Page "Oak" Paragraph 14

Frequent hybridization among oaks has consequences for oak populations around the world ; most notably, hybridization has produced large populations of hybrids with copious amounts of introgression, and the evolution of new species.

Frequent hybridization and high levels of introgression have caused different species in the same populations to share up to 50 % of their genetic information.

Having high rates of hybridization and introgression produces genetic data that often does not differentiate between two clearly morphologically distinct species, but instead differentiates populations.

Numerous hypotheses have been proposed to explain how oak species are able to remain morphologically and ecologically distinct with such high levels of gene flow, but the phenomenon is still largely a mystery to botanists.