| fibre digestion and digesta retention time in guinea-pigs (cavia porcellus), degus (octodon degus) and leaf-eared mice (phyllotis darwini). | 1. digestibilities of feed and turnover time (1/k), transit time (tt) and mean retention time (mrt: 1/k + tt) of fluid and particle markers were measured in the guinea-pig (cavia porcellus), degu (octodon degus) and leaf-eared mouse (phyllotis darwini) fed a diet containing 50% alfalfa. 2. the digestibility of fibre and the retention time of digesta were highest in the guinea-pig followed by the degu and lowest in the leaf-eared mouse. 3. the difference in the retention time of digesta, resultin ... | 1992 | 1361900 |
| comparative water economy of sympatric rodents in a chilean semi-arid habitat. | 1. water requirements, water balance components and dependence on exogenous water were estimated in four species of sympatric rodents inhabiting a chilean semi-arid region. 2. a significant increase in free water drinking was observed in all rodents when the diet composition was changed from 14 to 20% protein. 3. under water balance conditions the cricetid species (phyllotis darwini, oryzomys longicaudatus and akodon olivaceus) showed 1.66 to 1.88 times the weight-specific daily water gain of oc ... | 1988 | 2907435 |
| effect of ambient temperature and energy demands on digestive functions in leaf-eared mice (phyllotis darwini) from central chile. | the leaf-eared mouse, phyllotis darwini, is a nocturnal rodent inhabiting the semiarid and mediterranean habitats of northern and central chile. previous observations suggested that in the field, individuals may change food intake according to seasonal changes in ambient temperature. we therefore anticipated that p. darwini should increase food intake in response to lower ambient temperature. as predicted, results of food trials and digestive measurements demonstrated that p. darwini increases f ... | 1997 | 9334571 |
| digestive plasticity and the cost of acclimation to dietary chemistry in the omnivorous leaf-eared mouse phyllotis darwini. | we examined the costs associated with acclimation in an omnivorous mouse (phyllotis darwini) fed two contrasting diets (carbohydrate-rich and protein-rich). we studied the response of gut morphology and digestive performance in animals shifted to a novel diet at different developmental stages. when acclimated adult animals were shifted to the alternative diet, energy digestibility decreased. we also found long-term consequences to diet acclimation. animals reacclimated for 15 days to an alternat ... | 2000 | 11083524 |
| audiograms of five species of rodents: implications for the evolution of hearing and the perception of pitch. | behavioral audiograms were determined for five species of rodents: groundhog (marmota monax), chipmunk (tamias striatus), darwin's leaf-eared mouse (phyllotis darwinii), golden hamster (mesocricetus auratus), and egyptian spiny mouse (acomys cahirinus). the high-frequency hearing of these animals was found to vary inversely with interaural distance, a typical mammalian pattern. with regard to low-frequency hearing, the animals fell into two groups: those with extended low-frequency hearing (chip ... | 2001 | 11470193 |
| population-level consequences of antipredator behavior: a metaphysiological model based on the functional ecology of the leaf-eared mouse. | we present a predator-prey metaphysiological model, based on the available behavioral and physiological information of the sigmodontine rodent phyllotis darwini. the model is focused on the population-level consequences of the antipredator behavior, performed by the rodent population, which is assumed to be an inducible response of predation avoidance. the decrease in vulnerability is explicitly considered to have two associated costs: a decreasing foraging success and an increasing metabolic lo ... | 2002 | 12056865 |
| dynamic thermal balance in the leaf-eared mouse: the interplay among ambient temperature, body size, and behavior. | endotherms maintain constant body temperature through physiological and behavioral adjustments. behavioral thermoregulation is an important factor influencing energy balance. we exposed the leaf-eared mouse, phyllotis darwini, to temperatures corresponding to its natural thermal range and studied two forms of behavioral thermoregulation: diminishing surface to volume ratio by huddling and heat dissipation by increasing physical contact with the substrate (flattening). we predicted that at low am ... | 2002 | 12324896 |
| body size as a latent variable in a structural equation model: thermal acclimation and energetics of the leaf-eared mouse. | body size is one of the most important determinants of energy metabolism in mammals. however, the usual physiological variables measured to characterize energy metabolism and heat dissipation in endotherms are strongly affected by thermal acclimation, and are also correlated among themselves. in addition to choosing the appropriate measurement of body size, these problems create additional complications when analyzing the relationships among physiological variables such as basal metabolism, non- ... | 2003 | 12771164 |
| heritability of energetics in a wild mammal, the leaf-eared mouse (phyllotis darwini). | as a first examination of the additive genetic variance of thermoregulatory traits in a natural population of endotherms, we studied the quantitative genetics of key physiological ecology traits in the leaf-eared mouse, phyllotis darwini. we measured basal metabolic rate (bmr), nonshivering thermogenesis (nst), maximum metabolic rate for thermoregulation (mmr), thermal conductance (ct), body temperature (tb), and factorial aerobic scope (fas) in individuals acclimated to cold and warm conditions ... | 2003 | 12940370 |
| population dynamics of small mammals in semi-arid regions: a comparative study of demographic variability in two rodent species. | the seasonally determined demographic structure of two semi-arid rodents, both agricultural pest species (the leaf-eared mouse (phyllotis darwini) in chile and the multimammate mouse (mastomys natalensis) in tanzania), is analysed using capture-mark-recapture (cmr) statistical models and measures for elasticity (the relative change in the growth rate due to a relative unit change in the parameter of concern) derived from projection linear matrix models. we demonstrate that reproduction and survi ... | 2003 | 14561287 |
| phenotypic flexibility in a novel thermal environment: phylogenetic inertia in thermogenic capacity and evolutionary adaptation in organ size. | the goal of our work was to understand the role of a novel thermal environment in shaping the phenotypic expression of thermogenic capacity and organ size. to examine this we compared two populations of the south american rodent phyllotis darwini from different altitudes (andean and valley populations), taking advantage of the fact that this genus originated at high altitude in the andean plateau. dna mitochondrial analysis showed that the two populations were separated and then experienced diff ... | 2004 | 15547798 |
| dynamic digestive responses to increased energy demands in the leaf-eared mouse (phyllotis darwini). | a major area of interest in comparative physiology has been to understand how animals cope with changing environmental demands in time and space. the digestive system has been identified as one of the more sensitive systems to changes in environmental conditions. however, most research on this topic has evaluated these effects during peak energetic demands, which do not allow for evaluation of the dynamics of the digestive response along a more natural continuous gradient of environmental condit ... | 2005 | 15565308 |
| phenotypic flexibility at the molecular and organismal level allows desert-dwelling rodents to cope with seasonal water availability. | we examined the phenotypic flexibility of field urine osmolality (uosm) in response to seasonal rainfall and the experimental expression of renal aquaporins (aqps) in the leaf-eared mouse phyllotis darwini, a south american desert-dwelling rodent, through an integrative study at both the cellular and the organismal level. field uosm was higher in summer than in winter. fall and winter uosm were not significantly different. during a rainy year, winter uosm was 2,140 +/- 82.3 mosm kg(-1); the corr ... | 2005 | 15778934 |
| short report: trypanosoma cruzi infection in wild mammals from a chagasic area of chile. | we report results of pcr-dna based detection of trypanosoma cruzi in wild mammal reservoirs from a chagasic area of chile. we analyzed 157 blood samples from wild mammals including the marsupial thylamis elegans and the rodents octodon degus, phyllotis darwini, and abrothrix olivaceus. in addition, 42 blood samples from goats (i.e., a peridomestic mammal) were analyzed. blood samples were used to extract dna, and pcr was performed using the amplification of minicircle dna sequences. southern ana ... | 2005 | 16172474 |
| quantitative genetics of bioenergetics and growth-related traits in the wild mammal, phyllotis darwini. | we studied the potential for response to selection in typical physiological-thermoregulatory traits of mammals such as maximum metabolic rate (mmr), nonshivering thermogenesis (nst) and basal metabolic rate (bmr) on cold-acclimated animals. we used an animal model approach to estimate both narrow-sense heritabilities (h2) and genetic correlations between physiological and growth-related traits. univariate analyses showed that mmr presented high, significant heritability (h2 = 0.69 +/- 0.35, asym ... | 2005 | 16329249 |
| intraspecific variability in the basal metabolic rate: testing the food habits hypothesis. | several competing hypotheses attempt to explain how environmental conditions affect mass-independent basal metabolic rate (bmr) in mammals. one of the most inclusive and yet debatable hypotheses is the one that associates bmr with food habits, including habitat productivity. these effects have been widely investigated at the interspecific level under the assumption that for any given species all traits are fixed. consequently, the variation among individuals is largely ignored. intraspecific ana ... | 2007 | 17508340 |
| phenotypic integration of morphology and energetic performance under routine capacities: a study in the leaf-eared mouse phyllotis darwini. | a major goal of evolutionary physiology is to understand the intrinsic and the extrinsic factors that impose limitations on an animal's energy budget. although natural selection acts upon organismal traits such as performance (e.g., burst, sustained metabolic rates), from a mechanistic perspective, organismal performance results from the integrated functioning of different levels of biological organization. hence, a better understanding of whole-animal performance must necessarily incorporate an ... | 2010 | 19820952 |
| american tripanosomiasis: a study on the prevalence of trypanosoma cruzi and trypanosoma cruzi-like organisms in wild rodents in san luis province, argentina. | chagas disease is caused by trypanosoma cruzi. wild and perianthropic mammals maintain the infection/transmission cycle, both in their natural habitat and in the peridomestic area. the aim of this paper was to present the results from a study on wild rodents in the central and northern regions of san luis province, argentina, in order to evaluate the prevalence of this infection. | 2010 | 20563490 |
| symmorphosis in the proximal pathway for oxygen in the leaf-eared mouse phyllotis darwini. | in this report, we explore the matching of structures to functional needs by comparing previously reported data of maximal oxygen consumption and the development of the lung in the leaf-eared mouse phyllotis darwini in warm and cold environments. we discuss whether the state of structural design is commensurate with functional needs from regulated morphogenesis as predicted by the hypothesis of symmorphosis. we found a close match between respiratory structures and functional needs during postna ... | 2010 | 21157634 |
| feeding profile of mepraia spinolai, a sylvatic vector of chagas disease in chile. | american trypanosomiasis is a chronic disease transmitted mainly by vectors. the hematophagous triatomine vectors transmit trypanosoma cruzi to a wide variety of mammals, which usually are their food source. this study determined the feeding profile of mepraia spinolai, a sylvatic triatomine vector, present in endemic areas of chile. vectors were captured in the north-central area of chile. samples of intestinal contents were analyzed by an enzyme-linked immunosorbent assay (elisa) that identifi ... | 2016 | 27349188 |
| effects of mammal host diversity and density on the infection level of trypanosoma cruzi in sylvatic kissing bugs. | several reports have described host species diversity and identity as the most important factors influencing disease risk, producing either dilution or amplification of the pathogen in a host community. triatomine vectors, mammals and the protozoan trypanosoma cruzi (trypanosomatida: trypanosomatidae) chagas are involved in the wild cycle of chagas disease, in which infection of mammals occurs by contamination of mucous membranes or skin abrasions with insect-infected faeces. we examined the ext ... | 2014 | 24844934 |
| diet, dietary selectivity and density of south american grey fox, lycalopex griseus, in central chile. | the south american grey fox (lycalopex griseus) is a canid widely distributed in southern south america, however some aspects of its biology are still poorly known. we studied the diet and density of l. griseus in the lago peñuelas biosphere reserve, in central chile. the trophic niche breadth was b = 6.16 (bsta = 0.47) and prey diversity was h ' = 2.46 (hmax' = 3.17, j' = 0.78). the highest proportions of prey consumed in the diet were oryctolagus cuniculus (52.21%) and other mammals (32.78%). ... | 2017 | 28262006 |
| fruit size determines the role of three scatter-hoarding rodents as dispersers or seed predators of a fleshy-fruited atacama desert shrub. | scatter-hoarding rodents can act as both predators and dispersers for many large-seeded plants because they cache seeds for future use, but occasionally forget them in sites with high survival and establishment probabilities. the most important fruit or seed trait influencing rodent foraging behavior is seed size; rodents prefer large seeds because they have higher nutritional content, but this preference can be counterbalanced by the higher costs of handling larger seeds. we designed a cafeteri ... | 2016 | 27861550 |
| numerical and functional response of predators to a long-term decline in mammalian prey at a semi-arid neotropical site. | occurrence and diet of ten carnivorous predators (four falconiforms, four owls, and two foxes), and population levels of their mammalian prey, were monitored over 45 months at a semi-arid site in north-central chile. early in this period, small mammals irrupted and then declined markedly to a density 7% of that at peak. all four falconiforms (buteo polyosoma, falco sparverius, geranoaetus melanoleucus, parabuteo unicinctus) and one owl (tyto alba) responded numerically to the decline in mammalia ... | 1992 | 28313400 |
| mountaintops phylogeography: a case study using small mammals from the andes and the coast of central chile. | we evaluated if two sigmodontine rodent taxa (abrothrix olivacea and phyllotis darwini) from the andes and coastal mountaintops of central chile, experienced distributional shifts due to altitudinal movements of habitat and climate change during and after the last glacial maximum (lgm). we tested the hypothesis that during lgm populations of both species experienced altitudinal shifts from the andes to the lowlands and the coastal cordillera, and then range retractions during interglacial toward ... | 2017 | 28672032 |
| natural infection of leptospira species in the native rodents degu ( octodon degus ) and darwin's pericote ( phyllotis darwini ) in mediterranean ecosystem of chile. | we report natural infections by pathogenic leptospira of two rodent species endemic to chile: the degu ( octodon degus ) and darwin's pericote ( phyllotis darwini ). we detected leptospira dna in kidney and urine samples taken in different years and sites, reaching 33% infection. the effects of infection in these species requires further evaluation. | 2017 | 28328351 |
| population dynamics of two sympatric rodents in a variable environment: rainfall, resource availability, and predation. | precipitation plays an important role in the dynamics of species found in arid and semiarid environments. however, population fluctuations generally are driven by a combination of multiple factors whose relative contribution may vary through time and among species. we monitored fluctuations of species in three trophic levels for >17 years at a semiarid community in north-central chile. the region is strongly affected by the el niño southern oscillation, resulting in high variation in rainfall th ... | 2009 | 19694146 |
| test of the adaptive modulation hypothesis in rodents: dietary flexibility and enzyme plasticity. | the phenotypic response of digestive enzymes was assessed in two species of rodents with different foods habits. species were phyllotis darwini (omnivorous) and octodon degus (herbivorous). the activity of sucrase, maltase and aminopeptidase-n were determined in vitro in animals feeding two contrasting diets. no effect of dietary chemistry on sucrase and maltase activities was observed. nevertheless, aminopeptidase-n showed a reversible response to diet in p. darwini but not in o. degus. through ... | 1999 | 10425731 |
| early life experience drives short-term acclimation of metabolic and osmoregulatory traits in the leaf-eared mouse. | we studied the putative effect of early life experience on the physiological flexibility of metabolic and osmoregulatory traits in the leaf-eared mouse, phyllotis darwini, an altricial rodent inhabiting seasonal mediterranean environments. adult individuals were collected in central chile and maintained in breeding pairs. pups were isolated after weaning and acclimated to different temperatures (cold or warm) and water availability (unrestricted and restricted) until adulthood. subsequently, ind ... | 2017 | 28495870 |
| is maximum food intake in endotherms constrained by net or factorial aerobic scope? lessons from the leaf-eared mouse. | food availability varies substantially throughout animals' lifespans, thus the ability to profit from high food levels may directly influence animal fitness. studies exploring the link between basal metabolic rate (bmr), growth, reproduction, and other fitness traits have shown varying relationships in terms of both magnitude and direction. the diversity of results has led to the hypothesis that these relationships are modulated by environmental conditions (e.g., food availability), suggesting t ... | 2016 | 28082915 |
| integrating phylogeography and species distribution models: cryptic distributional responses to past climate change in an endemic rodent from the central chile hotspot. | biodiversity losses under the species level may have been severely underestimated in future global climate change scenarios. therefore, it is important to characterize the diversity units at this level, as well as to understand their ecological responses to climatic forcings. we have chosen an endemic rodent from a highly endangered ecogeographic area as a model to look for distributional responses below the species level: phyllotis darwini. | 2016 | 27453686 |
| the influence of heat increment of feeding on basal metabolic rate in phyllotis darwini (muridae). | one of the most important prerequisites for obtaining a reliable measure of basal metabolic rate (bmr) in endotherms is that the animal must be in a post-absorptive condition. however, because of the diversity of nutrition and digestion modes in vertebrates, it is not simple to generalize a standard procedure for bmr measurement. thus, information in this regard must be experimentally obtained by measuring the heat increment of feeding (hif). we used a repeated-measures design to test for the ef ... | 2003 | 12507617 |
| genomic compatibility between two phyllotine rodent species evaluated through their hybrids. | in order to investigate the genomic compatibility between allopatric rodent species, phyllotis darwini and phyllotis magister, we have studied several cytogenetic and reproductive features of their laboratory hybrids. of thirty-one pairings between species, only five were successful, producing eleven newborns. like parents, hybrids had 38 metacentric chromosomes, except for the subtelocentric y chromosome inherited from p. magister. there was almost total c and g band correspondence between home ... | 1999 | 10783533 |
| population extinction risks of three neotropical small mammal species. | the population persistence and extinction probabilities of three small mammal species were analyzed by estimating growth and extinction properties obtained from 10 years of live-trapping data at two different habitat types in semiarid chile. we used a stochastic formulation with an exponential growth model known as a wiener-drift process, out of which growth and extinction quantities were estimated. the rodent phyllotis darwini showed the lowest rates of growth, and the lowest infinitesimal vari ... | 1998 | 28308442 |
| phylogenetic analysis of phenotypic covariance structure. i. contrasting results from matrix correlation and common principal component analyses. | applications of quantitative techniques to understanding macroevolutionary patterns typically assume that genetic variances and covariances remain constant. that assumption is tested among 28 populations of the phyllotis darwini species group (leaf-eared mice). phenotypic covariances are used as a surrogate for genetic covariances to allow much greater phylogenetic sampling. two new approaches are applied that extend the comparative method to multivariate data. the efficacy of these techniques a ... | 1997 | 28565369 |
| genome size variation and its phenotypic consequences in phyllotis rodents. | constitutive heterochromatin and genome size were studied in phyllotis darwini, three phyllotis xanthopygus subspecies, and their interspecific laboratory hybrids. p. darwini, with no or only small c-bands, had the smallest genome size; p. xanthopygus rupestris and p. x. vaccarum, with large c-bands in all the chromosomes, had the largest; and p. x. xanthopygus, with heterochromatin only in a few chromosomes, showed intermediate genome size. to examine some phenotypic consequences of nuclear dna ... | 1991 | 1810909 |
| analysis of pore-rich areas on the nuclear envelope of spermatocytes. | serial sections analysis of spermatocytes of the rodent phyllotis darwini, reveal a persistent positional relationship between nucleolar material and centrioles. pore rich areas interposed between these nucleocytoplasmic components, are represented graphically. centriole replication takes place during the pachytene stage. pore rich areas could be the result of a preferential aggregational process which insures the exchange of information between nuclear and cytoplasmic regions. | 1984 | 6234960 |
| granular pneumocytes and altitude: a stereological evaluation. | stereological analysis demonstrates that the granular pneumocytes of mice native to high altitude (4660 m) are significantly larger than those of the same species (phyllotis darwini) living at sea level. such cells have larger nuclei and a significantly greater volume of mitochondria. there are both more and larger lamellar bodies in high altitude granular pneumocytes, resulting in about four times more surfactant per cell at high altitude. | 1979 | 527011 |
| a stereological analysis of the ultrastructure of the lungs of wild mice living at low and high altitude. | stereological analysis of the ultrastructural composition of the pulmonary alveolo-capillary region of mice living at sea level compared with that of the same species (phyllotis darwini) genetically adapted to life at 4,660 m reveals a trend at high altitude towards a greater volume percentage of tissue components. on a weight-specific basis, non-circulating tissue occupies a significantly greater volume in high-altitude mice, but air space and capillary contents are not correspondingly greater. ... | 1976 | 978747 |
| trypanosoma cruzi load in synanthropic rodents from rural areas in chile. | trypanosoma cruzi is the agent of chagas disease, a major public health problem in latin america. many wild and domestic animals are naturally infected with t. cruzi; rodents are one of the groups which have been consistently detected infected in different countries. the aim of this work was to characterize blood t. cruzi load in naturally infected rodents from a chagas disease endemic region in chile. | 2018 | 29530074 |
| helminthic infection in three native rodent species from a semiarid mediterranean ecosystem. | helminth parasites are still not a well-known component of animal biodiversity. in this study, we describe and compare the endoparasite assemblages of three native rodent species from a semiarid mediterranean ecosystem. a total of eight species of gastrointestinal helminth parasites were detected. the endoparasitic communities of the rodents phyllotis darwini (5 species), octodon degus (4 species), and abrothrix olivaceus (3 species) were described in terms of their prevalence and mean abundance ... | 2019 | 30916258 |
| morphometric variation of androlaelaps fahrenholzi (mesostigmata: laelapidae) associated with three sigmodontinae (rodentia: cricetidae) from the north of chile. | androlaelaps fahrenholzi is a mite with a large distribution and associated with a wide range of hosts. to assess morphometric variation of a. fahrenholzi associated with different host species (phyllotis xanthopygus and akodon albiventer, both from putre, chile) and localities (las chinchillas national reserve, fray jorge national park, and llanos de challe national park, all in chile and all from the host phyllotis darwini), 41 morphological characters of each specimen were measured, and princ ... | 2020 | 32285240 |
| el niño-southern oscillation-driven rainfall variability and delayed density dependence cause rodent outbreaks in western south america: linking demography and population dynamics. | it is well known that some rodent populations display dramatic density fluctuations in semiarid regions of western south america after the unusual rainfall levels associated with el niño-southern oscillation (enso) disturbances. these correlated phenomena have led some ecologists to believe that rodent outbreaks are determined solely by density-independent factors (e.g., rainfall regime). however, demographic studies have detected strong delayed density-dependent effects in one of the most irrup ... | 1999 | 29578796 |