A high standard metabolic rate constrains juvenile growth.
The allocation of energy to various components of an individual's energy budget is often viewed as a competitive process. As such, a tradeoff may exist between production (growth) and maintenance metabolism. One view of a potential tradeoff, termed "the principle of allocation", suggests that individuals with lower maintenance metabolic expenditures may have higher growth rates. To determine whether such a tradeoff exists, I analyzed the relationship between growth rate and maintenance metabolism of 225 juvenile snapping turtles housed in the laboratory. I measured growth from hatching to 6 months of age, and then measured oxygen consumption and calculated standard metabolic rate. Mean growth rate was 0.19 g d(-) and mean standard metabolic rate (SMR) was 1.41 kJ d(-). Maintenance metabolism and growth were negatively correlated after both were adjusted for body mass. The results support the "principle of allocation" theory: individuals with higher standard metabolic rates tended to have low growth rates.
Steyermark
Anthony C
AC
Department of Physiology, UCLA School of Medicine, Los Angeles, CA, USA. acsteyermark@stthomas.edu