Natural selection is a process by which organisms that are better adapted to their environment tend toincrease in size. migrate. evolve new traits. survive.

survive

Natural selection is the process of differential survival and reproduction of individuals, because of the differences in the phenotypic traits. Some organisms which have favorable phenotypic traits support their the survival against the changing environmental conditions. These survived organisms later on attains the chance to reproduce and grow in number.  Charles Darwin gave the example of beetles. The two beetle populations exhibiting green and red color being living on grass. The green beetle population color resembling the color of grass remained undetected by crows whereas, the red beetles were easily identified and eaten up by crows. Therefore, the presence of green color was the phenotypic advantage for green beetles, hence favored their survival.  

gametes or germ cells are haploid cells (example: sperm and ova) containing only one set (or n) number of chromosomes and autosomal or somatic cells are diploid cells containing 2n number of chromosomes.