Molecular ecological study for conservation of endangered species, Pyrus calleryana Decne var. dimorphopheylla (Makino) Koidz. : Genetic analysis on population structure, gene flow and reproductive deterioration

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In order to obtain genetic information for conservation of Pyrus calleryana Decne var. dimorphopheylla (Makino) Koidz., the endangered species, all of the individuals exist in Japan were sampled and inquired their origin, revealed that total number of individuals is 465 and they distributed only in Aich and Mie Prefecture. Genotypes of them were determined with ten nuclear SSR markers. Genetic diversity was maintained in this species, however, patterns of "isolation by distance" was not clear among all populations containing those affected by serious human impacts, such as, planting and transplanting. In contrast, genetic structure among the native populations was conserved. Phylogenetic tree and Bayesian cluster analysis revealed that the native populations were divided into two clusters, those are Aichi and Mie. Analyzing the nucleotide sequences for cDNAs corresponding to the alleles of the self-incompatible locus revealed eleven different alleles. Using the specific primers designed for each of S-allele, S-genotypes for 247 individuals collected from ten populations were determined and revealed that four to ten S-alleles were maintained in each population. Paternal analysis for seeds collected from four mother trees in the isolated population was performed with nine SSR markers and revealed that pollen parents were widely distributed in the population. Ecological and genetic factors which affect male contribution was analyzed with generalized linear mixed model (GLMM) and revealed that distance from the mother is the most significant factor for male reproductive success. Although self-incompatibility was functioned in the mating event within the population, degree of S-genotype identity between parents did not strongly affect pollen mediated gene dispersal.These results will provide important information for planning conservation programs of this species.