Effect of temperature on longevity and productivity in Drosophila ananassae: evidence for adaptive plasticity and trade-off between longevity and productivity.

The genetic response of body size to temperature in the laboratory provides an interesting example of phenotypic plasticity. We found that females of Drosophila ananassae reared to adulthood at 18 degrees C showed significant increase in body weight as compared to females reared at 25 degrees C. At a given temperature, early productivity and lifetime productivity were the highest when the rearing and test temperature were the same. The effect of test temperature was highly significant for total productivity and early productivity. The interaction between test temperature and development temperature was also highly significant. Effect of development temperature was not significant. The females reared at 18 degrees C showed greater body weight but their productivity was not significantly higher than smaller females reared at 25 degrees C. Thus, the usually close relationship between size and fecundity is lost when the size change is due to rearing temperature. These findings provide evidence for adaptive plasticity in D. ananassae. We also found a negative correlation (trade-off) between longevity and productivity, the first report of such a trade-off between longevity and productivity in D. ananassae.