  Associative learning allows animals to rapidly adapt to changes in the
environment. Whether and what aspects of such acquired traits may be
transmittable across generations remains unclear. Using prolonged olfactory
training and subsequent two-forced choice testing in Drosophila melanogaster,
it is observed that certain aspects of learned behavior were transmitted from
parents to offspring. Offspring of parents exposed to distinct odors during
both aversive and appetitive conditioning displayed a heightened sensitivity to
those same odors. The conditioned responses associated with those odors,
however, were not transmitted to the offspring as they displayed a constitutive
preference to the parent-exposed stimuli irrespective of whether they were
associated with aversive or appetitive training. Moreover, the degree to which
the offspring preferred the conditioned stimuli markedly varied from
odor-to-odor. These findings suggest that heightened sensitivities to certain
salient stimuli in the environment, but not their associated conditioned
behaviors, may be transmittable from parents to offspring. Such
trans-generational adaptations may influence animal traits over short
evolutionary time-scales.
