Consider the following scenario:
An antibiotic is applied to a petri dish of bacteria. The antibiotic will kill of most of the bacteria, but some will remain that are immune to the antibiotic. Therefore, only the immune bacteria will reproduce. Soon, the whole petri dish will be full of bacteria that is immune to the antibiotic. Nature "selects" the immune bacteria for survival.
An example of microevolution is the development of antibiotic resistance in bacteria due to natural selection. Over time, bacteria that are resistant to antibiotics survive and reproduce, leading to a population of bacteria that is predominantly resistant to that antibiotic.
Overuse of traditional antibiotics has caused a selection of those bacteria that are resistant to the antibiotic.
Future generations of these bacteria are likely to have a higher proportion of individuals that are resistant to the antibiotic due to natural selection. Over time, the resistant bacteria will survive and reproduce, potentially leading to the evolution of a population that is largely resistant to the antibiotic.
All bacteria, as are all organisms, are variants and some of these variants are resistant to antibiotics. So, a population of bacteria, in their immediate environment, are subjected to an antibiotic and most succumb. So, the resistant, survive the onslaught ( are naturally selected ) and reproduce progeny that are also resistant to the antibiotic. So, allele frequency shifts and evolution occurs die to the adaptive change conferred on the progeny population by natural selection.
All bacteria, as are all organisms, are variants and some of these variants are resistant to antibiotics. So, a population of bacteria, in their immediate environment, are subjected to an antibiotic and most succumb. So, the resistant, survive the onslaught ( are naturally selected ) and reproduce progeny that are also resistant to the antibiotic. So, allele frequency shifts and evolution occurs die to the adaptive change conferred on the progeny population by natural selection.
Exposure to penicillin can lead to the survival of antibiotic-resistant bacteria in a population as non-resistant bacteria are killed off, leaving behind those that have developed resistance. Over time, this can increase the prevalence of antibiotic-resistant strains within the population. It highlights the importance of responsible antibiotic use to prevent the emergence and spread of resistance.
Evolution is the process by which living organisms change and adapt over time through natural selection. An example of evolution is the development of antibiotic resistance in bacteria. When exposed to antibiotics, only the bacteria with genetic mutations that make them resistant survive and reproduce, leading to a population of bacteria that is mostly resistant to the antibiotic.
Also known as "superbugs", antibiotic resistant bacteria have evolved to a point that our usual antibiotics won't kill them. VRE and MRSA are common forms of antibiotic resistant bacteria.
The forces that affect bacteria population are competition, mutation and selection, just like any other population affected by the theory of evolution. In a large population of bacteria, some individuals will be mutated to have resistance to antibiotic drugs (or any other drug). This is a disadvantage to the individual as long as there is no antibiotic drug in the surroundings. In this case there is mutation but no selection. When an antibiotic drug is given to a patient, selection is being done in the evolutionary aspect of the bacteria. Only the drug-resistant mutants survive, since the selection does not affect them. All the non-mutant bacteria die; the mutants have no competition, and can flourish undisturbed.
You are an example of human micro-evolution as the population of humans has changed allele frequency over time. Micro-evolution is just evolution; change over time.
This term is misleading. The antibiotic "selects" bacteria that are not affected by it. If a person will grow bacteria on a petri dish and add an antibiotic to it, some bacteria may live and grow. This is actually a form of natural selection. The ones that will grow are resistance to the antibiotic. They have some way of not being affected. If a person takes a colony from the plate that has this resistance and grows it on another plate and add the antibiotic, all on the plate will be resistant.
A population of bacteria can become resistant to antibiotics through genetic mutations that confer resistance traits. These mutations can arise spontaneously or be acquired through gene transfer from other resistant bacteria. Over time, the selective pressure exerted by antibiotic use allows the resistant bacteria to survive and multiply, leading to the spread of resistance within the population.