Final answer:
The statement is false—genetic diversity, not uniform possession of 'fittest' genes, is key to evolution. Natural selection favors advantageous traits within populations, leading to evolutionary changes. The Hardy-Weinberg equilibrium describes a non-evolving population, but most real populations are subject to evolutionary forces.
Step-by-step explanation:
The statement that individuals in a population must all possess the fittest genes for evolution to occur is false. Evolution is driven by the genetic diversity within a population, which includes individuals possessing a range of different genes. Some genes are more advantageous than others in certain environments, which is the essence of natural selection. According to evolutionary theory, populations evolve when they are subject to factors such as mutations, gene flow, genetic drift, and selection.
When Darwin spoke of natural selection, he meant that populations evolve through this process when certain conditions are met. For example, new traits that appear through gene mutations or gene flow may increase in frequency in the population if they confer a favorable adaptation that is selected for by environmental pressures. It is critical to remember that evolution operates on populations over time, not on individual organisms. As such, the genetic variation within a population is crucial since different environmental pressures may favor different traits at different times.
The Hardy-Weinberg equilibrium is a theoretical framework which describes a non-evolving population. Real populations, however, are rarely in this state of equilibrium because they are constantly subject to evolutionary forces which can alter their genetic make-up, leading to evolution.