Chloroplast microsatellites and mitochondrial nad1 intron 2 sequences indicate congruent phylogenetic relationships among Swiss stone pine (Pinus cembra), Siberian stone pine (Pinus sibirica), and Siberian dwarf pine (Pinus pumila)

We studied the phylogenetic relationships among the three stone pine specie s, Pinus cembra, P. sibirica, and P. pumila, using chloroplast microsatelli tes and mitochondrial nad1 intron 2 sequences. The three chloroplast micros atellite loci combined into a total of 18 haplotypes. Fourteen haplotypes w ere detected in 15 populations of P. cembra and one population of P. sibiri ca, five of which were shared between the two species, and the two populati ons of P. pumila comprised four species-specific haplotypes. Mitochondrial intron sequences confirmed this grouping of species. Sequences of P. cembra and P. sibirica were identical, but P. pumila differed by several nucleoti de substitutions and insertions/deletions. A repeat region found in the for mer two species showed no intraspecific variation. These results indicate a relatively recent evolutionary separation of P. cembra and P.sibirica, des pite their currently disjunct distributions. The species-specific chloropla st and mitochondrial markers of P. sibirica and P. pumila should help to tr ace the hybridization in their overlapping distribution area and to identif y fossil remains with respect to the still unresolved postglacial re-coloni zation history of these two species.