Polpulation genetics and gene mapping Documents PDF..pptx

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1. POPULATION GENETICS

2. Natural selection(   survival of the fittest)   Natural selection  is the process where organisms with favorable traits are more likely to reproduce. In doing so, they pass on these traits to the next generation. Over time this process allows organisms to adapt to their environment.

3. GENETIC DRIFT It was explained by Sewall Wright (1931)hence called Sewall wright effect . Genetic drift is the change in allele frequencies of a population due to random chance events, such as natural disasters. Genetic drift can happen when a natural disaster or similar event randomly kills a large portion of the population. The remaining survivors may have allele frequencies that were very different from the previous population.

4. Mut a tion Mutation is the change of the structure of gene, resulting in a variant form that may be transmitted to subsequent generations, caused by the alteration of single base units in DNA, or the deletion, insertion or rearrangement of larger sections of genes or chromosomes. Mutation is the ultimate source of genetic variation, preventing populations from becoming genetically homogeneous in situations where they otherwise would. The allelic variations that make evolution possible are generated by the process of mutation, but new mutations change gene frequencies very slowly, because mutation rates are low.

5. MIGRATION Migration is the movement of individuals from one population to another or the movement of breeding individuals into or out of isolated populations. Results in evolutionary change because alleles move with the individuals. We call this movement gene flow . Immigration: Individuals migrate into a population. Emigration: Individuals migrate out of a population. Both processes allow for gene flow between populations. Gene flow may change the frequency and or the range of alleles in the populations