Genetic variation in red raspberries (Rubus idaeus L.; rosaceae) from sites differing in organic pollutants compared with synthetic tandem repeat DNA probes

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Abstract
Two synthetic tandem repetitive DNA probes were used to compare genetic variation at variable‐number‐tandem‐repeat (VNTR) loci among Rubus idaeus L. var. strigosus (Michx.) Maxim. (Rosaceae) individuals sampled at eight sites contaminated by pollutants (N = 39) and eight adjacent uncontaminated sites (N = 38; distances separating sites ranged from 5 to 350 m). For the 77 plants analyzed, the mean number of bands scored per individual was 16.5 (SD = 3.5). Mean genetic similarity (0.51) and heterozygosity (0.62) across all plants from contaminated sites did not differ significantly from that among all plants from uncontaminated sites (mean similarity = 0.52; mean heterozygosity = 0.63). Nor did similarity and heterozygosity differ between contaminated and uncontaminated sites when estimates of these values within each of the 16 sites were compared. Estimates ofFst (0.01‐0.04) indicated little genetic differentiation between plants from contaminated and uncontaminated sites. However, relative to plants from uncontaminated sites, plants from contaminated sites possessed significantly fewer private alleles (1 vs 18; p < 0.001) and alleles per individual (mean = 15.2 vs 17.9; p = 0.0002). Considering the 16 sites individually, uncontaminated sites possess significantly more population bands (p = 0.015), private alleles (p = 0.01), and alleles per individual (p = 0.027). These differences were distributed across sites rather than resulting from large, idiosyncratic differences attributable to one or a few outlier sites. The findings of this study suggest that a loss of genetic variation among R. idaeus individuals growing in impacted areas has occurred at all eight sites, and that VNTR markers may be useful biological indicators of plant populations under stress from human perturbations. In addition, extensive clonal spread of this species, previously documented for other species of Rubus, was not detected.