Phenotypic flexibility in body mass, basal metabolic rate and summit metabolism in southern red bishops (Euplectes orix): Responses to short term thermal acclimation

Abstract

Avian basal metabolic rate (BMR) and summit metabolism (M sum ) vary within individuals in response to seasonal acclimatization in free-ranging birds, and thermal acclimation under laboratory conditions. We examined relationships between acclimation air temperature (T acc ) and body mass (M b ), BMR and M sum in female southern red bishops (Euplectes orix) from a relatively mild coastal site and a seasonally colder, inland site. Following acclimation for 21 days to T acc ≈ 10, 22 or 35 °C, M b , BMR and M sum were all significantly and negatively related to T acc . The significant relationship between BMR and T acc did not remain after M b was included as a covariate, whereas that between M sum and T acc did. A subsequent reverse 2 acclimation protocol, where bishops were acclimated to a second T acc value and then reacclimated to the first, revealed that short-term changes in M b and BMR were completely reversible, but changes in M sum were only partially reversible. Following the reverseacclimation protocol, metabolic expansibility (M sum /BMR) varied significantly with air temperature, being greatest at T acc = 35 °C. Our data suggest that the intraspecific variation in seasonal metabolic variation previously reported for this species is at least partly driven by factors other than temperature.Keywords body mass intraspecific variation metabolic expansibility phenotypic plasticity resting metabolic rate

Cross-training in birds: cold and exercise training produce similar changes in maximal metabolic output, muscle masses and myostatin expression in house sparrows,Passer domesticus

“…M sum increased by 14.6% in cold-trained birds relative to pre-treatment values and was 12.7% higher than in controls. These values are similar to the percentage changes produced by cold acclimation in previous studies (Vézina et al, 2006;van de Ven et al, 2013b;Swanson et al, 2014b) and within the range (generally 10-50%) reported for winter acclimatization in small birds (Swanson, 2010). Exercisetrained sparrows in this study showed elevated MMR, with increases of 19.7% relative to pre-treatment birds and 14.2% compared with control birds.…”

Summit metabolism and metabolic expansibility in Wahlberg's epauletted fruit bats (Epomophorus wahlbergi): seasonal acclimatisation and effects of captivity

“…Among mammals, metabolic expansibility [ME, the ratio of M sum to basal metabolic rate (BMR); also referred to as factorial aerobic scope] is typically 4-8, but may be as high as 10-13 (Careau, 2013;Hinds et al, 1993). Most avian ME values are similar to those typical of mammals, with maximum reported values of 9.0-9.5 (Arens and Cooper, 2005;van de Ven et al, 2013a). Among mammals and birds, interspecific variation in heat production capacity is correlated with climate, with M sum generally being higher in species inhabiting colder regions (Rezende et al, 2004;Swanson and Garland, 2009).…”

Phenotypic flexibility of energetics in acclimated Siberian hamsters has a narrower scope in winter than in summer

“…1 ). Similar duration of short-term acclimation was shown to be sufficient to produce phenotypic adjustments of energetics in several mammalian as well as avian taxa (e.g., Li et al 2001 ; Nespolo et al 2002 ; Rezende et al 2004 ; McKechnie et al 2007 ; van de Ven et al 2013 ). After that, hamsters were again randomly divided, so that six out of 11 individuals kept at 10 °C were moved to T a = 20 °C and five to T a = 28 °C.…”

“…This range of irreversibly expressed phenotypes is defined by developmental reaction norm (Platt and Sanislow 1988 ; Scheiner 1993 ; Pigliucci 2005 ). The same concept was adopted to define the scope of phenotypic flexibility, which represents reversible changes in behavior, morphology or physiology (McKechnie et al 2007 ; McKechnie 2008 ; Nussey et al 2007 ; Charmantier et al 2008 ; van de Ven et al 2013 ; Petit and Vézina 2014 ). These flexible adjustments can be caused by predictable (usually inter-seasonal) or unpredictable (usually intra-seasonal) changes in the environment (Piersma and Drent 2003 ).…”