Effects of voluntary activity and genetic selection on aerobic capacity in house mice (Mus domesticus)

Abstract

. Effects of voluntary activity and genetic selection on aerobic capacity in house mice (Mus domesticus). J. Appl. Physiol. 84(1): 69-76, 1998.-An animal model was developed to study effects on components of exercise physiology of both ''nature'' (10 generations of genetic selection for high voluntary activity on running wheels) and ''nurture'' (7-8 wk of access or no access to running wheels, beginning at weaning). At the end of the experiment, mice from both wheel-access groups were significantly lighter in body mass than mice from sedentary groups. Within the wheel-access group, a statistically significant, negative relationship existed between activity and final body mass. In measurements of maximum oxygen consumption during forced treadmill exercise (V O 2 max ), mice with wheel access were significantly more cooperative than sedentary mice; however, trial quality was not a significant predictor of individual variation in V O 2 max . Nested two-way analysis of covariance demonstrated that both genetic selection history and access to wheels had significant positive effects on V O 2 max . A 12% difference in V O 2 max existed between wheelaccess selected mice, which had the highest mass-corrected V O 2 max , and sedentary control mice, which had the lowest. The respiratory exchange ratio at V O 2 max was also significantly lower in the wheel-access group. Our results suggest the existence of a possible genetic correlation between voluntary activity levels (behavior) and aerobic capacity (physiology).

Mice selectively bred for high voluntary wheel running have larger midbrains: support for the mosaic model of brain evolution

“…Lower body mass in HR lines has been a consistent finding in the selection experiment since generation 14 (13.6% smaller at 79days old) (Swallow et al, 1999), and a trend for reduced body mass was observed at generation 10 (e.g. Swallow et al, 1998b). The difference in body mass between HR and C lines makes it important to include body mass as a covariate in statistical comparisons of organ size, including brain mass and volume (see Tables2, 3).…”

Quantitative trait loci associated with maximal exercise endurance in mice

“…In brief, after a 1-wk vivarium acclimation, the mice were oriented twice to running in a small cell suspended above a human treadmill. A shock grid was mounted at the rear of the cell (1.5 mA, 150 V) to provide stimulus for the animals to run (35). During testing, each mouse was placed in the treadmill cell and allowed 3 min of rest.…”

Adaptation, Exaptation, and Constraint: A Hormonal Perspective

“…Application of systemic hormones in varying doses and at varying times in development, followed by measurement of impacts on trait development, would provide an assessment of trait interdependence. Estimates of heritability and of environmental effects on trait expression, as well as artificial selection on one or another member of a complex, would reveal the potential for correlated or independent response in the other traits (e.g., Sefton and Siegel 1975;Cunningham and Siegel 1978;Garland 1988;Siegel and Dunnington 1990;Bakker 1994;Zera and Zhang 1995;Van Tienderen and Van Hinsberg 1996;Swallow et al 1998).…”