Genetic diversity, population size, and fitness in central and peripheral populations of a rare plant Lychnis viscaria

Genetic diversity is expected to decrease in small and isolated populations as a consequence of bottlenecks founder effects, inbreeding, and genetic d rift. The genetics and ecology of the rare perennial plant Lychnis viscaria (Caryophyllaceae) were studied in both peripheral and central populations within its distribution area. We aimed to investigate the overall level of genetic diversity its spatial distribution, and possible differences betwee n peripheral and central populations by examining several populations with electrophoresis. Our results showed that the level of genetic diversity var ied substantially among populations (H-exp = 0.000-0.116) and that the tota l level of genetic diversity (mean H-exp = 0.056) was low compared to that of other species with similar life-history attributes. The peripheral popul ations oft. viscaria had less genetic variation (mean H-exp = 0.034) than t he central ones (0.114). Analysis of genetic structure suggested limited ge ne flow (mean F-ST = 0.430) and high differentiation among populations emph asizing the role of genetic drift (N(e)m = 0.33). Isolation was even higher than expected based on the physical distance among populations. We also fo cused on the association between population size and genetic diversity and possible effects on fitness of these factors. Population size was positivel y correlated with genetic diversity. Population size and genetic diversity, however, were not associated with fitness components such as germination r ate, seedling mass or seed yield. There were no differences in the measured fitness components between peripheral and central populations. Even though small and peripheral populations had lower levels of genetic variation, th ey were as viable as larger populations, which emphasizes their potential v alue for conservation.