TreeBASE Search-Analyses for study 14830

@ARTICLE{TreeBASE2Ref22485, author = {Tatiana Arias and Mark Alan Beilstein and Michelle Tang and Michael R. McKain and J. Chris Pires}, title = {Diversification Times Among Brassica Crops Suggest Hybrid Formation After Twenty Million Years of Divergence.}, year = {2013}, keywords = {Brassica, Mediterranean, Miocene, crops}, doi = {}, url = {http://}, pmid = {}, journal = {American Journal of Botany}, volume = {}, number = {}, pages = {}, abstract = {Premise of the study. Cruciferous vegetables, of which many are in the genus Brassica (Brassicaceae), are prized for their nutritive value and have been cultivated for thousands of years. There are numerous wild northwestern Mediterranean species in tribe Brassiceae and it is therefore assumed this center of diversity is also the region of origin. Crops in the genus Brassica comprise three major diploid species: B. oleracea, B. rapa and B. nigra. These species hybridized in the past to form the tetraploid species B. juncea, B. carinata and B. napus. Moreover, the three diploids retain the ability to hybridize, and this has been taken as evidence that they are closely related. Methods. Here we test the hypotheses of a Northwestern Mediterranean origin for the tribe and the proximal relationship and geographic origins of crop Brassicas using a combination of molecular phylogenetics and historical biogeography. Key results. We find evidence that the tribe originated around the forming intersection between the Arabian Peninsula and Saharan Africa approximately 24 Mya. Our data also suggest that the maternal genomes of the three diploid crop Brassicas are not closely related but separated by a 20 My divergence. Finally, our analyses indicate that the lineage giving rise to B. oleracea + B. rapa originated ≈ 3 Mya in the North Eastern Mediterranean, from where ancestors of B. oleracea spread through Europe and B. rapa to Asia. Conclusions. These results challenge previous hypotheses about the genetic proximity of three crop diploids and the biogeographical origins of crop Brassicas and the tribe to which they belong. } }