Final answer:
Natural selection leads to evolutionary change by favoring the survival and reproduction of individuals with advantageous traits, which increases their frequency in the population over time. This selective process drives adaptive evolution, shaping the genetic makeup of populations to better suit their environments.
Step-by-step explanation:
Natural selection is the process that leads to evolutionary change. It is the mechanism by which individuals in a population that possess favorable heritable traits survive and reproduce more successfully than others. This process results in the traits that confer an advantage increasing in frequency over generations, culminating in a population that is better adapted to its environment. However, it's crucial to understand that natural selection can only act on existing genetic variation within the population; it does not create new traits but selects among those already present.
By increasing the frequency of beneficial alleles and reducing that of deleterious ones, natural selection drives adaptive evolution. The survival and reproduction of individuals are influenced by their phenotypes, which are the expressions of their genotypes in the environment. Over time, those phenotypes that provide survival and reproductive advantages become more common in the population, thus steering evolutionary change.