User:Agoc/sandbox
I will be adding to Torpor
For the week 4 assignment I added the section "Functions of Torpor Besides Energy Conservation". These are mostly overlooked functions which are significant.
I plan on adding more information on these other functions of torpor.
Week 8: I fixed the formatting (it was just a paragraph with pieces of information I was going to use) and added more explanation of the topic, problems highlighted in my evaluation.
Evolution of Torpor
[edit]The evolution of torpor likely accompanied the development of homeothermy.[1] Animals capable of maintaining a body temperature above ambient temperature when other members of its species could not would have a fitness advantage. Benefits of maintaining internal temperatures includes increased foraging time and less susceptibility to extreme drops in temperature.[1] This adaptation of increasing body temperature to forage has been observed in small nocturnal mammals when they first wake up in the evening.[2][3][4]
Although homeothermy lends an advantage such as increased activity levels, small mammals and birds maintaining an internal body temperature spend up to 100 times more energy in low ambient temperatures compared to ectotherms.[5] To cope with this challenge, these animals maintain a much lower body temperature, staying just over ambient temperature rather than at normal operating temperature. This reduction in body temperature and metabolic rate allows the prolonged survival of animals capable of entering torpid states.
Examples of Torpor's Functions
[edit]Slowing metabolic rate to conserve energy in times of insufficient resources is the primarily noted purpose of torpor.[6] This conclusion is largely based on laboratory studies where torpor was observed to follow food deprivation.[7] There is evidence for other adaptive functions of torpor where animals are observed in natural contexts:
Fat Conservation Observed in Small Birds
[edit]Torpor has been shown to be a strategy of small migrant birds to increase their body fat. Hummingbirds, resting at night during migration, were observed to enter torpor which helped conserve fat stores for the rest of their migration.[7]
This strategy of using torpor to increase body fat has been observed in wintering chickadees as well. [8] Black-capped chickadees, living in temperate forests of North America, do not migrate south during winter. The chickadee can maintain a body temperature 12 °C lower than normal. This reduction in metabolism allows it to conserve 30% of fat stores amassed from the previous day. Without using torpor the chickadee would not be able to conserve its fat stores to survive winter.
Advantage in Environments With Unpredictable Food Sources
[edit]Torpor can be employed during reproduction, a strategy of animals with unpredictable food supplies.[9] For example, high-latitude living rodents use torpor seasonally when not reproducing. These rodents use torpor as means to survive winter and live to reproduce in the next reproduction cycle when food sources are plentiful, separating periods of torpor from the reproduction period. Some animals use torpor during their reproductive cycle, as seen in unpredictable habitats.[9] They experience the cost of a prolonged reproduction period but the payoff is survival to be able to reproduce at all.[9]
The Eastern Long-Eared bat uses torpor during winter and is able to arouse and forage during warm periods.[10]
Survival During Mass Extinctions
[edit]It is suggested that this daily torpor use may have allowed survival through mass extinction events.[11] Heterotherms, over the last 500 years, make up only four out of 61 mammals confirmed to have gone extinct.[11] The utilization of torpor enables animals to reduce energy requirements when needed and survive through harsh conditions easier than those animals not capable of torpor.
Inter-species competition occurs when two species require the same resource for energy production.[12] Torpor has been shown to be a strategy used to be able to increase fitness in the case of inter-specific competition with the nocturnal common spiny mouse.[12] When the golden spiny mouse experiences reduced food availability by diet overlap with the common spiny mouse it spends more time in a torpid state.
Parasite Resistance by Bats
[edit]A drop in temperature from torpor has been shown to reduce the ability of parasites to reproduce.[13] Ectoparasites of bats in temperate zones have reduced reproductive rates when bats enter torpor. Where bats do not enter torpor the parasites reproduce at a constant rate throughout the year.
References
[edit]- ^ a b Geiser, Fritz; Stawski, Clare; Wacker, Chris B.; Nowack, Julia (2017). "Phoenix from the Ashes: Fire, Torpor, and the Evolution of Mammalian Endothermy". Frontiers in Physiology. 8. doi:10.3389/fphys.2017.00842. ISSN 1664-042X.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Stawski, Clare; Geiser, Fritz (2010-01-01). "Fat and fed: frequent use of summer torpor in a subtropical bat". Naturwissenschaften. 97 (1): 29–35. doi:10.1007/s00114-009-0606-x. ISSN 0028-1042.
- ^ Warnecke, Lisa; Turner, James M.; Geiser, Fritz (2008-01-01). "Torpor and basking in a small arid zone marsupial". Naturwissenschaften. 95 (1): 73–78. doi:10.1007/s00114-007-0293-4. ISSN 0028-1042.
- ^ Körtner, Gerhard; Geiser, Fritz. "The key to winter survival: daily torpor in a small arid-zone marsupial". Naturwissenschaften. 96 (4): 525–530. doi:10.1007/s00114-008-0492-7.
- ^ Batholomew, G. (1982). "Energy Metabolism". Animal Physiology: Principles and Adaptations. MacMillian Publishing Co.
- ^ Allaby, Michael (2014). A Dictionary of Zoology. Oxford University Press. p. 963. ISBN 9780199684274.
- ^ a b Carpenter, F. Lynn; Hixon, Mark A. (May 1988). "A New Function for Torpor: Fat Conservation in a Wild Migrant Hummingbird". The Condor. 90: 376. doi:10.2307/1368565.
- ^ Chaplin, Susan Budd (1974-12-01). "Daily energetics of the Black-capped Chickadee,Parus atricapillus, in winter". Journal of comparative physiology. 89 (4): 321–330. doi:10.1007/BF00695350. ISSN 0340-7594.
- ^ a b c McAllan, B. M.; Geiser, Fritz (2014-09-01). "Torpor during Reproduction in Mammals and Birds: Dealing with an Energetic Conundrum". Integrative and Comparative Biology. 54 (3): 516–532. doi:10.1093/icb/icu093. ISSN 1540-7063.
- ^ Stawski, Clare; Turbill, Christopher; Geiser, Fritz (2009-05-01). "Hibernation by a free-ranging subtropical bat (Nyctophilus bifax)". Journal of Comparative Physiology B. 179 (4): 433–441. doi:10.1007/s00360-008-0328-y. ISSN 0174-1578.
- ^ a b Geiser, Fritz; Brigham, R. Mark. The Other Functions of Torpor. pp. 109–121. doi:10.1007/978-3-642-28678-0_10.
- ^ a b Levy, Ofir; Dayan, Tamar; Kronfeld-Schor, Noga (2011-09-01). "Interspecific Competition and Torpor in Golden Spiny Mice: Two Sides of the Energy-Acquisition Coin". Integrative and Comparative Biology. 51 (3): 441–448. doi:10.1093/icb/icr071. ISSN 1540-7063.
- ^ Lourenço, Sofia; Palmeirim, Jorge Mestre (2008-12-01). "Which factors regulate the reproduction of ectoparasites of temperate-zone cave-dwelling bats?". Parasitology Research. 104 (1): 127. doi:10.1007/s00436-008-1170-6. ISSN 0932-0113.