No abstract

We investigated the hierarchical genetic structure of SSR (simple sequence repeats) and cpDNA (chloroplast DNA) polymorphisms among and within populations of Primula sieboldii, a heterostylous clonal herb. Seven out of eight populations at the study site, located in a mountainous region of Nagano Prefecture, had each developed alongside a different stream, and the other occurred on a flat area 70 m from the nearest stream. The magnitude of genetic differentiation among streamside populations in maternally inherited cpDNA (Phi = 0.341) was much higher than that in biparentally inherited SSRs (Phi = 0.011). This result suggests that seed dispersal among streams was restricted, and pollen was the primary agent of gene flow among streamside populations. In contrast, genetic differentiation among subpopulations within streams were low at both markers (Phi = 0.053 for cpDNA, Phi = 0.025 for SSR). This low differentiation among subpopulations in cpDNA compared with that among streamside populations suggest that seed dispersal occur along the stream probably during flooding. This hypothesis was supported by the fact that in cpDNA haplotypes, no clear genetic structure was detected within the streamside population, while a significant genetic structure was found within 20 m in the nonstreamside population. Furthermore, within the streamside populations, two pairs of ramets with identical multilocus genotypes for eight SSR loci were distantly (> 50 m) distributed along the same streamside, suggesting dispersal of clonal propagule. Our study showed that the heterogeneity of the landscape can influence gene flow and hence spatial genetic structure.

We examined the origins of cultivated stocks of the endangered species Primula sieboldii at the individual plant level by using an assignment test based on eight microsatellite loci and regional features of chloroplast DNA (cpDNA) variation of wild populations. To confirm that we had sufficient information for estimating the origins of the stocks, we performed an assignment test with 920 genets that we collected from 32 wild populations with known origins. The test assigned 99.6% of the genets to the population from which they had been sampled, confirming the suitability of the method. We then performed the assignment test with 29 cultivated stocks. The alleged origins of 19 were confirmed by microsatellite and cpDNA variations. In contrast, the alleged origins of five were rejected by both markers. Five stocks, which do not have a reference population located within 30 km of their reputed origin, were not assigned to any population. Stocks whose alleged origins were rejected are inappropriate as restoration materials, because their introduction might disturb local gene pools. Six stock haplotypes could not be detected in wild populations. This may suggest the loss of genetic diversity in the wild and the value of stocks as a gene bank. The genetic method used in this study will also be helpful to detect cryptic invasion by nonendemic genotypes or to trace the origins of plants collected for commercial purposes, a threat to many endangered species.

No abstract

To promote programs for the conservation and restoration of the endangered species Primula sieboldii, we examined genetic variation at eight microsatellite loci among and within 32 remnant wild populations throughout Japan. Total allelic diversity within a population was higher in larger populations, but not so after rarefaction adjustment. The positive relationship between population size and the inbreeding coefficient may suggest that more heterozygous genets tend to survive the habitat contraction possibly because of the higher fitness associated with heterozygosity. By principal coordinate analysis and Bayesian analysis, we detected four genetic groups (Hokkaido, northern Honshu, central Honshu, and western Japan), which could be recognized as management units of P. sieboldii. If supplementation with plants from other populations were planned, it should be conducted among populations which belong to the same management unit and which are likely to represent the same adaptive variation.