Which term describes the ability of an organism to survive and reproduce in its environment?

The term that describes the ability of an organism to survive and reproduce in its environment is "fitness." In the context of biology and evolutionary theory, fitness refers to an organism's genetic contribution to the next generation, which encompasses both its ability to survive to reproductive age and to successfully reproduce.

Fitness is often measured in terms of the number of offspring that an organism can produce that survive to maturity and can themselves reproduce. This concept is central to the theory of natural selection, as those organisms that possess traits that enhance their fitness are more likely to pass those traits on to the next generation.

Other terms, while related to survival and reproduction, have different specific meanings. Adaptability refers to an organism's ability to adjust to changes in its environment, survivorship generally pertains to the proportion of individuals in a population that survive to a certain age, and natural selection is the process by which individuals with higher fitness are favored to survive and reproduce, leading to evolutionary change over time. Thus, fitness is the most accurate term to encapsulate the ability to thrive and reproduce within an environment.