What is defined as natural selection?

Natural selection is a key mechanism of evolution and is defined as the process through which organisms with traits that are favorable for their specific environment have a higher likelihood of surviving and reproducing. This concept was famously articulated by Charles Darwin.

When environmental pressures exist—such as competition for resources, predation, and climate factors—certain individuals within a population may possess characteristics that enable them to better adapt and thrive in those conditions. Over time, these advantageous traits can become more common in the population as those individuals are more likely to reproduce and pass on their advantageous traits to their offspring.

In contrast, random mutations (as described in the first choice) contribute to genetic diversity but do not necessarily lead to the consistent, advantageous changes that natural selection promotes. The introduction of new species (the third choice) does not describe natural selection itself, but rather ecological interactions and changes. Finally, while adaptation (the fourth choice) is related to the outcomes of natural selection, it does not encompass the mechanism of survival and reproduction based on favorable traits, which is at the core of the definition of natural selection.