Selective factors in the origin of the mammalian diaphragm
The origin of endothermic homeothermy and of high metabolic rate in mammals is currently believed to be the result of early (Mesozoic) selection in advanced cynodont therapsids and/or early mammals for either (1) enhanced thermoregulatory capacity or (2) increased powers of endurance and stamina. Se...
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Cambridge University Press (CUP)
1987
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Online Access: | http://dx.doi.org/10.1017/s0094837300008575 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0094837300008575 |
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crcambridgeupr:10.1017/s0094837300008575 2024-06-23T07:56:24+00:00 Selective factors in the origin of the mammalian diaphragm Ruben, John A. Bennett, Albert F. Hisaw, Frederick L. 1987 http://dx.doi.org/10.1017/s0094837300008575 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0094837300008575 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Paleobiology volume 13, issue 1, page 54-59 ISSN 0094-8373 1938-5331 journal-article 1987 crcambridgeupr https://doi.org/10.1017/s0094837300008575 2024-06-05T04:04:59Z The origin of endothermic homeothermy and of high metabolic rate in mammals is currently believed to be the result of early (Mesozoic) selection in advanced cynodont therapsids and/or early mammals for either (1) enhanced thermoregulatory capacity or (2) increased powers of endurance and stamina. Selective factors underlying the origin of specialized respiration/ventilation-support systems in mammals are possible indices of the validity of these two hypotheses. One such support structure is the diaphragm, a specialized muscle that facilitates lung ventilation. We tested capacity for maintenance of resting metabolic rate, thermoregulation, and for extended, intense exercise in laboratory rats ( Rattus rattus ) in which diaphragm function had been completely ablated. The results were virtual elimination of aeroboic scope (active metabolic rate — resting metabolic rate) but resting metabolic rate was unaffected. Thermoregulatory capacity was unimpaired to at least 8° below lower critical temperature. These and other data suggest that the origin of the mammalian diaphragm, as well as mammalian metabolic rates, may have been related to selection for greater levels of sustainable activity rather than for functions associated with thermoregulation. Article in Journal/Newspaper Rattus rattus Cambridge University Press Paleobiology 13 1 54 59 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
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English |
description |
The origin of endothermic homeothermy and of high metabolic rate in mammals is currently believed to be the result of early (Mesozoic) selection in advanced cynodont therapsids and/or early mammals for either (1) enhanced thermoregulatory capacity or (2) increased powers of endurance and stamina. Selective factors underlying the origin of specialized respiration/ventilation-support systems in mammals are possible indices of the validity of these two hypotheses. One such support structure is the diaphragm, a specialized muscle that facilitates lung ventilation. We tested capacity for maintenance of resting metabolic rate, thermoregulation, and for extended, intense exercise in laboratory rats ( Rattus rattus ) in which diaphragm function had been completely ablated. The results were virtual elimination of aeroboic scope (active metabolic rate — resting metabolic rate) but resting metabolic rate was unaffected. Thermoregulatory capacity was unimpaired to at least 8° below lower critical temperature. These and other data suggest that the origin of the mammalian diaphragm, as well as mammalian metabolic rates, may have been related to selection for greater levels of sustainable activity rather than for functions associated with thermoregulation. |
format |
Article in Journal/Newspaper |
author |
Ruben, John A. Bennett, Albert F. Hisaw, Frederick L. |
spellingShingle |
Ruben, John A. Bennett, Albert F. Hisaw, Frederick L. Selective factors in the origin of the mammalian diaphragm |
author_facet |
Ruben, John A. Bennett, Albert F. Hisaw, Frederick L. |
author_sort |
Ruben, John A. |
title |
Selective factors in the origin of the mammalian diaphragm |
title_short |
Selective factors in the origin of the mammalian diaphragm |
title_full |
Selective factors in the origin of the mammalian diaphragm |
title_fullStr |
Selective factors in the origin of the mammalian diaphragm |
title_full_unstemmed |
Selective factors in the origin of the mammalian diaphragm |
title_sort |
selective factors in the origin of the mammalian diaphragm |
publisher |
Cambridge University Press (CUP) |
publishDate |
1987 |
url |
http://dx.doi.org/10.1017/s0094837300008575 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0094837300008575 |
genre |
Rattus rattus |
genre_facet |
Rattus rattus |
op_source |
Paleobiology volume 13, issue 1, page 54-59 ISSN 0094-8373 1938-5331 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0094837300008575 |
container_title |
Paleobiology |
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13 |
container_issue |
1 |
container_start_page |
54 |
op_container_end_page |
59 |
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1802649456693215232 |