Demographic and environmental determinants of clonality in a self-incompatible scattered tree species, <i>Sorbus torminalis</i> (L.) Crantz

Abstract Many plant species can reproduce both generatively and vegetatively. Vegetative reproduction and the associated phenomenon of clonality in plants are often considered an effective strategy for periodic survival and maintaining population diversity during adverse environmental conditions, or the colonization of new areas. Using nuclear microsatellites, we investigated the extent of clonality in the wild service tree (Sorbus torminalis (L.) Crantz), a self-incompatible scattered tree species that is capable of vegetative reproduction, at the northeastern distribution limits of the species. The study involved 1796 adult trees belonging to 43 populations. We found a high degree of variation in clonality among populations. There was a negative relationship between clonality and the number of genets within populations. The clonality increased toward the borders of the species range and in the areas of highly variable land topography. Clonality appeared to be negatively correlated with temperature indices but positively with precipitation. While environmental conditions and demography might significantly induce clonality of woody plants, the observed within-population variation in the ability for clonal growth suggests that other factors such as genetic background might play an important role in determining an individual’s potential for clonality.