MRSA has evolved through natural selection, how?
Thanks.
Here's an article that explains how MRSA's resistance to antibiotics has evolved, touching on horizontal and vertical evolution.
http://evolution.berkeley.edu/evolibrary/news/080401_mrsa
MRSA (Methicillin-resistant Staphylococcus aureus) is a type of bacteria that has evolved through a process known as natural selection. Natural selection refers to the mechanism by which certain traits become more or less common in a population over time. In the case of MRSA, the process of natural selection can be explained as follows:
1. Variation: Within a population of Staphylococcus aureus bacteria, there is naturally occurring genetic variation. This means that different individuals have slightly different genetic makeups, resulting in variations in traits, such as antibiotic resistance.
2. Selection Pressure: The environment in which the bacteria exist exerts a selection pressure. In the case of MRSA, the selection pressure comes from the use of antibiotics. These drugs are designed to kill bacteria, but some individuals within the population may possess genes that make them resistant to certain antibiotics.
3. Differential Survival and Reproduction: When antibiotics are used to treat bacterial infections, the drugs kill most susceptible bacteria, leaving behind only those that are resistant. In this scenario, the resistant MRSA bacteria have a higher chance of survival and reproduction compared to non-resistant bacteria. This forms the basis of natural selection. The resistant bacteria have a selective advantage, as they can survive in the presence of antibiotics and continue to reproduce.
4. Inheritance: The resistant trait is passed on to future generations as the resistant bacteria reproduce. This occurs because the genetic material (DNA) of the resistant bacteria is copied and transferred to offspring during reproduction.
5. Accumulation of Resistance: Over time, with repeated exposure to antibiotics, the proportion of MRSA bacteria in the population increases. This is because the resistant bacteria have a higher chance of surviving and reproducing, passing on their resistant genes to subsequent generations.
In summary, natural selection has allowed MRSA to evolve by favoring the survival and reproduction of bacteria with antibiotic resistance genes. The repeated exposure to antibiotics has led to the accumulation of these resistant traits in the population of Staphylococcus aureus bacteria, resulting in the emergence and spread of MRSA strains.