Tropical Heterothermy: Does the Exception Prove the Rule or Force a Re-Definition?
Recent interest in heterothermy in the tropics and the subtropics has raised issues with the existing definitions of torpor. The current methods used to distinguish and define patterns of heterothermy are insufficient in face of the numerous forms of torpor expression and high daily variation in normothermic body temperature (T b) observed in species inhabiting the tropics. Tropical heterothermy often occurs at highly variable ambient temperatures that may lead to a continuum between hibernation, daily torpor and normothermia with no clear distinction between states. While we do not seek to redefine torpor in this review, by listing torpor patterns that fall outside the usual categories (the exceptions to the rule), we discuss these thermoregulatory behaviours in terms of the energetics and evolution of heterothermy under warm climates.
KeywordsBasal Metabolic Rate Mouse Lemur Torpor Bout Daily Torpor Periodic Arousal
The authors thank Prof. Fritz Geiser for suggested improvements to the manuscript. The research was financed by incentive grants from the University of KwaZulu-Natal, the National Research Foundation, South Africa and a Claude Leon Foundation Postdoctoral Fellowship to CIC and a post-graduate scolarship from National Science and Engineering Research Council (Canada) to DLL.
- Arlettaz R, Ruchet RC, Aeschimann J, Brun E, Genoud M, Vogel P (2000) Physiological traits affecting the distribution and wintering strategy of the bat Tadarida teniotis. Ecology 81:1004–1014Google Scholar
- Canale CI, Perret M, Henry P-Y (2012) Torpor use during gestation and lactation in a heterothermic primate. Naturwissenschaften 99:159–163Google Scholar
- Geiser F (1996) Torpor in reproductive endotherms. In: Geiser F, Hulbert AJ, Nicol SC (eds) Adaptations to the cold, 10th international hibernation symposium, University of New England Press, pp 81–86Google Scholar
- Geiser F, Ruf T (1995) Hibernation versus daily torpor in mammals and birds—physiological variables and classification of torpor patterns. Physiol Zool 68:935–966Google Scholar
- Geiser F, Drury RL, Körtner G, Turbill C, Pavey CR, Brigham RM (2004) Passive rewarming from torpor in mammals and birds: energetic, ecological and evolutionary implications. In: Barnes BM, Carey HV (eds) Life in the cold. Evolution, mechanisms, adaptation, and application, vol 27. Biological Papers of the University of Alaska, University of Alaska, Fairbanks, pp 199–208Google Scholar
- Geiser F, Christian N, Cooper CE, Körtner G, McAllan BM, Pavey CR, Turner JM, Warnecke L, Willis CKR, Brigham M (2008) Torpor in marsupials: recent advances. In: Lovegrove BG, McKechnie AE (eds) Hypometabolism in animals: hibernation, torpor and cryobiology. Interpack Books, Pietermaritzburg, pp 297–306Google Scholar
- Giroud S, Perret M, Gilbert C, Zahariev A, Goudable J, Le Maho Y, Oudart H, Momken I, Aujard F, Blanc S (2009) Dietary palmitate and linoleate oxidations, oxidative stress, and DNA damage differ according to season in mouse lemurs exposed to a chronic food deprivation. Am J Physiol Reg I 297:R950–R959Google Scholar
- Grigg GC (2004) An evolutionary framework for studies of hibernation and short term torpor. In: Barnes BM, Carey HV (eds) Life in the cold. Evolution, mechanisms, adaptation, and application, vol 27. Biological Papers of the University of Alaska, University of Alaska, Fairbanks, pp 1–11Google Scholar
- Lyman CP, Willis JS, Malan A, Wang LCH (1982) Hibernation and torpor in mammals and birds. Academic Press, New YorkGoogle Scholar
- McKechnie AE, Mzilikazi N (2011) Heterothermy in Afrotropical mammals and birds: a review. Integr Comp Biol 51:1–15Google Scholar
- Prendergast BJ, Freeman DA, Zucker I, Nelson RJ (2002) Periodic arousal from hibernation is necessary for initiation of immune responses in ground squirrels. Am J Physiol Reg I 282:R1054–R1062Google Scholar
- Schleucher E, Prinzinger R (2006) Heterothermia and torpor in birds: highly specialized physiological ability or just deep “nocturnal hypothermia”? The limitations of terminology. Acta Zool Sinica 52:393–396Google Scholar
- Stawski C, Geiser F (2011) Do season and distribution affect thermal energetics of a hibernating bat endemic to the tropics and subtropics? Am J Physiol Reg I 301:R542–R547Google Scholar
- Wein J (2010) Effects of ambient temperature on tropical hibernation in the lesser hedgehog tenrec, Echinops telfairi. Ph.D. dissertation, Universität Hamburg, HamburgGoogle Scholar