Log in

Relevant bibliographies by topics / Desert tortoise / Journal articles

To see the other types of publications on this topic, follow the link: Desert tortoise.

Journal articles on the topic 'Desert tortoise'

Author: Grafiati

Published: 4 June 2021

Last updated: 27 July 2024

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Desert tortoise.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Carter, SK, KE Nussear, TC Esque, IIF Leinwand, E. Masters, RD Inman, NB Carr, and LJ Allison. "Quantifying development to inform management of Mojave and Sonoran desert tortoise habitat in the American southwest." Endangered Species Research 42 (August 6, 2020): 167–84. http://dx.doi.org/10.3354/esr01045.

Full text

Abstract:

Two tortoise species native to the American southwest have experienced significant habitat loss from development and are vulnerable to ongoing threats associated with continued development. Mojave desert tortoises Gopherus agassizii are listed as threatened under the US Endangered Species Act, and Sonoran desert tortoises G. morafkai are protected in Arizona (USA) and Mexico. Substantial habitat for both species occurs on multiple-use public lands, where development associated with traditional and renewable energy production, recreation, and other activities is likely to continue. Our goal was to quantify development to inform and evaluate actions implemented to protect and manage desert tortoise habitat. We quantified a landscape-level index of development across the Mojave and Sonoran desert tortoise ranges using models of potential habitat for each species (152485 total observations). We used 13 years of Mojave desert tortoise monitoring data (4732 observations) to inform the levels and spatial scales at which tortoises may be affected by development. Most (66-70%) desert tortoise habitat has some development within 1 km. Development levels on desert tortoise habitat are lower inside versus outside areas protected by actions at national, state, and local levels, suggesting that protection efforts may be having the desired effects and providing a needed baseline for future effectiveness evaluations. Of the relatively undeveloped desert tortoise habitat, 43% (74030 km2) occurs outside of existing protections. These lands are managed by multiple federal, state, and local entities and private landowners, and may provide opportunities for future land acquisition or protection, including as mitigation for energy development on public lands.

APA, Harvard, Vancouver, ISO, and other styles

2

Cypher, Brian L., Erica C. Kelly, Tory L. Westall, and Christine L. Van Horn Job. "Coyote diet patterns in the Mojave Desert: implications for threatened desert tortoises." Pacific Conservation Biology 24, no. 1 (2018): 44. http://dx.doi.org/10.1071/pc17039.

Full text

Abstract:

Coyotes (Canis latrans) are generalist predators and are ubiquitous in North America. Occasionally, predation by coyotes can pose a threat to populations of rare species. We assessed diet patterns of coyotes over a 5-year period (2009–14) in a region of the Mojave Desert where high predation rates on threatened desert tortoises (Gopherus agassizii) had been reported. Our goal was to identify primary food items for coyotes and to assess the importance of desert tortoises in the diet. Coyotes primarily consumed rabbits and rodents with rabbits being consumed preferentially and rodents, along with secondary foods including various birds, reptiles, arthropods, and fruits, being consumed more opportunistically. In response to low annual precipitation in the last three years of the study, dietary diversity increased, as did use of anthropogenic food items by coyotes. However, coyotes did not seem to be dependent upon anthropogenic items. Remains of desert tortoises occurred in coyote scats at low frequencies (<6%) in all years and seasons, and use of tortoises appeared to be opportunistic as use varied with tortoise abundance. In the portion of the study area where 571 translocated desert tortoises had been released in 2008, the frequencies of tortoise remains in coyote scats were markedly higher in the two years following the releases (7.5% and 8.8%, respectively). The high predation rates on tortoises reported in this area may have resulted from focussed coyote foraging efforts due to the availability of vulnerable individuals (e.g. disoriented and displaced tortoises) as well as higher tortoise densities.

APA, Harvard, Vancouver, ISO, and other styles

3

Abella, Scott R., and Kristin H. Berry. "Enhancing and Restoring Habitat for the Desert Tortoise." Journal of Fish and Wildlife Management 7, no. 1 (March 1, 2016): 255–79. http://dx.doi.org/10.3996/052015-jfwm-046.

Full text

Abstract:

AbstractHabitat has changed unfavorably during the past 150 y for the desert tortoise Gopherus agassizii, a federally threatened species with declining populations in the Mojave Desert and western Sonoran Desert. To support recovery efforts, we synthesized published information on relationships of desert tortoises with three habitat features (cover sites, forage, and soil) and candidate management practices for improving these features for tortoises. In addition to their role in soil health and facilitating recruitment of annual forage plants, shrubs are used by desert tortoises for cover and as sites for burrows. Outplanting greenhouse-grown seedlings, protected from herbivory, has successfully restored (>50% survival) a variety of shrubs on disturbed desert soils. Additionally, salvaging and reapplying topsoil using effective techniques is among the more ecologically beneficial ways to initiate plant recovery after severe disturbance. Through differences in biochemical composition and digestibility, some plant species provide better-quality forage than others. Desert tortoises selectively forage on particular annual and herbaceous perennial species (e.g., legumes), and forage selection shifts during the year as different plants grow or mature. Nonnative grasses provide low-quality forage and contribute fuel to spreading wildfires, which damage or kill shrubs that tortoises use for cover. Maintaining a diverse “menu” of native annual forbs and decreasing nonnative grasses are priorities for restoring most desert tortoise habitats. Reducing herbivory by nonnative animals, carefully timing herbicide applications, and strategically augmenting annual forage plants via seeding show promise for improving tortoise forage quality. Roads, another disturbance, negatively affect habitat in numerous ways (e.g., compacting soil, altering hydrology). Techniques such as recontouring road berms to reestablish drainage patterns, vertical mulching (“planting” dead plant material), and creating barriers to prevent trespasses can assist natural recovery on decommissioned backcountry roads. Most habitat enhancement efforts to date have focused on only one factor at a time (e.g., providing fencing) and have not included proactive restoration activities (e.g., planting native species on disturbed soils). A research and management priority in recovering desert tortoise habitats is implementing an integrated set of restorative habitat enhancements (e.g., reducing nonnative plants, improving forage quality, augmenting native perennial plants, and ameliorating altered hydrology) and monitoring short- and long-term indicators of habitat condition and the responses of desert tortoises to habitat restoration.

APA, Harvard, Vancouver, ISO, and other styles

4

Agha, Mickey, Mason O. Murphy, Jeffrey E. Lovich, Joshua R. Ennen, Christian R. Oldham, Kathie Meyer, Curtis Bjurlin, et al. "The effect of research activities and winter precipitation on voiding behaviour of Agassiz’s desert tortoises (Gopherus agassizii)." Wildlife Research 41, no. 8 (2014): 641. http://dx.doi.org/10.1071/wr14196.

Full text

Abstract:

Context There is little information available on how research activities might cause stress responses in wildlife, especially responses of threatened species such as the desert tortoise (Gopherus agassizii). Aims The present study aims to detect behavioural effects of researcher handling and winter precipitation on a natural population of desert tortoises in the desert of Southwestern United States, over the period 1997 to 2014, through extensive assessments of capture events during multiple research studies, and capture–mark–recapture survivorship analysis. Methods Juvenile and adult desert tortoises were repeatedly handled with consistent methodology across 18 years during 10 study seasons. Using a generalised linear mixed-effects model, we assessed the effects of both research manipulation and abiotic conditions on probability of voiding. Additionally, we used a Cormack–Jolly–Seber model to assess the effects of winter precipitation and voiding on long-term apparent survivorship. Key results Of 1008 total capture events, voiding was recorded on 83 (8.2%) occasions in 42 different individuals. Our top models indicated that increases in handling time led to significantly higher probabilities of voiding for juveniles, females and males. Similarly, increases in precipitation resulted in significantly higher probabilities of voiding for juveniles and females, but not for males. Tortoise capture frequency was negatively correlated with voiding occurrence. Cormack–Jolly–Seber models demonstrated a weak effect of winter precipitation on survivorship, but a negligible effect for both voiding behaviour and sex. Conclusions Handling-induced voiding by desert tortoises may occur during common research activities and years of above average winter precipitation. Increased likelihood of voiding in individuals with relatively low numbers of recaptures suggested that tortoises may have perceived researchers initially as predators, and therefore voided as a defensive strategy. Voiding does not appear to impact long-term survivorship in desert tortoises at this site. Implications This study has demonstrated that common handling practices on desert tortoise may cause voiding behaviour. These results suggest that in order to minimise undesirable behavioural responses in studied desert tortoise populations, defined procedures or protocols must be followed by the investigators to reduce contact period to the extent feasible.

APA, Harvard, Vancouver, ISO, and other styles

5

Orton, Joseph P., Matheo Morales, Rafaela S. Fontenele, Kara Schmidlin, Simona Kraberger, Daniel J. Leavitt, Timothy H. Webster, et al. "Virus Discovery in Desert Tortoise Fecal Samples: Novel Circular Single-Stranded DNA Viruses." Viruses 12, no. 2 (January 26, 2020): 143. http://dx.doi.org/10.3390/v12020143.

Full text

Abstract:

The Sonoran Desert tortoise Gopherus morafkai is adapted to the desert, and plays an important ecological role in this environment. There is limited information on the viral diversity associated with tortoises (family Testudinidae), and to date no DNA virus has been identified associated with these animals. This study aimed to assess the diversity of DNA viruses associated with the Sonoran Desert tortoise by sampling their fecal matter. A viral metagenomics approach was used to identify the DNA viruses in fecal samples from wild Sonoran Desert tortoises in Arizona, USA. In total, 156 novel single-stranded DNA viruses were identified from 40 fecal samples. Those belonged to two known viral families, the Genomoviridae (n = 27) and Microviridae (n = 119). In addition, 10 genomes were recovered that belong to the unclassified group of circular-replication associated protein encoding single-stranded (CRESS) DNA virus and five circular molecules encoding viral-like proteins.

APA, Harvard, Vancouver, ISO, and other styles

6

Brown, M. B., G. S. McLaughlin, P. A. Klein, B. C. Crenshaw, I. M. Schumacher, D. R. Brown, and E. R. Jacobson. "Upper Respiratory Tract Disease in the Gopher Tortoise Is Caused by Mycoplasma agassizii †." Journal of Clinical Microbiology 37, no. 7 (1999): 2262–69. http://dx.doi.org/10.1128/jcm.37.7.2262-2269.1999.

Full text

Abstract:

Upper respiratory tract disease (URTD) has been observed in a number of tortoise species, including the desert tortoise (Gopherus agassizii) and the gopher tortoise (Gopherus polyphemus). Clinical signs of URTD in gopher tortoises are similar to those in desert tortoises and include serous, mucoid, or purulent discharge from the nares, excessive tearing to purulent ocular discharge, conjunctivitis, and edema of the eyelids and ocular glands. The objectives of the present study were to determine ifMycoplasma agassizii was an etiologic agent of URTD in the gopher tortoise and to determine the clinical course of the experimental infection in a dose-response infection study. Tortoises were inoculated intranasally with 0.5 ml (0.25 ml/nostril) of either sterile SP4 broth (control group; n = 10) or 108 color-changing units (CCU) (total dose) of M. agassizii 723 (experimental infection group;n = 9). M. agassizii caused clinical signs compatible with those observed in tortoises with natural infections. Clinical signs of URTD were evident in seven of nine experimentally infected tortoises by 4 weeks postinfection (p.i.) and in eight of nine experimentally infected tortoises by 8 weeks p.i. In the dose-response experiments, tortoises were inoculated intranasally with a low (101 CCU;n = 6), medium (103 CCU;n = 6), or high (105 CCU;n = 5) dose of M. agassizii 723 or with sterile SP4 broth (n = 10). At all time points p.i. in both experiments, M. agassizii could be isolated from the nares of at least 50% of the tortoises. All of the experimentally infected tortoises seroconverted, and levels of antibody were statistically higher in infected animals than in control animals for all time points of >4 weeks p.i. (P < 0.0001). Control tortoises in both experiments did not show clinical signs, did not seroconvert, and did not have detectableM. agassizii by either culture or PCR at any point in the study. Histological lesions were compatible with those observed in tortoises with natural infections. The numbers of M. agassizii 723 did not influence the clinical expression of URTD or the antibody response, suggesting that the strain chosen for these studies was highly virulent. On the basis of the results of the transmission studies, we conclude that M. agassizii is an etiologic agent of URTD in the gopher tortoise.

APA, Harvard, Vancouver, ISO, and other styles

7

Abella, Scott R., Lindsay P. Chiquoine, E. Cayenne Engel, Katherine E. Kleinick, and Fred S. Edwards. "Enhancing Quality of Desert Tortoise Habitat: Augmenting Native Forage and Cover Plants." Journal of Fish and Wildlife Management 6, no. 2 (May 1, 2015): 278–89. http://dx.doi.org/10.3996/022015-jfwm-013.

Full text

Abstract:

Abstract Vegetation in habitat of the federally listed desert tortoise Gopherus agassizii in the Mojave and western Sonoran Desert is now partly or mostly dominated by nonnative annual plants. To improve forage quality and augment availability of perennial cover plants, we tested seeding (pelletized or bare seeding), watering, and fencing for increasing a native annual forage species (desert plantain Plantago ovata), a perennial forage species (desert globemallow Sphaeralcea ambigua), and two shrub species (cheesebush Hymenoclea salsola and winterfat Krascheninnikovia lanata) that provide cover in desert tortoise habitat of southern Nevada. Treatments were ineffective at establishing the perennial species, even though greenhouse assays confirmed that some bare and pelletized seeds were germinable. In contrast, pelletized seeding quadrupled the density of desert plantain compared with not seeding or seeding untreated seed by the end of the first year (autumn 2013). Fencing tripled density of desert plantain to 17 plants/m2. Pelletized seeding plus fencing produced a desert plantain density of 39 plants/m2, the highest average density among all treatment combinations. The positive effect of fencing persisted until at least the second year after treatment (autumn 2014). Augmenting native annual forage plants favored by desert tortoises is feasible.

APA, Harvard, Vancouver, ISO, and other styles

8

Smith, Chuck. "Desert Tortoise Care." Bulletin of the Association of Reptilian and Amphibian Veterinarians 4, no. 1 (January 1994): 12–15. http://dx.doi.org/10.5818/1076-3139.4.1.12.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Hedrick, Philip W. "Comment on “Individual heterozygosity predicts translocation success in threatened desert tortoises”." Science 372, no. 6546 (June 3, 2021): eabg2673. http://dx.doi.org/10.1126/science.abg2673.

Full text

Abstract:

Scott et al. (Reports, 27 November 2020, p. 1086) suggest, on the basis of conclusions obtained from a desert tortoise reintroduction program, that higher genomic heterozygosity should be used to identify individuals for successful translocation. I contend that this recommendation is questionable given these relocated tortoises’ unknown origin, their high mortality, insufficient data on resident tortoises and other components of fitness, and potential allelic dropout.

APA, Harvard, Vancouver, ISO, and other styles

10

Sandmeier, F. C., K. L. Leonard, C. R. Tracy, K. K. Drake, T. E. Esque, K. Nussear, and J. M. Germano. "Tools to understand seasonality in health: quantification of microbe loads and analyses of compositional ecoimmunological data reveal complex patterns in Mojave Desert Tortoise (Gopherus agassizii) populations." Canadian Journal of Zoology 97, no. 9 (September 2019): 841–48. http://dx.doi.org/10.1139/cjz-2018-0255.

Full text

Abstract:

Using data from six wild Mojave Desert Tortoise (Gopherus agassizii (Cooper, 1861)) populations, we quantified seasonal differences in immune system measurements and microbial load in the respiratory tract, pertinent to this species’ susceptibility to upper respiratory tract disease. We quantified bacteria-killing activity of blood plasma and differential leukocyte counts to detect trends in temporal variation in immune function. We used centered log-ratio (clr) transformations of leukocyte counts and stress that such transformations are necessary for compositional data. We tested animals for the potential pathogen Pasteurella testudinis Snipes and Biberstein, 1982 with a newly created quantitative polymerase chain reaction (qPCR) assay, as well as for the known respiratory pathogens Mycoplasma agassizii Brown et al., 2001 and Mycoplasma testudineum Brown et al., 2004. We found very little disease and suggest that P. testudinis is a prevalent, commensal microbe in these Mojave Desert Tortoise populations, and its quantification may be a tool to study natural fluctuations in microbe levels in Mojave Desert Tortoise respiratory tracts. Our analyses showed that both the potential for inflammatory responses and microbe levels are highest in the spring for healthy Mojave Desert Tortoises, when lymphocyte levels are lowest. The genetic and statistical tools that we used are easily applicable to other wildlife systems and provide the necessary data to quantify species-wide trends in health and test hypotheses pertinent to host–microbe dynamics.

APA, Harvard, Vancouver, ISO, and other styles

11

Cummings, Kristy. "Micro-geographic variation in burrow use of Agassiz’s desert tortoises in the Sonoran Desert of California." Herpetological Journal, Volume 30, Number 4 (October 1, 2020): 177–88. http://dx.doi.org/10.33256/hj30.4.177188.

Full text

Abstract:

Little has been published regarding the burrowing habits of Agassiz’s desert tortoises (Gopherus agassizii) in the Sonoran Desert of California. We monitored the interactions of tortoises with their burrows, and other tortoises, via radio-telemetry at two nearby sites between the Cottonwood and Orocopia Mountains, from 2015-2018. We examined how annual cycles of drought and non-drought years, behaviourally affected how tortoises use their burrows (i.e., burrow fidelity, cohabitation, and location), including the timing of the tortoise brumation period. Burrow locations were strongly dependent on local geology and topography, with a tendency to orientate in conformance with the general aspect of the landscape. The timing of brumation was similar to records for G. agassizii throughout their range (with a few exceptions). There was no difference in the estimated number of burrows used per 30 days between the active seasons (2017 and 2018) at the Orocopia site, despite the occurrence of drought in 2018.

APA, Harvard, Vancouver, ISO, and other styles

12

Anderson, Ileene, Roy Averill-Murray, Kristin H. Berry, Ashley Emerson, Julie Yee, Jeremy Mack, Kemp Anderson, et al. "Desert Tortoise Council Symposium." Journal of Herpetological Medicine and Surgery 21, no. 2 (June 1, 2011): 37. http://dx.doi.org/10.5818/1529-9651-21.2.37.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Nafus, Melia G., Jacob A. Daly, Tracey D. Tuberville, A. Peter Klimely, Kurt A. Buhlmann, and Brian D. Todd. "Habitat use by female desert tortoises suggests tradeoffs between resource use and risk avoidance." PLOS ONE 17, no. 8 (August 19, 2022): e0263743. http://dx.doi.org/10.1371/journal.pone.0263743.

Full text

Abstract:

Animals may select habitat to maximize the benefits of foraging on growth and reproduction, while balancing competing factors like the risk of predation or mortality from other sources. Variation in the distribution of food resources may lead animals to forage at times or in places that carry greater predation risk, with individuals in poor quality habitats expected to take greater risks while foraging. We studied Mojave desert tortoises (Gopherus agassizii) in habitats with variable forage availability to determine if risk aversion in their selection of habitat relative was related to abundance of forage. As a measure of risk, we examined tortoise surface activity and mortality. We also compared tortoise body size and body condition between habitats with ample forage plants and those with less forage plants. Tortoises from low forage habitats selected areas where more annual plants were nutritious herbaceous flowering plants but did not favor areas of greater perennial shrub cover that could shelter them or their burrows. In contrast, tortoises occupying high forage habitats showed no preference for forage characteristics, but used burrows associated with more abundant and larger perennial shrubs. Tortoises in high forage habitats were larger and active above ground more often but did not have better body condition. Mortality was four times higher for females occupying low forage habitat than those in high forage habitat. Our results are consistent with the idea that tortoises may minimize mortality risk where food resources are high, but may accept some tradeoff of greater mortality risk in order to forage optimally when food resources are limiting.

APA, Harvard, Vancouver, ISO, and other styles

14

Peaden, J. Mark, Tracey D. Tuberville, Kurt A. Buhlmann, Melia G. Nafus, and Brian D. Todd. "Delimiting road-effect zones for threatened species: implications for mitigation fencing." Wildlife Research 42, no. 8 (2015): 650. http://dx.doi.org/10.1071/wr15082.

Full text

Abstract:

Context Roads are a pernicious form of habitat loss for many wildlife populations because their effects often extend far beyond the roads themselves, giving rise to reduced wildlife abundance in road-effect zones. Quantifying the extent of road-effect zones more accurately portrays their impact on populations and the true extent to which habitat is lost for many species. Aim The purpose of the present study was to evaluate ways of determining the extent of road-effect zones for a model study species to better quantify the effect of roads on habitat loss. Methods We conducted road-side surveys for signs of Mojave desert tortoises (Gopherus agassizii) 0, 200, 400, 800 and 1600 m from county roads and interstates, two of the most common road types in critical habitat of this threatened species. Using data from these road-side surveys, we estimated the extent of road-effect zones using piecewise regression and modified von Bertalanffy models. Key results We found reduced abundances of tortoise sign along both county roads and interstates. Reductions extended farther from the large, high-traffic interstate than from the smaller, lower-traffic county roads (306 m versus 230 m). The increase in the abundance of tortoise signs with distance from roads approximated a negative exponential curve. Conclusions Interstate and county roads both contribute to habitat loss in road-side areas by making these habitats unsuitable to desert tortoises, presumably by removing animals via mortality from collisions with vehicles. Larger roads with greater traffic have more extensive effects. Implications Roadside mitigation fencing has been proposed as one way to reduce mortality of desert tortoises and to reclaim habitat by allowing tortoises to recolonise currently depauperate road-effect zones. Immediate mortality is more likely to be prevented by fencing county roads where tortoises occur closer to roads and are more likely to be struck by vehicles and killed. However, fencing interstate should yield more reclaimed habitat than that obtained from fencing county roads. Managers must consider balancing these goals along with other concerns when deciding where to place roadside fencing.

APA, Harvard, Vancouver, ISO, and other styles

15

Scott, Peter A., Linda J. Allison, Kimberleigh J. Field, Roy C. Averill-Murray, and H. Bradley Shaffer. "Individual heterozygosity predicts translocation success in threatened desert tortoises." Science 370, no. 6520 (November 26, 2020): 1086–89. http://dx.doi.org/10.1126/science.abb0421.

Full text

Abstract:

Anthropogenic environmental modification is placing as many as 1 million species at risk of extinction. One management action for reducing extinction risk is translocation of individuals to locations from which they have disappeared or to new locations where biologists hypothesize they have a good chance of surviving. To maximize this survival probability, the standard practice is to move animals from the closest possible populations that contain presumably related individuals. In an empirical test of this conventional wisdom, we analyzed a genomic dataset for 166 translocated desert tortoises (Gopherus agassizii) that either survived or died over a period of two decades. We used genomic data to infer the geographic origin of translocated tortoises and found that individual heterozygosity predicted tortoise survival, whereas translocation distance or geographic unit of origin did not. Our results suggest a relatively simple indicator of the likelihood of a translocated individual’s survival: heterozygosity.

APA, Harvard, Vancouver, ISO, and other styles

16

Brown, D. R., J. L. Merritt, E. R. Jacobson, P. A. Klein, J. G. Tully, and M. B. Brown. "Mycoplasma testudineum sp. nov., from a desert tortoise (Gopherus agassizii) with upper respiratory tract disease." International Journal of Systematic and Evolutionary Microbiology 54, no. 5 (September 1, 2004): 1527–29. http://dx.doi.org/10.1099/ijs.0.63072-0.

Full text

Abstract:

Mycoplasma testudineum sp. nov., first cultured from the upper respiratory tract of a clinically ill tortoise (Gopherus agassizii) in the Mohave Desert, was distinguished from previously described mollicutes serologically and by 16S rRNA gene sequence comparisons. It lacks a cell wall; ferments glucose, mannose, lactose and sucrose; does not produce ‘film and spots’; does not hydrolyse arginine, aesculin or urea; is sensitive to digitonin; and lacks phosphatase activity. The organism causes chronic rhinitis and conjunctivitis of tortoises. The type strain of M. testudineum is BH29T (=ATCC 700618T=MCCM 03231T).

APA, Harvard, Vancouver, ISO, and other styles

17

Xiao, Lihua, Una M. Ryan, Thaddeus K. Graczyk, Josef Limor, Lixia Li, Mark Kombert, Randy Junge, et al. "Genetic Diversity of Cryptosporidium spp. in Captive Reptiles." Applied and Environmental Microbiology 70, no. 2 (February 2004): 891–99. http://dx.doi.org/10.1128/aem.70.2.891-899.2004.

Full text

Abstract:

ABSTRACT The genetic diversity of Cryptosporidium in reptiles was analyzed by PCR-restriction fragment length polymorphism and sequence analysis of the small subunit rRNA gene. A total of 123 samples were analyzed, of which 48 snake samples, 24 lizard samples, and 3 tortoise samples were positive for Cryptosporidium. Nine different types of Cryptosporidium were found, including Cryptosporidium serpentis, Cryptosporidium desert monitor genotype, Cryptosporidium muris, Cryptosporidium parvum bovine and mouse genotypes, one C. serpentis-like parasite in a lizard, two new Cryptosporidium spp. in snakes, and one new Cryptosporidium sp. in tortoises. C. serpentis and the desert monitor genotype were the most common parasites and were found in both snakes and lizards, whereas the C. muris and C. parvum parasites detected were probably the result of ingestion of infected rodents. Sequence and biologic characterizations indicated that the desert monitor genotype was Cryptosporidium saurophilum. Two host-adapted C. serpentis genotypes were found in snakes and lizards.

APA, Harvard, Vancouver, ISO, and other styles

18

Kampfer, Karen, and Jim Love. "Motivational Aspects of Desert Tortoise Caretaking." Anthrozoös 11, no. 2 (June 1998): 87–94. http://dx.doi.org/10.2752/089279398787000788.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Aiello, C. M., T. C. Esque, K. E. Nussear, P. G. Emblidge, and P. J. Hudson. "Associating sex-biased and seasonal behaviour with contact patterns and transmission risk in Gopherus agassizii." Behaviour 155, no. 7-9 (2018): 585–619. http://dx.doi.org/10.1163/1568539x-00003477.

Full text

Abstract:

Abstract Interactions between wildlife hosts act as transmission routes for directly transmitted pathogens and vary in ways that affect transmission efficiency. Identifying drivers of contact variation can allow both contact inference and estimation of transmission dynamics despite limited data. In desert tortoises, mating strategy, burrow use and seasonal change influence numerous behaviours and likely shape contact patterns. In this study, we ask to what extent tortoise contact behaviour varies between sexes and seasons, and whether space or burrow-use data can be used to infer contact characteristics consistent with those recorded by proximity loggers. We identified sex and season-biased contact behaviour in both wild and captive populations indicative of female-female avoidance and seasonal male mate-seeking behaviour. Space and burrow-use patterns were informative, but did not always predict the extent of sex or seasonal biases on contact. We discuss the implications these findings have for transmission patterns and disease mitigation in tortoise populations.

APA, Harvard, Vancouver, ISO, and other styles

20

Weitzman, Chava L., Franziska C. Sandmeier, and C. Richard Tracy. "Host species, pathogens and disease associated with divergent nasal microbial communities in tortoises." Royal Society Open Science 5, no. 10 (October 2018): 181068. http://dx.doi.org/10.1098/rsos.181068.

Full text

Abstract:

Diverse bacterial communities are found on every surface of macro-organisms, and they play important roles in maintaining normal physiological functions in their hosts. While the study of microbiomes has expanded with the influx of data enabled by recent technological advances, microbiome research in reptiles lags behind other organisms. We sequenced the nasal microbiomes in a sample of four North American tortoise species, and we found differing community compositions among tortoise species and sampling sites, with higher richness and diversity in Texas and Sonoran desert tortoises. Using these data, we investigated the prevalence and operational taxonomic unit (OTU) diversity of the potential pathogen Pasteurella testudinis and found it to be common, abundant and highly diverse. However, the presence of this bacterium was not associated with differences in bacterial community composition within host species. We also found that the presence of nasal discharge from tortoises at the time of sampling was associated with a decline in diversity and a change in microbiome composition, which we posit is due to the harsh epithelial environment associated with immune responses. Repeated sampling across seasons, and at different points of pathogen colonization, should contribute to our understanding of the causes and consequences of different bacterial communities in these long-lived hosts.

APA, Harvard, Vancouver, ISO, and other styles

21

Barraza-Guerrero, Sergio I., César A. Meza-Herrera, Cristina García-De la Peña, Vicente H. González-Álvarez, Felipe Vaca-Paniagua, Clara E. Díaz-Velásquez, Francisco Sánchez-Tortosa, Verónica Ávila-Rodríguez, Luis M. Valenzuela-Núñez, and Juan C. Herrera-Salazar. "General Microbiota of the Soft Tick Ornithodoros turicata Parasitizing the Bolson Tortoise (Gopherus flavomarginatus) in the Mapimi Biosphere Reserve, Mexico." Biology 9, no. 9 (September 5, 2020): 275. http://dx.doi.org/10.3390/biology9090275.

Full text

Abstract:

The general bacterial microbiota of the soft tick Ornithodoros turicata found on Bolson tortoises (Gopherus flavomarginatus) were analyzed using next generation sequencing. The main aims of the study were to establish the relative abundance of bacterial taxa in the tick, and to document the presence of potentially pathogenic species for this tortoise, other animals, and humans. The study was carried-out in the Mapimi Biosphere Reserve in the northern-arid part of Mexico. Bolson tortoises (n = 45) were inspected for the presence of soft ticks, from which 11 tortoises (24.4%) had ticks in low loads (1–3 ticks per individual). Tick pools (five adult ticks each) were analyzed through 16S rRNA V3–V4 region amplification in a MiSeq Illumina, using EzBioCloud as a taxonomical reference. The operational taxonomic units (OTUs) revealed 28 phyla, 84 classes, 165 orders, 342 families, 1013 genera, and 1326 species. The high number of taxa registered for O. turicata may be the result of the variety of hosts that this tick parasitizes as they live inside G. flavomarginatus burrows. While the most abundant phyla were Proteobacteria, Actinobacteria, and Firmicutes, the most abundant species were two endosymbionts of ticks (Midichloria-like and Coxiella-like). Two bacteria documented as pathogenic to Gopherus spp. were registered (Mycoplasma spp. and Pasteurella testudinis). The bovine and ovine tick-borne pathogens A. marginale and A. ovis, respectively, were recorded, as well as the zoonotic bacteria A. phagocytophilum,Coxiella burnetii, and Neoehrlichia sp. Tortoises parasitized with O. turicata did not show evident signs of disease, which could indicate a possible ecological role as a reservoir that has yet to be demonstrated. In fact, the defense mechanisms of this tortoise against the microorganisms transmitted by ticks during their feeding process are still unknown. Future studies on soft ticks should expand our knowledge about what components of the microbiota are notable across multiple host–microbe dynamics. Likewise, studies are required to better understand the host competence of this tortoise, considered the largest terrestrial reptile in North America distributed throughout the Chihuahuan Desert since the late Pleistocene.

APA, Harvard, Vancouver, ISO, and other styles

22

Walde, Andrew D., David K. Delaney, Meagan L. Harless, and Larry L. Pater. "OSTEOPHAGY BY THE DESERT TORTOISE (GOPHERUS AGASSIZII)." Southwestern Naturalist 52, no. 1 (March 2007): 147–49. http://dx.doi.org/10.1894/0038-4909(2007)52[147:obtdtg]2.0.co;2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Nussear, Kenneth E., Todd C. Esque, Dustin F. Haines, and C. Richard Tracy. "Desert Tortoise Hibernation: Temperatures, Timing, and Environment." Copeia 2007, no. 2 (May 2007): 378–86. http://dx.doi.org/10.1643/0045-8511(2007)7[378:dthtta]2.0.co;2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Alleman, Arthur R., Elliott R. Jacobson, and Rose E. Raskin. "Morphologic and cytochemical characteristics of blood cells from the desert tortoise (Gopherus agassizii)." American Journal of Veterinary Research 53, no. 9 (September 1, 1992): 1645–51. http://dx.doi.org/10.2460/ajvr.1992.53.09.1645.

Full text

Abstract:

SUMMARY Morphologic and cytochemical staining characteristics of erythrocytes, leukocytes, and thrombocytes of the desert tortoise (Gopherus agassizii) were evaluated, using blood smears prepared from 23 healthy tortoises of Kern County, Calif. Special emphasis was placed on differentiating features of the various leukocytes and thrombocytes. A variety of cytochemical stains, including benzidine peroxidase, Sudan black B, chloroacetate esterase, α-naphthyl butyrate esterase, acid phosphatase, leukocyte alkaline phosphatase, periodic acid-Schiff, and toluidine blue were used. Heterophils had a characteristic, large, focal area of positive staining with chloroacetate esterase, α-naphthyl butyrate esterase, and acid phosphatase. Eosinophils stained diffusely positive with benzidine peroxidase, allowing differentiation of this leukocyte from heterophils. Thrombocytes stained focally positive with periodic acid-Schiff, allowing differentiation of these cells from lymphocytes, which stained uniformly negative. An intracytoplasmic body, commonly observed within erythrocytes, was considered ultrastructurally to represent a degenerate organelle.

APA, Harvard, Vancouver, ISO, and other styles

25

Drake, K. Kristina, Todd C. Esque, Kenneth E. Nussear, Lesley A. Defalco, Sara J. Scoles-Sciulla, Andrew T. Modlin, and Philip A. Medica. "Desert tortoise use of burned habitat in the Eastern Mojave desert." Journal of Wildlife Management 79, no. 4 (April 2015): 618–29. http://dx.doi.org/10.1002/jwmg.874.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Dolby, Greer A., Matheo Morales, Timothy H. Webster, Dale F. DeNardo, Melissa A. Wilson, and Kenro Kusumi. "Discovery of a New TLR Gene and Gene Expansion Event through Improved Desert Tortoise Genome Assembly with Chromosome-Scale Scaffolds." Genome Biology and Evolution 12, no. 2 (February 1, 2020): 3917–25. http://dx.doi.org/10.1093/gbe/evaa016.

Full text

Abstract:

Abstract Toll-like receptors (TLRs) are a complex family of innate immune genes that are well characterized in mammals and birds but less well understood in nonavian sauropsids (reptiles). The advent of highly contiguous draft genomes of nonmodel organisms enables study of such gene families through analysis of synteny and sequence identity. Here, we analyze TLR genes from the genomes of 22 tetrapod species. Findings reveal a TLR8 gene expansion in crocodilians and turtles (TLR8B), and a second duplication (TLR8C) specifically within turtles, followed by pseudogenization of that gene in the nonfreshwater species (desert tortoise and green sea turtle). Additionally, the Mojave desert tortoise (Gopherus agassizii) has a stop codon in TLR8B (TLR8-1) that is polymorphic among conspecifics. Revised orthology further reveals a new TLR homolog, TLR21-like, which is exclusive to lizards, snakes, turtles, and crocodilians. These analyses were made possible by a new draft genome assembly of the desert tortoise (gopAga2.0), which used chromatin-based assembly to yield draft chromosomal scaffolds (L50 = 26 scaffolds, N50 = 28.36 Mb, longest scaffold = 107 Mb) and an enhanced de novo genome annotation with 25,469 genes. Our three-step approach to orthology curation and comparative analysis of TLR genes shows what new insights are possible using genome assemblies with chromosome-scale scaffolds that permit integration of synteny conservation data.

APA, Harvard, Vancouver, ISO, and other styles

27

Doak, Daniel, Peter Kareiva, and Brad Klepetka. "Modeling Population Viability for the Desert Tortoise in the Western Mojave Desert." Ecological Applications 4, no. 3 (August 1994): 446–60. http://dx.doi.org/10.2307/1941949.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Andersen, Mark C., Joseph M. Watts, Jerome E. Freilich, Stephen R. Yool, Gery I. Wakefield, John F. McCauley, and Peter B. Fahnestock. "REGRESSION-TREE MODELING OF DESERT TORTOISE HABITAT IN THE CENTRAL MOJAVE DESERT." Ecological Applications 10, no. 3 (June 2000): 890–900. http://dx.doi.org/10.1890/1051-0761(2000)010[0890:rtmodt]2.0.co;2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Grandmaison, David D., and Vincent J. Frary. "Estimating the probability of illegal desert tortoise collection in the Sonoran Desert." Journal of Wildlife Management 76, no. 2 (December 5, 2011): 262–68. http://dx.doi.org/10.1002/jwmg.299.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Jacobson, Elliot. "The Desert Tortoise and Upper Respiratory Tract Disease." Bulletin of the Association of Reptilian and Amphibian Veterinarians 4, no. 1 (January 1994): 6–7. http://dx.doi.org/10.5818/1076-3139.4.1.6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Johnson, Jay D., James L. Jarchow, and Roy Averill-Murray. "Captive Care of the Desert Tortoise, Gopherus agassizii." Journal of Herpetological Medicine and Surgery 11, no. 3 (January 2001): 16. http://dx.doi.org/10.5818/1529-9651.11.3.16.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Johnson, Jay D., Roy C. Averill-Murray, and James L. Jarchow. "Captive Care of the Desert Tortoise, Gopherus agassizii." Journal of Herpetological Medicine and Surgery 11, no. 3 (January 2001): 8–15. http://dx.doi.org/10.5818/1529-9651.11.3.8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Hagerty, Bridgette E., and C. Richard Tracy. "Defining population structure for the Mojave desert tortoise." Conservation Genetics 11, no. 5 (April 6, 2010): 1795–807. http://dx.doi.org/10.1007/s10592-010-0073-0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Abu-Seida, Ashraf, and Sherein Saeid. "Cutaneous adenocarcinoma in a desert tortoise (Gopherus agassizii)." International Journal of Veterinary Science and Medicine 1, no. 1 (June 2013): 48–50. http://dx.doi.org/10.1016/j.ijvsm.2013.05.002.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Peterson, Charles C. "Temporal, population, and sexual variation in hematocrit of free-living desert tortoises: correlational tests of causal hypotheses." Canadian Journal of Zoology 80, no. 3 (March 1, 2002): 461–70. http://dx.doi.org/10.1139/z02-021.

Full text

Abstract:

Hematocrit (packed cell volume, PCV) varies seasonally in some vertebrates and often differs between the sexes and among conspecific populations. Such variation in PCV may reflect variation in nutritional health, requirements for oxygen transport (metabolic rate), or hydration. The relative importance of these influences was tested with serial measurements of PCV in two Mojave Desert populations of the desert tortoise (Gopherus agassizii) over two activity seasons, during a period with large seasonal differences in availability of food and water. Hematocrit varied widely (range = 1440, CV = 20%), reflecting differences between populations, between sexes, between years, and over time within years. Causal hypotheses were tested by correlating PCV with physiological indicators of nutritional health (blood urea nitrogen), oxygen requirements (field metabolic rate), and hydration (length-relative mass, water-influx rate, urine osmolality, plasma sodium, and plasma osmolality). Results indicated a dominant influence of dehydration-induced hemoconcentration during this extreme drought period, although all correlations were relatively weak. Circumstantial evidence is marshalled to suggest longer term effects of nutrition (at seasonal, yearly, and population levels of variation) and perhaps oxygen requirements (driving sexual dimorphism). All these simultaneous and sometimes opposing effects interact in complex ways to produce the patterns of variation observed, and these interactions render PCV a poor indicator of physiological state in desert tortoises.

APA, Harvard, Vancouver, ISO, and other styles

36

Ravida, N., C. Young, L. Gokool, and B. S. Durrant. "113 DEVELOPING A CRYOPRESERVATION PROTOCOL FOR DESERT TORTOISE SPERM (GOPHERUS AGASSIZZII)." Reproduction, Fertility and Development 29, no. 1 (2017): 165. http://dx.doi.org/10.1071/rdv29n1ab113.

Full text

Abstract:

The desert tortoise (Gopherus agassizzii) is listed as threatened by the USA Fish and Wildlife Service and population declines continue to occur throughout most of their range. This species’ low reproductive rate, combined with the advanced age at which they reach sexual maturity, makes them vulnerable to multiple threats. Although assisted reproductive technologies can enhance breeding of many species, they are not widely used in tortoises. The objective of this study was to identify effective sperm cryopreservation protocols for the desert tortoise and possibly to other members of Testudinidae. We compared the effects of various concentrations of the cryoprotectants dimethyl sulfoxide (DMSO) and glycerol (6–20%) using 3 freezing devices at 4 freeze rates (CryoCooler, Ops Diagnostics, 2.3°C/m, 6.4°C/m; CryoMed, Thermo Scientific, 0.3°C/m or 1.0°C/m; and CoolCell, Biocision, 1.0°C/m) on several sperm parameters. Sperm was collected postmortem from the vas deferens of 9 individuals and tested either individually (n = 2), combined into 1 pool of 3 individuals, or 2 pools of 2 individuals. Sperm was extended in TEST-yolk buffer. Initial motility score (IMS; % motile × speed of progression2), plasma membrane integrity (IPL), and acrosome integrity (IAC) were recorded before cryoprotectant addition and freezing. For each treatment group, triplicate vials were thawed at 37°C for 60 s. Cryoprotectant was removed by centrifugation and the sperm pellet was resuspended in M199 + HEPES. Sperm were evaluated immediately following resuspension (T0), as well as 30 (T30) and 60 (T60) minutes postincubation at 22°C. All data were expressed as a percentage of initial (%IMS, %IPL, and %IAC). A sperm quality index (SQI) was calculated as (%IMS × %IPL × %IAC)/1,000, giving equal weight to each indicator of cryosurvival. The effects of freeze method on %IMS, %IPL, %IAC, and SQI were analysed by ANOVA and Tukey’s test. The effect of freeze method was significant at T0 and T60, with the 16% DMSO, 6.4°C/m method resulting in the highest %IMS at T0 (46.1%) and T30 (33.8%) and the 12% glyercol at 0.3°C/m highest at T60 (48.7%). Sperm frozen in 16% glycerol at 0.3°C/m had the highest %IPL at T0, T30, and T60 (91.9, 90.4, and 85.4%, respectively). Acrosome integrity was best maintained when sperm were frozen in 16% DMSO at 6.4°C/min (91.9%). The SQI was highest at T0 when sperm was frozen at 1.0°C/min in the CryoMed with highest post-thaw sperm parameters in 16% (T0) or 12% glycerol (T30 and T60). Interestingly, there were significant differences in SQI between the two 1.0°C/min freeze methods at each period, indicating that freezing device affected sperm cryosurvival, perhaps due to different freezing curves. This study indicates that mid-range (12 and 16%) cryoprotectant concentrations and slow freeze rates (0.3°C/m and 1.0°C/m) are optimal for desert tortoise sperm frozen in TEST-yolk buffer. Future studies will determine fertilizing capability of these sperm. These results may serve as a starting point for the study of sperm cryopreservation in other Testudinidae species.

APA, Harvard, Vancouver, ISO, and other styles

37

Schumacher, Isabella M., David C. Rostal, Rebecca A. Yates, Daniel R. Brown, Elliott R. Jacobson, and Paul A. Klein. "Persistence of maternal antibodies against Mycoplasma agassizii in desert tortoise hatchlings." American Journal of Veterinary Research 60, no. 7 (July 1, 1999): 826–31. http://dx.doi.org/10.2460/ajvr.1999.60.07.826.

Full text

Abstract:

Abstract Objective To investigate Mycoplasma agassizii-specific maternal antibodies in desert tortoise (Gopherus agassizii) hatchlings. Sample Population Plasma from 43 captive-reared desert tortoise hatchlings. Procedure ELISA for M agassizii-specific antibodies was performed. Four hatchlings from 4 clutches of 3 M agassizii-seropositive females with chronic upper respiratory tract disease (URTD) were tested on the day of hatching (set 1), and 20 hatchlings from 4 clutches of 4 M agassizii-seropositive females with URTD and 19 hatchlings from 4 M agassizii-seronegative healthy females were tested at 4, 8, 12, and 29 months old (set 2). Immunoblot analysis was performed to determine immunoglobulin classes in yolk and plasma of hatchlings. To determine infection status of hatchlings, yolk, egg shell membranes (set 1), and nasal lavage fluid (sets 1 and 2) were examined for M agassizii by use of polymerase chain reaction. Results Yolk and hatchling plasma had significantly lower amounts of specific antibodies than did plasma from adult females. The IgG and IgM antibodies were transferred, but M agassizii-specific antibodies were of the IgG class. Hatchlings were not infected with mycoplasmas. Offspring of sick females had significantly higher specific antibody titers than did offspring of healthy females. Titers were still significantly different in 1-year-old hatchlings. Conclusions Desert tortoise females transfer specific IgG and IgM antibodies to their offspring that are still detectable after 1 year. Clinical Relevance Infection with M agassizii may be misdiagnosed in hatchlings with persistent maternal antibodies. Passively acquired antibodies may have a role in pathogenesis of mycoplasma-induced respiratory tract disease and other diseases. (Am J Vet Res 1999;60:826–831)

APA, Harvard, Vancouver, ISO, and other styles

38

Esque, Todd C., Cecil R. Schwalbe, Lesley A. Defalco, Russell B. Duncan, and Timothy J. Hughes. "EFFECTS OF DESERT WILDFIRES ON DESERT TORTOISE (GOPHERUS AGASSIZII) AND OTHER SMALL VERTEBRATES." Southwestern Naturalist 48, no. 1 (March 2003): 103–11. http://dx.doi.org/10.1894/0038-4909(2003)048<0103:eodwod>2.0.co;2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Walde, Andrew D., Meagan L. Harless, David K. Delaney, and Larry L. Pater. "ANTHROPOGENIC THREAT TO THE DESERT TORTOISE (GOPHERUS AGASSIZII): LITTER IN THE MOJAVE DESERT." Western North American Naturalist 67, no. 1 (January 2007): 147–49. http://dx.doi.org/10.3398/1527-0904(2007)67[147:atttdt]2.0.co;2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Abdulkream, Awatif Farag Abdulsyid, and Yousef K. A. Abdalhafid. "CHANGES IN SERUM LEVELS OF TESTOSTERONE, TRIGLYCERIDES AND CHOLESTEROL, BEFORE DURING, AND AFTER HIBERNATION OF THE DESERT TORTOISE, TESTUDO GRAECA CYRENAICA." EPH - International Journal of Applied Science 2, no. 2 (June 27, 2016): 12–17. http://dx.doi.org/10.53555/eijas.v2i2.36.

Full text

Abstract:

In this study we examined the levels of testosterone, triglycerides and cholesterol, before during, and after hibernation of the Desert Tortoise .The results revealed that testosterone reached high level after hibernation when compared with the level during hibernation. On the other hand, triglycerides and cholesterol reached high levels during hibernation.

APA, Harvard, Vancouver, ISO, and other styles

41

Berry, Kristin H., Mary B. Brown, Mercy Vaughn, Timothy A. Gowan, Mary Ann Hasskamp, and Ma Cristina Meléndez Torres. "MYCOPLASMA AGASSIZIIIN MORAFKA'S DESERT TORTOISE (GOPHERUS MORAFKAI) IN MEXICO." Journal of Wildlife Diseases 51, no. 1 (January 2015): 89–100. http://dx.doi.org/10.7589/2014-04-083.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Mueller, James M., Kamila R. Sharp, Katherine K. Zander, Danny L. Rakestraw, Kurt R. Rautenstrauch, and Patrick E. Lederle. "Size-Specific Fecundity of the Desert Tortoise (Gopherus agassizii)." Journal of Herpetology 32, no. 3 (September 1998): 313. http://dx.doi.org/10.2307/1565443.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Nussear, Kenneth E., and C. Richard Tracy. "CAN MODELING IMPROVE ESTIMATION OF DESERT TORTOISE POPULATION DENSITIES?" Ecological Applications 17, no. 2 (March 2007): 579–86. http://dx.doi.org/10.1890/05-1970.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Drake, K. K., K. E. Nussear, T. C. Esque, A. M. Barber, K. M. Vittum, P. A. Medica, C. R. Tracy, and K. W. Hunter. "Does translocation influence physiological stress in the desert tortoise?" Animal Conservation 15, no. 6 (May 16, 2012): 560–70. http://dx.doi.org/10.1111/j.1469-1795.2012.00549.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Duda, Jeffrey J., Anthony J. Krzysik, and Jerome E. Freilich. "Effects of Drought on Desert Tortoise Movement and Activity." Journal of Wildlife Management 63, no. 4 (October 1999): 1181. http://dx.doi.org/10.2307/3802836.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Tuma, Michael W., Chris Millington, Nathan Schumaker, and Paul Burnett. "Modeling Agassiz's desert tortoise population response to anthropogenic stressors." Journal of Wildlife Management 80, no. 3 (February 6, 2016): 414–29. http://dx.doi.org/10.1002/jwmg.1044.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Johnson, A. J., D. J. Morafka, and E. R. Jacobson. "Seroprevalence of Mycoplasma agassizii and tortoise herpesvirus in captive desert tortoises (Gopherus agassizii) from the Greater Barstow Area, Mojave Desert, California." Journal of Arid Environments 67 (January 2006): 192–201. http://dx.doi.org/10.1016/j.jaridenv.2006.09.025.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Dutcher, Kirsten E., Kenneth E. Nussear, Jill S. Heaton, Todd C. Esque, and Amy G. Vandergast. "Move it or lose it: Predicted effects of culverts and population density on Mojave desert tortoise (Gopherus agassizii) connectivity." PLOS ONE 18, no. 9 (September 28, 2023): e0286820. http://dx.doi.org/10.1371/journal.pone.0286820.

Full text

Abstract:

Roadways and railways can reduce wildlife movements across landscapes, negatively impacting population connectivity. Connectivity may be improved by structures that allow safe passage across linear barriers, but connectivity could be adversely influenced by low population densities. The Mojave desert tortoise is threatened by habitat loss, fragmentation, and population declines. The tortoise continues to decline as disturbance increases across the Mojave Desert in the southwestern United States. While underground crossing structures, like hydrological culverts, have begun receiving attention, population density has not been considered in tortoise connectivity. Our work asks a novel question: How do culverts and population density affect connectivity and potentially drive genetic and demographic patterns? To explore the role of culverts and population density, we used agent-based spatially explicit forward-in-time simulations of gene flow. We constructed resistance surfaces with a range of barriers to movement and representative of tortoise habitat with anthropogenic disturbance. We predicted connectivity under variable population densities. Simulations were run for 200 non-overlapping generations (3400 years) with 30 replicates using 20 microsatellite loci. We evaluated population genetic structure and diversity and found that culverts would not entirely negate the effects of linear barriers, but gene flow improved. Our results also indicated that density is important for connectivity. Low densities resulted in declines regardless of the landscape barrier scenario (> 75% population census size, > 97% effective population size). Results from our simulation using current anthropogenic disturbance predicted decreased population connectivity over time. Genetic and demographic effects were detectable within five generations (85 years) following disturbance with estimated losses in effective population size of 69%. The pronounced declines in effective population size indicate this could be a useful monitoring metric. We suggest management strategies that improve connectivity, such as roadside fencing tied to culverts, conservation areas in a connected network, and development restricted to disturbed areas.

APA, Harvard, Vancouver, ISO, and other styles

49

Curtin, A. J., G. R. Zug, and J. R. Spotila. "Longevity and growth strategies of the desert tortoise (Gopherus agassizii) in two American deserts." Journal of Arid Environments 73, no. 4-5 (April 2009): 463–71. http://dx.doi.org/10.1016/j.jaridenv.2008.11.011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Rostal, David C., Valentine A. Lance, Janice S. Grumbles, and Allison C. Alberts. "Seasonal Reproductive Cycle of the Desert Tortoise (Gopherus agassizii) in the Eastern Mojave Desert." Herpetological Monographs 8 (1994): 72. http://dx.doi.org/10.2307/1467071.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!