Field Studies in Southern Tunisia on Water Turnover and Thyroid Activity in Two Species of Meriones

Lachiver, F; Cheniti, Tahar Lamine; Bradshaw, Don; Berthier, Jacques; Petter, F.

doi:10.1007/978-3-642-66981-1_15

Cited by 25 publications

(3 citation statements)

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“…Mean rates of water turnover of bettongs were significantly higher than those of the other 3 species in the dry trips, averaging 25.7% of the total body water content exchanged per day , compared with only 3-4% in the case of the hare wallabies and 5.5% for the euro. This situation is reminiscent of that reported during mid-summer in desert rodents in the Sahara, Israel, and in North America where water influxes ty pically range from 13-20% per day (Bradshaw, 2003), indicating that these desert species are not water deprived and benefit substantially from their burrowing and nocturnal habit (Ben Chaouacha-Chekir, Lachiv er and Cheniti, 1983;Bradshaw, et al, 1976;Degen, 1997;Degen, Hazan, Kam and Nagy, 1991;Degen, Pinshow and Ilan, 1990;Lachiver, et al, 1978;Nagy and Gruchacz, 1994;Petter, Lachi v er and Chekir, 1984). The impressiv e hormonal control of water loss from the kidney seen in the hare wallaby, and to a lesser extent in the euro, is a necessary concomitant of their lack of an adequate diurnal thermal re fuge which forcib ly exposes them to the full onslaught of the arid situation and prescribes the need for phy siological adaptations of a high order if they are to surv i ve.…”

Section: Discussionmentioning

confidence: 73%

“…Many arid-zone mammals are crepuscular or nocturnal and rest in the shade during the hottest part of the day , feeding mainly in the early mornings and late evenings when temperatures are low and food plants have taken up moisture from the humid night air, (Ealey , 1967;Nagy, 1987Nagy, , 1994Nagy and Gruchacz, 1994;Nagy and Knight, 1994). Many small arid-adapted mammals make use of burrows which have a relativ ely cool, humid env ironment and are thus able to reduce further ev aporativ e water loss (Bradshaw, Cheniti and Lachiver, 1976;Lachiver, Cheniti, Bradshaw, Berthier and Petter, 1978;Nagy and Gruchacz, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Comparative water metabolism of Barrow Island macropodid marsupials: Hormonal versus behavioural-dependent mechanisms of body water conservation

King

Bradshaw

2008

General and Comparative Endocrinology

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Seasonal variations in rates of water turnover were measured over a 7-year period in four species of macropodid marsupials (Lagorchestes conspicillatus, Bettongia lesueur, Petrogale lateralis and Macropus robustus isabellinus), on Barrow Island off the arid Pilbara coast of Western Australia. These ranged from over 100 mL kg(-0.82) d(-1) in wet seasons to as low as 28.2 mL kg(-0.82) d(-1) in dry seasons in the Spectacled hare wallaby, L. conspicillatus. Plasma osmolality increased significantly in both Barrow Island euros (M. robustus isabellinus) and Spectacled hare wallabies in November 1994, in the driest year yet recorded on the island. In contrast, there was no change in plasma osmolality of the other two species (Black-footed rock wallaby, P. lateralis and Lesueur's burrowing bettong, B. lesueur) that exploit cool and humid thermal refugia such as caves and underground warrens to avoid diurnal temperature extremes. Plasma levels of the marsupial antidiuretic hormone (ADH), lysine vasopressin (LVP), were for the most part below the detectable limit of the assay of 0.41 pg mL(-1) in rock wallabies and bettongs, but reached high levels of 16.7+/-4.6 pg mL(-1) and 20.25+/-5.1 pg mL(-1) in euros and hare wallabies, respectively, in dry seasons. LVP levels were positively correlated with plasma osmolality in both euros and hare wallabies, and negatively correlated with total body water content in euros, supporting its rôle as an antidiuretic hormone in these two species. The study highlights the importance of environmental features, such as caves and underground warrens, which are critical for the long-term survival of endangered species such as the Black-footed rock wallaby and the Lesueur's bettong. These species appear to lack ADH-controlled renal systems for the conservation of body water and are thus dependent on behavioural strategies for the maintenance of fluid homeostasis in arid environments.

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Section: Discussionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Comparative water metabolism of Barrow Island macropodid marsupials: Hormonal versus behavioural-dependent mechanisms of body water conservation

King

Bradshaw

2008

General and Comparative Endocrinology

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“…Thyroid hormones (THs), in contrast, can act directly and indirectly to influence metabolism through both peripheral and central actions (Kim, 2008;Mullur et al, 2014), yet are surprisingly understudied in free-living mammals. We are only aware of one study examining the role of THs as modulators of metabolic rate, activity or total energy expenditure within or across life-history stages in a freeliving mammal (Lachiver et al, 1978).…”

Section: Introductionmentioning

confidence: 99%

Energy regulation in context: Free-living female arctic ground squirrels modulate the relationship between thyroid hormones and activity among life history stages

Wilsterman

Buck

Barnes

et al. 2015

Hormones and Behavior

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Thyroid hormones (THs), key regulators of lipid and carbohydrate metabolism, are likely modulators of energy allocation within and among animal life history stages. Despite their role in modulating metabolism, few studies have investigated whether THs vary among life history stages in free-living animals or if they exhibit stage-specific relationships to total energy expenditure and activity levels. We measured plasma total triiodothyronine (tT3) and thyroxine (tT4) at four, discrete life history stages of female arctic ground squirrels from two different populations in northern Alaska to test whether plasma THs correlate with life history stage-specific changes in metabolic rate and energy demand. We also tested whether THs explained individual variation in aboveground activity levels within life history stages. T3 peaked during lactation and was lowest during pre-hibernation fattening, consistent with known changes in basal metabolism and core body temperature. In contrast, T4 was elevated shortly after terminating hibernation but remained low and stable across other life-history stages in the active season. THs were consistently higher in the population that spent more time above-ground but the relationship between THs and activity varied among life history stages. T3 was positively correlated with activity only during lactation (r(2)=0.50) whereas T4 was positively correlated with activity immediately following lactation (r(2)=0.48) and during fattening (r(2)=0.53). Our results support the hypothesis that THs are an important modulator of basal metabolism but also suggest that the relationship between THs and activity varies among life history stages.

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Vertebrate Ecophysiology

Bradshaw

2003

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Ecophysiology attempts to clarify the role and importance of physiological processes, such as digestion and respiration, in the ecological relations of species in their natural habitats. The basic principles and methods that are central to any ecophysiological study are outlined and discussed, including animal capture, blood collection, and the measurement of plasma components and hormone levels. Attention is paid to animal welfare and ethical considerations, and the question of stress and how to identify its presence in animals in their natural environment is approached through a series of case studies. Examples are given from a wide range of vertebrates living in deserts, cold climates and oceans, and recent findings on the physiological adaptations of Antarctic birds and mammals are a highlight of the book. This textbook will provide an introduction to the study of ecophysiology for advanced undergraduates and postgraduate students, as well as researchers in ecology, biodiversity and conservation.

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Field Studies in Southern Tunisia on Water Turnover and Thyroid Activity in Two Species of Meriones

Cited by 25 publications

References 3 publications

Comparative water metabolism of Barrow Island macropodid marsupials: Hormonal versus behavioural-dependent mechanisms of body water conservation

Comparative water metabolism of Barrow Island macropodid marsupials: Hormonal versus behavioural-dependent mechanisms of body water conservation

Energy regulation in context: Free-living female arctic ground squirrels modulate the relationship between thyroid hormones and activity among life history stages

Vertebrate Ecophysiology

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