The genomes of species are plastic and continuously changing and therefore causing genetic variation. If the genetic variation is expressed as physical traits compatible with the selection pressure, the organism carrying the new genetic traits may be able to reproduce and, hence, transfer the new genetic traits to its descendants. Without genetic variation species would not be able to adapt to a changing environment.
Genetic variation can be analysed at various levels
Genetic variation between:
- individuals is called polymorphisms
- populations is called gene frequency differences
- species or higher taxa is called divergence
Events causing genetic variation within a single individual prokaryote are the genetic variation mechanisms.