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Dr. Deanna McCullough, Associate Professor, Assistant Chair
PhD, Oklahoma State University, 1972.
MS, Oklahoma State University, 1968.
BS, Oklahoma Christian College, 1967.
Research InterestsPlant Taxonomy, Plant Systematics, Ecology.
Study of Hymenoxys texana of the Asteraceae. :This little plant is native to the Texas Gulf Coastal Prairie and Marshes vegetative zone and it is on the endangered species list. I am utilizing a process of DNA fingerprinting called AFLP analysis (amplified fragment length polymorphism) to study the genetic differences within each of three populations of Hymenoxys and between the three populations to determine the extent of genetic variability of the species and to determine if it has the genetic variability to escape extinction.
Re-evaluating the Schrankia (Fabaceae) complex within the genus Mimosa :The genus Schrankia has been incorporated, taxonomically,?within the Mimosa genus of the legume family. We are looking at two genes, the rRNA gene and the rbc L chloroplast gene to determine if this taxonomic change is valid. We are sequencing these genes from the 15 species of Mimosa that are found in Texas and plan to analyze the data using some or all of the following programs to create phylogenetic trees showing relationships between these taxa in an attempt to answer this question: PHYLP, neighbor joining, and maxim mum likelihood
An analysis of the Mimosa quadravalvis complex:The 5 species of Schrankia that were incorporated into the Mimosa genus were initially classified under the species name quadravalvis with each being represented as a variety within that species.If indeed the Schrankia members do belong within the Mimosa genus, the question of their status needs to be clarified. At first they were put within the quadravalvis complex and later elevated to the level of individual species. The question remains - which taxonomic designation is the most correct for these members of Mimosa. Using molecular analysis of sequences of the rRNA and rbc L genes we hope to answer these questions.
Re-evaluation of Mimosa strigillosa:Mimosa strigillosa is always described in taxonomic keys as being herbaceous and unarmed (no prickles) while the rest of the Mimosa group are armed with prickles. M. strigillosa is found in many counties along the Texas Gulf Coast and we do see variations between the members in the upper Gulf Coast region and members in the Rio Grande valley. Specimens collected in the valley frequently have some prickles (a few) and tend to have woody stem bases, unlike their herbaceous members. Using molecular analysis of the rRNA gene and the rbc L chloroplast gene we hope to answer this question.
Celtis laevigata, sugar hackberry, has three varietal forms that are difficult to distinguish morphologically and there is some disagreement of the naming of these varieties. Some feel that one of them should have a species designation. We will investigate this taxonomic problem using the molecular techniques mentioned above.
Ecological restoration at Sheldon Lake State ParkI have been involved with the Sheldon Lake State Park Grassland Restoration and Succession Study for several years. This is a collaborative study involving several members of the Department of Natural Sciences at UHD. A large area of the park has been under cultivation for over 50 years but TPWD is now trying to return it to its natural state of a Gulf Coastal Prairie. I have evaluated the plant life within a woodland adjacent to the to-be-restored prairie. The prairie area is characterized by low areas that hold water during wet periods and raised areas called mima mounds that act as areas of microhabitat. As the Parks Department sows native Texas grass seeds, we will study the distribution of the native grasses throughout the prairie looking for areas of preferential growth and compare that with changes in soil microbes and fungal populations as the area undergoes ecological change. Research is underway on characterizing soil microbes and fungi but I am waiting on the Parks Department to sow the grass seeds. We hope to determine if restoration of a native grass prairie is possible by comparing the changes occurring at Sheldon Lake State Park with a remnant of native Gulf Coastal Prairie located near League City and owned by the University of Houston. My work should resume in the spring of 2005.
Environmental Assessment of the Presence of Xylella fastidiosa in native Gulf Coastal plants.
Working with Dr. Lisa Morano I have been involved in identifying plants in the area that we are testing for the presence of Xylella fastidiosa, a bacterium that causes Pierce's Disease of grapes.
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Last updated or reviewed on 12/21/11