The scenario:
Imagine a bacterial population living in a human body. Some bacteria are naturally more resistant to antibiotics than others due to slight variations in their genes.
The change:
When the human takes antibiotics, the susceptible bacteria are killed off, leaving only the resistant bacteria to survive and reproduce. Over generations, the resistant bacteria become more prevalent in the population, leading to a shift in the overall genetic makeup of the bacterial population.
The outcome:
The bacteria are now more resistant to the antibiotic, making it less effective in treating infections.
Why this is micro-evolution:
This is a prime example of micro-evolution because it involves:
* Small-scale change: The change occurs within a single species (bacteria) over a short period.
* Genetic variation: The initial variation in antibiotic resistance within the bacterial population is essential for this process.
* Natural selection: The antibiotic acts as a selective pressure, favoring the survival of resistant bacteria.
* Change in frequency of traits: The frequency of the resistant gene increases in the population.
Further implications:
This example highlights the importance of using antibiotics responsibly and the potential consequences of overuse, which can drive the evolution of antibiotic-resistant strains, posing a serious threat to public health.
