Temporal genetic structure in Camellia japonica (Theaceae)

The temporal genetic structure of four pairs of juvenile (2-3 years old) and adult (ca. 50-100 years old) populations of Camellia japonica was examined using allozyme markers. No significant differences in genetic variability between two groups were found in the populations examined. About 52 and 37% of positive fixation indices calculated in the four juvenile and adult populations were significantly larger than zero with mean F-IS values of 0.254 and 0.194, respectively. This indicates a considerable deficiency of heterozygotes in the juvenile and adult populations as a possible result of family structuring. Values of F-IS, F-IT, estimates of migration rate per generation (Nm), and F-ST were not significantly different between juvenile and adult populations, though slightly higher mean values of F-IS, F-IT and Nm, and a lower F-ST were found in the juvenile populations in comparison to the adult populations. However, previous studies on other woody plants showed that the seed, seedling, and juvenile stages generally have significantly higher levels of inbreeding than found in adults. The high evolutionary potential maintained in C. japonica may in part result in homogeneous levels of genetic diversity and genetic structure in time.