The various ways in which individuals with a particular trait may increase in population are-

• Geographical barrier- if sexually reproducing organisms are isolated by geographical barriers then the gene flow through gametes stops and the isolated members interbreed thus leading to the formation of new species hence increasing the traits.

• Natural Selection- Nature selects individuals that are better adapted to the environment. Those organisms who are better adapted, survive and reproduce more, there characteristics are passed on whereas the organisms that are not adapted well to the environmental conditions are slowly erased from the environment as there characteristics are not passed on.

• Genetic drift- is when the frequency of some genes is changed due to any reasons. It can give rise to differential changes in sub-population. Genetic drift rarely produces adaptations to environment.