Genetic drift is a mechanism of evolution. It refers to random fluctuations in the frequencies of alleles from generation to generation due to chance events. Genetic drift can cause traits to be dominant or disappear from a population. The effects of genetic drift are most pronounced in small populations.
Genetic drift is the drifting of the frequency of an allele relative to that of the other alleles in a population over time as a result of a chance or random event. An example where the effect of genetic drift is magnified is the so-called bottleneck effect. Synonyms: allelic drift; Sewall Wright effect.
Drift leads to an increase in homozygosity for diploid organisms and causes an increase in the inbreeding coefficient. Drift increases the amount of genetic differentiation among populations if no gene flow occurs among them. Genetic drift also has two significant longer-term evolutionary consequences.
Genetic drift can be caused by a number of chance phenomena, such as differential number of offspring left by different members of a population so that certain genes increase or decrease in number over generations independent of selection, sudden immigration or emigration of individuals in a population changing gene ...
The corrected mathematical treatment and term "genetic drift" was later coined by a founder of population genetics, Sewall Wright. His first use of the term "drift" was in 1929, though at the time he was using it in the sense of a directed process of change, or natural selection.
A mother with blue eyes and a father with brown eyes can have children with brown or blue eyes. If brown is the dominant allele, even though there is a 50% chance of having blue eyes, they might have all children with brown eyes by chance.
Natural selection and genetic drift tend to enhance genetic differences among populations; migration tends to homogenize genetic difference, decreasing the differences among populations.
This sudden influx of genes that lead to blue eyes being present in the village is gene flow. The blue eye version (or allele) of an eye color gene has flowed into the population. Before the population had 100% brown versions. Now it is more 50-50.
Green is the rarest eye color of the more common colors. Outside of a few exceptions, nearly everyone has eyes that are brown, blue, green or somewhere in between. Other colors like gray or hazel are less common.
Additionally, consanguineous parents possess a high risk of premature birth and producing underweight and undersized infants. Viable inbred offspring are also likely to be inflicted with physical deformities and genetically inherited diseases.
People with hazel eyes are often perceived as having a sharp mind and a determined personality. Read more: Do hazel eyes need more protection from the sun? Hazel eyes are a combination of gold, green, and brown colors and can be predominantly any one of those colors.
Less than 1 percent of people have gray eyes. Gray eyes are very rare. Gray eyes are most common in Northern and Eastern Europe. Scientists think gray eyes have even less melanin than blue eyes.
An individual is said to have grey eyes when the dominate color falls between blue, brown and green, casting off a mystical look that is highly desired. Over the centuries, many people have attributed the trait of grey eyes to supernatural, empathic abilities.
Only about 5 percent of the population worldwide has the hazel eye genetic mutation. After brown eyes, they have the most melanin. . The combination of having less melanin (as with green eyes) and a lot of melanin (like brown eyes) make this eye color unique.
Eye Color Statistics From Most Common to Most Rare
|Rank||Eye Color||Estimated Percentage of World Population|
Mar 14, 2022
The way light scatters in hazel irises is a result of Rayleigh scattering, the same optical phenomenon that causes the sky to appear blue. Anyone can be born with hazel eyes, but it's most common in people of Brazilian, Middle Eastern, North African, or Spanish descent.
Brown is the least rare of eye colours and can range from dark chocolate hues to lighter chestnut shades. They can sometimes appear black as they tend to blend with the pupil of the eye; however, this is an illusion as black irises don't exist.
Gray: The Rarest Eye Color
|EYE COLOR||U.S. POPULATION||WORLD POPULATION|
|Blue||27%||8% to 10%|
|Brown||45%||55% to 79%|
Mar 10, 2022
Violet is an actual but rare eye color that is a form of blue eyes. It requires a very specific type of structure to the iris to produce the type of light scattering of melanin pigment to create the violet appearance.
Around 1 in 4 people in the U.S. have blue eyes. Brown, which is the most common eye color in the world.