Speciation is the evolutionary process by which new species arise, and it primarily occurs through allopatric and sympatric mechanisms. Allopatric speciation happens when a population is divided by physical barriers such as rivers, mountains, or glaciers, which prevent gene flow between the separated groups. Over generations, genetic differences accumulate through mutation, natural selection, and genetic drift, eventually producing distinct species. A classic example is Darwin’s finches in the Galapagos, where isolated island populations evolved different beak shapes adapted to specific diets. Sympatric speciation, in contrast, occurs without physical separation. Here, ecological niches, behavioral differences, or reproductive barriers drive divergence. For instance, cichlid fish in African lakes became different species by exploiting diverse food sources, leading to mate selection based on diet. In plants, polyploidy—chromosome duplication—can instantaneously produce new species, as seen in wheat. Together, these processes illustrate how environmental pressures, genetic variation, and reproductive isolation shape biodiversity.