Ejk. Noach et al., PHENOTYPIC PLASTICITY IN MORPHOLOGICAL TRAITS IN 2 POPULATIONS OF DROSOPHILA-MELANOGASTER, Journal of evolutionary biology, 9(6), 1996, pp. 831-844
Isofemale lines of two populations of Drosophila melanogaster, origina
ting from France and Tanzania, were examined over a range of temperatu
res. Morphological traits showed distinct patterns in phenotypic plast
icity; flies of the two populations differed in shape. Genotype-by-Env
ironment (GE) interactions were frequently found in the Tanzania popu
lation, but were hardly present in the France population. If GE inter
action was present over temperature, estimates of additive genetic var
iance and additive genetic covariance were made to compare theoretical
models with our data. The conclusion is that in France Drosophila mel
anogaster has been selected over a wider range of temperatures, result
ing in parallel reaction norms of more optimal slope. In contrast, sel
ection must have taken place over a narrower temperature range in Tanz
anian flies, and will have exerted no direct influence on the slope of
the reaction norm.