Research Summary

Dr. Overath is a population geneticist interested in how characteristics of organisms or their environment may influence the amount and distribution of genetic diversity in natural populations and the potential for evolutionary change. She has studied the effects of asexual reproduction and polyploidy on the maintenance of genetic variation in and among populations both empirically and theoretically. Dr. David Grisé is a plant ecophysiologist interested in the physiological basis of ecologically-important traits and how these impact plant community composition. He is also interested in how plants deal with stress at both the physiological and ecological level and has worked with species in both terrestrial and aquatic environments. Recently, due to growing interest in ecological genetics, they have begun to collaborate on projects related to the genetic basis of and variation in traits of ecological importance, such as life history, competitive abilities, and invasiveness.

Projects for student researchers include

• 1. Genetic basis and ecological consequences of genetically-based differences in traits related to competitive ability in Chenopodium album, a relatively abundant road-side weed. This research involves quantifying these genetically-based physiological differences between plants that respond normally and newly discovered phenotypes that do not. They will address the questions: a) do these differences translate into differences in performance or fitness under different environmental conditions, b) what are the suites of genes involved in controlling these important physiological traits, c) does this trait vary in other populations of this species, d) how can this trait vary when it should be under strong natural selection, and e) how does variation in this trait compare to variation in DNA markers that are presumably not under selection, e.g. microsatellites?
  
• 2. Ecological and genetic differences in local sunflower species. This project is beginning with mapping the locations and soil characteristics of populations of local sunflower species in Nueces County. They will address the question: do the local sunflower species prefer particular soil types? Future work may involve studies of genetic variation and competitive abilities of one or more of these species, depending on the results of the soil characteristic studies.
  
• 3. Genetic variation in an invasive species of grass, King Ranch Bluestem. This species was introduce for ground cover and fodder in Texas and surrounding states, but is replacing many of the native grasses. Ecological studies are being conducted by researchers at UT-Austin and the Lady Bird Johnson Wildflower Center, but little is known about the genetic make-up of this and related species.
  
• 4. Stress ecophysiology of local halophytes. This research is will involve fieldwork with local species such as black mangrove and, possibly, Salicornia.
  
• 5. Other projects of interest to the student in the intersection of ecology of genetics or in one of the specialties of Dr. Overath or Dr. Grisé.