Potential for the Evolution of Heavy Metal Tolerance in Bryum argenteum, a Moss. I. Variation within and among Populations

Bryum argenteum frequently occurs in urban environments and therefore appears to have the ability to tolerate high levels of such atmospheric pollutants as lead. The presence of genetic variation for tolerance to lead was assessed within and among three populations of this species from Ithaca, New York state. Plants from these populations contained extremely different concentrations of lead and other metals, but there was little or no variation in metal tolerance among the populations. There were, however, significant differences in general vigor (growth rates across all experimental treatments) among populations. Moreover, the rural and suburban populations contained high levels of variation in vigor among haploid-sib families (families of gametophytes derived from different sporophytes). The urban population, in contrast, contained conspicuously less variation than the other two.