Genförlust

Genförlust, also known as genetic drift, is a mechanism of evolution in which allele frequencies in a population change over generations due to random chance. This effect is particularly pronounced in small populations where random events can have a disproportionately large impact on the genetic makeup of the next generation. Unlike natural selection, which favors alleles that increase survival and reproduction, genetic drift is a random process and can lead to the loss of certain alleles or the fixation of others, regardless of their adaptive value.

The consequences of genetic drift can be significant. It can lead to a reduction in genetic variation within a population, making it less adaptable to environmental changes. In extreme cases, genetic drift can cause rare alleles to become extinct or common alleles to become fixed, meaning they are the only allele present for a particular gene in the population. This can happen even if the allele is neutral or slightly deleterious.

Two important scenarios illustrate genetic drift: the founder effect and the bottleneck effect. The founder effect occurs when a new population is established by a small number of individuals from a larger population. The genetic makeup of the new population will likely differ from the original population simply due to the random sampling of alleles in the founders. The bottleneck effect occurs when a population undergoes a drastic reduction in size, often due to a catastrophic event. The surviving population may have a very different allele frequency from the original population due to random chance. Both these effects can lead to reduced genetic diversity.