Abstract

A positive genetic correlation between basal metabolic rate (BMR) and maximal (VO₂max) rate of oxygen consumption is a key assumption of the aerobic capacity model for the evolution of endothermy.  We estimated the genetic (V_A, additive, and V_D, dominance), prenatal (V_N), and postnatal common environmental (V_C) contributions to individual differences in metabolic rates and body mass for a genetically heterogeneous laboratory strain of house mice (Mus domesticus).  Our breeding design did not allow the simultaneous estimation of V_D and V_N.  Regardless of whether V_D or V_N was assumed, estimates of V_A were negative under the full models.  Hence, we fitted reduced models (e.g., V_A + V_N + V_E or V_A + V_E) and obtained new variance estimates.  For reduced models, narrow-sense heritability (h²_N) for BMR was < 0.1, but estimates of h²_N for VO₂max were higher.  When estimated with the V_A + V_E model, the additive genetic covariance between VO₂max and BMR was positive and statistically different from zero.  This result offers tentative support for the aerobic capacity model for the evolution of vertebrate energetics.  However, constraints imposed on the genetic model may cause our estimates of additive variance and covariance to be biased, so our results should be interpreted with caution and tested via selection experiments.

Copyright 2001 the Genetics Society of America.