Energetic efficiency under stress underlies positive genetic correlations between longevity and other fitness traits in natural populations.
Evolutionary relationships among fitness traits are considered in terms of the near-to-universal scenario of stressful environments leading to a resource-deficient and hence energy-deficient world. Fitness approximates to energetic (and metabolic) efficiency under this environmental model. When fitness is high, stress resistance (reducible to oxidative-stress resistance) and metabolic stability are maximal, and energy expenditure is minimal. Rapid development should then be favored followed by a long lifespan and high adult survival. Positive associations among diverse fitness or life-history traits are expected, controlled by stress-resistant 'good genotypes'. Heterozygotes tend to show higher energetic efficiency and hence higher fitness than do corresponding homozygotes under extreme environments, and to give parallel associations among life-history traits. Energy budgets under abiotic environments are pivotal for integrative evolutionary studies of life histories in natural populations.
Parsons
Peter A
PA
La Trobe University, Bundoora, Vic 3083, Australia. pparsons@internode.on.net
D000818:Animals; D005075:Biological Evolution; D004734:Energy Metabolism; D004777:Environment; D005828:Genetics, Population; D006579:Heterozygote; D008136:Longevity / Q000235:genetics* / Q000502:physiology*; D008954:Models, Biological; D013312:Stress, Physiological