East Asian oaks in the Ice Age

25 Oct
It may sound botanically erudite but it is also of great relevance in order to better understand the ecology and geography of people living in East Asia in the Upper Paleolithic. Hence worth mentioning here.
Dongmei Chen et al., Phylogeography of Quercus variabilis Based on Chloroplast DNA Sequence in East Asia: Multiple Glacial Refugia and Mainland-Migrated Island Populations. PLoS ONE 2012. Open access ··> LINK [doi:10.1371/journal.pone.0047268]


The biogeographical relationships between far-separated populations, in particular, those in the mainland and islands, remain unclear for widespread species in eastern Asia where the current distribution of plants was greatly influenced by the Quaternary climate. Deciduous Oriental oak (Quercus variabilis) is one of the most widely distributed species in eastern Asia. In this study, leaf material of 528 Q. variabilis trees from 50 populations across the whole distribution (Mainland China, Korea Peninsular as well as Japan, Zhoushan and Taiwan Islands) was collected, and three cpDNA intergenic spacer fragments were sequenced using universal primers. A total of 26 haplotypes were detected, and it showed a weak phylogeographical structure in eastern Asia populations at species level, however, in the central-eastern region of Mainland China, the populations had more haplotypes than those in other regions, with a significant phylogeographical structure (NST = 0.751 > GST = 0.690, P < 0.05). Q. variabilis displayed high interpopulation and low
intrapopulation genetic diversity across the distribution range. Both
unimodal mismatch distribution and significant negative Fu’s FS indicated a demographic expansion of Q. variabilis
populations in East Asia. A fossil calibrated phylogenetic tree showed a
rapid speciation during Pleistocene, with a population augment occurred
in Middle Pleistocene. Both diversity patterns and ecological niche
modelling indicated there could be multiple glacial refugia and possible
bottleneck or founder effects occurred in the southern Japan. We dated
major spatial expansion of Q. variabilis population in eastern
Asia to the last glacial cycle(s), a period with sea-level fluctuations
and land bridges in East China Sea as possible dispersal corridors. This
study showed that geographical heterogeneity combined with climate and
sea-level changes have shaped the genetic structure of this wide-ranging
tree species in East Asia.

Maybe most interesting of all is this map: 

Figure 5. Ecological niche modelling.
distribution probability (in logistic value) is shown in each 2.5
arc-min pixel, based on the palaeodistribution modelling at present
(0BP) (a) and at the last glacial maximum (LGM) (21KaBP) (b). The
distribution of river systems on the exposed East China Sea during the
LGM was drawn from Shota et al. (2012). Occurrence records of Q. variabilis at present are also plotted as black points in the maps.

Much more data for those interested in the genetic details can be found in the paper. 


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