Genetic variability of a scattered temperate forest tree: Sorbus torminalis L-(Crantz)

Genetic variation has been assessed in 73 (mostly French) populations of th e wild service tree (Sorbus torminalis) using 15 isozymes loci. In spite of a relatively high coefficient of genetic differentiation among populations (F-ST = 15%). only a weak geographical structure was detected. This may be explained by the small size and young age of the populations due to the im portance of founder effects, combined with the high levels of seed flow amo ng populations. These features are typical of species characterised by meta population dynamics.