Excess use of herbicides, pesticides, etc., has only resulted in selection of resistant varieties in a much lesser time scale. This is an example of evolution by

Antibiotic or drug resistant microbes, DDT resistant mosquitoes, etc., are examples of evolution by anthropogenic action. The evolution of resistant varieties is hastened by the human use of antibiotics and pesticides. Genetic drift is a mechanism of evolution in which change in allele frequencies of a population over generations occurs by chance. In adaptive convergence, the animals of unrelated groups occupying the same habitat exhibit common features.