New results published last week report on an experiment that monitored more than 600 generations of the fruit fly. In this laboratory experiment fly populations were selected for accelerated development. But new genes did not arise and take control in these populations as evolutionary theory predicts. The results suggest problems for evolution in the wild:
Despite decades of sustained selection in relatively small, sexually reproducing laboratory populations, selection did not lead to the fixation of newly arising unconditionally advantageous alleles. This is notable because in wild populations we expect the strength of natural selection to be less intense and the environment unlikely to remain constant for ~600 generations. Consequently, the probability of fixation in wild populations should be even lower than its likelihood in these experiments.
In other words, evolution must work differently than expected. Just how it works, in this case, is yet to be determined, but we can add yet another entry to the seemingly never ending list of evolution's failed expectations.