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Abstract and Figures

Body maintenance costs are often considered a proxy for performance in fitness traits. Maintenance energy requirements are measured as minimal metabolic rate of inactive, postabsorptive individuals in the laboratory. For mountain-dwelling species, translocation to the laboratory often means that they are also moved to another elevation. Due to physiological adaptations to local oxygen pressure, rapid elevational change can alter metabolic rate and translocation may result in erroneous estimates of body maintenance costs. In this study, we measured resting metabolic rate (RMR) of three populations of the Mesquite lizard (Sceloporus grammicus, Wiegmann 1828) at their native elevations (i.e., 2600, 3200 and 4100 m). Our results showed that at native elevations, mass specific RMR of lizards from the high elevation population (4100 m) did not differ from the RMR of the other populations (i.e., 2600 and 3200 m), whereas the lizards from the low elevation (2600 m) had lower RMR than those from the intermediate population. These results differ from a previous study in which the RMR of lizards from the same populations were reported to increase with native elevation when translocated and measured at an intermediate elevation. Hence, our results show that translocation in elevation can affect metabolic measures. We caution researchers that changes in elevation may preclude accurate measures of RMR in some animals and may therefore incorrectly predict performance of fitness-related traits.
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Journal of Comparative Physiology B (2022) 192:659–668
https://doi.org/10.1007/s00360-022-01448-3
ORIGINAL PAPER
Avoiding theeffects oftranslocation ontheestimates ofthemetabolic
rates acrossanelevational gradient
MelissaPlasman1,2 · AmandoBautista1 · AníbalH.DíazdelaVega‑Pérez3
Received: 9 August 2021 / Revised: 30 May 2022 / Accepted: 24 June 2022 / Published online: 18 July 2022
© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2022
Abstract
Body maintenance costs are often considered a proxy for performance in fitness traits. Maintenance energy requirements are
measured as minimal metabolic rate of inactive, postabsorptive individuals in the laboratory. For mountain-dwelling species,
translocation to the laboratory often means that they are also moved to another elevation. Due to physiological adaptations to
local oxygen pressure, rapid elevational change can alter metabolic rate and translocation may result in erroneous estimates
of body maintenance costs. In this study, we measured resting metabolic rate (RMR) of three populations of the Mesquite
lizard (Sceloporus grammicus, Wiegmann 1828) at their native elevations (i.e., 2600, 3200 and 4100m). Our results showed
that at native elevations, mass specific RMR of lizards from the high elevation population (4100m) did not differ from the
RMR of the other populations (i.e., 2600 and 3200m), whereas the lizards from the low elevation (2600m) had lower RMR
than those from the intermediate population. These results differ from a previous study in which the RMR of lizards from
the same populations were reported to increase with native elevation when translocated and measured at an intermediate
elevation. Hence, our results show that translocation in elevation can affect metabolic measures. We caution researchers
that changes in elevation may preclude accurate measures of RMR in some animals and may therefore incorrectly predict
performance of fitness-related traits.
Keywords Energetics· Mountain ecosystem· Oxygen pressure· Sceloporus· Temperature
Introduction
The energy cost of body maintenance (measured as minimal
metabolic rate) is a central component of life and correlates
positively with many performance traits (reviewed in Biro
and Stamps 2010; Burton etal. 2011; Mathot etal. 2019). In
ectotherms it has also been found that individuals with high
body maintenance costs may be more resilient to adverse
environmental conditions (Norin etal. 2016), can be active
with lower body temperatures (e.g., Rao and Bullock 1954;
Tsuji 1988; Pörtner etal. 2000; Berg etal. 2017), can reach
high activity levels during short thermal windows (Žagar
etal. 2018), and recover faster from extreme low tempera-
tures (Williams etal. 2016). In mountains, where environ-
mental temperatures decrease with elevation, cold condi-
tions at high elevation may favor high body maintenance in
ectotherms (i.e., the metabolic cold adaptation hypothesis;
Krogh 1916). Accordingly, individuals from high elevation
often exhibit higher metabolic rates at rest than low elevation
conspecifics (Patterson 1984; Snyder and Weathers 1977;
Lardies etal. 2004; Plasman etal. 2020).
However, atmospheric pressure also drops with eleva-
tion (Peacock 1998) and may affect metabolic performance.
The reduced partial oxygen pressure limits oxygen exchange
between air and lungs, lowering oxygen saturation in the
blood and tissues (Storz etal. 2010). Animals generally
counteract low oxygen pressure by augmenting affinity for
oxygen in the blood (e.g., more hemoglobin, bigger red
Communicated by K.H. Dausmann.
* Melissa Plasman
melissaplasman@hotmail.com
1 Centro Tlaxcala de Biología de la Conducta, Universidad
Autónoma de Tlaxcala, Carretera Tlaxcala-Puebla km 1.5,
90062Tlaxcala, Mexico
2 Present Address: Facultad de Ciencias, Universidad
Nacional Autónoma de México, Circuito exterior s/n, Ciudad
Universitaria, Coyoacán, 04510MexicoCity, Mexico
3 Consejo Nacional de Ciencia y Tecnología-Centro Tlaxcala
de Biología de la Conducta, Universidad Autónoma de
Tlaxcala, Carretera Tlaxcala-Puebla km 1.5, 90062Tlaxcala,
Mexico
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