Module 8 - Genetic Variation

 Genetic variation is maintained in populations because mutations occur all the time. Though most of these mutations are neutral, they still present variation in the allelic frequencies in a population and thus genetic variation. Some mutations are negative and will be selected against, which also alters the allelic frequency and genetic variation. Some mutations will be favored, and natural selection will increase the frequency of this allele, thus changing the genetic make-up of the population as more of this allele is reproduced do to its beneficence. Genetic recombination can lead to genetic variation. I recently watched a video that explained that eye color is more complicated than we thought. I was taught in school that if a blue eyed person, who had homozygous recessive bb alleles, reproduced with a homozygous dominant brown eyed person, who had alleles represented by BB, there child would have to have brown eyes. The only outcomes for children that they would have would be Bb; in other words, they would be heterozygous, but the dominant brown eye allele B would run the show. My father has blue eyes, and my mother has very dark brown eyes. I grew up thinking I had brown eyes, but one day I really studied my eyes in a mirror and realized that they were hazel. They were not as near as brown as my mother’s, and they had many flecks of green in them. I knew then that what I had been taught did not hold all the answers, and this video confirmed it (X). Sexual recombination and crossing-over add to genetic variation. Although my mom has BB and my dad has bb, I do not have Bb. There is something else, and this contributes to a different allelic frequency and genetic variation. 


Additionally, migration definitely contributes to genetic variations in populations. New alleles coming into the population and integrating their information through reproduction with original members changes the frequencies and thus genetic variation. The difference in alleles and the amount of migration determines the extent of genetic variation. Natural selection itself can change over time. What was selected for and beneficial for the species/individuals in the past may not be so in the future. This happens because there is a change in the environment. The environment/natural selection may select a different factor and change the allele frequency and variation in this manner. 

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