Recent changes in environmental conditions in populations of peat-bog pine (Pinus uliginosa Neumann) caused rapid decline or even extinction of the species in several stands in Central Europe. Conservation strategies for P. uliginosa require information about the evolutionary history and genetic structure of its populations. Using isozymes we assessed the genetic structure of P. uliginosa from four isolated stands in Poland and compared the results to genetic structures of other closely related pine species including eight populations of Pinus mugo, ten of Pinus sylvestris and one of Pinus uncinata. The level of genetic variability of P. uliginosa measured by the mean number of alleles per locus and average heterozygosity was similar to others related to P. uliginosa taxa from the reference group but it differs among populations. High genetic similarity was found between two populations of P. uliginosa from Low Silesian Pinewood. The populations were genetically distinct as compared to other populations including locus classicus of the species from the peat bog at Batorow Reserve. Very low genetic distance (DN = 0.002) and small genetic differentiation (GST = 0.003) were found between P. uliginosa and P. mugo in the sympatric populations of the species from Zieleniec peat bog suggesting the ongoing natural hybridisation and genetic contamination of peat-bog pine from this area. Some evidence for skew in allele frequency distribution potentially due to recent bottleneck was found in population from Low Silesian Pinewood. The analysed open pollinated progeny derived from two P. uliginosa stands from Low Silesian Pinewood showed the excess of homozygotes as compared to the maternal trees indicating high level of inbreeding (F = 0.105, F = 0.081). The results are discussed in the context of evolution of P. uliginosa populations, taxonomic relationships between the analysed species and conservation strategies for active protection of peat-bog pine.
A species-specific marker of cpDNA (paternally inherited in pines) was used to verify the hybrid origin of seedlings from controlled reciprocal crosses between Pinus sylvestris and P. mugo. A very low degree of compatibility between those two species has been revealed. In the three consecutive years of experiments, no filled seeds were obtained in the combination with P. mugo as the seed parent. From P. sylvestris as the seed parent and P. mugo as the pollen donor, we succeeded to obtain four filled seeds (about 1 %), but only in one year. The seedling obtained from the seeds had cpDNA haplotypes specific to P. mugo, which proves their hybrid origin. This method enables verification of the result of controlled crosses. The importance of the results has been discussed in the aspect of postulated natural hybridisation in sympatric populations of the two species.
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