With the help of any two suitable examples explain the effect of anthropogenic actions on organic evolution.

Explanation

Pesticide resistance and antibiotic resistance are very good examples of evolution by anthropogenic (man) action.
(i) Pesticide Resistance. DDT was discovered by Muller (1939). It was found to be highly effective against mosquitoes, flies and insects, causing malaria, sleeping sickness and crop pests in general. However, after about two decades, this was found to be ineffective against most pests. New pesticides were used but after a lapse of a few years, the pests were found to develop resistance against them as well. At present sorne 400 insect pests are known to possess resistance against most pesticides. Therefore, newer pesticides are entering market every year for effectively controlling the pests.
(ii) Antibiotic Resistance. When first discovered, penicillin was widely used as an antibiotic against bacterial pathogens. Soon it was found to be ineffective against many bacteria. Reduction ir effectiveness of antibiotic is naturally due to development of resistance against it. The antibiotic kills the pathogens and successfully treats most patients. However, some patients will show relapse of disease after initial success. It is because antibiotic kills most of the bacteria which are sensitive. A few with resistance survive. They multiply and cause relapse.