Mutations are random. A mutation may have no noticeable effect on the organism. Mutations can be helpful, neutral, and even harmful. This depends on the environmental conditions. Mutation provides the start for other forces, like natural selection. Natural selection can spread the mutation or eliminate it. .
Not all mutations start evolution. Some mutations occur on non-reproductive cells and won't be passed onto the offspring. Some mutations can have changes in phenotype or genotype or both. There are three basic types of mutation: substitution, insertion, and deletion. Substitution is when one base exchanged for another in the DNA sequence (A to G). Insertion is adding extra base pairs to DNA. Deletion is when a section of the DNA sequence is deleted. There are more kinds of mutations but these are the basic and most common ones.
Gene flow is when alleles are transferred from one gene pool of a population to another. This changes the allele frequencies in gene pools. For example, if an individual moves from one population to another and mates at the new population. . There are many factors that affect gene flow. The main is mobility; the more mobility an organism has greater mobility the more it can migrate. Mobility determines the rate of gene flow. .
Gene flow spreads helpful alleles throughout the species. Migration can spread beneficial alleles. Without gene flow populations would develop large differences in allele frequencies and speciation would occur. If a population remains isolated with no gene flow from other populations of the same species, a new species can be created. The loss gene flow between two populations the more chances that they two populations will evolve into different species .
Sex introduces new genetic combinations into the gene pool of a population. It is another source of genetic variation. When organisms reproduce sexually genes shuffle and bring new combination of genes.
