AGB 211: Livestock and Poultry Breeding (2+1)

NATURAL SELECTION

• The main force of natural selection is the survival of fittest in a particular environment. The survival is for the particular environment in which the population lives e.g., wild animals. In nature, the animals best adapted to their environment survived and produced the largest number of offspring. This natural selection acts through the variations produced by mutations and recombination of genetic factors and eliminates unsuccessful genetic combination and allows nature’s successful experiments to multiply.
• Natural selection is a very complicated process and many factors determine the proportion of individuals that will reproduce. Those factors are:
• differences in mortality in the population especially early in life,
• differences in the duration of sexual activity,
• degree of sexual activity and
• differences in the degree of fertility of individuals in that population. Natural selection operates through differences of fertility among the parents or of viability among the progeny. Therefore, in natural selection by means of survival of the fittest, there is a tendency towards elimination of the defective or detrimental genes that have arisen through mutation.