Data from: Complex constraints on allometry revealed by artificial selection on the wing of Drosophila melanogaster

Precise exponential scaling with size is a fundamental aspect of
phenotypic variation. These allometric power laws are often invariant
across taxa and have long been hypothesized to reflect developmental
constraints. Here we test this hypothesis by investigating the
evolutionary potential of an allometric scaling relationship in
drosophilid wing shape that is nearly invariant across 111 species
separated by at least 50 million years of evolution. In only 26
generations of artificial selection in a population of Drosophila
melanogaster, we were able to drive the allometric slope to the outer
range of those found among the 111 sampled species. This response was
rapidly lost when selection was suspended. Only a small proportion of this
reversal could be explained by breakup of linkage disequilibrium, and
direct selection on wing shape is also unlikely to explain the reversal,
because the more divergent wing shapes produced by selection on the
allometric intercept did not revert. We hypothesize that the reversal was
instead caused by internal selection arising from pleiotropic links to
unknown traits. Our results also suggest that the observed selection
response in the allometric slope was due to a component expressed late in
larval development and that variation in earlier development did not
respond to selection. Together, these results are consistent with a role
for pleiotropic constraints in explaining the remarkable evolutionary
stability of allometric scaling.