At 00:33 22/01/97 GMT, Paul wrote:
>Can anyone tell me why nematodes are becoming immune to
>anthelminphic drugs ?
The simplest answer is that the worms that happen (by chance) to be
resistant to the drug leave more progeny than those that are susceptible.
Selection does the rest! The more the drug is used, the greater the
advantage enjoyed by the resistant worms.