Geographic distribution of chloroplast variation in Italian populations of beech (Fagus sylvatica L.)

Abstract

The distribution of chloroplast DNA (cpDNA) variation in Italian beech ( Fagus sylvatica L.) populations was studied using PCR-RFLP and microsatellite markers. In total, 67 populations were analysed, and 14 haplotypes were identified by combining the two marker types. A remarkable subdivision of cpDNA diversity in Italian beech was found, as indicated by a high level of genetic differentiation ( G(st)=0.855). The highest level of total haplotype diversity ( h(t)=0.822) was estimated for southern Italian populations. The highest number of haplotypes was found in the central-southern region of the peninsula. The nested clade analysis provided evidence for past fragmentation events that may have been occurred during the Quaternary glaciations and had a major role in defining the genetic structure of the central-southern Italian beech populations. Only one haplotype apparently spread towards the north of Italy along the Apennine chain and reached the Italian slope of the western part of the Alps (Maritime Alps, Liguria). All haplotypes found along the Apennines remained trapped in the Italian peninsula. Southern and central Italy represent hotspots of haplotype diversity for Italian beech.

Reticulate evolution patterns in western-Eurasian beeches

“…Peculiar is a genetic proximity and even partial sharing of chloroplast haplotypes between south-Italian and Balkan populations (Gömöry et al 1999;Vettori et al 2004), reflected also in the direct relationship between Calabria and Balkan populations (Gre, Rod) shown in the reticulogram (Fig. 3) and the position of both groups in the neighbor-net network (Fig.…”

Chloroplast DNA variation of Betula humilis Schrk. in Poland and Belarus

“…In order to test these hypotheses, we analysed chloroplast DNA (cpDNA) using the PCRrestriction fragment length polymorphism (RFLP) method. Organelle markers are uniparentally inherited and exhibit reduced effective population sizes; hence, they reveal a clearer picture of the genealogical history of a species than do nuclear markers (Vettori et al 2004). Previous studies have successfully used cpDNA markers to deduce the locations of glacial refugia and postglacial colonisation routes in Alnus glutinosa (King and Ferris 1998), Fagus sylvatica (Demesure et al 1996;Magri et al 2006), Fraxinus excelsior (Heuertz et al 2004), Quercus (Csaikl et al 2002;Petit et al 2002a, b), Populus (Cottrell et al 2005;Fussi et al 2010) and Betula (Palmé et al 2003;Maliouchenko et al 2007;Thórsson et al 2010).…”

Distribution of chloroplast DNA haplotypes in the contact zone of Fagus crenata in the southwest of Kanto District, Japan

“…The current geographical distribution of the haplotypes of a species is a result of contraction/expansion of the geographical range after climate fluctuations during the Quaternary period (Trewick et al 2000;Palme et al 2003) and/ or of topographical barriers to colonization, for example the main mountain ranges and oceans (Ferris et al 1998;Taberlet et al 1998;Lugon-Moulin et al 1999;Vettori et al 2004;Huang et al 2005). The spread and geographical boundary of the two haplotypes of clades I and II of F. crenata do not seem to be related to any topographical characteristics, e.g.…”

“…This is because cpDNA is maternally inherited in most angiosperms (Hillis and Moritz 1990;Ennos 1994;Newton et al 1999). Several studies have revealed the geographical structuring of cpDNA variation at the population level, and the history of colonization or the location of refugia has been inferred in a variety of plant species (Ferris et al 1998;Taberlet et al 1998;Ohi et al 2003;Palme et al 2003;Vettori et al 2004;Huang et al 2005).…”