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A Shift in the Thermoregulatory Curve as a Result of Selection for High Activity-Related Aerobic Metabolism1.92 MB
Published VersionCC BY V4.0, Open Access
Journal article
A Shift in the Thermoregulatory Curve as a Result of Selection for High Activity-Related Aerobic Metabolism
Frontiers in Physiology, Vol.8, pp.1-11
2017
PMCID: PMC5741638
PMID: 29326604
Abstract
According to the "aerobic capacity model," endothermy in birds and mammals evolved as a result of natural selection favoring increased persistent locomotor activity, fuelled by aerobic metabolism. However, this also increased energy expenditure even during rest, with the lowest metabolic rates occurring in the thermoneutral zone (TNZ) and increasing at ambient temperatures (T-a) below and above this range, depicted by the thermoregulatory curve. In our experimental evolution system, four lines of bank voles (Myodes glareolus) have been selected for high swim-induced aerobic metabolism and four unselected lines have been maintained as a control. In addition to a 50% higher rate of oxygen consumption during swimming, the selected lines have also evolved a 7.3% higher mass-adjusted basal metabolic rate. Therefore, we asked whether voles from selected lines would also display a shift in the thermoregulatory curve and an increased body temperature (T-b) during exposure to high T-a. To test these hypotheses we measured the RMR and T-b of selected and control voles at T-a from 10 to 34 degrees C. As expected, RMR within and around the TNZ was higher in selected lines. Further, the T-b of selected lines within the TNZ was greater than the T-b of control lines, particularly at the maximum measured T-a of 34. C, suggesting that selected voles are more prone to hyperthermia. Interestingly, our results revealed that while the slope of the thermoregulatory curve below the lower critical temperature (LCT) is significantly lower in the selected lines, the LCT (26.1 degrees C) does not differ. Importantly, selected voles also evolved a higher maximum thermogenesis, but thermal conductance did not increase. As a consequence, the minimumtolerated temperature, calculated froman extrapolation of the thermoregulatory curve, is 8.4 degrees C lower in selected (-28.6 degrees C) than in control lines (-20.2 degrees C). Thus, selection for high aerobic exercise performance, even though operating under thermally neutral conditions, has resulted in the evolution of increased cold tolerance, which, under natural conditions, could allow voles to inhabit colder environments. Further, the results of the current experiment support the assumptions of the aerobic capacity model of the evolution of endothermy.
Details
- Title
- A Shift in the Thermoregulatory Curve as a Result of Selection for High Activity-Related Aerobic Metabolism
- Authors
- Clare Stawski (Author) - Jagiellonian UniversityPawel Koteja (Author) - Jagiellonian UniversityEdyta T Sadowska (Author) - Jagiellonian University
- Publication details
- Frontiers in Physiology, Vol.8, pp.1-11
- Publisher
- Frontiers Research Foundation
- Date published
- 2017
- DOI
- 10.3389/fphys.2017.01070
- ISSN
- 1664-042X
- PMID
- 29326604; PMC5741638
- Copyright note
- Copyright © 2017 Stawski, Koteja and Sadowska. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
- Organisation Unit
- University of the Sunshine Coast, Queensland; School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 99629735302621
- Output Type
- Journal article
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