Seasonal Study of Daily Torpor in Southeastern Peromyscus maniculatus and                Peromyscus leucopus from Mountains and Foothills

Tannenbaum, Michael G.; Pivorun, Edward B.

doi:10.1086/physzool.61.1.30163731

Cited by 38 publications

(18 citation statements)

References 10 publications

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“…In each case, animals from warmer localities rarely entered torpor or did so in fewer numbers than those from colder areas, which suggests that selection for torpor was greater in more energetically stressful environments (Tannenbaum and Pivorun 1988). In the present study, there were no such geographical differences in the proportion of Pouched mice entering torpor and a similar number of individuals from populations throughout southern Africa had the capacity to exhibit torpor.…”

Section: Discussioncontrasting

confidence: 50%

Evidence of climatic adaptation in spontaneous torpor amoung Pouched mice Saccostomus campestris from southern Africa

Ellison¹

1993

Acta Theriol.

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Ellison G. T. H. 1993. Evidence of climatic adaptation in spontaneous torpor among Pouched mice Saccostomus campestris from southern Africa. Acta theriol. 38: 49 -59.Spontaneous torpor was examined in 36 Pouched mice Saccostomus campestris Peters, 1846 from 6 localities in southern Africa. Fifteen .individuals displayed characteristic bouts of torpor in which oxygen consumption (VO2) fell below 50% of the resting levels of non-torpid pouched mice for more than 2 hr during the early morning. These bouts ended in an abrupt increase in VO2 which overshot resting levels during arousal to normothermia. Minimum oxygen consumption (VC>2min) was not correlated with the energy saved during torpor, but there was a significant positive correlation between V02min and the duration of torpor (Dt) and also between Dt and energy saved. In contrast, there was a negative correlation between the cost of arousal and energy saved which suggests that the cost of regaining homeothermy can limit the energetic efficiency of short bouts of torpor. Pouched mice from all 6 localities had the capacity to enter torpor and there were no significant geographical differences in the incidence of torpor. However, there were substantial differences in the expression of torpor, and Pouched mice from localities experiencing more variable temperatures underwent significantly longer bouts of torpor which suggests that selection for torpor had been greater in more energetically unpredictable environments.

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Section: Discussioncontrasting

confidence: 50%

Evidence of climatic adaptation in spontaneous torpor amoung Pouched mice Saccostomus campestris from southern Africa

Ellison¹

1993

Acta Theriol.

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“…However, this correlation may also be explained if temperature loss in infected mice during the trial led to inaccurate MR max measures. Finally, the changes in body temperature during cold exposure may indicate that parasitized mice are more willing to enter brief torpor under cold conditions (Hill, 1983;Tannenbaum and Pivorun, 1988). This could be an adaptive plastic behavior employed by infected mice to avoid situations that require sustained high energy output (Hill, 1983;Vogt and Lynch, 1982).…”

Section: Discussionmentioning

confidence: 99%

Schistosome infection in deer mice (Peromyscus maniculatus):impacts on host physiology, behavior and energetics

Schwanz

2006

Journal of Experimental Biology

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Phenotypic plasticity is an important means through which animals respond to unpredictability and stressors in the environment (Fordyce, 2006;Schlichting and Pigliucci, 1998). Plasticity can occur at many levels, from physiology and morphology to behavior and life history (King and Murphy, 1985). Organ morphology, for example, can be highly flexible in many animals (Piersma and Lindström, 1997;Starck, 1999). The size of gastrointestinal (GI) tract organs changes with energetic and functional demands, increasing during lactation and cold exposure in rodents, decreasing in preparation for migration in birds, and changing over active and hibernation seasons in lizards (e.g. Hammond et al., 1994;Piersma and Lindström, 1997;Tracy and Diamond, 2005). Similarly, metabolic rates can change with season and ambient temperature (e.g. Hill, 1983).Parasites represent an important stressor for many animals, and their effects on host phenotypes can include direct pathologies and host plasticity. For example, parasitism can cause liver and intestinal damage, anemia and increased thermal conductance (Booth et al., 1993;Holmes and Zohar, 1990;Meagher, 1998;Schall et al., 1982;Tocque, 1993;Wiger, 1977). Parasitism can also lead to changes in the energetics and performance of animals, including reduced feeding and activity, impaired anti-predator and competitive behavior, and altered metabolic rates (Arneberg et al., 1996;Booth et al., 1993;Cunningham et al., 1994;Freeland, 1981;Poirier et al., 1995;Rau, 1983a;Rau, 1983b;Rau and Putter, 1984;Schall et al., 1982;Symons, 1985). Finally, parasitized animals may show shifts in organ size and body tissue composition (Kristan, 2002;Kristan and Hammond, 2000;Kristan and Hammond, 2001;Tocque, 1993). Although it is difficult to distinguish between direct parasite impact and host compensation, host alterations in some systems appear to represent phenotypic plasticity to minimize the fitness costs of infection (e.g. Booth et al., 1993;Kristan and Hammond, 2001;Podesta and Mettrick, 1976). Indeed, parasitism can have strong, negative impacts on host fitness through decreases in survival and reproduction (e.g. Crews and Yoshino, 1989;Fuller and Blaustein, 1996;Goater and Ward, 1992;Neuhaus, 2003;Zuk, 1987). The host-parasite relationship, therefore, provides an interesting and ecologically important stage on which to examine phenotypic plasticity and fitness consequences of stressors. Additionally, understanding the phenotypic response of individual hosts is imperative for understanding populationlevel effects and coevolution between hosts and parasites Animals routinely encounter environmental stressors and may employ phenotypic plasticity to compensate for the costs of these perturbations. Parasites represent an ecologically important stressor for animals, which may induce host plasticity. The present study examined the effects of a trematode parasite, Schistosomatium douthitti, on deer mouse (Peromyscus maniculatus) physiology, behavior and energetics. Measures were taken to assess direct pa...

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“…), and small insectivorous marsupials from Australian arid zones with unpredictable rainfall and low winter T a (Sminthopsis spp.) revealed that torpor is usually more frequent and deeper in winter; however, it may occur occasionally during most times of the year (Gaertner et al 1973;Geiser and Baudinette 1987;Tannenbaum and Pivorun 1988). The hamster Phodopus sungorus from Siberia shows no spontaneous torpor in summer, but like other species displays torpor in winter (Heldmaier and Steinlechner 1981;Geiser and Heldmaier 1995).…”

Section: Discussionmentioning

confidence: 99%

Seasonal changes in energetics and torpor patterns in the subtropical blossom-bat Syconycteris australis (Megachiroptera)

Coburn

Geiser

1998

Oecologia

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Little is known about how animals from tropical and subtropical climates adjust their energy expenditure to cope with seasonal changes of climate and food availability. To provide such information, we studied the thermal physiology, torpor patterns and energetics of the nocturnal blossom-bat (Syconycteris australis 18 g) from a subtropical habitat in both summer and winter. In both seasons, S. australis frequently entered daily torpor at ambient temperatures between 12 and 25°C when food and water were withheld. Unlike patterns observed in temperate animals, mean minimum metabolic rates during torpor were lower in summer (0.47 ± 0.07 ml O g h) than in winter (0.75 ± 0.11 ml O g h). Body temperatures during torpor were regulated at 19.3 ± 1.0°C in summer and at 23.4 ± 2.0°C in winter. Torpor bout duration was significantly longer in summer (7.3 ± 0.6 h) than in winter (5.5 ± 0.3 h), but in both seasons, bout duration was not affected by ambient temperature. Consequently, average daily metabolic rates were also significantly lower in summer than in winter. Body temperatures and metabolic rates in normothermic bats did not change with season. Our findings on seasonal changes of torpor in this bat from the subtropics are opposite to those made for many species from cold climates which generally show deeper and longer torpor in winter and are often entirely homeothermic in summer. More pronounced torpor in subtropical S. australis in summer may be due to low or unpredictable nectar availability, short nights which limit the time available for foraging, and long days without access to food. Thus, the reversed seasonal response of this subtropical bat in comparison to temperate species may be an appropriate response to ecological constraints.

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Seasonal Study of Daily Torpor in Southeastern Peromyscus maniculatus and Peromyscus leucopus from Mountains and Foothills

Cited by 38 publications

References 10 publications

Evidence of climatic adaptation in spontaneous torpor amoung Pouched mice Saccostomus campestris from southern Africa

Evidence of climatic adaptation in spontaneous torpor amoung Pouched mice Saccostomus campestris from southern Africa

Schistosome infection in deer mice (Peromyscus maniculatus):impacts on host physiology, behavior and energetics

Seasonal changes in energetics and torpor patterns in the subtropical blossom-bat Syconycteris australis (Megachiroptera)

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