PHENOTYPIC PLASTICITY IN POLYGONUM PERSICARIA. I. DIVERSITY AND UNIFORMITY IN GENOTYPIC NORMS OF REACTION TO LIGHT

Several aspects of genotype-environment interaction may act to modulate natural selection in populations that encounter variable environments. In this study the norms of reaction (phenotypic responses) of 20 cloned genotypes from two natural populations of the annual plant Polygonum persicaria were determined over a broad range of controlled light environments (8%-100% full sun). These data reveal both the extent of functionally adaptive phenotypic plasticity expressed by individual genotypes, and the patterns of diversity among genotypes for characters relevant to fitness, in response to an environmental factor that is both highly variable within populations and critical to growth and reproduction.     

Evidence for massive clonal growth in the invasive weed Fallopia japonic a (Japanese Knotweed)

Clonal growth in introduced populations of Japanese Knotweed ( Fallopia juponica ) in Britain was assessed using RAPDs (Randomly Amplified Polymorphic DNA). A total of 150 British samples was analysed for genetic variation using ten arbitrary decamer primers, and compared with data from 16 samples of other introduced populations from Europe and the U.S.A. All samples produced an identical multi-primer RAPD profile. Accepting that RAPD profile identity need not equate to genet identity, based on the sensitivity of these markers for detecting genetic diversity in related taxa and on the absence of male fertile individuals of this species in Britain, we interpret this result as consistent with the presence of a single, exceptionally widespread clone. This clone must represent one of the world's largest vascular plants.