Conclusions

The experiment gives no indication of directional selection for correct ovipositional choice. Directional selection might have evolved if selection had been continued for longer, but it would appear that there are many problems which need to be ironed out before this type of experiment is held up as evidence for the sympatric speciation process.

A high degree of inbreeding and gene drift in the experimental page 11 system is suggested by the great range of variability between strains and generations in such diverse factors as egg numbers, migration rates and pupal hatch times.

The results of these processes could well mask any positive results in the selection experiment, and hence inbreeding and gene drift should be eliminated so that the experimental system can function in an unambiguous fashion.

Further confusion in selection results is indicated by the fact that freshly laid eggs can themselves be attractants. A full investigation of this possibility seems warranted.

If these problems can be eliminated, the experimental system devised by Pimentel et al could provide a valuable tool in research on the nature of sympatric speciation.