scholarly journals Countergradient Variation in Reptiles: Thermal Sensitivity of Developmental and Metabolic Rates Across Locally Adapted Populations

2020 ◽  
Vol 11 ◽  
Author(s):  
Amanda K. Pettersen
Keyword(s):  
Thermal Sensitivity ◽  
Metabolic Rates ◽  
Countergradient Variation

scholarly journals Countergradient variation in reptiles: thermal sensitivity of developmental and metabolic rates across locally adapted populations

2020 ◽  
Author(s):  
Amanda Kate Pettersen
Keyword(s):  
Genetic Variation ◽  
Environmental Gradients ◽  
Thermal Sensitivity ◽  
Empirical Work ◽  
Thermal Adaptation ◽  
Environmental Variation ◽  
Developmental Time ◽  
Metabolic Rates ◽  
Countergradient Variation ◽  
Developmental Rates

Environmental temperature is a key driver of variation in physiological developmental rates in reptiles. Cooler temperatures extend development time and increase the amount of energy required to achieve hatching success, which can pose fitness consequences later in life. Yet, in locally-adapted populations, genetic variation often opposes environmental variation across ecological gradients, known as countergradient variation (CnGV). It is therefore not only the presence, but the absence of phenotypic variation that can reveal insights into the mechanisms underlying local adaptation across environmental gradients. While evidence for genetic variation opposing environmental variation in physiological rates has been summarised in other taxa, the generality of CnGV variation in reptiles is yet unknown. Here I present a summary of studies measuring developmental time and metabolic rates in locally-adapted populations across thermal clines for 15 species of reptiles across 8 families. CnGV in developmental time is found to be common, while no clear pattern emerges for the thermal sensitivity of metabolic rates across locally-adapted populations. CnGV in developmental time may be an adaptive response in order to decrease the costly development in cool climates, however empirical work is needed to disentangle plastic from genetic responses, and to uncover potentially general mechanisms of local thermal adaptation in reptiles.

Standard metabolic rate and preferred body temperatures in some Australian pythons

1998 ◽  
Vol 46 (4) ◽  
pp. 317 ◽  
Author(s):  
Gavin S. Bedford ◽  
Keith A. Christian
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Metabolic Rate ◽  
Thermal Sensitivity ◽  
Standard Metabolic Rate ◽  
Allometric Equations ◽  
Metabolic Rates ◽  
Body Temperatures ◽  
Daily Cycle ◽  
Preferred Body Temperature

Pythons have standard metabolic rates and preferred body temperatures that are lower than those of most other reptiles. This study investigated metabolic rates and preferred body temperatures of seven taxa of Australian pythons. We found that Australian pythons have particularly low metabolic rates when compared with other boid snakes, and that the metabolic rates of the pythons did not change either seasonally or on a daily cycle. Preferred body temperatures do vary seasonally in some species but not in others. Across all species and seasons, the preferred body temperature range was only 4.9˚C. The thermal sensitivity (Q10) of oxygen consumption by pythons conformed to the established range of between 2 and 3. Allometric equations for the pooled python data at each of the experimental temperatures gave an equation exponent of 0.72–0.76, which is similar to previously reported values. By having low preferred body temperatures and low metabolic rates, pythons appear to be able to conserve energy while still maintaining a vigilant ‘sit and wait’ predatory existence. These physiological attributes would allow pythons to maximise the time they can spend ‘sitting and waiting’ in the pursuit of prey.

Thermal sensitivity of metabolic rates and swimming performance in two latitudinally separated populations of cod, Gadus morhua L.

2007 ◽  
Vol 177 (4) ◽  
pp. 447-460 ◽  
Author(s):  
Eve-Lyne Sylvestre ◽  
Dominique Lapointe ◽  
Jean-Denis Dutil ◽  
Helga Guderley
Keyword(s):  
Gadus Morhua ◽  
Swimming Performance ◽  
Thermal Sensitivity ◽  
Metabolic Rates

METABOLIC AND ENDOCRINE ASPECTS OF THE WHIRLER MUTATION IN MALE MICE

1970 ◽  
Vol 64 (2) ◽  
pp. 347-358
Author(s):  
A. Stanley Weltman ◽  
Arthur M. Sackler
Keyword(s):  
Locomotor Activity ◽  
Endocrine Function ◽  
Metabolic Rates ◽  
Heterozygous Female ◽  
Endocrine Organ ◽  
General Body ◽  
Adrenocortical Activity ◽  
Body Weights ◽  
Seminal Vesicle Weight ◽  
Eosinophil Counts

ABSTRACT Body weight, metabolic rate, locomotor activity and alterations in endocrine organ activity were noted in recessive homozygous male whirler mice and the phenotypically »normal« heterozygotes. Representative populations of the two types were studied at different age levels. In general, body weights of the whirler mice were consistently and significantly lower. Open-field locomotion studies similarly indicated heightened locomotor activity. Total leukocyte and eosinophil counts were either markedly or significantly lower in the homozygous vs. heterozygous whirler groups. Evaluation of relative organ weights showed significantly increased adrenal weights in whirler mice sacrificed at 14 weeks and 11 months of age. These changes were accompanied by involution of the thymus. Thus, the varied data indicate persistent increased metabolism and adrenocortical activity during the life-span of the whirler mice. Seminal vesicle weight decreases in the whirler males at 11 months suggest lower gonadal function. The findings are in accord with previous studies of alterations in metabolic rates and endocrine function of homozygous whirler vs. heterozygous female mice.

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