Detecting interspecific and geographic differentiation patterns in two interfertile oak species (Quercus petraea (Matt.) Liebl. and Q. robur L.) using small sets of microsatellite markers

Abstract

a b s t r a c tGenetic analysis was carried out in order to provide insights into differentiation among populations of two interfertile oak species, Quercus petraea and Quercus robur. Gene flow between the two species, local adaptation and speciation processes in general, may leave differential molecular signatures across the genome. Three interspecific pairs of natural populations from three ecologically different regions, one in central Europe (SW Germany) and two in the Balkan Peninsula (Greece and Bulgaria) were sampled. Grouping of highly informative SSR loci was made according to the component of variation they express-interspecific or provenance specific. 'Species' and 'provenance discriminant' loci were characterized based on F ST s. Locus specific F ST s were tested for deviation from the neutral expectation both within and between species. Data were then treated separately in a Bayesian analysis of genetic structure. By using three 'species discriminant' loci, high membership probability to inferred species groups was achieved. On the other hand, analysis of genetic structure based on five 'provenance discriminant' loci was correlated with geographic region and revealed shared genetic variation between neighbouring Q. petraea and Q. robur. Small sets of highly variable nuclear SSRs were sufficient to discriminate, either between species or between provenances. Thus, an effective tool is provided for molecular identification of both species and provenances. Furthermore, data suggest that a combination of gene flow and natural selection forms these diversity patterns. 'Species discriminant' loci might represent genome regions affected by directional selection, which maintains species identity. 'Provenance specific' loci might represent genome regions with high interspecific gene flow and common adaptive patterns to local environmental factors.

Is Quercus virgiliana a distinct morphological and genetic entity among European white oaks?

“…The results obtained for the observed heterozygosity are consistent with those reported for Q. pubescens in France (Lepais et al 2006) and with those reported for other white oak species, such as sessile oak or pedunculate oak in stands from Greece, Bulgaria, and Germany (Neophytou et al 2010). …”

Fragmentation-related patterns of genetic differentiation in pedunculate oak (<i>Quercus robur</i>) at two hierarchical scales

“…Moreover, the level of genetic differentiation detected (F ST = 0.12) is markedly high as compared to that observed in oak populations closer to the core of their distribution. For comparison, using 14 microsatellite loci, Neophytou et al (2010) observed a notably lower F ST of 0.04 among three Q. robur populations located in Germany, Greece and Bulgaria, respectively, i.e. across a geographic range much larger than the one covered by the present study.…”

Morphological and Molecular Differentiation in Populations of Persian Oak (Quercus Brantii Lindl.) in Southwestern Iran

“…The balance achieved by a population among these factors determines its special genetic structure (Valencia-Cuevas et al, 2014). Genetic structure can be associated with geographical region, climate conditions (Neophytou et al, 2010), hybridization (Curtu et al, 2014), breaking of primary reproductive barriers (Valencia-Cuevas et al, 2014), altitude, historical movements, evolution, phenology and seed dispersal over a large area by animals (Ohsawa et al, 2007;Zhang et al, 2013 andWang et al, 2014).…”