Three types of natural selection are f 

(1) Stabilizing or Balancing Selection : It leads to the elimination of organisms having overspecialized characters and maintains homogenous population which is genetically constant. It favours the average or normal phenotypes while eliminates the individual with extreme expression, e.g., sickle cell anaemia in human beings.

(2) Direction or Progressive Selection : In this selection, the population changes towards one particular direction along with change in environment. As environment is undergoing, continuous change, the organism having acquired new characters survive, and others are eliminated e.g., Industrial melanism.

(3) Disruptive or Diversifying Selection : It is a type of natural selection which favours extreme expression of certain traits to increase variance in a population. It breaks a homogeneous population into many adapted forms and results in balanced polymorphism, e.g., Three types of snails in sea.