The term associated with an organism's reproductive success is fitness. In evolutionary biology, fitness refers to an organism's ability to survive and reproduce in its environment, contributing its genes to future generations. Factors influencing fitness include survival rates, mating success, and offspring viability. High fitness indicates that an organism is well-adapted to its ecological niche, whereas low fitness suggests that it may struggle against environmental pressures or competition. Understanding fitness is essential in the study of natural selection and evolution.