In search of hybridity: the case of Karelian spruces

Abstract

Distribution ranges of spruces, European and Siberian intersect in the Eastern Europe and Urals, forming wide zone of introgressive hybridization where species discrimination is difficult. We applied both molecular (mtDNA and cpDNA sequences) and morphological approaches with goals of elucidating the origin of spruces in undisturbed forests of Russian Karelia (considered as part of the abovementioned introgression zone). Karelian spruces have morphology that is typical for and characterized with genetic variation, described previously for . This contradiction between morphology and organellar DNA could be itself an evidence of hybrid origin because morphological data should have a genetic basis. If the genes responsible for the observed morphological differences are nuclear, that explains why we did not see any deviation of Karelian spruces towards in organellar markers. In this situation nuclear gene flow from should be performed via pollen. Thus, we should expect Karelian spruces to have cpDNA haplotypes (inherited paternally in conifers) typical for . However, it is not the case for the majority of plants sampled and requires additional explanation like chloroplast capture in the introgresson zone. In all, we think that Karelian spruces evolved due to introgression between and . However, it is unclear whether Karelian spruces could be treated as , because unequivocal morphological and genetic characters of this hybridogenous species are still absent.Picea abiesP. obovataP. obovataP. abiesP. obovataP. obovataP. obovataP. abiesP. obovataP. fennica