Answer: Darwin proposed the concept of Natural Selection which revolves around the organism's survival amidst the harsh conditions of the surroundings. Those who better evolve themselves and modify their genes according to the survival,he fits the criteria of Survival of fittest and thus adapt perfectly and produce offsprings.
ARTIFICIAL SELECTION is the manual method in which humans manipulates plants and animals according to their own needs . Eg the poultry we use vegetables such as broccoli cabbage we eat