More oxygen during development enhanced flight performance but not thermal tolerance of Drosophila melanogaster

High temperatures can stress animals by raising the oxygen demand above the oxygen supply. Consequently, animals under hypoxia could be more sensitive to heating than those exposed to normoxia. Although support for this model has been limited to aquatic animals, oxygen supply might limit the heat tolerance of terrestrial animals during energetically demanding activities. We evaluated this model by studying the flight performance and heat tolerance of flies (Drosophila melanogaster) acclimated and tested at different concentrations of oxygen (12%, 21%, and 31%). We expected that flies raised at hypoxia would develop into adults that were more likely to fly under hypoxia than would flies raised at normoxia or hyperoxia. We also expected flies to benefit from greater oxygen supply during testing. These effects should have been most pronounced at high temperatures, which impair locomotor performance. Contrary to our expectations, we found little evidence that flies raised at hypoxia flew better when tested at hypoxia or tolerated extreme heat better than did flies raised at normoxia or hyperoxia. Instead, flies raised at higher oxygen levels performed better at all body temperatures and oxygen concentrations. Moreover, oxygen supply during testing had the greatest effect on flight performance at low temperature, rather than high temperature. Our results poorly support the hypothesis that oxygen supply limits performance at high temperatures, but do support the idea that hyperoxia during development improves performance of flies later in life

Data from: Developmental plasticity evolved according to specialist–generalist trade-offs in experimental populations of Drosophila melanogaster

We studied the evolution of developmental plasticity in populations of Drosophila melanogaster that evolved at either constant or fluctuating temperatures. Consistent with theory, genotypes that evolved at a constant 16°C or 25°C performed best when raised and tested at that temperature. Genotypes that evolved at fluctuating temperatures performed well at either temperature, but only when raised and tested at the same temperature. Our results confirm evolutionary patterns predicted by theory, including a loss of plasticity and a benefit of specialization in constant environments

data for Dryad

This file contain data on the flight performance of flies in a standard assay. The variables are described as follows: 1) selection "treatment" (C, H, or T); 2) experimental "population" within the selection treatment (1-5); 3) isofemale line within the population (#.#); 4) temperature at which flies were reared (16 or 25C); 5) temperature at which flies were tested (16 or 25C); and whether flies successfully demonstrated flight (0 or 1)

Flight performance depended on body temperature and oxygen supply.

<p>At 37°C (left) and 39°C (center), flies performed better if they had developed with a greater supply of oxygen. At 41°C (right), flies performed poorly overall. The color of each bar denotes the oxygen level at which flies were tested (light gray = 12%, dark gray = 21%, black = 31%). The most likely probability of flight under each condition was computed by multimodel averaging. The number of observations used to estimate the mean is marked at the top of each bar.</p

The importance of factors in our models of flight performance and knockdown time.

<p>Importance equals the sum of Akaike weights for models that include the factor (or the probability that the factor would occur in the best model). A dash indicates that a factor was not considered in the set of models.</p

All likely models included an effect of temperature on flight performance.

<p>The two most likely models also included an effect of developmental temperature. For each model, we provide the Akaike information criterion (<i>AIC</i>_<i>c</i>) and the Akaike weight, which equals the probability that the model describes the data better than other models. All models contained an intercept and an error term associated with isofemale line.</p

At 25°C, flies raised at normoxia performed best when tested at normoxia.

<p>The most likely probability of flight under each condition was computed by multimodel averaging. Fifty flies were tested at each concentration of oxygen.</p