The Phylogeography And Landscape Genetics Studies Of Cotinus Coggygria(Anacardiaceae)

Cotinus coggygria Scop.(Anacardiaceae)is a deciduous shrub or small tree,located in Hebei, Henan, Hubei, Shaanxi, Shandong and Shanxi,which covered most distributes area of current deciduous broad-leaved forest(DBLF) in China. In this study, we selected Cotinus coggygria, which is widespread species in China’s warm-temperate zone, to investigate its phylogeographical pattern and landscape genetic pattern. The results are as follows:1 One chloroplast DNA(cp DNA)region and an ecological niche modeling were used to examine the phylogeographical pattern of C. coggygria. The cp DNA data revealed two phylogeographical group( Southern and Northern groups)corresponding to the geographical regions. The divergence time analysis revealed that the divergence of the two groups occurred at approximately 147 kilo years before present(BP), which coincided with the formation of the Yellow River’s downstream, indicating that the Yellow River was a weak phylogeographic divide for C. coggygria. The molecular data and ecological niche modeling also indicated that C. coggyria did not experience population expansion after glaciations in this study. This study thus supported the fact that the Pleistocene glacial cycles only slightly affected C. coggygria, which survived in situ and occupied multiple localized glacial refugia during glaciations. This finding is contrary to the hypothesis of the large-scale range contraction of warm-temperate plants and retreat into a few main refugia during Pleistocene glacial.2 Microsatellite markers used to analysis the landscape genetics. First, Shotgun 454 pyrosequecing was used to develop microsatellite markers from the genome of C. coggygria. 349 microsatellite loci were identified from 40,074 individual sequence reads produced by one-sixteenth run, and primer pairs were designed for these loci. To test the primer amplification efficiency, 50 microsatellite primer pairs were selected from 349 microsatellite loci. Among the 50 tested primer pairs, eight primer pairs were found to be polymorphic. The average allele number of the microsatellites was 3.5 per locus, ranging from two to five. The inbreeding coefficient rang from-0.478 to 0.222. The observed and expected heterozygosities varied from 0.167 to 0.750 and from 0.163 to 0.743. Second, we used eight developed microsatellite loci to examine the adaptive genetic variations of C. coggygria. A total of 43 microsatellite alleles were genotyped in 142 individual plants from 16 wild populations. The data demonstrated significant population differentiation within C. coggygria, which was caused by geographical distance, human activities, and precipitation. Five ecologically relevant microsatellite alleles, which were all related to the precipitation, were identified by association analysis. Our results indicate that precipitation is an important factor that drives adaptive genetic differentiation in C. coggygria.