Natural hybridization in the genus Abies : II. Mitochondrial variation in the hybridogenous complex Abies alba – A. borisii-regis – A. cephalonica

Abstract

Twenty nine fir populations originating from the putative zones of interspecific hybridization in southern Balkans were studied using a mitochondrial nad5-4 gene marker. The populations were classified to three taxa based on their geographical distribution and an overall taxonomical assessment at the population level based on needle and twig morphology: Abies alba Mill., Abies cephalonica Loud. and Abies borisii regis Mattf. Three haplotypes were found: 230 bp in Calabrian A. alba populations, 150 bp in Bulgarian and Macedonian A. alba populations, and 341 bp in A. cephalonica populations. Populations from central and northern Greece, classified as A. borisii regis, shared the 150 bp and 341 bp haplotypes with their closest neighbours, whereby haplotype frequencies changed clinally along the latitudinal gradient. This geographical distribution of mtDNA haplotypes supports the hypothesis that A. borisii regis represents a relatively recent hybrid swarm.