Many pathogenic bacteria species are becoming resistant to a

Many pathogenic bacteria species are becoming resistant

to antibiotics. Explain how such adaptations can develop

through the process of natural selection. (

Hint:

Relate

this example to the conditions that are necessary for nat-

ural selection to occur.)

Solution

Explanation: How a new trait (for example; antibiotic resistance) can spread through a bacterial population

We have a good idea that bacteria reproduce at a very high rate. In bacteria like in all other living organisms, the process of reproduction is not perfect. The new copy of the bacterial DNA is not always exactly the same copy as the old one.

We can understand this with different angles;

If the environment that the bacteria live in changes, the bacteria that have an ‘error’ that allows them to do something new, become much more likely to reproduce than the bacteria without the ‘error’. The entire population is going to change very quickly. The bacteria that have the ‘error’ will produce more bacteria that have the ‘error’. The bacteria that lack the ‘error’ will produce fewer bacteria without it. As a result, the vast majority of the bacteria in the population will have the ‘error’.

Generation of antibiotic resistant bacteria through natural selection:-

Antibiotics change the environment in which the bacteria live. Bacteria that have DNA copying errors that result in making them better able to survive and reproduce in the presence of the antibiotic will produce more bacteria like themselves. After a small number of generations, the vast majority of bacteria in the population will be resistant to the antibiotic.

This also explains the process of evolution through the mechanism of natural selection. This process is discussed in depth in The Origin of Species by Darwin.

Due to overuse of antibiotics stronger resistant bacteria are being created. When bacteria become resistant to antibiotics it becomes harder and more expensive to treat the infection. Nowadays, it is becoming a major threat to public health.

A Superbug: When a bacterium carries several resistance genes, it becomes multiresistant.