title: Variation in the link between oxygen consumption and ATP production, and its relevance for animal performance.
abstract: It is often assumed that an animal's metabolic rate can be estimated through measuring the whole-organism oxygen consumption rate. However, oxygen consumption alone is unlikely to be a sufficient marker of energy metabolism in many situations. This is due to the inherent variability in the link between oxidation and phosphorylation; that is, the amount of adenosine triphosphate (ATP) generated per molecule of oxygen consumed by mitochondria (P/O ratio). In this article, we describe how the P/O ratio can vary within and among individuals, and in response to a number of environmental parameters, including diet and temperature. As the P/O ratio affects the efficiency of cellular energy production, its variability may have significant consequences for animal performance, such as growth rate and reproductive output. We explore the adaptive significance of such variability and hypothesize that while a reduction in the P/O ratio is energetically costly, it may be associated with advantages in terms of somatic maintenance through reduced production of reactive oxygen species. Finally, we discuss how considering variation in mitochondrial efficiency, together with whole-organism oxygen consumption, can permit a better understanding of the relationship between energy metabolism and life history for studies in evolutionary ecology.
authors.affiliation: Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK salin.karine@gmail.com.
authors.forename: Karine
authors.initials: K
authors.lastname: Salin
authors.affiliation: Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Sonya K
authors.initials: SK
authors.lastname: Auer
authors.affiliation: Laboratoire de Biométrie et Biologie Évolutive, UMR 5558, CNRS, Université de Lyon 1, Lyon, France Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Rey
authors.affiliation: Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Colin
authors.initials: C
authors.lastname: Selman
authors.affiliation: Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Neil B
authors.initials: NB
authors.lastname: Metcalfe
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D005075:Biological Evolution; D004734:Energy Metabolism; D007448:Invertebrates / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D010101:Oxygen Consumption; D014714:Vertebrates / Q000378:metabolism
chemical_list: D000255:Adenosine Triphosphate
keywords: life history; mitochondrial coupling efficiency; oxidative stress; reactive oxygen species; trade-off; uncoupling