EFFECTS OF TEMPERATURE-CHANGE ON ECTOTHERM METABOLISM AND EVOLUTION -METABOLIC AND PHYSIOLOGICAL INTERRELATIONS UNDERLYING THE SUPERIORITYOF MULTILOCUS HETEROZYGOTES IN HETEROGENEOUS ENVIRONMENTS

1. Metabolic sensitivity to environmental temperature change increases in positive exponential relation with initial acclimated rates of ene rgy expenditure, and is influenced by the relative rate with which int racellular amino acids are being mobilised by protein turnover. 2. Gre ater metabolic sensitivity results in greater physiological variabilit y with fluctuating temperatures, higher energy costs incurred during t he response to temperature change, and reduced viability upon exposure to extreme high temperatures. 3. These interrelations help explain th e faster production and greater viability of multi-locus heterozygotes experimentally exposed to increased temperature and other stressors, as well as ecogeographical associations indicating the superiority of multi-locus heterozygotes in heterogeneous environments. 4. Implicatio ns are discussed for understanding the effects of temperature change o n ectotherm metabolism and evolution.