TYPES OF NATURAL SELECTION

Natural selection occurs with or without environmental change .

1- Directional natural selection - This occurs when natural selection favours one with continuous variation e.g. crabs will be less able to pray upon thicker shelled oysters than thinner shelled oysters .

2- Stabilizing selection - It occurs when natural selection favours the intermediate state of continuous variation , overtime the intermediate colour of an oyster become more common and the extreme variation become less common or lot.

3- Disruptive selection - It occurs when natural selection favours both extremes of continuous variation .

4- Kin selection - Kin selection occurs when natural selection favours a trait that benefits related members of a group . Altruistic behaviours are a result of kin selection e.g. sterile workers bees serve the fertile queen to produce a large number of offsprings .

5- Sexual selection - Natural selection favours the traits that maximize the ability of an individual to compete and attracting mates. This is called sexual selection .

6- Sexual dimorphism - Sexual dimorphism is when males look different then females of the species .

7- Male-male competition - In species with males that battles over right to mate with females such as elephants , deers ,etc . The male that win a fight because he is the strongest and most dominant.