Fitness is a crucial concept in evolution as it refers to an organism's ability to survive and reproduce in a particular environment. In other words, fitness can be understood as an organism's adaptability to its environment or its ability to pass on its genes to the next generation. Evolution is driven by the natural selection of advantageous traits that provide a reproductive advantage, such as stronger muscles for catching prey or greater stamina for long-distance running. These traits increase an organism's fitness and, therefore, their likelihood of survival and reproduction. Over time, these advantageous traits become more common in a population, leading to the evolution of new species. Thus, fitness plays an essential role in the evolutionary process by selecting for traits that improve an organism's suitability to its environment.
