North America is home to 91 species of oak trees. Astoundingly, the various species rarely, if ever, occur alone. Where one kind of oak is found, invariably at least one more will be found. How can nature support a setup like that when it operates on the principle that only the fittest survive in any one setting?
A study recently published in the American Journal of Botany has unearthed the secret: A unique evolutionary history that allows oak species to be different and similar at the same time — making them the most diverse and dominant trees species on the continent.