The gene as the unit of selection

The gene as the unit of selection means that natural selection primarily acts on genes—the basic units of heredity—rather than entire organisms or species. Genes influence traits that help an organism survive and reproduce. Those genes that increase an organism's chances of passing on their traits tend to become more common over generations. This perspective focuses on how genetic variations are selected because they affect individual reproductive success, shaping the evolution of populations. Essentially, evolution operates at the level of genes, with successful genes spreading through reproduction, driving the long-term change in populations over time.