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Modeling variable phanerozoic oxygen effects on physiology and evolution

TitleModeling variable phanerozoic oxygen effects on physiology and evolution
Publication TypeBook Chapter
Year of Publication2016
AuthorsGraham JB, Jew C.J, Wegner NC
EditorRoach R.C, Wagner P.D, Hackett P.H
Series TitleAdvances in Experimental Medicine and Biology
CityNew York
ISBN Number0065-2598<br/>978-1-4899-7678-9; 978-1-4899-7676-5
Accession NumberWOS:000396397300027
Keywordsatmospheric oxygen; drosophila-melanogaster; evolution; Hyperoxia; hypoxia; insect body-size; mudskipper; oxygen; Paleoatmosphere; Paleozoic; periophthalmodon-schlosseri; perspectives; plethodontid salamanders; rise; Tetrapod; unidirectional air-flow

Geochemical approximation of Earth's atmospheric O-2 level over geologic time prompts hypotheses linking hyper- and hypoxic atmospheres to transformative events in the evolutionary history of the biosphere. Such correlations, however, remain problematic due to the relative imprecision of the timing and scope of oxygen change and the looseness of its overlay on the chronology of key biotic events such as radiations, evolutionary innovation, and extinctions. There are nevertheless general attributions of atmospheric oxygen concentration to key evolutionary changes among groups having a primary dependence upon oxygen diffusion for respiration. These include the occurrence of Devonian hypoxia and the accentuation of air-breathing dependence leading to the origin of vertebrate terrestriality, the occurrence of Carboniferous-Permian hyperoxia and the major radiation of early tetrapods and the origins of insect flight and gigantism, and the Mid-Late Permian oxygen decline accompanying the Permian extinction. However, because of variability between and error within different atmospheric models, there is little basis for postulating correlations outside the Late Paleozoic. Other problems arising in the correlation of paleo-oxygen with significant biological events include tendencies to ignore the role of blood pigment affinity modulation in maintaining homeostasis, the slow rates of O-2 change that would have allowed for adaptation, and significant respiratory and circulatory modifications that can and do occur without changes in atmospheric oxygen. The purpose of this paper is thus to refocus thinking about basic questions central to the biological and physiological implications of O-2 change over geological time.

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