Browsing by Subject "Mammals"
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Item Age-dependent and hypoxic/ischemic changes in akt/protein kinase B activation in rat hippocampus(Texas Tech University, 2003-12) Titus, Rebin TIncreased vulnerability to neuronal injury following ischemia in the aging brain has been well documented in humans as well as in rat models, especially within the hippocampus. An early response to hypoxia/ischemia is the transient and reversible depression of synaptic transmission, which is mediated by adenosine acting on neuronal adenosine Ai receptors. This depression of synaptic transmission is believed to be neuroprotective. Adenosine in turn activates the PI3K-Akt survival pathway, which is believed to exert neuroprotection from ischemic damage. Akt or Protein Kinase B is of particular interest as its activation may be a critical regulator of neuronal survival. Recent studies have suggested that this pathway is downregulated with aging in various non-neural tissues. The response to cerebral ischemia or stroke is thought to exhibit an age-related impairment, with a disproportionate increase in morbidity with age. Stroke is the third largest killer after heart disease and cancer in the United States; almost 700,000 people are affected annually, most of them being elderly individuals. Though there is a strong connection between stroke-related morbidity and aging, the precise cause for this increased susceptibility is not known. It is imperative, now more than ever before, to investigate this problem, as the proportion of elderly in our population is ever increasing. Our current knowledge seems to suggest that the extent of neuronal injury is dependent on the fine balance that exists between apoptotic and survival pathways. There is substantial evidence that the Akt-mediated survival pathway is suppressed with age, though this has never been shown in neuronal tissue. This thesis explores our hypothesis that that the increased damage following cerebral hypoxia in the aged brain is due to an age-related impairment of the neuroprotective pathway mediated by adenosine and Akt.Item Alternative approaches to the identification and reconstruction of paleoecology of Quaternary mammals(2012-12) George, Christian Owens; Bell, Christopher J., 1966-; Czaplewski, Nicholas J; Leibold, Matthew A; Rowe, Timothy; Sprinkle, James TSince the 19th century the remains of Quaternary mammals were an important source of data for reconstructing past environmental conditions. I tested two basic assumptions that underlie Quaternary vertebrate paleoecology. The first assumption is that fossils mammals can be identified reliably to species. The second assumption is that correlations established between extant mammals and environmental parameters can be used to interpret reliably the paleoenvironment from the latest Pleistocene. Incorrect specimen identifications could lead to errors in paleoecologic interpretations. I explicitly tested an alternative to the traditional approach to identification by identifying fossil shrews based on apomorphies. My results indicated that some traditional characters are useful for identification, but only complete specimens with a combination of characters can be identified to species. This indicates that previous authors who identified shrews to species did not compare them to the full diversity of species. I tested the reliability of cenograms and species-richness models as approaches for the reconstruction of environmental conditions in the past. I used faunal data from Hall’s Cave, Kerr County, Texas to construct cenograms and species-richness models and compared the results to independent paleoclimate proxies. Neither species-richness models nor cenograms agree with paleoenvironmental reconstructions based on proxy data from the Late Pleistocene and Holocene. Cenograms and species-richness models are unreliable and fraught with problems, and both approaches should be abandoned as tools for paleoecological reconstruction. To test for potential geographic bias in the identification of Quaternary fossils I developed a GIS (geographic information systems) database of Quaternary paleontological sites within Texas. I was able to show that the identification of species of fossil soricids, heteromyids, Odocoileus, and Spilogale was influenced by geography. Those fossils should be treated as generic identifications until they are re-evaluated against the full diversity of species. Utilizing GIS I also developed a method of paleoecological analysis. My analysis showed that the environmental conditions found today in Texas might not be limiting the current range of shrews. Based on the known geographic range of shrew fossils, other ecological factors besides environmental conditions are shaping the current distribution of shrews.Item Areographic fragmentation analysis of Texas mammal distributions: a fractal analysis(Texas Tech University, 2000-08) Allen, Kelly ElaineHabitat fragmentation, the leading cause in the decline of biodiversity, affects the geographic range distribution of Texas mammals through the loss of habitat and the disjunction of populations. The fragmentation of a distribution has been referred to as areographic fragmentation and the effects of fragmenting a distribution can be quantified by measurements of area and perimeter that are not affected by scale. Fractal theory provides an appropriate method of determining areographic fragmentation through the quantification of distribution shape, perimeter length, and patchiness via the fractal dimension. The sensitivity of the fractal dimension to changes in distribution morphology requires measurements of area and perimeter be determined from detailed maps. Through the use of geographic information systems, maps depicting distributions at greater spatial resolution than currently available were produced with reasonable accuracy. Fractal dimensions were used as a scale-invariant statistic to quantify shape (areato-perimeter), perimeter length (length-of-trail), and patchiness (Korcak's empirical law). Like other biological objects, the distributions of Texas mammals may be scale invariant at several separate scales; however, this phenomenon may actually represent a lack of fit by the areographic models with the data. Fractal dimensions of mammal distributions were examined for patterns in taxonomy, feeding preference, and spatial structure. No significant difference was found between taxonomic and feeding structure categories. However, differences between eastern and western distributions did exist. These differences were primarily based upon the perimeter length of distributions with western species exhibiting more complex boundaries. Maps have long been used as resources of data when collecting data in the field is too labor intensive or when the biological question being addressed is extremely complex. Yet, all maps are made with limitations that affect the data extracted from them. The effects of cartographic design, model impro\ement, and spatial resolution were examined. Fractal dimensions calculated from predicted distribution maps representing increased model complexit}- did not differ significantly from those dimensions calculated using simple mapping models for the length-of-rail and Korcak areographic methods. Significant differences were only found to exist for dimensions calculated from the areato-perimeter method. Further examination of the fractal dimensions calculated using increased model resolution revealed no differences exist between taxonomic, feeding preferences, and spatial categories. The results of this study indicate that Texas mammal distributions are the function of individualistic responses to environmental variables and evolutionary history.Item Automated data management in systematics collections(Texas Tech University, 1997-05) Monk, Robert RichardSystematics collections are valuable resources both to the scientific community in particular, and to society in general. The justification for maintaining collections is based on the wealth of data that may be acquired by the examination of specimens contained in them (Yates, 1987). Some of the disciplines that use the specimens in systematics collections include genetics, molecular biology, evolutionary biology, environmental toxicology, public health, ecology, biogeography, systematics, and taxonomy. Obviously, there are many other fields that make use of systematics collections, but the aforementioned serve to illustrate the diversity of use. Collections of specimens have been used innumerable times for many unportant scientific studies, not the least of which was the formulation of the theory of evolution by Darwin in 1859 (Baker, 1994). The recent increase in biodiversity-related research and the use of computer-based geographic information systems (GIS) and satellite-linked global positoning systems (GPS) have renewed public awareness of the value of systematics collections (for example, see Baker et al., 1996).Item Comparative morphology of the vestibular semicircular canals in therian mammals(2011-12) Rodgers, Jeri Cameron; Rowe, Timothy, 1953-The peripheral vestibular membranous ducts that detect angular motion are contained within bony semicircular canals of mammalian petrosals. I investigated morphology and function in the three membranous semicircular ducts through measurements on the bony semicircular canals of 31 skeletonized skulls from different genera. While the prevailing theory of semicircular canal researchers is that the locomotor agility of extant and extinct mammals can be understood by measuring the size of the three bony semicircular canal arcs, I propose that there are important and quantifiable features other than the adult size of radius of curvature of the semicircular canal arc (R) that influence angular movement detection in mammals and perhaps in their ancestors. Initially, I sought to verify that there was no significant asymmetry of R across the study specimens. However, there was significant asymmetry in canal pair angles between contralateral sets: ipsilateral canal pair angles differed by up to 14◦, and contralateral synergistic angle pairs differed by up to 18◦. Canal pair contralateral differences were lower for specimens of more agile taxa. In addition, the angle between the left and right lateral canals varied by up to 27◦ from parallelism, so the use of the lateral bony canal in one petrosal to represent the horizontal animal resting position could result in significant skull orientation errors. I utilized a program to quantify the effects of canal plane non-orthogonality and to calculate a maximum rotational sensitivity axis for a given taxon. My results concur with earlier research indicating that canal orientation significantly affects the location of maximum rotational sensitivity axes in the head, and should be considered in future quantitative research. Finally, I determined the volumes of the subarcuate fossa and the petrosal lobule in three Monodelphis domestica animals (76 days postnatal) by utilizing both cranial and tissue volumes in fresh specimens. The petrosal lobule fills 93-97% of the Monodelphis domestica fossa, a greater volume than the 50% estimated by previous researchers. These results highlight the difficulties of using histologic or preserved specimens to make quantitative determinations of brain tissue volumes, and reopen the question of whether the subarcuate fossa volume provides a record of the agility for an extinct taxon.Item Conservation of vertebrate biodiversity in Texas: Setting priorities for reserve selection(2006-12) Law, Jeffrey J.; Willig, Michael R.; McIntyre, Nancy E.; Cox, Stephen B.Species extinction rates are increasing throughout the world. A way to combat the global loss of species is through the creation of well-placed wildlife reserves. The principle objective of this study was to determine which areas throughout Texas most efficiently and effectively preserve extant vertebrate biodiversity (amphibians, reptiles, and mammals) if protected in reserves. Secondarily, I quantified the effectiveness of using a particular vertebrate class as a surrogate for others. The Sites Simulated Annealing Algorithm was used to determine areas that effectively preserve biodiversity while minimizing cost. This was accomplished through the use of irreplaceability values. Irreplaceability is equal to the number of times each planning unit is selected in a final solution to the SSAA. The SSAA was run 200 times for each scenario to determine this value. Species distribution maps obtained from the Texas GAP project were the basis for biodiversity data, whereas economic value of land came from the National Agriculture Statistics Service. I identified the best sites to establish reserves with current protected areas forced into the solution and also ignoring current protection status. The areas of the highest conservation concern, based on irreplaceability, were the Edwards Plateau of Central Texas and the Trans Pecos Region of West Texas. Although the irreplaceability values of planning units for incorporation into the reserve systems are correlated for all possible pairs of vertebrate classes, the associations are quite weak.Item Cytogenetics of some mammal species from central Argentina(Texas Tech University, 1996-08) Tiranti, Sergio I.This study is to assess the karyology of several small mammalian taxa in central Argentina, using chromosomes to assist in identifying species, and to provide new chromosomal data for several species from geographic áreas where studies have not been done. Specimens of small mammals, representing 24 species belonging to 6 families, were live-trapped in 26 localities in 6 provinces of central Argentina. Specimens were subjected to the standard in vivo procedure of colchicine mitotic arrest for obtaining chromosomes from bone marrow. Chromosome slides were observed and photographed and the diploid number and morphology determined for each specimen.Item Data management in recent mammal collections(Texas Tech University, 2000-12) King, Raegan DeanneCurrent trends in museum practices show increasing awareness of the important role complete and accurate data play in collection management. Careful integration of computer technology into data management procedures can reduce the effort associated with multiple transcriptions of data, increase the accuracy and consistency of data, and result in a more useful electronic database. WildCat is a relational database management system developed in 1997 to facilitate data management in the Recent mammal collection of Texas Tech University. WildCat consists of four distinct parts, the third of which, WildCat III, is a data entry application for use in-house and in the field. WildCat III allows a new approach to data management by introducing computerized data entry into the first stages of data gathering rather than at the more traditional final stage. This thesis determines the effectiveness of WildCat III in the capture of field-generated data, provides information concerning the use of computers in field situations, and discusses the impact electronic data capture has on mammal collections management.Item Distribution of mammals in the davis mountains, texas and surrounding areas(Texas Tech University, 2008-08) DeBaca, Robert S.; Zak, John; Bravo, Jorge S.; Phillips, Carleton J.; Mulligan, Kevin; Bradley, Robert D.This project focused on the dispersal and distribution patterns of mammals in or near the Davis Mountains, Texas. Data were obtained from existing museum and literature records and from extensive field sampling of the region, which resulted in the acquisition of more than 2,000 museum specimens and related data (Appendix A). The purpose of this research was to investigate regional and local patterns of mammalian biodiversity as these relate to dispersal and distribution in montane ecosystems at a regional scale in the Trans-Pecos and at a local scale in and near the Davis Mountains. In the first chapter, paleontological data suggested that now isolated mountain ranges in the Trans-Pecos were once connected in a north-south network. Research in that chapter examined modern patterns of biodiversity in the mountains that could have resulted from patterns inherited from Pleistocene distributions and dispersal routes of species in mixed-conifer forests or piñon-juniper-oak woodlands. Evidence presented in chapter one indicated that connectivity to source areas could have improved dispersal opportunities through highland corridors and montane areas. The second research chapter evaluated an observed pattern of greater species richness at a middle elevation study site in the Davis Mountains that was about 15 percent the size of a larger study site in the highlands of this mountain range. Rodents were the focus of research to find a partial explanation for this pattern, in which a dispersal filter may have allowed dispersal of some species but hindered others along an elevational gradient from lowlands to highlands. This pattern suggested a decrease in the body size of a lowland group of species along this gradient in response to a substrate that becomes more unavailable to larger burrowing rodents. That pattern was not statistically significant, but an alternative investigation showed that the smaller mid-elevation site likely had greater habitat variety in comparison to the high elevation one, which could have provided more microhabitats for more species to coexist at the smaller, more diverse site. In the final research chapter, biodiversity patterns were investigated for bats in relation to broad-scaled ecological patterns and site-specific resource partitioning that could account for the observed spatial and temporal distribution patterns. Along an elevational gradient, five species were specific to a smaller series of elevations and habitat types; whereas, twelve species were either too rare to analyze or were widespread throughout the sampled array of environmental conditions. Five species also showed elevational segregation by sex, with females occupying a lower range of elevations than males, which was a surrogate measure of warmer macrohabitat utilization by females. Lastly the most prolific sampling site, a semi-perennial pool, was analyzed for temporal differences in its use by month and by time of night. The results showed that vespertilionid bats dominated use of this resource during mid-summer and during the first two hours of the night and that molossid bats dominated its use after the first two hours and during the latter part of the summer. This partitioning could result from the thermoregulation constraints of the main vespertilionid species that concentrated activity early in the evening and during the warmer months of the sampling period. In response to vespertilionid use and to prevent collisions, the fast-flying, less maneuverable molossid bats may avoid the area until use by other bats dwindles both during the night and warmer months of the season.Item Diversity, distribution, and natural history of the mammals of Big Bend Ranch State Park, Texas(Texas Tech University, 1996-12) Yancey, Franklin DelanoA comprehensive study of the mammalian fauna of Big Bend Ranch State Park (BBRSP), Texas, was conducted. Extensive field work performed during 1994 and 1995, supplemented with the examination of museum specimens and a review of the literature, resulted in the documentation of five orders, 18 families, and 59 species of native mammals in the park. The mammalian fauna of BBRSP was compared to that of eight other areas in the Chihuahuan Desert, and was found to most closely resemble the mammalian fauna of Big Bend National Park. Species composition was determined for bats (Chiroptera) and rodents (Rodentia). Western pipistrelles (Pipistrellus hesperus), ghost-faced bats (Mormoops meqalophylla), and Brazilian free-tailed bats (Tadarida brasiliensis) were the three most abundant species of bats, and Chihuahuan Desert pocket mice (Chaetodipus eremicus), Merriam's kangaroo rats (Dipodomys merriami), and cactus mice (Peromyscus eremicus) were the most common rodents in the park. A dichotomous key to all species of mammals treated is included. Using a geographic information system (GIS), the distribution of each of the 59 species of native mammals at BBRSP was mapped. Various aspects of the natural history of these mammals are presented; they include habitat affinities, relative abundance, seasonal and daily activity, reproductive habits, feeding strategies, annual molt, and parasites and diseases. In addition, systematic problems were identified and acknowledged for several taxa. Two nondomestic introduced species, seven domestic species, 27 species of postulated occurrence, and two extirpated species are treated briefly. Finally, a list of recommendations for future research and management is presented.Item Effects of perchlorate exposure on resting metabolism, peak metabolism, and thyroid function in the prairie vole (Microtus ochrogaster)(Texas Tech University, 2004-08) Isanhart, John PPerchlorate is the oxidizer component in most solid rocket propellant formulations. It is known to reduce the production and output of the thyroid hormones, triiodothyronine (T3) and thyroxine (T4). Thyroid hormones regulate metabolism in endothermic organisms and are responsible for maintenance of body temperatures above that of the environment. Little is known about the effects of perchlorate on metabolic capacity. The objectives of this study were to 1) determine if subchronic (51 days; 0, 1, and 10 mg/kg/day) and chronic (180 days; 0.75 mg/kg/day) perchlorate exposure in adult male prairie voles {Microtus ochrogaster) would alter resting metabolic rates as a result of decreased circulating thyroid hormone concentrations, and 2) determine if perchlorate exposure disrupts thermogenesis in mammals challenged with cold-stress. Voles exposed to perchlorate for 51 or 180 days experienced no significant alterations in resting metabolic rates at any point during the exposure period. Additionally, there was no treatment effect on peak metabolic rates or plasma thyroid hormone concentrations. Mean peak metabolic rates were 10.17 ± 0.85, 10.17 ± 1.50, and 9.37 ± 0.89 mL oxygen consumed per gram of body mass per hour for 0, 1, and 10 mg/kg/day groups, respectively. Mean plasma T4 concentrations were 3.01 ± 0.83, 2.74 ± 1.36, and 1.70 ± 0.91 pg/dL, and mean plasma T3 concentrations were 109.29 ± 15.05, 94.83 ± 13.36, and 95.57 ± 5.92 ng/dLforO, 1, and 10 mg/kg/day treatment groups, respectively. However, thyroid gland thyroxine concentrations, 704.62 ± 372.62, 454.20 ± 290.52, and 219.54 ± 196.76 ng T4 per thyroid gland for 0, 1, and 10 mg/kg/day treatment groups, respectively, were significantly lower in perchlorate-exposed voles than controls indicating that thyroid gland thyroxine content is a more sensitive endpoint for assessing perchlorate exposure in prairie voles. This study indicates that perchlorate-induced alterations in thyroid function do not necessarily translate into alterations in metabolic rate and/or decreases in thermogenic response. Overall, this study did not provide evidence for energetic alterations associated with perchlorate exposure at concentrations that are higher than those typically found in water in the environment. It may require a longer duration of exposure or higher dose to see a significant effect on resting metabolic rate and/or cold-tolerance. This is also the first study to present data on cold-induced PMR in a helox atmosphere in prairie voles and to show that thyroid gland thyroid T4 decreases are the most sensitive measure of thyroid function in mammals in comparison to plasma thyroid hormone concentrations.Item Effects of prescribed fire on small mammals and beetle assemblages in conservation reserve program (CRP) grasslands(Texas Tech University, 1998-05) Davis, Stephen SethThe Conservation Reserve Program (CRP) was established as a portion of the 1985 Food Security Act. The CRP removed highly erodible farmland from production by seeding perennial grasses. Acreage enrolled in CRP could not be grazed or harvested for 10 years. Since 1985, 400,000 ha in the Southern High Plains have been enrolled in CRP providing the unique opportunity for scientists to study a variety of animals in relatively homogenous man-made habitats. The stands of CRP in the Southern High Plains are dominated by weeping lovegrass (Eragrostis curvula). Information on community structure and microhabitat use of small mammals in homogenous CRP grasslands is severely lacking. Therefore, the hypothesis that rodents within CRP grasslands differed in microhabitat use was examined. Small mammals were live-trapped on 12 study plots from 11 to 15 March 1996 in Lynn County, Texas. First captures of small mammals were separated into four vegetation categories based on canopy cover at the trap site. Eight species of small mammals were captured during 6000 trapnights. The deer mouse (Peromyscus maniculatus) and the hispid pocket mouse rChaetodipus hispidus) differed from the expected distribution of captures (chi square, 3 df, P < 0.001 and P = 0.001) with more captures in open trap sites. In contrast, the cotton rat (Sigmodon hispidus) and the western harvest mouse (Reithrodontomys megalotis^ differed from the expected distribution of captures (chi square, 3 df, P < 0.001 and P = 0.058) with more captures in densely vegetated trap sites. Results suggest rodents living in weeping lovegrass monocultures select different microhabitat cover. The effects of prescribed fire on small mammals and beetle assemblages in CRP grasslands have yet to be documented. Small mammals and beetles were sampled on six burned and six non-burned areas over the summers of 1996 and 1997. Small mammal trapping revealed 2532 captures of 1380 individuals of 10 species. R. megalotis and S. hispidus decreased dramatically following fire (P = 0.001 and P = 0.003). The northern grasshopper mouse (Onychomys leucogaster) increased following fire ( P = 0.044). Three other species, the spotted ground squirrel (Spermophilus spilosoma). P. maniculatus. and C. hispidus. all exhibited burn by time interactions and increased in at least one time period on burned areas. Rodent postfire succession in CRP grassland is a dynamic process. Habitats are continually being optimized by changing groups of rodents even when grasses return to preburn densities. Beetle trapping revealed 13 different beetle families, with six families captured in sufficient numbers for statistical analysis. Scarabaeidae, Tenebrionidae, and Meloidae beetles were not affected by fire. Carabidae and Cicindelidae, although not significant at the P < 0.05 level, had trends which suggested possible fire effects. Elateridae beetles decreased 16 months postburn but did not differ in previous samples. Beetles seem to be resilient to fire and families that are affected most are those depended on litter and detritus for habitat.Item Fire effects on small mammals and vegetation of the Northern Chihuahuan Desert(Texas Tech University, 1997-12) Monasmith, Tony JohnThe role of fire in the Northern Chihuahuan Desen has been of great interest and also heavily debated for 40 years. However, few replicated studies have documented the changes brought about by fire. .My study documented the short term effects of fire on a creosotebush (Larrea tridentata) dominated community and associated small mammal community. Prescribed burns were ignited during 13-15 June 1995 on 10 pairs (10 bumed. 10 unbumed) of 25- ha study sites. The 1995 bums reduced shmb (P = '» 006) and grass (P < 0.000) canopy cover to 64 and 16% of the preburn cover, respectively Complete recovery' of the canopy cover had not taken place 1 year post bum Densities of shrubs, primarily creosotebush. tarbush (Flourencia cemua). and cacti species (Opuntia) were reduced 1 year post bum. Mortality of creosotebush (25.6%) was lower than previously reported for summer burns. Tarbush monality (26 3°o) was similar to creosotebush on the study sites. Above average precipitation during June and July 1996 and lower competition by shmbs for available resources promoted an 1160% increase in forb canopy cover on the bumed sites.Item Heavy metal and arsenic bioaccumulation in small mammals inhabiting the Anaconda Smelter Superfund Site, Montana(Texas Tech University, 2004-08) Reynolds, Kevin D.A key component in accurately assessing bioavailability of environmental metals at large National Priority List (NPL) sites is a reduction of uncertainty within exposure estimates. This reduction in uncertainty can be facilitated by collecting empirical data from individual animals inhabiting hazardous waste sites. Site-specific metal bioavailability data are also useful in supporting decisions regarding clean up and demediation, and regulators and scientists also support the use of these data in their exposure assessment models. However, rarely are data available to confirm modeled results. The primary objective of this study was quantifying the site-specific bioavailability and accumulation of heavy metals and arsenic in small mammals inhabiting a metals-contaminated NPL hazardous waste site in southwest Montana Deer mice (Peromyscus maniculatus) and northern pocket gophers (Thomomys talpoides) inhabiting areas contaminated with a gradient of heavy metals and arsenic were collected from the Anaconda Smelter SuperfUnd Site, Montana, USA. A total of 299 deer mice were collected in 1999 and 2000. Arsenic (As), cadmium (Cd), lead (Pb), copper (Cu), and zinc (Zn) were determined in blood, kidney, liver, mammary tissue, carcass, and stomach contents and compared to metal levels in the soils across six respective trapping grids established on spontaneously revegetated areas of the site. Among deer mouse stomach contents and tissues, only Zn and Cu were detected with regularity in all tissues. Lead and As were detected primarily in carcass samples, and Cd was detected most frequently in liver and kidney samples. Among all tissues analyzed, there were no differences (p > 0.05) between male and female mice for any of the metals except for Pb. When all mice were grouped by sex, there was a larger (p = 0.0380) proportion of female liver samples with detectable concentrations of Pb compared to males. Differences between adult and nonadult mice were mostly observed for Pb, Cd and As concentrations in kidney, liver and carcass samples.Item Microsite and habitat boundary influences on small mammal capture, diversity, and movements(Texas Tech University, 1997-08) Root, J. JeffreyHabitat, habitat edges, and microhabitat are important components for theories and concepts of community ecology. However, their effects have not been examined in many locations. Replicated studies in different ecosystems are necessary to determine the generality of the effects of these habitat variables. The effects of trap-site disturbance and microhabitat on small mammal capture rates were examined in the Tularosa Basin of south-central New Mexico during 7-14 April, 1996. The study was conducted in a mixed desert scrub habitat characteristic of the Chihuahuan Desert. Small mammals were live-trapped on 32 study plots. Soil disturbance and microhabitat treatments were assigned to study plots in a completely randomized factorial design to test the hypothesis that trap-site disturbance can influence small mammal captures between microhabitats. Thirteen species of small mammals were captured, including four species of Heteromyidae, eight species of Muridae, and one species of Sciuridae. Peromyscus eremicus was captured more frequently at undisturbed sites (P=0.004) and was recaptured more frequently under shrubs j[P=0.048). Neotoma micropus was captured less frequently at undisturbed sites in the open (P=0.035). No other species were affected by microhabitat, trap-site disturbance, or interactions (P>0.05). These results provide limited support to the hypothesis that trap-site disturbance can influence small mammal captures between microhabitats.Item Redescription of teeth and epithelial plates from the platypus (Ornithorhynchus anatinus) : morphological and evolutionary implications(2014-05) Latimer, Ashley Emilie; Rowe, Timothy, 1953-The evolutionary history of mammals, when including extinct taxa, is mainly reconstructed using tooth morphology and employs terminology based on non-monotreme mammals. Although adult monotremes are edentulous, juvenile platypuses have teeth that can be compared with extinct monotremes, but terminology can be a barrier to efficient comparison to non-monotreme mammals. Deciduous teeth and thickened epithelial plates of the extant platypus, Ornithorhynchus anatinus, are sparsely figured in the literature. New imagery of those teeth and plates from high-resolution x-ray computed tomography and scanning electron microscopy contribute to the understanding of mammal evolution and the unique morphology of platypus teeth. The teeth of the juveniles are highly variable, but early-forming features (major cusps and transverse valleys) are stable enough for comparison. Transverse lophs on monotreme teeth contain complexity not reflected in cusps alone, unlike therian mammals. These differences reinforce the need for caution when applying dental terminology that originally was produced for therian mammals. New imagery highlights potential phylogenetically informative morphology in the pulp cavity and roots. As the roots of the juvenile teeth degenerate, the epithelium below the teeth thickens into epithelial plates. Structures in the epithelial plates are broadly similar to those found in the keratin plates. New images of the epithelial plates offer insight into a series of tubes concentrated under the juvenile teeth. The tubes are a continuous conduit to the plate surface and may serve a sensory function or result from the ever-growing nature of the epithelial plate.Item Relational database for Ecuadorian mammals deposited in museums around the world(Texas Tech University, 2007-08) Estupiñán, Juan Pablo Carrera; Baker, Robert J.; Edson, Gary F.; Ladkin, NicolaNatural history collections play an essential role in the conservation and study of the biodiversity of our planet. Since the 19th century, increasing collections of fauna from Ecuador have been deposited in numerous institutions around the world. These collections have allowed a better understanding of the distribution and systematics of Neotropical mammals. During 2006, an extensive survey based on scientific literature, natural history museum databases, and personal communications with museum’s staff, was carried out to update our knowledge about collections of Ecuadorian mammals. The main goal of this project was to create a central database, hosted at the Museum of Texas Tech University, with the list of institutions that hold those specimens, dates of collections, taxa represented, and regions surveyed in Ecuador. A total of 42 institutions from South America, North America, and Europe have been identified. An effective collaboration with 28 of these 42 institutions made it possible to compile more than 20,000 records allowing the creation of a centralized database. The system has the advantage of being simple and easily accessed via internet. The information is organized by Geography and Taxonomy criteria allowing queries without limitations. The scope of this project demonstrates effective collaboration among natural history museums in the 21st century.Item Systematics, distribution, and zoogeography of mammals of Tunisia(Texas Tech University, 1997-12) Gharaibeh, Burhan M.The taxonomic identity of each species of mammals that occurs in the Republic of Tunisia, North Africa has been determined to the subspecific level. History of names was followed and descriptions of types were studied to better provide opinions on the nomenclamre and minimize the confusion existing in the literature concerning the taxonomic identity of many Tunisian species. Keys to distinguish related taxa were constructed and maps depicting the distribution of species within the borders of Tunisia and in the whole North African region were drawn. These maps show original records obtained during this study as well records reported in the literature. Furthermore, the available natural history information on the Tunisian mammal fauna and background information on the vegetation, rainfall, topography, and land forms of the country were presented. Chromosomal G-band data for Merlones shawl from Tunisia, hitherto unavailable, was used to reexamine proposed chromosomal homologies and update the phylogenetic tree of Family Gerbillidae. G-banded chromosomal complement for Jaculus orlentalls was reported. Notable differences in pelage color were seen between populations of the North African elephant shrew, Elephantulus rozetl in northern and southern Tunisia. However, no disjunction was seen in morphometric measurements analyzed using principal components analysis (PCA). Differences in pelage color between 5 populations of Gerblllus campestrls are discussed. Two populations of this gerbil, one on the Island of Djerba and the other around Medenine deserve systematic studies using molecular data or multivariate analyses of morphometric measurements. Differences in pelage color, mandibular foramina number, color of foot pad hair and other characters between 2 populations of Jaculus jaculus were also noted and further investigation of the taxonomic status recommended. Zoogeographical analyses of the mammalian faunal elements in Tunisia and the whole area were made. Two groups of bats were recognized. Bat fauna that invaded Tunisia from the north, and one that invaded from the south. Land mammals were in three groups: strictly Mediterranean zone, widely-distributed Mediterranean, and Saharan mammals. Species richness in quadrates 1° latimde X 1° longitude spanning Tunisia was discussed. The species richness provided evidence to areas of high biodiversity. Areas that deserve conservation are Djebel Zaghouan, Ghardimaou, Tamerza-Kasserine, and Dahar-Djeffara plain. Finally, conclusions and recommendations for future mammalian studies in the area were suggested.Item Telomere Dynamics and End Processing in Mammalian Cells(2006-05-15) Sfeir, Agnel J.; Shay, Jerry W.Telomeres are repetitive DNA sequences that end in single-stranded 3' overhangs. With each cell division, normal human cells lose a small amount of telomeric DNA due to the end-replication problem and the action of an unidentified nuclease. In order for tumor cells to divide indefinitely, they maintain telomere length by expressing the enzyme telomerase. The end structure of mammalian telomeres is not very well understood. Two assays were developed using ligation and PCR amplification to identify the terminal nucleotides of both the C-rich and G-rich telomeric strands in human cells. The results showed that ~ 80 % of the C-strands terminate precisely in ATC-5', demonstrating that the nuclease resection of the C-strand post replication is specific for a single nucleotide. In contrast, the last base of the G-strand in normal human cells was less precise with 70% of the ends being TAG-3', TTA-3' or GTT-3'. An enrichment for the TAG-3' end was noted in cells that express telomerase. A series of nucleases were tested for their involvement in specifying the last base of C-strands and the results indicated that none of those nucleases were responsible for telomere-end resection. Inhibiting the normal function of most telomere binding proteins altered normal telomere function, however only one protein (POT-1) influenced last base specificity. Knocking down POT-1 in normal and tumor cells randomized the last base of the C-strand. These finding have important implications for the processing events that act on the telomere ends and they will help identify the nuclease that resects the chromosome ends. In the second part of this study, the dynamics of telomerase action in mammalian cells was examined. Using a PCR-based, single telomere-length measurement assay (STELA) we showed that telomerase adds an average of 250-nucleotides per end in one replication cycle. Cell cycle studies showed that while the telomeres on the Xp chromosome replicated in early S-phase their elongation by telomerase took place during late S/early G2 phase. Therefore, in mammalian cells telomerase action is not coupled to DNA replication. These studies will provide much needed information for exploiting our knowledge of telomere biology for telomerase-based therapeutic purposes.Item The mammals of Caprock Canyons State Park(Texas Tech University, 1998-05) Roberts, Kristie JoSeveral objectives were addressed in this study. The first goal was to determine the distribution and status of mammals living within the boundaries of CCSP and to determine whether or not the trailway was a corridor for passage of mammals between two distinct habitat types (High Plains and Rolling Plains). Determining other biogeographic implications of the trailway also was crucial to the study. Another major goal of this study was to determine the status of the bat colony inhabiting the railroad tunnel located on the trailway. Finally, management recommendations regarding the mammals of CCSP were to be provided to the officials of the TPWD.