Article source: College of Life Sciences
Author: Zhang Yufen
Editor: Shao Pengyu
The research team of Zhang Dayong, Institute of Ecology, College of Life Sciences, Beijing Normal University, used the phylogenetic and population genetics analysis methods based on genomic data to systematically study the evolutionary origin of cultivated walnuts. Their research found that cultivated walnuts were formed by the hybridization of two previously extinct species about 3.45 million years ago. In the late Oligocene, walnuts arrived in Europe from the Americas, then spread to Asia and further expanded in Europe. The ancestors of black and white walnuts met and crossed about 3.45 million years ago. Although walnuts were further differentiated in Asia and the New World, they disappeared from Europe during the Pleistocene climate turmoil, and eventually only the newly formed hybrid lineage survived and formed today's cultivated walnuts.
Population structure based on independent non-missing SNPs
Chloroplast phylogeny and species network inference
The research paper was published online on Molecular Biology and Evolution, and was reported by many foreign science news media such as the Press Association of the American Association for the Advancement of Science: