5 Processes That Make Evolution RANDOM
1. Mutations
Published in
2 min readOct 28, 2016
- Definition: A random change in someone’s genetic code due to a mistake while copying DNA
- Example: You probably have at least a hundred mutations in your genome, meaning you have new genes that neither of your parents had and that just occurred because your DNA mistakenly copied an adenine instead of a thymine
2. Gene Flow
- Definition: When random individuals move from one population to another and alter the genetic composition of both populations
- Example: some blue-eyed Swedish people move to Mexico and produce half-Mexican, half-Swedish offspring who now have blue eyes
3. Genetic Drift
- Definition: A change in the genetic composition of a population over time as a result of random mating
- Example: Genetic drift is subtle in large populations, but in smaller populations, if a couple individuals with a rare trait don’t find a mating partner, their genes can disappear from the gene pool
4. Founder Effect
- Definition: When a small, random group of colonizing individuals found a new population that has less genetic diversity than the original population
- Example: the population of Dutch settlers in South Africa comes from just a few colonists, and today the Dutch in South Africa have a high frequency of Huntington’s disease because those original Dutch colonists just happened to carry that gene with unusually high frequency
5. Bottleneck Effect
- Definition: When a population’s size dramatically decreases, the random few who survive represent a loss of genetic diversity in the new population
- Example: Northern elephant seals were hunted down in the 1900s from 30,000 individuals to just 20, so now those 20 survivors have had an unusually large impact on the population as it has grown back
