Introgressive hybridization between Scots pine and mountain dwarf pine at two localities of northern Slovakia

Abstract

Introgressive hybridization within hybrid swarm populations of Pinus sylvestris and P. mugo was analyzed in
the localities Medzi Bormi and Sokolie, northern Slovakia, using species-specific trnV-trnH/Hinf I restriction
profiles of chloroplast DNA of needles and zygotic embryos. The presence of trees with both P. sylvestris
and P. mugo haplotypes indicates hybrid nature of the swarms. Molecular analysis revealed a relatively high
rate of introgressive hybridization between putatively hybrid swarm individuals and the parental trees of the
pure species P. sylvestris and P. mugo growing in the same localities. The proportion of hybrid seeds with P.
sylvestris pollen donor averaged at 30.3%, whereas those with pollen donor of P. mugo at 19.8%. The results
are discussed within context of the established crossability relationship between P. sylvestris and P. mugo.