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Genetic marker is a gene or DNA sequence that is located in a chromosome. It can be used to determine a species or organism. It usually is the place that can trace for variation where the deletion, substitution, insertion, inversion and duplication of nucleotides occur. Genetic markers are not influenced by environmental factors and the number of markers is unlimited.

1.RAPD (Randomly amplified polymorphic DNA)

2)RFLP (Restriction fragment length polymorphism )

3)AFLP (Amplified fragment length polymorphism )

4)SSR  (Simple-sequence repeats)

5)SNP ( Single-nucleotide polymorphism)

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Darwin’s finches is the most known example where different other species have evolved from one common ancestor to develop different sizes and shapes of beaks to acquire different food sources.

The ancestor of the Galapagos hawk, Swainson’s hawk, does not ordinarily fly over open water, but it appears that the Galapagos hawk has become very sedentary. On the other hand, marine iguanas and Darwin’s finches have been documented to move between islands, possibly suggesting that any advantage of reduced migration increasing fitness has been countered by an advantage of increased introduced genetic variation from this movement.

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Natural selection acts upon genetic variation. It leads to evolutionary adaptation of a population to different lifestyles and environments by increasing or decreasing allele frequency in the population. There are three types of natural selections:

Natural selection can lead to the formation of a distinct species via the evolutionary process of a population from its ancestral population which is known as speciation.

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Genetic variation is the difference in DNA sequence between individuals of a population or species.

Genetic variation is the fundamental force of evolution. It helps to maintain the survival of a certain species by changing its allele frequencies under unfavorable conditions which also helps to prevent its extinction.

Genetic variation can be caused by random mating, random fertilization, gene flow and mutation of genes.

Genetic variation allows the favorable traits that are better-suited for the environment to be passed on for a better survival of the population through natural selection, this idea is also known as ‘survival of the fittest’ by Charles Darwin.

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Population genetics is the study of genetic constitution within and between populations. This biology field also studies the changes in genetic composition due to various factors such as natural selection and mutation.

Population genetics also helps to explain the evolutionary process by determining the changes of allele frequency and genotype from time to time.