The ability of an individual to survive and reproduce in its specific environment is called fitness. In the context of biology and evolution, fitness refers to how well an organism can adapt to its environment and produce offspring. Higher fitness means the organism has traits that are advantageous for survival and reproduction, while lower fitness indicates the opposite.
Fitness is a key concept in natural selection, which is the process by which certain traits become more common in a population over time. Organisms with higher fitness are more likely to pass on their genes to the next generation, leading to the evolution of species.