Data from: Phylogeography and paleodistribution models of a widespread birch (Betula platyphylla Suk.) across East Asia: multiple refugia, multidirectional expansion, and heterogeneous genetic pattern

Widespread tree species cover large geographical areas and play important
roles in various vegetation types. Understanding how these species
responded to historical climatic changes is important for understanding
community assembly mechanisms with evolutionary and conservation
implications. However, the location of refugial areas and postglacial
history of widespread trees in East Asia remain poorly known. We combined
microsatellite data (63 populations, 1756 individuals) and ecological
niche modeling to examine the range-wide population diversity, genetic
structure and historical demography of a pioneer tree species, Asian white
birch (Betula platyphylla Suk.) across East Asia. We found a north to
south trend of declining genetic diversity and five clusters,
corresponding to geographic regions. Different clusters were inferred to
have diverged through Pleistocene climatic oscillations and have different
expansion routes, leading to genetic admixture in some populations.
Ecological niche models indicated that the distribution of Betula
platyphylla during the Last Glacial Maximum still had a large latitude
span with slight shifts towards southeast, and northern populations had
more variable distribution ranges than those in the south during later
climatic oscillations. Our results reflect the relatively stable
distribution through the last glacial-interglacial cycles and recent
multidirectional expansion of Betula platyphylla, providing new hypotheses
for the response pattern of widespread tree species to climate change. The
gradual genetic pattern from northeast to southwest and alternative
distribution dynamics possibly resulted from environmental differences
caused by latitude and topographic heterogeneity.