less tangible phenotypes, such as those involving physiology and behavior. The goal in my research is to integrate data from phylogenetic, morphological, ecological, behavioral, neuroendocrine, genetic, and genomic efforts in an attempt to develop a more complete picture of evolution of poorly understood phenotypes.
The topic of my current and future research is the evolution of mating systems, with a primary focus on cichlid fishes of the genus Herichthys, which are native to Mexico and southern Texas. One particular species, the Cuatro Cienegas cichlid, which is endemic to a series of isolated pools in the Chihuahuan desert of northern Mexico, displays very unexpected mating behavior. Almost all of the 100+ cichlids from Central America are unusual among fishes in that they form monogamous pairs to mate and care for their offspring, but the Cuatro Cienegas cichlid has been reported to be polygamous, with single males mating with several females. My associates and I recently began an investigation to better understand why and how this mating system occurs in the Cuatro Cienegas cichlid, and have collected two important data sets: (1) in collaboration with Hans Hofmann at the University of Texas I used an arginine vasotocin (AVT) antagonist to determine that social affiliation in another, monogamous, Central American cichlid species is related to AVT activity, and (2) I made comparative observations of wild Cuatro Cienegas cichlids in Mexico and wild Texas cichlids (the sister species) in Austin and demonstrated that the former nearly always exhibit female-only parental care while the latter always exhibit bi-parental care. This is even true of Cuatro Cienegas cichlids generations later in a population that was relocated to outdoor ponds in Texas.
The next steps in the progress of this research program are to construct an appropriate phylogeny and, through in situ studies in Mexico, compare ecological factors among the environments of the Cuatro Cienegas cichlid and its close relatives to determine what may have selected the novel behavioral phenotype. Next, I will perform lab experiments to show that a change in AVT expression is the molecular mechanism responsible for producing this phenotype. I also plan to use an existing cichlid microarray to identify changes in functional genomics that are involved in mating system evolution. These findings will be extremely important to science because the evolution of non-morphological phenotypes is generally not well understood, and they will provide a complete picture of evolution at the phylogenetic, ecological, behavioral, neuroendocrine, genetic, and genomic levels.
Key Words: Evolutionary Ecology, Behavior, Ecology, and Evolution of Fishes
Last Updated 11/25/08
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