Answer to Question #101307 in Genetics for Mike

Question

In the two potatoes fields (A and B) we used same amount of insecticide against colorado beetles. Results showed that in field A all colorado beetles died neverthless in field B after some time population grown up again. Why this is directional selection type?

Answer 1

Directional selection occurs under the conditions of slow changes of environment in a certain direction. In this case, individuals with features that deviate from the avarage in a particular direction receive benefits; other variations of the trait are subject to elimination. In this case insecticide killed every organism which had avarage genotype, but left few mutated beetles, which were resistant to this kind of chemical. Mutated organisms transfered their modificated genes to their offsprings and created new reaction norm.