College Biology Placement Practice Test

Natural selection is a critical mechanism in the evolutionary process, defined as the differential survival and reproduction of individuals due to differences in phenotype. It results in the evolution of organisms that are best adapted to their environment. This process occurs because individuals with traits that give them a competitive advantage are more likely to survive, reproduce, and pass those advantageous traits on to the next generation. Over time, these adaptations become more common within the population, leading to evolutionary changes that help species thrive in their specific habitats.

In contrast, random changes in species, such as genetic drift, do occur but are not a direct result of natural selection. Mass extinction of species can happen due to various factors, including environmental changes and human activity, but this is not an outcome of natural selection itself. Lastly, the creation of new species through human intervention refers to artificial selection or selective breeding, rather than natural selection, which is a process driven by environmental pressures rather than human choices.