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Jan A Randall - One of the best experts on this subject based on the ideXlab platform.

  • neighbor recognition in a solitary desert rodent Dipodomys merriami
    Ethology, 2010
    Co-Authors: Jan A Randall
    Abstract:

    Neighbor recognition in the Merriam’s kangaroo rat (Dzpodomys merrzamz) was tested in neighbor and nonneighbor pairs of the same and opposite sex in a large enclosure in the field. Mutual tolerance, rather than aggression, occurred in the encounters, and neighbor recognition was more apparent in females than in males. Females tolerated and engaged in nonagonistic contact with familiar males and females; males approached and attempted to contact neighbors and nonneighbors alike. Neighbor recognition is important to both spacing and mating in females. Males’ persistent attempts to interact with any conspecific may be important to their mating success.

  • species specific footdrumming in kangaroo rats Dipodomys ingens d deserti d spectabilis
    Animal Behaviour, 1997
    Co-Authors: Jan A Randall
    Abstract:

    Abstract Footdrumming was compared in three allopatric species of kangaroo rat, Dipodomys from three habitats. Analysis of footdrumming recordings revealed species-specific patterns of drumming ranging from single thumps to individual footdrumming signatures. The desert kangaroo rat, D. deserti drums single thumps spaced 0.25–0.30 s apart that are sometimes introduced with a short footroll. The giant kangaroo rat, D. ingens drums long footrolls that can average over 100 drums at 18 drums/s. The banner-tailed kangaroo rat, D. spectabilis drums three to 38 footdrums in a footroll combined into sequences of two to 12 footrolls at a rate of 17 drums/s. In playback tests, all three species stood in alert postures and entered the burrow in response to footdrumming of their own and the other species. The rats also responded in species-specific ways. Dipodomys spectabilis drummed to its own species’ footdrumming, but not to playbacks of the single drums of D. deserti Instead of footdrumming to playbacks of its own species, D. deserti approached the speaker more frequently than did either of the other two species. Dipodomys ingens footdrummed equally to all footdrumming playbacks. The species’ differences reflect differences in social tolerance and spacing. Dipodomys deserti rarely engages in footdrumming exchanges and chases visitors from the burrow. Dipodomys spectabilis engages in frequent footdrumming exchanges and some chases, and D. ingens seems to tolerate close neighbours and footdrums periodically.

  • why do kangaroo rats Dipodomys spectabilis footdrum at snakes
    Behavioral Ecology, 1997
    Co-Authors: Jan A Randall, Marjorie D Matocq
    Abstract:

    We examined alternative hypotheses for the benefits of footdrumming in the presence of snakes by the banner-tailed kangaroo rat, Dipodomys spectabilis, by testing whether the target of the signal includes conspecifics, the predator or both. Footdrumming recorded in the field revealed that rats altered their footdrumming signatures when drumming at snakes. In playback tests, however, neighbors failed to show any measurable change in behavior to broadcasts of die snake drumming pattern, but mothers •

  • discrimination of footdrumming signatures by kangaroo rats Dipodomys spectabilis
    Animal Behaviour, 1994
    Co-Authors: Jan A Randall
    Abstract:

    Abstract Abstract. Playback experiments were conducted to test whether banner-tailed kangaroo rats, Dipodomys spectabilis, use individually distinct footdrumming signatures to communicate identity to territorial neighbours. Responses of territory owners to playbacks of footdrumming signatures of neighbours and strangers that differed in at least one signal element were tested in a year in which population densities were low and then repeated in a year with higher densities. Territory owners footdrummed at higher rates in response to playbacks of a stranger than to playbacks of a neighbour in both years. They either drummed the same footdrumming pattern used during spontaneous territorial footdrumming and in the playback tests, or added extra footrolls to a footdrumming sequence during the playback. Juveniles exhibited the least consistency in drumming patterns in the two contexts. These results demonstrate that D. spectabilis discriminates the footdrumming signatures of neighbours and strangers and suggest that territorial footdrumming functions in neighbour recognition. Familiarity among neighbours promotes a stable social organization in this solitary, nocturnal rodent.

  • mating strategies of a nocturnal desert rodent Dipodomys spectabilis
    Behavioral Ecology and Sociobiology, 1991
    Co-Authors: Jan A Randall
    Abstract:

    The mating system of a nocturnal, desert rodent, the banner-tailed kangaroo rat (Dipodomys spectabilis) was studied through direct observation, live-trapping, and radiotelemetry over a 13-month period from August 1986 to August 1987. Mating behavior varied from exclusive matings between male and female neighbors to competitive mate searching and direct male competition. In summer matings and early in a November to May breeding season, males located receptive females and mated exclusively with them without disturbance from other males. As the operational sex ratio changed in favor of males, multiple males converged on an estrous female's territory and competed for access to her. However, an older, experienced male usually monopolized the matings of the same one to two close female neighbors for the entire breeding period, and females mated with the same male neighbor over several estrous cycles. Monopolization of females by neighbor males was facilitated by female relaxation of individual territorial defense. Dominant males spent considerable time in the territories of the females they monopolized before and during mating. This relaxation in territorial defense was seen in dyadic encounters in which females tolerated all males but allowed significantly more contact by neighbor than stranger males. Neighbor recognition, therefore, seems important in coordinating the mating interactions of this solitary rodent.

Tadeh Issaian - One of the best experts on this subject based on the ideXlab platform.

  • architecture of vasa recta in the renal inner medulla of the desert rodent Dipodomys merriami potential impact on the urine concentrating mechanism
    American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2012
    Co-Authors: Tadeh Issaian, Vinoo B Urity, William H Dantzler, Thomas L Pannabecker
    Abstract:

    We hypothesize that the inner medulla of the kangaroo rat Dipodomys merriami, a desert rodent that concentrates its urine to over 6,000 mosmol/kg H2O, provides unique examples of architectural feat...

  • three dimentional architecture of the renal inner medulla of the desert rodent Dipodomys merriami potential impact on the urinary concentrating mechanism
    The FASEB Journal, 2010
    Co-Authors: Tadeh Issaian
    Abstract:

    The objective of the following research project was to analyze the methods behind the urinary concentrating mechanism in Dipodomys merriami, Merriam’s kangaroo rat. We hypothesize that the inner medulla of Dipodomys merriami contains extreme examples of various architectural features as well as transport properties which enable it to produce concentrated urine at over 6000mOsm/Kg water. The three-dimensional architecture of the vasculature and nephron segments inside the renal inner medulla (IM) was assessed using digital reconstruction from tissue sections. Descending thin limbs (DTLs), ascending thin limbs (ATLs), collecting ducts (CDs), and ascending vasa recta (AVR) were identified with indirect immunofluorescence using antibodies and lectins that recognize segment-specific proteins associated with solute and water transport (AQP1, ClC-K1, and AQP2). Electron microscopy shows close contact between CDs, AVR, and ATLs at adherence areas. The CDs, AVR, and ATLs are sufficiently close together to form discrete interstitial compartments. This architectural arrangement and apparent isolation of these compartments raise questions regarding their function. One possibility is that lateral solute diffusion from ATLs and CDs into AVR could be preferentially restricted to these areas. Interstitial cell architecture, which could increase and define compartmentalization, may further restrict diffusive exchange.

Glenn E. Walsberg - One of the best experts on this subject based on the ideXlab platform.

  • IN A DESERT RODENT, Dipodomys MERRIAMI
    2020
    Co-Authors: Randall L. Tracy, Glenn E. Walsberg
    Abstract:

    A species' thermal and hydric environments may vary significantly through- out its range. However, geographic variation in physiological parameters related to water- saving ability has been largely ignored in mammals, even though there are dramatic dif- ferences among the environments in which many species exist. Heteromyid rodents long have been the focus of investigations concerning mammalian adaptations to severely des- iccating environments. Representatives of one widely distributed subspecies of Merriam's kangaroo rat, Dipodomys merriami merriami, were collected from three locations that differ in environmental temperatures and aridity. Mass, evaporative water loss, urine osmolality, rate of fractional body-mass loss, fecal water content, and metabolic rate were measured under desiccating conditions. Individuals from the most arid locality were smaller, possessed lower total and mass-specific evaporative water loss (EWL), and lost proportionately less mass under dehydrating conditions than those from less arid locations. These results indicate that EWL, but not kidney function or fecal water loss, is a trait associated with conserving water in this subspecies.

  • unappreciated tolerance to high ambient temperatures in a widely distributed desert rodent Dipodomys merriami
    Physiological and Biochemical Zoology, 2000
    Co-Authors: Randall L. Tracy, Glenn E. Walsberg
    Abstract:

    Abstract A long‐held assertion has been that nocturnality is an escape mechanism for many nocturnal desert rodents because of limited tolerances to heat. To test this claim, we used a treadmill to examine the tolerances to high ambient temperatures (Ta's) of one subspecies of desert rodent, Merriam’s kangaroo rat, Dipodomys merriami merriami, from contrasting environments. We simultaneously measured body temperature (Tb), evaporative water loss, and metabolic rates at an ecologically relevant speed (0.6 km h−1) at different ambient temperatures ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{...

Douglas A Kelt - One of the best experts on this subject based on the ideXlab platform.

  • differential responses of two species of kangaroo rat Dipodomys to heavy rains a humbling reappraisal
    Journal of Mammalogy, 2008
    Co-Authors: Douglas A Kelt, James A Wilson, Eddy S Konno, Jessica D Braswell, Douglas H Deutschman
    Abstract:

    Reanalysis of a recently published data set on the responses of 2 species of kangaroo rats to the 1997-1998 El Nino Southern Oscillation (ENSO) event revealed an error during data manipulation, and underscored the perils associated with electronic data storage, manipulation, and analyses. Renewed analyses revealed that Dipodomys simulans was not catastrophically impacted by the ENSO event. Both species were negatively impacted by 2 separate rainy periods, and both species appeared to recover rapidly. The rate of demographic recovery may be a function of habitat preferences. Dipodomys stephensi occurs in valley bottoms and recovered numerically only after cessation of rains, whereas D. simulans, which occurs on better-drained habitat in adjacent hill slopes, appeared to initiate demographic recovery half way through the rainy period associated with the 1998 ENSO. In contrast, however, D. simulans was not observed to recover for about 5 months after the rainy period in 2000.

  • keystone effects of the endangered stephens kangaroo rat Dipodomys stephensi
    Biological Conservation, 2004
    Co-Authors: Rachel E Brock, Douglas A Kelt
    Abstract:

    Abstract Kangaroo rats ( Dipodomys ) have been argued to exert keystone effects because they interact strongly with other species, and their removal results in major changes in community structure. We evaluated the nature and magnitude of such impacts by the endangered Stephens' kangaroo rat ( Dipodomys stephensi ), employing an exclosure experiment to determine how the removal of this species impacted relative cover by vegetation, plant species diversity, abundance of a dominant annual plant genus ( Erodium ), and predation of seeds from artificial trays. Fifteen months of D. stephensi removal resulted in significant increases in herb cover and Erodium abundance, and significant declines in bare ground and in seed predation. These results support the hypothesis that D. stephensi has major impacts on plant community structure and seems to function as a keystone species. It remains to be seen how the loss of this species from much of its range will influence local community composition and dynamics.

Thomas L Pannabecker - One of the best experts on this subject based on the ideXlab platform.