Karyotype - Diversity and Evolution of Karyotypes

Diversity and Evolution of Karyotypes

Although the replication and transcription of DNA is highly standardized in eukaryotes, the same cannot be said for their karyotypes, which are highly variable. There is variation between species in chromosome number, and in detailed organization, despite their construction from the same macromolecules. This variation provides the basis for a range of studies in evolutionary cytology.

In some cases there is even significant variation within species. In a review, Godfrey and Masters conclude:

"In our view, it is unlikely that one process or the other can independently account for the wide range of karyotype structures that are observed... But, used in conjunction with other phylogenetic data, karyotypic fissioning may help to explain dramatic differences in diploid numbers between closely related species, which were previously inexplicable.

Although much is known about karyotypes at the descriptive level, and it is clear that changes in karyotype organization has had effects on the evolutionary course of many species, it is quite unclear what the general significance might be.

"We have a very poor understanding of the causes of karyotype evolution, despite many careful investigations... the general significance of karyotype evolution is obscure." Maynard Smith.