The synthetic theory of evolution, also called the modern synthesis, integrates Darwin’s concept of natural selection with Mendelian genetics to explain how species evolve. Developed by scientists like Theodosius Dobzhansky and Ernst Mayr, it views evolution as changes in allele frequencies within populations over time. Natural selection favors traits that enhance survival and reproduction—for example, antibiotic resistance in bacteria or camouflage in birds—allowing advantageous alleles to increase in frequency. Genetic drift causes random changes in allele frequencies, especially in small populations, while mutations introduce new genetic variations. Gene flow transfers alleles between populations, maintaining diversity. By combining these mechanisms, the modern synthesis explains adaptation, population dynamics, and speciation. It also incorporates population genetics, showing how recombination, environmental pressures, and selective forces shape genetic diversity. Overall, this framework unites genetics and evolution, providing a comprehensive explanation for how species adapt to their surroundings and evolve over generations.