GENETIC-VARIATION IN RED RASPBERRIES (RUBUS-IDAEUS L., ROSACEAE) FROMSITES DIFFERING IN ORGANIC POLLUTANTS COMPARED WITH SYNTHETIC TANDEM REPEAT DNA PROBES

Two synthetic tandem repetitive DNA probes were used to compare geneti c variation at variable-number-tandem-repeat (VNTR) loci among Rubus i daeus 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 scor ed per individual was 16.5 (SD = 3.5). Mean genetic similarity (0.51) and heterozygosity (0.62) across all plants from contaminated sites di d not differ significantly from that among all plants from uncontamina ted sites (mean similarity = 0.52; mean heterozygosity = 0.63). Nor di d similarity and heterozygosity differ between contaminated and uncont aminated sites when estimates of these values within each of the 16 si tes were compared. Estimates of F-st (0.01-0.04) indicated little gene tic differentiation between plants from contaminated and uncontaminate d 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 si tes possess significantly more population bands (p = 0.015), private a lleles (p = 0.01), and alleles per individual (p = 0.027). These diffe rences 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 a mong R. idaeus individuals growing in impacted areas has occurred at a ll eight sites, and that VNTR markers may be useful biological indicat ors of plant populations under stress from human perturbations. In add ition, extensive clonal spread of this species, previously documented for other species of Rubus, was not detected.