El. Rezende et al., Does thermal history affect metabolic plasticity?: a study in three Phyllotis species along an altitudinal gradient, J THERM BIO, 26(2), 2001, pp. 103-108
(1) The aim of this study was to understand the effects of thermal history
in metabolic features such as maximum (MMR) and basal (BMR) metabolic rates
, as well as in metabolic plasticity, considered as the total variation of
MMR and BMR during the acclimation period, (2) We studied three species of
the genus Phyllotis, from different thermal environments, in an altitudinal
gradient from sea level to 3800 m.a.s.l. Animals were acclimated to contra
sting temperatures of 5 and 30 degreesC. To determine the metabolic flexibi
lity, MMR was measured at intervals of 6 days during the acclimation period
, while BMR values were obtained at the end of acclimations. Aerobic scope
and the rates of change of MMR were estimated in all populations. (3) High-
and low-altitude rodents did not show differences in BMR. However, both up
per and lower limits of MMR, as well as aerobic scope, were significantly d
ifferent between high- and low-altitude species, indicating similar ranges
of metabolic plasticity. On the other hand, the rates of change of MMR were
similar in all populations. (4) Our results indicate that thermal history
has a profound effect on the individuals' thermogenic capacity, probably in
both phylogenetic and ontogenetic levels. Low-altitude species could not i
ncrease MMR to the same levels as high-altitude species, while the later we
re unable to decrease MMR to achieve the values of the low-altitude species
. (C) 2001 Elsevier Science Ltd. All rights reserved.