The bacteria in the example evolved because of…
gene flow
genetic drift
natural selection
The Correct Answer and Explanation is :
The evolution of bacteria in a given example is often attributed to natural selection. This process involves the differential survival and reproduction of individuals due to variations in traits that are advantageous in a specific environment.
Explanation:
Natural selection is a fundamental mechanism of evolution, first described by Charles Darwin. In any population of bacteria, there is genetic variation among individuals. These variations can arise from mutations, gene transfer, or other genetic changes. When bacteria are exposed to environmental pressures—such as antibiotics, changes in nutrient availability, or competition for resources—individuals with traits that confer advantages in those conditions are more likely to survive and reproduce.
For instance, consider a scenario where a particular strain of bacteria is exposed to an antibiotic. Most of the bacteria may be susceptible and die off, but a few may have random mutations that render them resistant to the antibiotic. These resistant bacteria will survive and reproduce, passing on their resistance genes to the next generation. Over time, the population of bacteria will evolve to consist predominantly of antibiotic-resistant individuals. This is a clear demonstration of natural selection in action.
While gene flow (the transfer of genes between populations) and genetic drift (random changes in gene frequencies in a population) can also lead to evolutionary changes, they do not necessarily result in adaptations to specific environmental pressures. Gene flow can introduce new genetic material and genetic drift can cause random loss of alleles, but these processes do not focus on the survival of the fittest in the same way that natural selection does.
In summary, bacteria evolve primarily due to natural selection when they encounter environmental pressures that favor certain traits. This process drives the adaptation and survival of bacterial populations in changing conditions, ultimately shaping their evolution.