台灣特有針葉樹種台灣肖楠、香杉及台灣杉遺傳及表觀遺傳在地適應性演化

Evolutionary adaptation can be shaped by a combination of ecological factors as well as geographic isolation interacting with gene flow. We collected 243 samples from 12 populations of Calocedrus formosana along an elevational gradient from 436 to 2209 m. Amplified fragment length polymorphism (AFLP) and methylation-sensitive amplification polymorphism (MSAP) were, respectively, used in quantifying genetic and epigenetic variations. Lower levels of genetic and epigenetic diversities and higher level of population differentiation were found in Ca. formosana compared with other Taiwanese conifers including Cunninghamia konishii, Keteleeria davidiana var. formosana, and Taiwania cryptomerioides. Based on 437, 819, and 346 AFLP, MSAP-m, and MSAP-u loci, 34, 51, and 24 loci, respectively, were found to be FST outliers detected using BAYSCAN and DFDIST. These outlier loci were found to be strongly associated with various environmental variables assigned in three categories: bioclimatic, ecological, and topological categories, using multiple univariate logistic regression, latent factor mixed model, and Bayesian logistic regression. Outlier genetic and epigenetic variations were explained most prominently by ecological factors compared with bioclimatic and topological factors analyzed separately. Annual mean temperature, relative humidity, mean wind speed, and sunshine hours could have been the most important drivers for adaptive genetic and epigenetic variations in Ca. formosana. We found outlier loci with high frequencies in low- and high-elevation populations, indicating their involvement in local adaptation and could be important in the future assisted migration program for conservation of this species.