RAPD MARKERS REVEAL DIVERSITY WITHIN AND AMONG CLONAL AND SEEDLING STANDS OF ASPEN IN YELLOWSTONE-NATIONAL-PARK, USA

Fire in 1988 created a situation that allowed a rare aspen seedling re cruitment event io occur within Yellowstone National Park. Through the use of (i) 194 randomly amplified polymorphic DNA (RAPD) markers from 14 select primers, (ii) measures of population diversity. and (iii) n eighbor-joining analysis it was determined that the postfire aspen see dling population contains greater diversity within each of the four sa mpled stands than that found within all of the 10 sampled mature aspen stands that pre-existed tile file. Unlike previous studies, a large p ortion of the molecular variation in both the seedling and mature popu lations was partitioned among stands. Furthermore, variation was unexp ectedly detected among ramets within each mature stand. The mature sta nds appear to be clonally derived, yet individual ramets within stands varied slightly and incrementally in their RAPD profile. These data s uggest that somatic mutations may be occurring and accumulating in clo nal aspen stands. A proposed scenario of stand establishment and devel opment involving the accumulation of somatic mutations and elimination of genetically related seedlings arising from a rare founder event pr ovides the theoretical basis for the observed differences among and wi thin seedling and mature stands of aspen in Yellowstone National Park.