CYTOGENETIC ABERRANCY AND ORGANOCHLORINE PESTICIDE ACCUMULATION IN THE MEXICAN FREE-TAILED BAT:
A COMPARISON BETWEEN OKLAHOMA AND NEW MEXICO POPULATIONS

Degree:  Doctor of Philosophy
Date of Degree:  May, 1993
Dissertation Advisor:  Dr. Karen McBee
Institution:  Oklahoma State University, Stillwater, Oklahoma
Major Field:  Wildlife and Fisheries Ecology

Scope and Method of Study:  Organochlorine (OC) pesticide accumulation, frequencies of chromosomal aberrancy, and nuclear DNA content variation were monitored in populations of Mexican free-tailed bats (Tadarida brasiliensis) collected from Carlsbad Caverns, New Mexico, and Vickery Cave, Oklahoma, during the summers of 1990 and 1991.  Pesticide residues in brain and carcass tissues were identified and quantified using electron capture gas chromatography.  Chromosomal aberrancy was examined using the standard bone marrow chromosomal aberration assay and nuclear DNA content variation was measured in spleen and testicular tissues using flow cytometry (FCM).  Relationships among pesticide content, observed chromosomal aberrancy, and nuclear DNA content variation were examined for statistical differences and possible correlations.

Findings and Conclusions:  Both populations demonstrated significant levels of OC contamination; however, the Carlsbad Caverns population showed consistently higher pesticide loads.  Males also demonstrated higher levels as compared to females.  Transfer of pesticides across the placenta into developing embryos was observed in both populations.  No statistical differences in chromosomal aberrancy or nuclear DNA content variation were observed among sexes, sites, or collection periods.  No correlations among OC contamination and genetic assays were found for females.  Males, however, showed significant positive correlations among brain and carcass DDE concentrations and negative correlations among spleen FCM and brain DDE concentration.

Associated publications:

SPATIAL DISTRIBUTION OF NEOTOMA MICROPUS NESTS IN SOUTHWESTERN OKLAHOMA





Degree:  Master of Science
Date of Degree:  December, 1987
Thesis Advisor:  Dr. William Caire
Institution:  University of Central Oklahoma, Edmond, Oklahoma
Major Field:  Field Biology

Abstract:  This study examined the dispersal patterns of 1129 nests of a natural population of Neotoma micropus.  The study plot (475m by 1609m) was located approximately 8km southwest of Hollis, Harmon Co., Oklahoma.  Dispersion patterns were analyzed using a Poisson comparison method, a nearest-neighbor method, and Holgate's point-to-nest distance ratio method.  These three methods suggested that the woodrat nests were distributed in an aggregated pattern across the study plot.  Vegetation occurring within the study area which was utilized in nest construction was characterized by a tine transect method.  Prickly-pear cactus (Opuntia phaeacantha and O. cymochila) and mesquite (Prosopis julioflora) were determined to be the dominant plant species on the study plot.  The extent of coassociation between the woodrat nests and those plant species involved in their construction was examined using 2x2 contingency tables, Phi-2, Cole's C7, and Hurlbert's C8 coefficients of association.  Positive correlations were observed only for the two Opuntia species occurring on the plot.

The structure of the woodrat population on the study plot was examined by live trapping individuals from 52 active nests.  From the data collected, a density of 1.71 woodrats per nest was determined.  A total of 1931 woodrats was estimated to occur on the entire study plot, with a density of 25.7 woodrats per hectare.  Sex ratios were determined to be 1:1.  Utilizing fluorescent powders to facilitate night tracking, home range size and number of nests utilized by individual rats were examined.  Home ranges were not significantly different for male and female woodrats, with male home range estimates to be 1502m2 and 343m2 for females.  Limited tracking data indicated that woodrats moved between adjacent nests but did not travel far from the nest sites where they were captured.

Associated publications:

GAR ICHTHYOOTOXIN: IT’S EFFECT ON NATURAL PREDATORS AND THE TOXIN’S EVOLUTIONARY FUNCTION

Kenneth G. Ostrand
Master of Arts in Biology, May 1995.
Thesis Advisor: Darrell D. Hall
Sam Houston State University, Huntsville, Texas

Abstract:  Spotted gar (Lepisosteus oculatus) and alligator gar (L. spatula) roe were fed to green sunfish (Lepomis cyanellus) and channel catfish (Ictalurus punctatus) at a rate of 2 eggs/g of body weight for 14 days.  The dosage, equivalent to the LD50 established for small mammals and crayfish, did not result in mortality of these fish.  Further, our study showed that fish fed gar roe maintained or gained weight, which leads to the conclusion that these fish do not reject the gar roe as a food source.  Consumption of gar roe by potential natural predators, such as L. cyanellus and I. punctatus, establishes the basis for the argument that gar roe toxin has not been evolutionarily selected to serve as a protective mechanism.  Gar roe may simply be toxic to small mammals and crayfish by chance.

Associated publications:


AN EVALUATION OF THE U.S. ARMY’S SATELLITE IMAGERY BASED SITE SELECTION PROCESS

John P. McHugh

Master of Arts in Biology, May 1996.

Thesis Advisor: Monte L. Thies

Sam Houston State University, Huntsville, Texas.

Abstract:  The effectiveness of the site selection process for determining Land Condition Trend Analysis (LCTA) plots was examined.  The sixty plots chosen using the satellite image based selection process were field-sampled, then categorized into 14 different plant community types using ecological ordination and classification procedures.  Surface geology was examined to see if there were consistent patterns between geology, the image clusters, and the vegetation communities.  In addition, the 5:4 and normalized difference vegetation index (NDVI) band ratios were used to compare the spectral values with the spectral values for the seven raw TM bands.  This was done to see which method provided the closest match to the vegetation.  Results suggest the site selection process used in this study did not adequately represent the different vegetation communities for the study area.  Surface geology did not indicate any consistency with the imagery clusters or the vegetation.  Furthermore, the 5:4 and NDVI band ratios provided better delineation between forested versus non-forested areas than the seven raw TM bands that were used in the site selection process.  Suggestions for improvement in the site selection process would be to use various band ratios for additional spectral data into the maximum likelihood classification, and  using ancillary data other than surface geology or soil types.
 



 
 
 
BIRD AND SMALL MAMMAL HABITAT ASSOCIATIONS AT CAMP NAVAJO ARMY DEPOT, ARIZONA: IMPLICATIONS FOR MANAGEMENT.

Gregory P. Creacy

Master of Arts  in Biology, December 1996.

Thesis Advisor: Monte L. Thies

Sam Houston State University, Huntsville, Texas.
 

Abstract:  Bird and small mammal habitat associations at Camp Navajo Army Depot, Arizona were identified, and the effects of military activities on those habitats were investigated.  The study was conducted in association with the Land Condition Trend Analysis Program (LCTA) in an effort to determine future needs for natural resource management.  Study results indicate that the installation has not been significantly impacted by military training activities.  Evidence of previous military activities was sparse, and study sites with evidence of activities did not significantly differ from sites with no evidence with regard to frequencies of early successional, or invasive, plant species.  A positive correlation (r = 0.413, P = .002) between invasive plant species and Chipping Sparrow abundance suggests the possible benefit of this bird species as a bioindicator of increased habitat disturbance.  Cluster analysis revealed five major habitat types on the installation, each with distinctly different bird and small mammal assemblages.  Species richness, species diversity, breeding bird density, and total numbers of birds and small mammals were lowest within the densely forested Ponderosa pine habitat type.  Most bird species preferred the “open” Ponderosa pine habitat type, whereas small mammals were most abundant within habitats containing Gambel oak.  Mann-Whitney univariate analyses and multivariate logistic regression analysis were used to determine specific habitat associations for each bird and small mammal species.  This information, together with results from cluster analyses, was used to predict effects of habitat modification on each bird and small mammal species.  Results from this study indicate that a proposed ecological restoration of Ponderosa pine forests within Camp Navajo Army Depot would benefit most wildlife species in addition to restoring natural forest density and structure.  Minor thinning of the densely forested areas and the re-introduction of fire through prescribed burning should have either no effect or a positive effect on 29 of the 33 species (88%) examined in this study.



 
SPECIES ASSEMBLAGES AND HABITAT PREFERENCES
OF RODENTS ON SOUTH TEXAS RANGELANDS.

Denise M. Ruffino 

Master of Arts in Biology, May 1997. 

Thesis Advisor: Monte L. Thies 

Sam Houston State  University, Huntsville, Texas.

Abstract:  Six sites were evaluated on the Dixie Target Site and Escondido Ranch (DTSER), McMullen Co., Texas, to determine the effects of microhabitat variables on rodent assemblages and habitat preferences.  Soil, vegetation, and capture data associations were investigated to:  ascertain relationships between species diversity and particular components within each site, estimate the effects of seasonal changes on assemblage diversity, and assess the degree of variability in certain rodent species to utilize multiple habitats.  Study results indicated nine species of rodents inhabiting the study sites, with a prevalence of Peromyscus leucopus throughout the entire study area.  Cluster analyses, using discriminant function and correlation analysis, were performed for soil, vegetation, and capture data and revealed limiting characteristics used to sort sites by their degree of dissimilarity.  A strong dependence upon sandy soils with a high organic content; vegetation within the Cactaceae, Euphorbiaceae, and Ebenaceae families; and the occurrence of Baiomys taylori, Onychomys leucogaster, and Dipodomys compactus, were primary criteria for differentiating between the site assemblages.  Seasonal differences in assemblage diversity were examined to determine if any direct impact was observed.  Rodent populations remained stable throughout the study and seasonal fluctuations were not found to significantly affect rodent assemblages on any site.

Three species were classified as generalist species (P. leucopus, Sigmodon hispidus, and Reithrodontomys fulvescens), occurring on multiple sites, while four species were found to exhibit specialist behavior (Neotoma micropus, Perognathus merriami, O. leucogaster, and D. compactus).  Results for B. taylori and Chaetodipus hispidus were inconclusive.  Since correlation analysis selects for rare variables, the effects of generalist rodent species or predominant species, floral or faunal, on assemblages could not be determined.