Fine scale genetic structure in a wild soybean (Glycine soja) population and the implications for conservation

The fine-scale spatial distribution of a wild soybean (Glycine soja Sieb. et Zucc) population was measured using kinship coefficients and spatial autocorrelation coefficients to reveal fine-scale spatial patterns of genetic structure for guiding collection in ex situ conservation. Individual families (100) of a single population were sampled in Jiangwan (Shanghai, China) and their specific locations mapped. Individual plants were genotyped for 331 ISSR loci from 15 selective ISSR primers; 45% were demonstrated to be polymorphic. Pairwise kinship coefficients between individuals were calculated, and then regressed based on the spatial distance between individuals. The results indicated a close genetic relationship among individual families in the patch with a diameter of c. 30 m. Spatial autocorrelation analysis suggested that there were significant clusters of genes within the population; c. 81.4% of the loci were found to be positively correlated in the first two distance classes (0-10 m). The results suggest, for conservation genetics, sampling within a wild soybean population should be conducted at 10 m intervals across the entire population to optimize the genetic diversity in collections taken from that population.