GENETIC-VARIATION IN NORTH-AMERICAN LEAFY SPURGE (EUPHORBIA-ESULA) DETERMINED BY DNA MARKERS

Levels of inter- and intrapopulation genetic variation were determined in five North American populations of leafy spurge using chloroplast DNA (cpDNA) RFLPs and RAPD markers. Thirteen plastome types were ident ified among 123 individuals collected from five geographically separat ed populations. Number of plastomes within a population ranged from on e to seven, with four of the populations having a predominate type plu s one or more rarer types. Some plastome types were shared by populati ons, but plastome distribution among populations was nonrandom. RAPD m arkers indicated greatest relatedness among individuals within a popul ation. Relatedness among populations as established through RAPDs was greater for geographically closer populations; this relationship was n ot observed for cpDNA markers. Differences in the range of movement fo r pollen and seed may account for differences between results of the c pDNA and RAPD analyses. The high degree of genetic variability among N orth American leafy spurge suggests possible multiple introductions or a high degree of variability within leafy spurge populations in its n ative range.