AUTHOR=Lyu Jia , Song Jia , Liu Yuan , Wang Yuyao , Li Junqing , Du Fang K. 

TITLE=Species Boundaries Between Three Sympatric Oak Species: Quercus aliena, Q. dentata, and Q. variabilis at the Northern Edge of Their Distribution in China

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.00414

DOI=10.3389/fpls.2018.00414

ISSN=1664-462X

ABSTRACT=<p>Oaks are important timber trees with wide distributions in China, but few genetic studies have been conducted on a fine scale. In this study, we seek to investigate the genetic diversity and differentiation of three sympatric oak species (<italic>Quercus aliena</italic> Blume, <italic>Quercus dentata</italic> Thunb. ex Murray, and <italic>Quercus variabilis</italic> Blume) in their northern distribution in China using 17 bi-parentally inherited nSSRs markers and five maternally inherited chloroplast DNA (cpDNA) fragments. Both the cpDNA and the nSSRs show a high level of genetic differentiation between different oak sections. The chloroplast haplotypes are clustered into two lineages. Clear species boundaries are detected between <italic>Q. variabilis</italic> and either <italic>Q. aliena</italic> or <italic>Q. dentata</italic>. The sharing of chloroplast haplotype H1 between <italic>Q. aliena</italic> and <italic>Q. dentata</italic> suggests very recent speciation and incomplete lineage sorting or introgression of H1 from one species to another. The nSSRs data indicate a complete fixation of variation within sites for all three oak species, and that extensive gene flow occurs within species whereas only limited gene flow is detected between <italic>Q. aliena</italic> and <italic>Q. dentata</italic> and nearly no gene flow can be detected between <italic>Q. aliena</italic> and <italic>Q. variabilis</italic> and between <italic>Q. dentata</italic> and <italic>Q. variabilis</italic>. Prezygotic isolation may have contributed to the species boundaries of these three sympatric oak species.</p>