The Oaks Rule, says Paul Manos
How did the oaks come to rule North American forests? As champions of diversification and hybridization the oaks both became essential species in forest ecology and created a baffling evolutionary history. Professor Paul Manos, together with two colleagues, has published an article in the August issue of Scientific American broadly describing the evolution and diversification of oaks since the start of the Eocene. Starting as a single population in the Canadian Arctic, the oaks spread south as the climate cooled. Divided into the red oaks and white oaks, they were split further by the Rocky Mountains, then by adaptation to local climates, hotter or colder, drier or wetter, higher or lower altitude. Today 435 different species of Quercus are known, with 60% in the Americas. The researchers combined recent advances in genome sequencing with statistical analysis and fossil evidence to create a vista of 56 million years of oaks.