Browsing by Subject "Pocket gophers"
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Item Biosystematics of the yellow-faced pocket gopher, Cratogeomys castanops, in the United States(Texas Tech University, 1988-12) Hollander, Robert R.The problem addressed herein is the systematic and evolutionary relationships, from a morphometric perspective, of currently recognized races of Cratogeomys in the United States. On the basis of published findings to the end of 1987, nine subspecies of Q.. castanops currently are recognized as occurring in the United States. Eight of these occur in Texas, with the possibility of the ninth occurring in the extreme northwestern corner of the Texas Panhandle. This species also occurs in Colorado, Kansas, New Mexico, and Oklahoma, and southward into Mexico. Since Russell's (1968^1) revision of the genus Pappogeomys (sensu latoL no taxonomic study has been done concerning more than two adjacent subspecies. Several criticisms of Russell's (1968ii) work can be made: his analysis was not of a statistical nature; specimens from many intermediate geographic areas were not available to him, and, in fact, his study was based on relatively few specimens from the overall distribution of the species. Moreover, Russell (1968ii) discussed two subspecies as "...occurring sympatrically with no apparent intergradation..." in the Guadalupe Mountains of Texas. Schmidly (1977) also reported two races from another locality in the Trans-Pecos region of Texas. Such situations likely do not exist unless more than one species is involved.Item Dynamics of a contact zone between two cytotypes of Geomys bursarius.(Texas Tech University, 1975-08) Pembleton, Edward F.Not availableItem Ecology and systematics of the pocket gophers of the Davis Mountains, Texas(Texas Tech University, 1970-05) Reichman, Omer James.Item Evolution of 12S rRNA gene in pocket gophers (Genus: Geomys)(Texas Tech University, 1997-12) Jolley, Ted W.Pocket gophers are known for their fossorial lifestyle, small isolated populations, and low fecundity. These characteristics make pocket gophers an ideal group for examining rate heterogeneity and sequence divergence in light of recent hypotheses concerning metabolic-rate and body size. To test these hypotheses, the mitochondrial 12S ribosomal (rRNA) gene was sequenced from individuals representing 10 species of the genus Geomys. In addition, specimens of Cratogeomys castanops. Thomomvs bottae. T^ umbrinus. Dipodomvs philHpsii. and Pedetes capensis were examined as outgroups. Specifically, the goals of this study were to: (1) determine if heterogeneity existed in rates of sequence divergence between fossorial and nonfossorial rodents, (2) determine intrageneric nucleotide sequence variation at the 12S rRNA gene, and (3) determine if the 12S rRNA gene contains phylogenetic signal to resolve the phylogenetic relationships within Geomys. The overall levels of 12S rRNA sequence divergence observed (average 3.5, range 0.6-7.5) support a low level of divergence within Geomvs. with the overall transition/transversion ratio lower than that observed in other mammalian groups. Relative rate tests did not detect significant overall levels of rate heterogeneity within and among Geomvs and outgroup taxa, nontheless certain taxa did show rate heterogeneity when compared to other members within group. The resultant 12S rRNA gene phylogenies provided strong phylogenetic signal and consistently supported several relationships within species and subspecies of Geomvs.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 Karyotypes and chromosomal evolution in West Texas pocket gophers (Rodentia, geomyidae)(Texas Tech University, 1969-05) Berry, Dale LawrenceNot availableItem Morphometric analysis of seven species of pocket gophers (geomyidae)(Texas Tech University, 1996-05) Mauk, Charlene L.Pocket gophers of the genus Geomys (Mammaha, rodentia) are fossorial rodents that are restricted geographically to North and Central America (Hall, 1981) Thirty-eight species and subspecies of Geomys have been recognized from this region (Davis, 1940; Hart, 1978; HaU, 1981). Of this group, G. arenahus, G. attwateri, G. breviceps, G. bursarius, G. knoxjonesi, G. personatus, and G. texensis occur in the southwestern United States. The distribution and diversity of this genus reaches a maximum in the state of Texas where all seven species occur. Consequently, this region (Texas) has received much of the focus of systematic and taxonomic questions. The distribution of members of this genus encompasses all four of the ecological regions of Texas as depicted in Davis and Schmidly (1994). These distributions in Texas can be described as endemic (G. attwateri, G. personatus, and G. texensis), allopatric (G. arenarius), and parapatric (G. attwateri diid G. breviceps, G. attwateri and G. personatus, G. attwateri and G. texensis, G. bursarius and G. breviceps, and G. bursarius and G. knoxjonesi). In addition, sympatric distributions have been identified in the contact zone studies of G. attwateri and G. breviceps (Tucker and Schmidly, 1981; Burton and Bickham, 1989; Dowler, 1989). Specifically, the distributions are as follows. Geomys arenahus is found only in the western Trans-Pecos region along the Rio Grande Valley. The range of G. attwateri includes central Texas west of the Brazos River, south to the San Antonio River, and along the central Gulf coast. Geomys breviceps occurs in the eastern portion (east of the Brazos River) of Texas. Geomys bursarius is located in northwestern and north-central Texas. Geomys knoxjonesi inhabits the deep sandy soils of the southwestern plains of Texas and eastern New Mexico. Geomys personatus occurs throughout most of south Texas, and G. texensis occurs only in two isolated areas of the Texas Hill Country.Item Non-geographic variation in the Mexican pocket gopher, Cratogeomys castanops perplanus, from Lubbock County, Texas(Texas Tech University, 1968-08) McReynolds, Robert ClayNot availableItem Population Genetic Analyses of the Baird's Pocket Gopher, Geomys breviceps(2012-10-19) Welborn, SarahThe Baird?s pocket gopher (Geomys breviceps) is a solitary, fossorial rodent found throughout areas of Texas, Arkansas, Oklahoma, and Louisiana. Research focusing on the population genetics of pocket gophers and other species with limited vagility and isolated populations is lacking. Through the use of mitochondrial and microsatellite data, a series of population genetic analyses were completed to better understand the population structure and gene flow among a series of G. breviceps localities. Pocket gophers were captured from five localities in the Brazos Valley and used in this study. Due to the lack of microsatellite loci available for G. breviceps, 10 loci were created for use in this study. Overall estimates from the population genetic analyses showed high levels of gene flow amongst nearby localities with decreasing levels as distance between localities increased. Findings suggest that 2-3 localities located within 2 km of each other function as one genetic cluster thus showing 3-4 total genetic clusters total in this study. Results also suggest that the Baird?s pocket gopher is capable of moving at least 2 km, but further analyses should be completed to better understand dispersal distance.Item Reproductive studies of the Mexican pocket gopher, Cratogeomys castanops perplanus(Texas Tech University, 1964-08) Ikenberry, Roy DewayneNot availableItem Vagility and local movements of pocket gophers (Thomomys and Pappogeomys) in an area of sympatry(Texas Tech University, 1973-12) Williams, Stephen L.Not available