Question

Appearance of antibiotic-resistant bacteria is an example of evolution due to:

• A. Adaptive radiation
• B. Divergent evolution
• C. Artificial selection
• D. Anthropogenic action

Hint:

The word "Anthropogenic" comes from the Greek roots anthropos (human) and genesis (origin). Whenever you see rapid modern evolutionary shifts caused by chemical pollutants, pesticides, or medicines, it is always a direct result of anthropogenic action.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks us to identify the specific evolutionary driver or context that explains the rapid emergence of antibiotic-resistant strains of bacteria.

Step 2: Key Formula or Approach:
Evolution can occur via natural processes over geological time scales, or it can be accelerated within very short time frames due to human interventions. Changes driven directly or indirectly by human activities are classified as evolutionary phenomena due to anthropogenic action.

Step 3: Detailed Explanation:
Before antibiotics are widely used, a massive bacterial population naturally contains a few rare individuals with random genetic mutations that confer resistance to a particular chemical.
When humans introduce antibiotics into clinical and agricultural settings on a massive scale, an intense selective pressure is created.
The antibiotic kills off all sensitive bacteria (the vast majority). The few pre-existing resistant mutants survive and reproduce without competition.
Over a short period, these resistant individuals multiply rapidly, turning the entire population into a drug-resistant strain.
Because this natural selection is driven by the use of synthetic chemical agents created by humans, it is a clear example of evolution by anthropogenic action (human-induced evolution).
Let's review the other options:
* Adaptive radiation (Option A): This describes the evolutionary process where a single ancestral species rapidly diversifies into many different forms to fill different ecological niches (e.g., Darwin's finches).
* Divergent evolution (Option B): This refers to structural diversification from a common ancestral form over long geological periods (e.g., vertebrate limbs).
* Artificial selection (Option C): This involves intentional, deliberate breeding programs managed by humans to select for specific traits, such as breeding domesticated dogs or high-yield crops. Humans do not intentionally breed resistant bacteria; it is an accidental byproduct of medicine.

Step 4: Final Answer:
The appearance of antibiotic-resistant bacteria is an example of microevolution driven by anthropogenic action, corresponding to option (D).