Meeting Abstract
53.3 Monday, Jan. 5 Cross-test of the aerobic capacity model of the evolution of endothermy GEBCZYNSKI, Andrzej K*; KONARZEWSKI, Marek; Institute of Biology, University of Bialystok; Institute of Biology, University of Bialystok andgebcz@uwb.edu.pl
Bennett and Ruben’s aerobic capacity model proposed that the high basal metabolic rates (BMR) underlying endothermy evolved as a correlated response to selection favoring the capacity for high and sustained high activity and hence high levels of oxygen consumption (VO2). However, the original formulation of the model left unclear if the postulated selection affected short-term maxima (VO2max) or activity (and VO2) sustained over extended periods. Subsequently, most studies testing the model have focused on short-term VO2max, usually elicited by forced running. To cross-test the model we subjected laboratory mice to two independent artificial selection experiments, in which we selected on (1) VO2max elicited by swimming (VO2swim) and (2) body mass-corrected BMR. Experiment (1) resulted not only in significant between-line differences in VO2swim, but also in the VO2max elicited by forced treadmill running (VO2run) and exercise endurance as indicated by the duration of running (trun) and the distance (srun) run to exhaustion. However, this selective regime did not generate any between-line differences in BMR. In contrast, experiment (2) resulted in substantial between-line differences in BMR but did not produce differences VO2run, trun or srun. On the other hand, high BMR was significantly associated with high food consumption and high levels of voluntary activity. Our results indicate a genetic correlation between voluntary activity and BMR rather than between BMR and VO2max and suggest that the high BMR of endotherms evolved as a by-product of selection for long-term energy expenditures, rather than short-term VO2max.
