Dehydration, with and without heat, in kangaroos from mesic and arid habitats: different thermal responses including varying patterns in heterothermy in the field and laboratory

T.J. Dawson, C.E. Blaney, H.C.K. Mccarron, Shane Maloney

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    10 Citations (Scopus)

    Abstract

    Field data showing the daily patterns in body temperature (T-b) of kangaroos in hot, arid conditions, with and without water, indicate the use of adaptive heterothermy, i.e. large variation in T-b. However, daily T-b variation was greater in the Eastern Grey Kangaroo (Macropus giganteus), a species of mesic origin, than in the desert-adapted Red Kangaroo (Macropus rufus). The nature of such responses was studied by an examination of their thermal adjustments to dehydration in thermoneutral temperatures (25 degrees C) and at high temperature (45 degrees C) via the use of tame, habituated animals in a climate chamber. At the same level of dehydration M. rufus was less impacted, in that its T-b changed less than that for M. giganteus while it evaporated significantly less water. At a T-a of 45 degrees C with water restriction T (b) reached 38.9 +/- 0.3 degrees C in M. rufus compared with 40.2 +/- 0.4 degrees C for M. giganteus. The ability of M. rufus to reduce dry conductance in the heat while dehydrated was central to its superior thermal control. While M. giganteus showed more heterothermy, i.e. its T-b varied more, this seemed due to a lower tolerance of dehydration in concert with a strong thermal challenge. The benefits of heterothermy to M. giganteus were also limited because of thermal (Q(10)) effects on metabolic heat production and evaporative heat loss. The impacts of T-b on heat production were such that low morning T-b's seen in the field may be associated with energy saving, as well as water saving. Kangaroos respond to dehydration and heat similarly to many ungulates, and it is apparent that the accepted notions about adaptive heterothermy in large desert mammals may need revisiting.
    Original languageEnglish
    Pages (from-to)797-807
    JournalJournal of Comparative Physiology B: biochemical, systemic, and environmental physiology
    Volume177
    Issue number7
    DOIs
    Publication statusPublished - 2007

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    Macropodidae
    Macropus giganteus
    Dehydration
    dehydration
    Ecosystem
    Macropus rufus
    Hot Temperature
    heat
    heat production
    habitat
    habitats
    desert
    Water
    Thermogenesis
    body temperature
    ungulate
    deserts
    water
    mammal
    tolerance

    Cite this

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    title = "Dehydration, with and without heat, in kangaroos from mesic and arid habitats: different thermal responses including varying patterns in heterothermy in the field and laboratory",
    abstract = "Field data showing the daily patterns in body temperature (T-b) of kangaroos in hot, arid conditions, with and without water, indicate the use of adaptive heterothermy, i.e. large variation in T-b. However, daily T-b variation was greater in the Eastern Grey Kangaroo (Macropus giganteus), a species of mesic origin, than in the desert-adapted Red Kangaroo (Macropus rufus). The nature of such responses was studied by an examination of their thermal adjustments to dehydration in thermoneutral temperatures (25 degrees C) and at high temperature (45 degrees C) via the use of tame, habituated animals in a climate chamber. At the same level of dehydration M. rufus was less impacted, in that its T-b changed less than that for M. giganteus while it evaporated significantly less water. At a T-a of 45 degrees C with water restriction T (b) reached 38.9 +/- 0.3 degrees C in M. rufus compared with 40.2 +/- 0.4 degrees C for M. giganteus. The ability of M. rufus to reduce dry conductance in the heat while dehydrated was central to its superior thermal control. While M. giganteus showed more heterothermy, i.e. its T-b varied more, this seemed due to a lower tolerance of dehydration in concert with a strong thermal challenge. The benefits of heterothermy to M. giganteus were also limited because of thermal (Q(10)) effects on metabolic heat production and evaporative heat loss. The impacts of T-b on heat production were such that low morning T-b's seen in the field may be associated with energy saving, as well as water saving. Kangaroos respond to dehydration and heat similarly to many ungulates, and it is apparent that the accepted notions about adaptive heterothermy in large desert mammals may need revisiting.",
    author = "T.J. Dawson and C.E. Blaney and H.C.K. Mccarron and Shane Maloney",
    year = "2007",
    doi = "10.1007/s00360-007-0176-1",
    language = "English",
    volume = "177",
    pages = "797--807",
    journal = "Journal of Comparative Physiology B: biochemical, systemic, and environmental physiology",
    issn = "0174-1578",
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    TY - JOUR

    T1 - Dehydration, with and without heat, in kangaroos from mesic and arid habitats: different thermal responses including varying patterns in heterothermy in the field and laboratory

    AU - Dawson, T.J.

    AU - Blaney, C.E.

    AU - Mccarron, H.C.K.

    AU - Maloney, Shane

    PY - 2007

    Y1 - 2007

    N2 - Field data showing the daily patterns in body temperature (T-b) of kangaroos in hot, arid conditions, with and without water, indicate the use of adaptive heterothermy, i.e. large variation in T-b. However, daily T-b variation was greater in the Eastern Grey Kangaroo (Macropus giganteus), a species of mesic origin, than in the desert-adapted Red Kangaroo (Macropus rufus). The nature of such responses was studied by an examination of their thermal adjustments to dehydration in thermoneutral temperatures (25 degrees C) and at high temperature (45 degrees C) via the use of tame, habituated animals in a climate chamber. At the same level of dehydration M. rufus was less impacted, in that its T-b changed less than that for M. giganteus while it evaporated significantly less water. At a T-a of 45 degrees C with water restriction T (b) reached 38.9 +/- 0.3 degrees C in M. rufus compared with 40.2 +/- 0.4 degrees C for M. giganteus. The ability of M. rufus to reduce dry conductance in the heat while dehydrated was central to its superior thermal control. While M. giganteus showed more heterothermy, i.e. its T-b varied more, this seemed due to a lower tolerance of dehydration in concert with a strong thermal challenge. The benefits of heterothermy to M. giganteus were also limited because of thermal (Q(10)) effects on metabolic heat production and evaporative heat loss. The impacts of T-b on heat production were such that low morning T-b's seen in the field may be associated with energy saving, as well as water saving. Kangaroos respond to dehydration and heat similarly to many ungulates, and it is apparent that the accepted notions about adaptive heterothermy in large desert mammals may need revisiting.

    AB - Field data showing the daily patterns in body temperature (T-b) of kangaroos in hot, arid conditions, with and without water, indicate the use of adaptive heterothermy, i.e. large variation in T-b. However, daily T-b variation was greater in the Eastern Grey Kangaroo (Macropus giganteus), a species of mesic origin, than in the desert-adapted Red Kangaroo (Macropus rufus). The nature of such responses was studied by an examination of their thermal adjustments to dehydration in thermoneutral temperatures (25 degrees C) and at high temperature (45 degrees C) via the use of tame, habituated animals in a climate chamber. At the same level of dehydration M. rufus was less impacted, in that its T-b changed less than that for M. giganteus while it evaporated significantly less water. At a T-a of 45 degrees C with water restriction T (b) reached 38.9 +/- 0.3 degrees C in M. rufus compared with 40.2 +/- 0.4 degrees C for M. giganteus. The ability of M. rufus to reduce dry conductance in the heat while dehydrated was central to its superior thermal control. While M. giganteus showed more heterothermy, i.e. its T-b varied more, this seemed due to a lower tolerance of dehydration in concert with a strong thermal challenge. The benefits of heterothermy to M. giganteus were also limited because of thermal (Q(10)) effects on metabolic heat production and evaporative heat loss. The impacts of T-b on heat production were such that low morning T-b's seen in the field may be associated with energy saving, as well as water saving. Kangaroos respond to dehydration and heat similarly to many ungulates, and it is apparent that the accepted notions about adaptive heterothermy in large desert mammals may need revisiting.

    U2 - 10.1007/s00360-007-0176-1

    DO - 10.1007/s00360-007-0176-1

    M3 - Article

    VL - 177

    SP - 797

    EP - 807

    JO - Journal of Comparative Physiology B: biochemical, systemic, and environmental physiology

    JF - Journal of Comparative Physiology B: biochemical, systemic, and environmental physiology

    SN - 0174-1578

    IS - 7

    ER -