Genetic variation in Silene acaulis increases with population age

This study examined the relationship between genetic variation and the mean age of individuals within populations of the alpine cushion plant Silene acaulis (L.) Jacq. along a chronosequence on a glacier foreland in the Central European Alps. We studied 67 individuals of S. acaulis from four populations located at 2390, 2530, 2680, and 2820 m a.s.l. on the glacier foreland and applied a combined approach of growth-ring analysis and individual size measurements to determine the mean age of individuals within populations. Genetic variation was studied using amplified fragment length polymorphism analysis. The mean age of individuals within populations ranged from 11 to 20 years and increased with decreasing altitude toward the older stages of the chronosequence, reaching a maximum age of 50 years. According to regression analysis, genetic variation increased slightly from early to late successional stages and was associated with the mean age of individuals within populations. The results suggest that genetic variation in S. acaulis depends on the mean age of individuals within populations, and emphasize that both species diversity and genetic diversity in plant species can increase during succession on glacier forelands. Integration of age determination methods proves to be a promising approach in the analysis of genetic variation in plant species.