Final answer:
An adaptation is a heritable trait that helps an organism's survival and reproduction in its present environment. It occurs when a change in genetic variation increases or maintains the population's fit to its environment. Examples of adaptations include a cheetah's fast speed for catching prey.
Step-by-step explanation:
A heritable trait that helps an organism's survival and reproduction in its present environment is called an adaptation. Scientists describe groups of organisms adapting to their environment when a change in the range of genetic variation occurs over time that increases or maintains the population's "fit" to its environment. An example of an adaptation is a cheetah's fast speed, which is an adaptation for catching prey.