Scaling of CO₂Production in the Timber Rattlesnake (Crotalus horridus), with Comments on Cost of Growth in Neonates and Comparative Patterns

Abstract

To understand the bioenergetic fluxes of free-ranging timber rattlesnakes (Crotalus horridus) better, we measured CO(2) production rate of 83 snakes in response to body mass, body temperature, time of day, sex, and geographic locality (northwest Arkansas and coastal Virginia). Effects of body mass, temperature, time of day, and the temperature-by-time interaction were remarkably similar to effects reported for other rattlesnakes. We noted that C. horridus has relatively high, but precedented, Q(10) (3.71-4.78); however, the adaptive significance of this observation, if any, remains obscure. Once the confounding effect of body mass was statistically adjusted, C. horridus exhibited no sex-specific effects; however, there was a significant locality-by-time effect, which is of equivocal biological significance. In contrast to the findings of a recent review on cost of growth in neonatal reptiles, C. horridus neonates exhibited metabolic rates that were from 200% to 400% greater than expectations from the mass scaling of yearlings and older animals. We interpreted this as evidence for a cost of synthesis in growing neonates. We report regression equations for the estimation of resting CO(2) production rate in C. horridus as a function of body mass, body temperature, and time of day. Our data contribute to a growing, comparative database documenting rattlesnakes as low-energy specialists.

Functional and Numerical Responses of Predators: Where Do Vipers Fit in the Traditional Paradigms?

“…Young vipers have higher energy requirements than adults, largely because of energetic allocations focusing on rapid growth rather than storage (Beaupre & Zaidan, 2001). For example, Dorcas et al (2004) calculated that a 1 kg (juvenile) eastern diamond‐backed rattlesnake would need to consume between 0.33 and 6.80 rodent meals (given ambient temperatures of 5 and 35°C, respectively) to meet annual standard metabolic rate (SMR) costs; while a 4 kg snake (adult) would require between 0.30 (5°C) and 6.17 (35°C) rodents per year to meet annual standard metabolic costs.…”

“…Diller & Johnson, 1988). However, juvenile vipers may also differ in their energy allocations to growth both between and within species, depending on maternal yolk provisioning, food availability, and abiotic factors such as elevation, temperature, and latitude (Macartney, Gregory & Charland, 1990; Bonnet et al , 1998, 2001; Beaupre & Zaidan, 2001; Beaupre, 2002).…”

Using A Priori Contrasts for Multivariate Repeated-Measures ANOVA to Analyze Thermoregulatory Responses of the Dibbler (Parantechinus apicalis; Marsupialia, Dasyuridae)

“…The recent physiological literature includes various approaches to this problem. Some repeated-measures studies simply do not evaluate the pattern of the repeated measure (e.g., Beaupre and Zaidan 2001;Gomez et al 2006), and some use a Bonferronitype adjustment for multiple comparison tests (e.g., Rezende et al 2004;Berg and Biewener 2008;Park et al 2009;Wu et al 2009;Dunlap et al 2010) or post hoc ANOVA tests that do not account for repeated measurements (e.g., McLean and Speakman 2000;Gilmour et al 2001;Zerm et al 2004;Zhao and Cao 2009;Dupont-Prinet et al 2010).…”

An emerging fungal pathogen is associated with increased resting metabolic rate and total evaporative water loss rate in a winter‐active snake

“…Erratic records associated with physical activity are readily identifiable from inspection of continuous flow‐through respirometry records (Beaupre & Zaidan, ; Kristín & Gvoždík, ). We inspected all raw CO 2 records and excluded any such hourly (and corresponding EWL) records including erratic traces indicative of activity.…”

“…We estimated the allometric exponent separately by SFD status using repeated‐measures multiple regression (SAS PROC MIXED) with log 10 (ml/hr) as the response and log 10 body mass ( W , g) and temperature ( T , °C) as independent variables. Following back‐transformation, allometric equations were of the form = aW b 10 cT , where a , b and c are estimated constants (Beaupre & Zaidan, ). In simulating T b cycles, we assumed night‐time T b (18:00–07:00 hr) for all individuals was equivalent to mean night‐time soil temperature at 10 cm depth (19°C; obtained from a Florida Automated Weather Network station in Pierson, Florida, ~13.5 km from the study site: https://fawn.ifas.ufl.edu/data/).…”