Final answer:
Natural selection refers to the process where traits beneficial for survival and reproduction become more common over generations. Examples include the peppered moths' color changes during the Industrial Revolution and the development of pesticide-resistant insects and antibiotic-resistant bacteria.
Step-by-step explanation:
Natural Selection and Its Examples
Natural selection is a cornerstone of evolutionary biology, famously formulated by Charles Darwin. It refers to the process by which hereditary traits that enhance survival and reproduction become more common in successive generations of a population. The classic example of this process can be seen in the peppered moths during the Industrial Revolution in England. Light-colored moths were initially prevalent because they were camouflaged against tree bark. However, once pollution darkened the trees, dark moths had a survival advantage and thus became more common. This is known as directional selection, where environmental changes favor a specific phenotype, leading to a shift in the population's allele frequencies.
In another example, pesticide resistance in insects and antibiotic resistance in bacteria demonstrate how natural selection equips populations with beneficial adaptations. When only the individuals that can withstand these substances survive to reproduce, the next generation inherits these resistive traits. Similarly, bird observations in the laboratory experiments show that the response of one species to certain visual signals - like the absence of butterflies' eyespots - can affect the survival and reproduction rates of the other species, evidencing how one species' behavior can drive natural selection in another.
The theory of natural selection is reaffirmed by observing organisms like the Galápagos finches. The Grants' studies of finch beak shapes highlighted how environmental factors, like food availability affected by the El Niño event, can cause certain traits to become more prevalent due to better survival and reproductive success of some individuals over others.