There are four mechanisms that can cause changes in the frequencies of genes in populations: mutation, migration, genetic drift, and natural selection. All four are mechanisms of evolutionary change. What is genetic drift? A) In a population, it is the changes in allelic frequencies of a gene that are due to chance.
B) A random error/change in the DNA sequence. These may be inherited or occur in cells during the lifetime of the organism
C) Also known as gene flow. It is any movement of individuals and/or the genetic material they carry, from one population to another.
D) There is variation in any population differential reproduction occurs and over time a more advantageous trait exists in the population.