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Phylogeographic breaks within Asian butternuts indicate the existence of a phytogeographic divide in East Asia
Author(s) -
Bai WeiNing,
Wang WenTing,
Zhang DaYong
Publication year - 2016
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.13711
Subject(s) - vicariance , phylogeography , range (aeronautics) , juglans , east asia , biology , pleistocene , biogeography , clade , geography , ecology , evolutionary biology , phylogenetic tree , paleontology , botany , china , archaeology , biochemistry , materials science , composite material , gene
Summary East Asia has been hypothesized to be subdivided into two distinct northern and southern areas, separated by a band of dry climate that was far more severe in the early Tertiary but still exists today. However, this biogeographic hypothesis has rarely been tested using a molecular phylogeographic approach. We genotyped 70 populations throughout the distributional range of Asian butternuts ( Juglans section Cardiocaryon ) using eight chloroplast DNA regions, one single‐copy nuclear gene, and 17 nuclear microsatellite loci, supplemented with paleodistribution modeling of the major genetic clades. The genetic data consistently identified two clades, one northern, comprising Juglans mandshurica and Juglans ailantifolia , and one southern, comprising Juglans cathayensis . The two clades diverged through climate‐induced vicariance of an ancestral northern range during the mid‐Miocene and remained mostly separate thereafter, with geographical isolation of the Japanese Islands and refugial isolation or secondary contacts in the late Pleistocene producing further subdivision within the northern clade. But beyond all that, we also discovered a role of environmental adaptation in maintaining and/or reinforcing the north–south divergence. Asian butternuts offer a strong case for the existence of a biogeographic divide between the northern and southern parts of East Asia during the Neogene and into the Pleistocene.