| 英文摘要
| Taiwan has dramatic elevation gradient changes of terrain, and the altitudinal gradients of diversified environment may lead to the increased opportunities for local adaptation of different ecotypic species. Populations distributed at different altitudes may encounter reproductive isolation and even speciation. Rhododendron pseudochrysanthum complex (Ericaceae) includes four species. Among them, Rhododendron rubropunctatum is restricted to low elevation and the other three (Rhododendron morii, Rhododendron pseudochrysanthum, Rhododendron hyperythrum) are restricted to higher elevations. We used amplified fragment length polymorphism (AFLP) technique to quantify the genetic variation and divergence of 172 individuals from nine populations of R. pseudochrysanthum complex. In order to evaluate genetic structure and genetic differentiation of the R. pseudochrysanthum complex, STRUCTURE and DAPC were used to infer genetic composition of R. pseudochrysanthum complex. To detect genetic loci deviated from neutral evolution, we used ARLEQUIN and BAYESCAN to detect the outlier loci. To evaluate the suitable whether environmental factors variation among species in R. pseudochrysanthum complex, we applied PCA analysis the environmental factors among different populations. Further, to co-evaluate the Association between genetic data and environmental variables, we applied RDA to study correlation among genetic data, population data and environmental variables. Finally, we used SAMBADA to assess the correlation between outlier loci and environmental variables to examine whether local adaptation signal exist among these outlier loci. Both DAPC and STRUCTURE showed that R. rubropunctatum formed its own cluster within R. pseudochrysanthum complex. Outlier loci analysis detected six loci that deviated from neutral selection. PCA and RDA portrayed that environment factor of R. pseudochrysanthum complex can be diversified into two groups. SAMBADA results showed that the outlier loci were significantly correlated with the environmental factors about temperature. In conclusion, according to the genetic data and environmental variables analysis, R. rubropunctatum has the local adaptation in R. pseudochrysanthum complex, We proposed that the R. rubropunctatum may be phylogenetically separated from R. pseudochrysanthum complex. In addition, although the R. hyperythrum is morphologically different from the other three species in R. pseudochrysanthum complex, but the genetic analysis does not support the maximum genetic distance between the R. hyperythrum and the other three species in the complex. So this study doesnu0027t support that the R. hyperythrum belong to the Hymenanthes subgenus’s Ponica subsection. |
