Final answer:
Fitness is an organism's ability to survive and reproduce in a specific environment. It is a term used in the context of evolution by natural selection. Relative fitness, compared to other organisms in the population, helps determine how the population might evolve.
Step-by-step explanation:
Fitness refers to an organism's ability to survive and reproduce in a specific environment. It is a term used in the context of evolution by natural selection. Fitness is often quantifiable and measured by scientists, but what matters is the relative fitness compared to other organisms in the population. This concept allows researchers to determine how the population might evolve.