Sometimes, groups of living things change by chance.
This can happen in small groups. Some traits might go away. Other traits might stay. It is like picking marbles from a jar. Can you imagine how that works?
Living things change by chance.
This is called genetic drift. It is like picking marbles from a jar.
Imagine a jar with red and blue marbles. If you pick marbles to make a new group, the colors might change.
Sometimes, one color might disappear. This happens by luck. In small groups, this happens fast.
A small group can lose its variety. This makes all the living things look more alike. It is a random way that groups change over time.
Living things change in many ways. One way is called genetic drift. This happens by chance. It is not about which animal is strongest. It is just about luck.
Imagine a jar of 20 marbles. Half are red and half are blue. These colors represent alleles. An allele is a version of a gene. To make a new generation, you pick marbles at random. You put the new marbles in a new jar. The colors in the new jar might change. You might get more red than blue. This change in color is genetic drift.
Sometimes, one color might disappear completely. If no red marbles are picked, the red allele is lost. The blue allele then becomes fixed. Fixed means every member of the group has it.
This happens faster in small groups. A small group can face a population bottleneck. This is when a group gets very small.
In a small group, luck has a big effect. Large groups do not change as much. Genetic drift reduces variety over time. It makes a population look more the same.
{
"text": "Genetic drift is a way that living things change over time. It happens because of chance rather than survival skills. In a population, there are different versions of a gene called alleles. Genetic drift changes how often these alleles appear in a group. Sometimes, an allele might disappear completely from the group. This reduces the genetic variation, or the different types of genes available. Other times, a rare allele might become very common.
\n\nYou can imagine this process using a jar of 20 marbles. Half of the marbles are red and half are blue. Each color represents a different allele in a population. To make a new generation, you pick marbles at random to create offspring. If you pick more red marbles by luck, the new jar will have more red. This random shift is exactly how genetic drift works in nature. If you never pick a red marble, that color is lost forever. The blue allele then becomes fixed, meaning every member has it.
\n\nScientists have debated how important this process is for a long time. In the middle of the 20th century, experts argued about natural selection. Ronald Fisher was a famous scientist who studied these ideas. He believed that genetic drift played only a minor role in evolution. However, in 1968, a scientist named Motoo Kimura changed the debate. He proposed the neutral theory of molecular evolution. He argued that many genetic changes are actually caused by
{
"text": "Genetic drift is a fundamental process in biology that changes the frequency of alleles in a population. An allele is a specific version of a gene. Unlike natural selection, which is driven by how well an organism survives, genetic drift is driven
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