What is the process by which individuals that are better adapted to their environment survive and reproduce more successfully?

Natural Selection is a process which individuals are better adapted to their enviorment are more likely to survive and reproduce. Say there are turtles barely hatching and there are hungry seagul waiting to be fed, the fastest ones will make it to the water safely while the slow ones are being eaten. so eventually all the turtles in the sea will become faster to get away from predators. hopefully that answered your question.