The populations of bacteria discussed within the article, “The Ecology of Antibiotic Resistance,” clearly show that there is ‘variation’ in regards to the degree of resistance to treatment. Also, the text illustrates how, ‘individual differences,’ among the bacteria impact individuals’ chances at ‘reproduction and survival.’ Since these two conditions are satisfied one may say the situation is a representative example of evolution by natural selection.
Within a population, there are bacteria with varying levels of antibiotic resistance; therefore it is easy to determine that the condition of variation is being met. The administration of antibiotic medication results in those bacteria with the genetic capacity to resist termination to survive, while those bacteria lacking the necessary genes for tolerance to the treatment are eliminated. Additionally, there are differences in how a bacterium may acquire its resistance to antibiotics in order to achieve increased chances of survival: transformation, plasmid transmission and spontaneous mutation. Collectively these varied conditions set the stage for natural selection to occur.
Furthermore, once the antibiotic takes effect and bacteria lacking resistance are destroyed, those bacteria which do survive readily multiply and in doing so confer resistance to the next generation. As the cycle repeats, one can see natural selection at work. With so many different possibilities, so many different ways for bacteria to survive and multiply it is evident that the conditions are ripe for bacterial antibiotic resistance to continue evolving through the process of natural selection.