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Respir Physiol Neurobiol. 2016 Apr;224:11-6. doi: 10.1016/j.resp.2015.09.016. Epub 2015 Oct 21.

Evolution of lung breathing from a lungless primitive vertebrate.

Author information

1
Department of Veterinary Medicine, University of Alaska Fairbanks, United States.
2
Institute of Arctic Biology, University of Alaska Fairbanks, United States; Department of Biology and Wildlife, University of Alaska Fairbanks, United States.
3
Department of Veterinary Medicine, University of Alaska Fairbanks, United States; Institute of Arctic Biology, University of Alaska Fairbanks, United States; Department of Biology and Wildlife, University of Alaska Fairbanks, United States. Electronic address: mbharris@alaska.edu.

Abstract

Air breathing was critical to the terrestrial radiation and evolution of tetrapods and arose in fish. The vertebrate lung originated from a progenitor structure present in primitive boney fish. The origin of the neural substrates, which are sensitive to metabolically produced CO2 and which rhythmically activate respiratory muscles to match lung ventilation to metabolic demand, is enigmatic. We have found that a distinct periodic centrally generated rhythm, described as "cough" and occurring in lamprey in vivo and in vitro, is modulated by central sensitivity to CO2. This suggests that elements critical for the evolution of breathing in tetrapods, were present in the most basal vertebrate ancestors prior to the evolution of the lung. We propose that the evolution of breathing in all vertebrates occurred through exaptations derived from these critical basal elements.

KEYWORDS:

Breathing; CO(2); Cough; Evolution; Exaptation; Lamprey

PMID:
26476056
PMCID:
PMC5138057
DOI:
10.1016/j.resp.2015.09.016
[Indexed for MEDLINE]
Free PMC Article

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