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Šumbera R, Lövy M, Nevo E, Okrouhlík J. Thermal biology in the Upper Galili Mountain blind mole rat (Nannospalax galili) and an overview of spalacine energetics. J Therm Biol 2023; 115:103618. [PMID: 37399744 DOI: 10.1016/j.jtherbio.2023.103618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/26/2023] [Accepted: 06/09/2023] [Indexed: 07/05/2023]
Abstract
Several hundred mammalian species thrive in complex burrow systems, which protect them from climatic extremes and predation. At the same time, it is also a stressful environment due to low food supply, high humidity, and, in some cases, a hypoxic and hypercapnic atmosphere. To face such conditions, subterranean rodents have convergently evolved low basal metabolic rate, high minimal thermal conductance and low body temperature. Although these parameters have been intensively studied in the last decades, such information is far from being well-known in one of the most studied groups of subterranean rodents, the blind mole rats of the genus Nannospalax. The lack of information is particularly noticeable for parameters such as the upper critical temperature and the width of the thermoneutral zone. In our study, we analysed the energetics of the Upper Galilee Mountain blind mole rat Nannospalax galili and found its basal metabolic rate of 0.84 ± 0.10 mL O2×g-1 × h-1, thermoneutral zone between 28 and 35 °C, mean Tb within the zone of 36.3 ± 0.6 °C, and minimal thermal conductance equal to 0.082 mL O2×g-1 × h-1 × C-1. Nannospalax galili is a truly homeothermic rodent well adapted to face lower ambient temperatures, because its Tb was stable down to the lowest temperature measured (10 °C). At the same time, a relatively high basal metabolic rate and relatively low minimal thermal conductance for a subterranean rodent of such body mass, and the difficulty of surviving ambient temperatures slightly above upper critical temperature, indicates problems with sufficient heat dissipation at higher temperatures. This can easily lead to overheating, that is relevant mainly during the hot-dry season. These findings suggest that N. galili can be threatened by ongoing global climate change.
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Affiliation(s)
- Radim Šumbera
- Department of Zoology, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic.
| | - Matěj Lövy
- Department of Zoology, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
| | - Eviatar Nevo
- Institute of Evolution, University of Haifa, 3498838, Haifa, Israel
| | - Jan Okrouhlík
- Department of Zoology, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
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Luna F, Sastre-Serra J, Oliver J, Antenucci CD. Growing underground: Development of thermogenesis in pups of the fossorial rodent Ctenomys talarum. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1120415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023] Open
Abstract
In mammals, during the pup’s development and adult life, integrated requirements of all activities of the individual must conform to a sustained rate of metabolism. Thus, partitioning the available energy according to short-term priorities at a specific moment allows animals to survive and optimize long-term reproductive success. In altricial rodents, thermal balance is a key factor for survival. When no exogenous source of heat is present, altricial pups rapidly lose heat, reaching ambient temperature (Ta). Fossorial rodents showed a strong dependence on burrows, where Ta remains relatively stable within narrow ranges. Pups of the fossorial rodent Ctenomys talarum are altricial, making them an excellent model to evaluate the development of thermogenic capacity. In this study, the ontogeny of the thermogenic capacity of pups of C. talarum was evaluated. Using respirometry techniques, non-shivering thermogenesis (NST), total thermogenic capacity (cold-induced maximum metabolic rate, MMR), and resting metabolic rate (RMR) in pups until post-weaning age (day 60) were analyzed. No NST was present in pups until day 60 despite the presence of molecular markers for NST in brown adipose tissue deposits, which became functional in adults. Although pups are altricial at birth, they maintain their thermal balance behaviorally during lactation. Total thermogenic capacity became fixed at an early age, indicating an improvement in shivering thermogenesis (ST) efficiency after day 10, which might be related to the development of musculature related to digging. Before the aboveground dispersal period (~day 60), pups gradually reached adult Tb by improving ST and thermal isolation, allowing them to confront climatic fluctuations on the surface.
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Digestive Tract Morphology and Gut Microbiota Jointly Determine an Efficient Digestive Strategy in Subterranean Rodents: Plateau Zokor. Animals (Basel) 2022; 12:ani12162155. [PMID: 36009744 PMCID: PMC9404879 DOI: 10.3390/ani12162155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 08/08/2022] [Accepted: 08/17/2022] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Investigation of mechanistic insights of digestive strategies in rodents can be difficult, but it is important to understand how rodents adapt to different environments. Applying physiological analyses to compare the differences between digestive tracts in plateau zokor and laboratory rats, we found that the length and weight of the digestive tract of the plateau zokor was significantly greater than the laboratory rat. Particularly, the weight and length of the large intestine and cecum in plateau zokor is three times that of the laboratory rat. Our gut microbiota analysis results showed that bacteria associated with cellulose degradation were significantly enriched in laboratory rats, when compared to plateau zokor. However, both plateau zokor and laboratory rats were predicted to share the same functions in carbohydrate metabolism and energy metabolism. Our findings suggest that both the morphology of the digestive tract and gut microbiota are vital to the digestion in wild rodents. Abstract Rodents’ lifestyles vary in different environments, and to adapt to various lifestyles specific digestion strategies have been developed. Among these strategies, the morphology of the digestive tracts and the gut microbiota are considered to play the most important roles in such adaptations. However, how subterranean rodents adapt to extreme environments through regulating gut microbial diversity and morphology of the digestive tract has yet to be fully studied. Here, we conducted the comparisons of the gastrointestinal morphology, food intake, food assimilation, food digestibility and gut microbiota of plateau zokor Eospalax baileyi in Qinghai-Tibet Plateau and laboratory rats Rattus norvegicus to further understand the survival strategy in a typical subterranean rodent species endemic to the Qinghai-Tibet Plateau. Our results revealed that plateau zokor evolved an efficient foraging strategy with low food intake, high food digestibility, and ultimately achieved a similar amount of food assimilation to laboratory rats. The length and weight of the digestive tract of the plateau zokor was significantly higher than the laboratory rat. Particularly, the weight and length of the large intestine and cecum in plateau zokor is three times greater than that of the laboratory rat. Microbiome analysis showed that genus (i.e., Prevotella, Oscillospira, CF231, Ruminococcus and Bacteroides), which are usually associated with cellulose degradation, were significantly enriched in laboratory rats, compared to plateau zokor. However, prediction of metagenomic function revealed that both plateau zokor and laboratory rats shared the same functions in carbohydrate metabolism and energy metabolism. The higher digestibility of crude fiber in plateau zokor was mainly driven by the sizes of cecum and cecum tract, as well as those gut microbiota which associated with cellulose degradation. Altogether, our results highlight that both gut microbiota and the morphology of the digestive tract are vital to the digestion in wild rodents.
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Cutrera AP, Luna F, Zenuto RR. Acute-Phase Immune Response Involves Fever, Sickness Behavior, and an Elevated Metabolic Rate in the Subterranean Rodent Ctenomys talarum. Physiol Biochem Zool 2022; 95:183-199. [PMID: 35148257 DOI: 10.1086/718409] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
AbstractThe acute-phase response (APR) is an induced innate response and may involve pronounced physiological and behavioral changes. One of the most common assays to study the APR involves the use of a lypopolysaccharide (LPS) from the cell wall of gram-negative bacteria. In this study, we determined the energetic costs of the APR in the subterranean rodent Ctenomys talarum, as well as the effects of the exposure to LPS on body temperature, body mass loss, and behavior in this species. Furthermore, we monitored levels of circulating endotoxin after LPS exposure. Our results suggest that in C. talarum, the APR is energetically costly, resulting in a 14% increase in metabolic rate. Animals exposed to LPS experienced a short-term thermal response, weight loss, and changes in their behavior that included more time spent resting and with their eyes totally or partially closed. However, the magnitude of the effects of LPS exposure varied between sexes and among animals. Also, there was a clear peak in circulating endotoxin levels in plasma 3 h postinjection (hpi) and a significant decrease of these levels 24 hpi, but peak endotoxin concentration values recorded were highly variable among animals. In light of these results, ecological determinants of immune function variation in tuco-tucos are discussed considering the roles of pace of life, habitat, and degree of pathogen exposure in these subterranean rodents.
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Vejmělka F, Okrouhlík J, Lövy M, Šaffa G, Nevo E, Bennett NC, Šumbera R. Heat dissipation in subterranean rodents: the role of body region and social organisation. Sci Rep 2021; 11:2029. [PMID: 33479351 PMCID: PMC7820455 DOI: 10.1038/s41598-021-81404-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 12/30/2020] [Indexed: 01/29/2023] Open
Abstract
The relatively warm and very humid environment of burrows presents a challenge for thermoregulation of its mammalian inhabitants. It was found that African mole-rats dissipate body heat mainly through their venter, and social mole-rats dissipate more body heat compared to solitary species at lower temperatures. In addition, the pattern of the ventral surface temperature was suggested to be homogeneous in social mole-rats compared to a heterogeneous pattern in solitary mole-rats. To investigate this for subterranean rodents generally, we measured the surface temperatures of seven species with different degrees of sociality, phylogeny, and climate using infrared thermography. In all species, heat dissipation occurred mainly through the venter and the feet. Whereas the feet dissipated body heat at higher ambient temperatures and conserved it at lower ambient temperatures, the ventral surface temperature was relatively high in all temperatures indicating that heat dissipation to the environment through this body region is regulated mainly by behavioural means. Solitary species dissipated less heat through their dorsum than social species, and a tendency for this pattern was observed for the venter. The pattern of heterogeneity of surface temperature through the venter was not related to sociality of the various species. Our results demonstrate a general pattern of body heat exchange through the three studied body regions in subterranean rodents. Besides, isolated individuals of social species are less able to defend themselves against low ambient temperatures, which may handicap them if staying alone for a longer period, such as during and after dispersal events.
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Affiliation(s)
- František Vejmělka
- Department of Zoology, Faculty of Science, University of South Bohemia, 370 05, České Budějovice, Czech Republic
| | - Jan Okrouhlík
- Department of Zoology, Faculty of Science, University of South Bohemia, 370 05, České Budějovice, Czech Republic
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Pretoria, 0002, South Africa
| | - Matěj Lövy
- Department of Zoology, Faculty of Science, University of South Bohemia, 370 05, České Budějovice, Czech Republic
| | - Gabriel Šaffa
- Department of Zoology, Faculty of Science, University of South Bohemia, 370 05, České Budějovice, Czech Republic
| | - Eviatar Nevo
- Institute of Evolution, University of Haifa, 3498838, Haifa, Israel
| | - Nigel Charles Bennett
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Pretoria, 0002, South Africa
| | - Radim Šumbera
- Department of Zoology, Faculty of Science, University of South Bohemia, 370 05, České Budějovice, Czech Republic.
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Pleštilová L, Okrouhlík J, Burda H, Sehadová H, Valesky EM, Šumbera R. Functional histology of the skin in the subterranean African giant mole-rat: thermal windows are determined solely by pelage characteristics. PeerJ 2020; 8:e8883. [PMID: 32296606 PMCID: PMC7150539 DOI: 10.7717/peerj.8883] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 03/10/2020] [Indexed: 11/29/2022] Open
Abstract
Excavation of burrows is an extremely physically demanding activity producing a large amount of metabolic heat. Dissipation of its surplus is crucial to avoid the risk of overheating, but in subterranean mammals it is complicated due to the absence of notable body extremities and high humidity in their burrows. IR-thermography in a previous study on two species of African mole-rats revealed that body heat was dissipated mainly through the ventral body part, which is notably less furred. Here, we analyzed the dorsal and ventral skin morphology, to test if dermal characteristics could contribute to higher heat dissipation through the ventral body part. The thickness of the epidermis and dermis and the presence, extent and connectivity of fat tissue in the dermis were examined using routine histological methods, while vascular density was evaluated using fluorescent dye and confocal microscopy in the giant mole-rat Fukomys mechowii. As in other hitherto studied subterranean mammals, no subcutaneous adipose tissue was found. All examined skin characteristics were very similar for both dorsal and ventral regions: relative content of adipose tissue in the dermis (14.4 ± 3.7% dorsally and 11.0 ± 4.0% ventrally), connectivity of dermal fat (98.5 ± 2.8% and 95.5 ± 6.8%), vascular density (26.5 ± 3.3% and 22.7 ± 2.3%). Absence of large differences in measured characteristics between particular body regions indicates that the thermal windows are determined mainly by the pelage characteristics.
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Affiliation(s)
- Lucie Pleštilová
- Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Jan Okrouhlík
- Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Hynek Burda
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Prague, Czech Republic
| | - Hana Sehadová
- Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre of the Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Eva M. Valesky
- Department of Dermatology, Venereology and Allergology, University Hospital, Johann Wolfgang Goethe Universität Frankfurt am Main, Frankfurt am Main, Germany
| | - Radim Šumbera
- Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
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Evaporative water loss in seven species of fossorial rodents: Does effect of degree of fossoriality and sociality exist? J Therm Biol 2020; 89:102564. [DOI: 10.1016/j.jtherbio.2020.102564] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 02/26/2020] [Accepted: 02/27/2020] [Indexed: 01/09/2023]
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8
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Genoud M, Isler K, Martin RD. Comparative analyses of basal rate of metabolism in mammals: data selection does matter. Biol Rev Camb Philos Soc 2017; 93:404-438. [PMID: 28752629 DOI: 10.1111/brv.12350] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 05/29/2017] [Accepted: 06/05/2017] [Indexed: 12/21/2022]
Abstract
Basal rate of metabolism (BMR) is a physiological parameter that should be measured under strictly defined experimental conditions. In comparative analyses among mammals BMR is widely used as an index of the intensity of the metabolic machinery or as a proxy for energy expenditure. Many databases with BMR values for mammals are available, but the criteria used to select metabolic data as BMR estimates have often varied and the potential effect of this variability has rarely been questioned. We provide a new, expanded BMR database reflecting compliance with standard criteria (resting, postabsorptive state; thermal neutrality; adult, non-reproductive status for females) and examine potential effects of differential selectivity on the results of comparative analyses. The database includes 1739 different entries for 817 species of mammals, compiled from the original sources. It provides information permitting assessment of the validity of each estimate and presents the value closest to a proper BMR for each entry. Using different selection criteria, several alternative data sets were extracted and used in comparative analyses of (i) the scaling of BMR to body mass and (ii) the relationship between brain mass and BMR. It was expected that results would be especially dependent on selection criteria with small sample sizes and with relatively weak relationships. Phylogenetically informed regression (phylogenetic generalized least squares, PGLS) was applied to the alternative data sets for several different clades (Mammalia, Eutheria, Metatheria, or individual orders). For Mammalia, a 'subsampling procedure' was also applied, in which random subsamples of different sample sizes were taken from each original data set and successively analysed. In each case, two data sets with identical sample size and species, but comprising BMR data with different degrees of reliability, were compared. Selection criteria had minor effects on scaling equations computed for large clades (Mammalia, Eutheria, Metatheria), although less-reliable estimates of BMR were generally about 12-20% larger than more-reliable ones. Larger effects were found with more-limited clades, such as sciuromorph rodents. For the relationship between BMR and brain mass the results of comparative analyses were found to depend strongly on the data set used, especially with more-limited, order-level clades. In fact, with small sample sizes (e.g. <100) results often appeared erratic. Subsampling revealed that sample size has a non-linear effect on the probability of a zero slope for a given relationship. Depending on the species included, results could differ dramatically, especially with small sample sizes. Overall, our findings indicate a need for due diligence when selecting BMR estimates and caution regarding results (even if seemingly significant) with small sample sizes.
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Affiliation(s)
- Michel Genoud
- Department of Ecology and Evolution, University of Lausanne, CH-1015, Lausanne, Switzerland.,Division of Conservation Biology, Institute of Ecology and Evolution, Department of Biology, University of Bern, CH-3012, Bern, Switzerland
| | - Karin Isler
- Department of Anthropology, University of Zürich-Irchel, CH-8057, Zürich, Switzerland
| | - Robert D Martin
- Integrative Research Center, The Field Museum, Chicago, IL, 60605-2496, U.S.A.,Institute of Evolutionary Medicine, University of Zürich-Irchel, CH-8057, Zürich, Switzerland
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Hofstede L, Dziminski MA. Greater bilby burrows: important structures for a range of species in an arid environment. AUSTRALIAN MAMMALOGY 2017. [DOI: 10.1071/am16032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Greater bilbies (Macrotis lagotis) have been described as ecosystem engineers and their burrows are significant structures across an often featureless and harsh arid landscape. Remote cameras were deployed at bilby burrows to determine whether bilby burrows were important structures for other species. Cameras detected two mammal species, brush-tailed mulgara (Dasycercus blythi) and spinifex hopping mice (Notomys alexis), permanently occupying bilby burrows, and a further two species, short-beaked echidnas (Tachyglossus aculeatus acanthion) and sand goannas (Varanus gouldii), regularly using bilby burrows for shelter. An additional suite of 16 mammal, bird, reptile, amphibian and invertebrate species were detected interacting with bilby burrows. There was no difference in the number of species using disused or occupied bilby burrows, indicating that even disused bilby burrows are important structures for other species. We show that bilby burrows are used by a range of species and are analogous to the traditional, mostly North American, and commonly provided text book examples of the gopher tortoise and kangaroo rat. The disappearance of bilbies across at least 80% of their former range and thus the disappearance of their burrows as important structural resources in a harsh, arid environment may have had important consequences for a range of species.
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Andino N, Borghi CE, Giannoni SM. Characterization and selection of microhabitat of Microcavia australis (Rodentia: Caviidae): first data in a rocky habitat in the hyperarid Monte Desert of Argentina. MAMMALIA 2016. [DOI: 10.1515/mammalia-2014-0081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractA rocky habitat, in its broadest sense, may be described as any locality that contains boulders, rocks, scree, pebbles, outcrops, cliffs, or caves. In these habitats, mammals find shelter sites that they use as nesting sites or dens to raise their young in a stable microclimate that is relatively secure from predators. The aim of this study was to characterize and evaluate the microhabitat selection by the southern mountain cavy (
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11
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Horner AM, Hanna JB, Biknevicius AR. Crouching to fit in: the energetic cost of locomotion in tunnels. J Exp Biol 2016; 219:3420-3427. [DOI: 10.1242/jeb.132449] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 08/22/2016] [Indexed: 11/20/2022]
Abstract
Animals that are specialized for a particular habitat or mode of locomotion often demonstrate locomotor efficiency in a focal environment when compared to a generalist species. However, measurements of these focal habitats or behaviors are often difficult or impossible to do in the field. In this study, the energetics and kinematics of simulated tunnel locomotion by two unrelated semi-fossorial mammals, the ferret and degu, were analyzed using open-flow respirometry and digital video. Animals were trained to move inside of normal (unconstrained, overground locomotion) and height-decreased (simulated tunnel, adjusted to tolerance limits for each species) Plexiglas chambers that were mounted flush onto a treadmill. Both absolute and relative tunnel performance differed between the species; ferrets tolerated a tunnel height that forced them to crouch at nearly 25% lower hip height than in an unconstrained condition, while degus would not perform on the treadmill past a ∼9% reduction in hip height. Both ferrets and degus exhibited significantly higher metabolic rates and cost of transport (CoT) values when moving in the tunnel condition relative to overgound locomotion. When comparing CoT values across small (<10kg) mammals, ferrets demonstrated a lower than predicted metabolic cost during both tunnel and terrestrial locomotion, whereas degus were very close to line of best fit. Although tunnel locomotion requires a more striking change in posture for ferrets, ferrets are more efficient locomotors in both conditions than mammals of similar mass.
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Affiliation(s)
- Angela M. Horner
- Department of Biology, California State University, San Bernardino, CA, 92407, USA
| | - Jandy B. Hanna
- Department of Biomedical Sciences, West Virginia School of Osteopathic Medicine, Lewisburg, WV 24901, USA
| | - Audrone R. Biknevicius
- Department of Biomedical Sciences, Ohio University College of Osteopathic Medicine, Athens, OH 45701, USA
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12
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Tachinardi P, Tøien Ø, Valentinuzzi VS, Buck CL, Oda GA. Nocturnal to Diurnal Switches with Spontaneous Suppression of Wheel-Running Behavior in a Subterranean Rodent. PLoS One 2015; 10:e0140500. [PMID: 26460828 PMCID: PMC4603895 DOI: 10.1371/journal.pone.0140500] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 09/25/2015] [Indexed: 01/15/2023] Open
Abstract
Several rodent species that are diurnal in the field become nocturnal in the lab. It has been suggested that the use of running-wheels in the lab might contribute to this timing switch. This proposition is based on studies that indicate feed-back of vigorous wheel-running on the period and phase of circadian clocks that time daily activity rhythms. Tuco-tucos (Ctenomys aff. knighti) are subterranean rodents that are diurnal in the field but are robustly nocturnal in laboratory, with or without access to running wheels. We assessed their energy metabolism by continuously and simultaneously monitoring rates of oxygen consumption, body temperature, general motor and wheel running activity for several days in the presence and absence of wheels. Surprisingly, some individuals spontaneously suppressed running-wheel activity and switched to diurnality in the respirometry chamber, whereas the remaining animals continued to be nocturnal even after wheel removal. This is the first report of timing switches that occur with spontaneous wheel-running suppression and which are not replicated by removal of the wheel.
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Affiliation(s)
| | - Øivind Tøien
- Institute of Arctic Biology, University of Alaska, Fairbanks, United States of America
| | - Veronica S. Valentinuzzi
- Centro Regional de Investigaciones Científicas y Transferencia Tecnológica (CRILAR), La Rioja, Argentina
| | - C. Loren Buck
- Department of Biological Sciences, University of Alaska, Anchorage, United States of America
| | - Gisele A. Oda
- Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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Otto HW, Wilson JA, Beever EA. Facing a Changing World: Thermal Physiology of American Pikas (Ochotona princeps). WEST N AM NATURALIST 2015. [DOI: 10.3398/064.075.0402] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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14
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Baldo MB, Antenucci CD, Luna F. Effect of ambient temperature on evaporative water loss in the subterranean rodent Ctenomys talarum. J Therm Biol 2015; 53:113-8. [DOI: 10.1016/j.jtherbio.2015.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 09/14/2015] [Accepted: 09/15/2015] [Indexed: 11/25/2022]
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15
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Oosthuizen MK, Bennett NC. The effect of ambient temperature on locomotor activity patterns in reproductive and non-reproductive female Damaraland mole-rats. J Zool (1987) 2015. [DOI: 10.1111/jzo.12254] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. K. Oosthuizen
- Department of Zoology and Entomology; University of Pretoria; Pretoria South Africa
| | - N. C. Bennett
- Department of Zoology and Entomology; University of Pretoria; Pretoria South Africa
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Wu NC, Alton LA, Clemente CJ, Kearney MR, White CR. Morphology and burrowing energetics of semi-fossorial skinks (Liopholis). J Exp Biol 2015; 218:2416-26. [DOI: 10.1242/jeb.113803] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 05/20/2015] [Indexed: 11/20/2022]
Abstract
Burrowing is an important form of locomotion in reptiles, but no study has examined the energetic cost of burrowing for reptiles. This is significant since burrowing is the most energetically expensive mode of locomotion undertaken by animals, and many burrowing species therefore show specialisations for their subterranean lifestyle. We examined the effect of temperature and substrate characteristics (coarse sand or fine sand) on the net energetic cost of burrowing (NCOB) and burrowing rate in two species of the Egernia group of skinks (Liopholis striata and Liopholis inornata) and compared it with those of other burrowing animals. We further tested for morphological specialisations among burrowing species by comparing the relationship between body shape and retreat preference in Egernia skinks. For L. striata and L. inornata, NCOB is 350 times more expensive than the predicted cost of pedestrian terrestrial locomotion. Temperature had a positive effect on burrowing rate for both species, and a negative effect on NCOB for L. striata but not L. inornata. Both NCOB and burrowing rate were independent of substrate type. Burrows constructed by skinks had smaller cross-sectional area than those constructed by mammals of comparable mass, and NCOB of skinks was lower than that of mammals of similar mass. After accounting for body size, retreat preference was significantly correlated with body shape in Egernia group skinks. Species of Egernia group skinks that use burrows for retreats have narrower bodies and shorter front limbs than other species. We conclude that the morphological specialisations of burrowing skinks allow them to construct relatively narrow burrows, thereby reducing NCOB and the total cost of constructing their burrow retreats.
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Affiliation(s)
- Nicholas C. Wu
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Lesley A. Alton
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Christofer J. Clemente
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Michael R. Kearney
- Department of Zoology, The University of Melbourne, Victoria 3010, Australia
| | - Craig R. White
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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Okrouhlík J, Burda H, Kunc P, Knížková I, Šumbera R. Surprisingly low risk of overheating during digging in two subterranean rodents. Physiol Behav 2015; 138:236-41. [DOI: 10.1016/j.physbeh.2014.10.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 10/28/2014] [Accepted: 10/30/2014] [Indexed: 10/24/2022]
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Baldo MB, Luna F, Schleich CE, Antenucci CD. Thermoregulatory development and behavior of Ctenomys talarum pups during brief repeated postnatal isolation. Comp Biochem Physiol A Mol Integr Physiol 2014; 173C:35-41. [PMID: 24667557 DOI: 10.1016/j.cbpa.2014.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 03/05/2014] [Accepted: 03/16/2014] [Indexed: 01/14/2023]
Abstract
In altricial mammals, the role of the mother and siblings throughout pup's early ontogeny is critical to determine "normal" development in neonates. It has been reported that variations in parental investment during pups' development affect thermoregulatory capacity, growth patterns, brain development and behavior during lifetime, such as spatial learning and memory in adults. Ctenomys talarum (tuco-tuco) is a solitary subterranean rodent, who inhabits complex burrows and exhibits developed spatial orientation abilities. Tuco-tuco's pups display an altricial development, spending more than 80% of the time in contact with the mother. Throughout weaning period, pups display active exploratory behavior and improvements in their spatial capabilities. Then, we determined the effect of repeated brief postnatal isolations on the acquisition of physiological thermoregulation and the development of spatial learning capabilities in tuco-tuco's pups. As it occurs in wild animals, daily brief isolations (30min) did not affect the acquisition of adult's body temperature nor resting metabolic rate's development pattern. Moreover, behavioral response and adult spatial abilities of isolated pups were similar to that observed in non-isolated ones. Then, during periods of mother's absence, minor physiological and behavioral adjustments, such as shivering and postural changes, are required to keep C. talarum pups within allostasis.
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Affiliation(s)
- María Belén Baldo
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de Mar del Plata, Mar del Plata, Argentina.
| | - Facundo Luna
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
| | - Cristian E Schleich
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
| | - C Daniel Antenucci
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
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Tachinardi P, Bicudo JEW, Oda GA, Valentinuzzi VS. Rhythmic 24 h variation of core body temperature and locomotor activity in a subterranean rodent (Ctenomys aff. knighti), the tuco-tuco. PLoS One 2014; 9:e85674. [PMID: 24454916 PMCID: PMC3893220 DOI: 10.1371/journal.pone.0085674] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 12/05/2013] [Indexed: 11/19/2022] Open
Abstract
The tuco-tuco Ctenomys aff. knighti is a subterranean rodent which inhabits a semi-arid area in Northwestern Argentina. Although they live in underground burrows where environmental cycles are attenuated, they display robust, 24 h locomotor activity rhythms that are synchronized by light/dark cycles, both in laboratory and field conditions. The underground environment also poses energetic challenges (e.g. high-energy demands of digging, hypoxia, high humidity, low food availability) that have motivated thermoregulation studies in several subterranean rodent species. By using chronobiological protocols, the present work aims to contribute towards these studies by exploring day-night variations of thermoregulatory functions in tuco-tucos, starting with body temperature and its temporal relationship to locomotor activity. Animals showed daily, 24 h body temperature rhythms that persisted even in constant darkness and temperature, synchronizing to a daily light/dark cycle, with highest values occurring during darkness hours. The range of oscillation of body temperature was slightly lower than those reported for similar-sized and dark-active rodents. Most rhythmic parameters, such as period and phase, did not change upon removal of the running wheel. Body temperature and locomotor activity rhythms were robustly associated in time. The former persisted even after removal of the acute effects of intense activity on body temperature by a statistical method. Finally, regression gradients between body temperature and activity were higher in the beginning of the night, suggesting day-night variation in thermal conductance and heat production. Consideration of these day-night variations in thermoregulatory processes is beneficial for further studies on thermoregulation and energetics of subterranean rodents.
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Affiliation(s)
- Patricia Tachinardi
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - José Eduardo Wilken Bicudo
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Gisele Akemi Oda
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
| | - Verónica Sandra Valentinuzzi
- Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (CRILAR-CONICET). Entre Ríos y Mendoza s/n, Anillaco, La Rioja, Argentina
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Zemanová M, Šumbera R, Okrouhlík J. Poikilothermic traits in Mashona mole-rat (Fukomys darlingi). Reality or myth? J Therm Biol 2012. [DOI: 10.1016/j.jtherbio.2012.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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21
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Luna F, Roca P, Oliver J, Antenucci CD. Maximal thermogenic capacity and non-shivering thermogenesis in the South American subterranean rodent Ctenomys talarum. J Comp Physiol B 2012; 182:971-83. [PMID: 22614630 DOI: 10.1007/s00360-012-0675-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 04/23/2012] [Accepted: 04/30/2012] [Indexed: 10/28/2022]
Abstract
Subterranean rodents inhabit closed tunnel systems that are hypoxic and hypercapnic and buffer aboveground ambient temperature. In contrast to other strictly subterranean rodents, Ctenomys talarum exhibits activity on the surface during foraging and dispersion and hence, is exposed also to the aboveground environment. In this context, this species is a valuable model to explore how the interplay between underground and aboveground use affects the relationship among basal metabolic rate (BMR), cold-induced maximum metabolic rate (MMR), shivering (ST), and non-shivering thermogenesis (NST). In this work, we provide the first evidence of the presence of NST, including the expression of uncoupling proteins in brown adipose tissue (BAT), and shivering thermogenesis in Ctenomys talarum, a species belonging to the most numerous subterranean genus, endemic to South America. Our results show no differences in BMR, cold-induced MMR, and NST between cold- (15 °C) and warm- (25 °C) acclimated individuals. Furthermore, thermal acclimation had no effect on the expression of mitochondrial uncoupling protein 1 (UCP1) in BAT. Only cytochrome c oxidase (COX) content and activity increased during cold acclimation. When interscapular BAT was removed, NST decreased more than 30%, whereas cold-induced MMR remained unchanged. All together, these data suggest that cold-induced MMR reaches a maximum in warm-acclimated individuals and so a probable ceiling in NST and UCP1 expression in BAT. Possible thermogenic mechanisms explaining the increase in the oxidative capacity, mediated by COX in BAT of cold-acclimated individuals and the role of ST in subterranean life habits are proposed.
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Affiliation(s)
- Facundo Luna
- Laboratorio de Ecología Fisiológica y del Comportamiento, Instituto de Investigaciones Marinas y Costeras (IIMyC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Mar del Plata, Mar del Plata, Argentina.
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22
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Alvarez GI, Díaz AO, Longo MV, Becerra F, Vassallo AI. Histochemical and Morphometric Analyses of the Musculature of the Forelimb of the Subterranean Rodent Ctenomys talarum (Octodontoidea). Anat Histol Embryol 2012; 41:317-25. [DOI: 10.1111/j.1439-0264.2012.01137.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Accepted: 01/01/2012] [Indexed: 11/26/2022]
Affiliation(s)
- G. I. Alvarez
- Departamento de Biología; Instituto de Investigaciones Marinas y Costeras, FCEyN, CONICET; Universidad Nacional de Mar del Plata; Provincia de Buenos Aires; Argentina
| | - A. O. Díaz
- Departamento de Biología; Instituto de Investigaciones Marinas y Costeras, FCEyN, CONICET; Universidad Nacional de Mar del Plata; Provincia de Buenos Aires; Argentina
| | - M. V. Longo
- Departamento de Biología; Instituto de Investigaciones Marinas y Costeras, FCEyN, CONICET; Universidad Nacional de Mar del Plata; Provincia de Buenos Aires; Argentina
| | - F. Becerra
- Departamento de Biología; Instituto de Investigaciones Marinas y Costeras, FCEyN, CONICET; Universidad Nacional de Mar del Plata; Provincia de Buenos Aires; Argentina
| | - A. I. Vassallo
- Departamento de Biología; Instituto de Investigaciones Marinas y Costeras, FCEyN, CONICET; Universidad Nacional de Mar del Plata; Provincia de Buenos Aires; Argentina
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Vera F, Zenuto RR, Antenucci CD, Busso JM, Marín RH. Validation of a radioimmunoassay for measuring testosterone concentrations in plasma samples of the subterranean rodent Ctenomys talarum: outstandingly elevated levels in the wild and the effect of captivity. ACTA ACUST UNITED AC 2011; 315:572-83. [DOI: 10.1002/jez.707] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 08/01/2011] [Accepted: 08/03/2011] [Indexed: 12/22/2022]
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Zelová J, Šumbera R, Okrouhlík J, Burda H. Cost of digging is determined by intrinsic factors rather than by substrate quality in two subterranean rodent species. Physiol Behav 2010; 99:54-8. [DOI: 10.1016/j.physbeh.2009.10.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 10/06/2009] [Accepted: 10/07/2009] [Indexed: 10/20/2022]
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Effect of diet quality and soil hardness on metabolic rate in the subterranean rodent Ctenomys talarum. Comp Biochem Physiol A Mol Integr Physiol 2009; 154:298-307. [PMID: 19497381 DOI: 10.1016/j.cbpa.2009.05.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 05/22/2009] [Accepted: 05/26/2009] [Indexed: 11/23/2022]
Abstract
The present work is aimed to establish, in Ctenomys talarum, the physiological and behavioral adjustments undergone by individuals when they are allowed to dig burrows in soils with different hardness and fed with diets of different quality. For each soil-diet combination, we estimated: resting metabolic rate (RMR), body temperature (T(b)), body mass, digestibility, food consumption rate, transit time, reingestion rate, feces production and time devoted to feeding, resting, locomotor activity and coprophagy. Soil type and diet quality affected RMR, but response to soil hardness was verified later. Animals fed with high quality (HQ) diet showed similar body temperature irrespective of soil condition, while animals fed with low quality (LQ) diet showed lower T(b) under soft soil (SS). Individuals fed with LQ diet showed lower RMR and both, lower digestibility and high transit time of food than those fed with HQ diet. Moreover, increments in feeding and defecation rates were observed in the former group. Number of reingested feces did not differ between animals fed with diets of different quality. However, when incidence of reingestion was considered, animals fed with HQ diet showed higher values of feces ingestion. Either feeding, resting and activity patterns were arrhythmic. However, for animals fed with LQ diet a tendency to rhythmic coprophagy was observed and it could be considered as a way to optimize feeding. This study shows that RMR is limited by digestive efficiency which is influenced by diet quality, but also thermal stress may limit the conversion of assimilated energy into work and heat.
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Luna F, Antenucci C, Bozinovic F. Comparative Energetics of the SubterraneanCtenomysRodents: Breaking Patterns. Physiol Biochem Zool 2009; 82:226-35. [DOI: 10.1086/597526] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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27
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del Valle JC, López Mañanes AA. Digestive strategies in the South American subterranean rodent Ctenomys talarum. Comp Biochem Physiol A Mol Integr Physiol 2008; 150:387-94. [DOI: 10.1016/j.cbpa.2008.03.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 03/19/2008] [Accepted: 03/19/2008] [Indexed: 10/22/2022]
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Sumbera R, Zelová J, Kunc P, Knízková I, Burda H. Patterns of surface temperatures in two mole-rats (Bathyergidae) with different social systems as revealed by IR-thermography. Physiol Behav 2007; 92:526-32. [PMID: 17544016 DOI: 10.1016/j.physbeh.2007.04.029] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2007] [Revised: 04/16/2007] [Accepted: 04/23/2007] [Indexed: 11/26/2022]
Abstract
Furred subterranean mammals face the problem of dissipating heat to the environment because high humidity and absence of air flow in sealed belowground tunnels constrain heat loss from body by convection and evaporation. In order to detect body areas responsible for heat loss, surface temperatures in two species of African mole-rats were measured at different ambient air temperatures by infrared thermography. Fur characteristics were also evaluated. Thinner pelage of the ventrum, its moderate temperature and large size suggest that ventral side of the body is the main thermal avenue for heat loss in both species. Interspecific differences could be explained by different fur characteristics connected with social thermoregulation. Compared to the social Fukomys mechowii, the solitary Heliophobius argenteocinereus has denser and longer fur on most of its body; its surface temperature was thus lower than in F. mechowii at lowered ambient temperatures. On the other hand, the denser and longer hair cover in H. argenteocinereus impedes heat dissipation at highest ambient temperatures (and probably also during digging activity) resulting in increase of core body temperature. H. argenteocinereus seems to be more sensitive to overheating than F. mechowii. At lower air temperatures, the social species may uses huddling to combat hypothermia.
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Affiliation(s)
- Radim Sumbera
- Department of Zoology, Faculty of Biological Sciences, University of South Bohemia, Branisovská 31, 370 05, Ceské Budejovice, Czech Republic.
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29
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Luna F, Antinuchi CD. Energy and distribution in subterranean rodents: Sympatry between two species of the genus Ctenomys. Comp Biochem Physiol A Mol Integr Physiol 2007; 147:948-54. [PMID: 17407828 DOI: 10.1016/j.cbpa.2007.02.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Revised: 02/26/2007] [Accepted: 02/26/2007] [Indexed: 11/15/2022]
Abstract
The low basal metabolic rate (BMR) observed in subterranean rodents, compared to that of surface-dwelling species of comparable size, has been proposed to be an adaptation to underground life. Two main hypotheses have been proposed to explain this finding, the cost of burrowing and the thermal stress. The former states that the low BMR is due to the high cost of extending the tunnel system whereas the other relates it to the possibility of overheating in burrows where evaporative and convective heat exchange are restricted. Additionally, both hypotheses related the energetics of subterranean rodent with spatial distribution. The genus Ctenomys is an excellent model to evaluate the cost of burrowing or thermal stress, since they are widely distributed, with members differing markedly in body mass. The aim of this study was to assess digging and basal energetics in two Ctenomys species that live in sympatry in a coastal grassland, but differ in their microspatial distribution by soil preference. We used the obtained energetic data to test both energy-distribution hypotheses. We measured BMR and digging metabolic rate (DMR) through open flow respirometry in two species exposed to soft and hard soils. In brief, DMR in Ctenomys talarum (100-170 g), as in Ctenomys australis (250-600 g), was unaffected by soil hardness. Within thermoneutral zone of each species, DMR/RMR quotient was lower in the smaller species. Our data did not support the thermal stress hypothesis, but the cost of burrowing hypothesis was not rejected. Other alternative hypotheses are proposed to explain the distribution of C. talarum and C. australis.
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Affiliation(s)
- Facundo Luna
- Laboratorio de Ecofisiología, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), CC 1245, Mar del Plata, Argentina.
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30
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Zenteno-Savín T, Beleboni RO, Hermes-Lima M. The cost of Latin American science Introduction for the second issue of CBP-Latin America. Comp Biochem Physiol A Mol Integr Physiol 2006; 146:463-9. [PMID: 16962348 DOI: 10.1016/j.cbpa.2006.06.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 05/17/2006] [Accepted: 06/12/2006] [Indexed: 11/28/2022]
Abstract
Latin American researchers in science and engineering (S&E), including those in biology and biomedical sciences, are frequently exposed to unstable conditions of financial support, material and human resources, and a limited number of positions at public and private institutions. Such uncertainties impose continuous challenges for the scientific community which, in the best of cases, responds with careful planning and creativity, and in the worst scenario endures the migration of scientists to the USA or Europe. Still, the number of scientific publications from Latin American institutions in the last decade increased at a much faster rate than publications from the USA and Canada. A brief analysis per country of the gross domestic product (GDP) spent in research and development (R&D) and the S&E production reported by the Pascal bibliographic database suggests that the number and quality of S&E publications is directly proportional to the financial support for R&D. However, the investment in R&D in Latin America did not increase at the same rate (from 0.49 to 0.55% of GDP, from 1990 to 2003) at which S&E publications did in the same period (2.9-fold increase, from 1988 to 2001). In Latin America, the traditional financial support for scientific research continues to be from federal and state government funds, associated in some cases with institutional funds that are mostly directed towards administrative costs and infrastructure maintenance. The aim of this introduction is to briefly discuss the production cost of articles published in refereed S&E journals, including the cost of the scientific research behind them, and, at the same time, to increase the awareness of the high quality of scientific research in Latin American institutions despite the many challenges, especially financial constraints, faced by their scientists. The second issue of Comparative Biochemistry and Physiology dedicated to Latin America ("The Face of Latin American Comparative Biochemistry and Physiology") celebrates, by means of 26 manuscripts from five countries, the diversity and quality of biological science in the continent.
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Affiliation(s)
- Tania Zenteno-Savín
- Centro de Investigaciones Biológicas del Noroeste, S.C., Planeación Ambiental y Conservación, Mar Bermejo 195, Playa Palo de Santa Rita, La Paz, Baja California Sur, C.P. 23090, Mexico.
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31
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Luna F, Antinuchi CD. Cost of foraging in the subterranean rodent Ctenomys talarum: effect of soil hardness. CAN J ZOOL 2006. [DOI: 10.1139/z06-040] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Subterranean burrows provide inhabitants with shelter, a relatively stable thermal environment, and potentially access to food resources. However, one cost of living in such burrows is the energetically expensive mode of locomotion. Soil hardness and the physiological capabilities of animals are likely important factors that affect the cost of burrow construction, and hence, distribution of burrows. We assessed the effect of soil hardness on the cost of digging by captive individual Ctenomys talarum Thomas, 1898 in soft soils. Digging metabolic rate (DMR) was higher in harder soil than in softer soil (408.30 ± 51.35 mL O2·h–1 vs. 267.59 ± 20.97 mL O2·h–1, respectively). In C. talarum, a higher soil hardness augments DMR by increasing, in terms of the cost of burrowing model, the costs of shearing and of pushing the removed soil. Additionally, these costs differ between C. talarum and other subterranean species (e.g., Thomomys bottae (Eydoux and Gervais, 1836)), depending on soil hardness and digging mode. Thus, the relationship between digging cost and soil hardness appears to be one of the most important factors that affect burrowing efficiency in subterranean rodents.
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Affiliation(s)
- Facundo Luna
- Laboratorio de Ecofisiología, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, CC1245, Mar del Plata, Argentina
| | - C. Daniel Antinuchi
- Laboratorio de Ecofisiología, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, CC1245, Mar del Plata, Argentina
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