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An integrated approach to environmental stress tolerance and life-history variation: desiccation tolerance in Drosophila
- HOFFMANN, ARY A., PARSONS, P.A.
- Biological journal of the Linnean Society 1989 v.37 no.1/2 pp. 117-136
- Drosophila melanogaster, body size, energy, ethanol, genetic correlation, genetic variation, heritability, life history, longevity, mortality, prediction, selection response, starvation, stress tolerance
- The availability of metabolic energy provides a general measure of the environmental stress that can be tolerated by organisms, leading to the hypothesis that increased tolerance to a range of environmental stresses will be associated with a reduction in metabolic rate in Drosophila and many other organisms. This hypothesis makes three predictions about genetic variation for stress tolerance: (1) increased stress tolerance will tend to be associated with decreased metabolic rate; (2) genetic correlations between tolerance of different environmental stresses will tend to be positive; (3) stress tolerance and life-history traits will tend to be genetically correlated; in Drosophila correlations with life-history traits other than longevity will tend to be negative. These predictions were tested by artificially selecting for increased desiccation tolerance in Drosophila melanogaster, using an 85% mortality level. The response to selection was rapid and the mean realized heritability was c. 0.65. The selection response was associated with a decreased rate of water loss, reduced activity and a decrease in metabolic rate in agreement with prediction (1). Selection did not alter body size. Selected lines were relatively more tolerant of starvation and a toxic concentration of ethanol in agreement with prediction (2), and had lower fecundities in agreement with prediction (3).