Definition for View source for Five agents of evolutionary change

'''Mutations'''

Mutations are changes in the DNA sequence, these sequence changes are sudden and spontaneous variances in the cell. The changes in the genotype at times may lead to changes in the organisms physical traits. If the mutated phenotype is favourable  the organism will survive and be able to reproduce. Mutations are sometimes very lethal to the cell they are found in, and will not always be advantageous to the organism.

If DNA is mutated it can be corrected by the cell or it is killed, mutations are detected by a DNA proofreading system. Most mutations are silent changes in the DNA sequence, and have no effect on the organism or cell. These mutations are called silent mutations.

'''Genetic Drift'''  

Genetic drift is the change frequency change in allele a population, this change is entirely based on chance. These changes may occur because some members of the population leave more offspring not because the specie is more well adapted, but because of chance. Environmental events also may be the cause of members of population carrying certain allele to be whipped out.  Natural disasters usually cause the rare allele in a population to become more common, this works most effectively in small populations.

'''Gene Flow''' 

Is the transfer of alleles from one population to another, it is also known as migration. This is because certain animals are able to travel for long periods of time to far destinations, this causes reproduction with members of different populations. Plants are capable of this due to wind and bees as well, they transfer their pollen. Other examples are the mixture of races in our world today, war and exploration.

'''Non- Random Mating''' 

Mates are chosen on based on phenotype to ensure that a good set of genes is passed on to the next generations. Non- random mating implies that not all members of a population have and equal chance to leave offspring or mate.

'''Natural Selection'''

The process by which favourable traits become more common in successive generations, and unfavourable traits become less common. Organisms with unfavourable traits leave less organisms or die off, while those with the favourable trait survive and leave more offspring. Also known as survival of the fittest.