Genetic variability of indigenous (Quercus robur L.) and late flushing oak (Quercus robur L. subsp. slavonica (Gáyer) Mátyás) in adult stands compared with their natural regeneration

Abstract

Slavonian oak (Quercus robur subsp. slavonica (Gáyer) Mátyás) is currently gaining interest in forestry due to forest restructuring in Germany caused by climate change. Slavonian oaks originating from Croatia have been introduced into Germany mainly in the Münsterland region of North Rhine-Westphalia since the second half of the nineteenth century. They are characterized by their late bud burst, long clear bole, stem straightness and faster height and diameter growth compared to indigenous oaks in Germany. In this study, the genetic differentiation of adult trees and their respective progeny of two Slavonian and two indigenous stands in Hamm-Westtünnen, was evaluated. Genetic diversity and structure were estimated using 23 nuclear simple sequence repeat (SSRs) and 5 maternally inherited chloroplast microsatellite markers (cpSSRs). The mean expected heterozygosity of 0.545 and allelic richness of 6.23 indicate high genetic diversity in the studied populations. The group of progenies (AR = 8.40, Ho = 0.524, He = 0.559, FIS = 0.064) shows similar levels of genetic variation as the adult stands (AR = 8.37, Ho = 0.513, He = 0.554, FIS = 0.075). The genetic differentiation between adult stands and progeny was low (FST = 0.013). Genetic assignment of individuals using STRUCTURE revealed that the studied populations were divided into two clusters. There was no evidence of extensive hybridization or gene flow between Slavonian and native populations, possibly due to the different timing of bud burst of the two taxa.

Genetic Diversity in Peripheral Pedunculate Oak (Quercus robur L.) Provenances—Potential Climate Change Mitigators in the Center of Distribution despite Challenges in Natural Populations

“…Therefore, we presume that, in this case, deviation from HWE is due to the different origin than the surrounding stands, possibly causing reproductive isolation from the main complex. This is similar to Germany, where indigenous stands of pedunculate oak grow side by side with introduced Slavonian oak stands but sustain separate gene pools, mainly due to phenological differences [7]. In the case of P08 (Lipovljani) we think that the lower H O might be the result of sampling.…”

“…Therefore, the samples represent the collection of the progeny of 2006 from the sampled populations, not the adult individuals from those populations. Such sampling was chosen for better connectivity of the obtained data with measurements of adaptive traits conducted in the trial, under the presumption that the diversity of the progeny from a full crop year is a good representative of populations' standing genetic diversity, as noted in certain studies [7].…”

“…Slavonian oak is in increasing demand throughout Europe as an imported timber. This is because of its many good qualities, which include its high growth performance, straightness, long clear trunk and fine branches [7]. Additionally, its late flushing makes it significantly less affected by the European oak leaf roller (Tortrix viridana L.) and late spring frost [8].…”

Chloroplast Haplotype Diversity in the White Oak Populations of the Italian Peninsula, Sicily, and Sardinia

“…Consequently, chloroplast microsatellites (or Simple Sequence Repeats, SSRs) have progressively replaced PCR-RFLPs over the years, becoming the most used markers due to their higher efficacy, low cost, and ease of analyses. Exemplary utilizations of cpSSRs include the assessment of geographic patterns of diversity in other widespread Italian oaks such as Quercus cerris and Quercus suber [40,41] and clear genealogical reconstructions of several white oaks in Western Europe [42], Central Europe [38,43], the Balkans [39,[44][45][46], and Northeastern Europe [47][48][49][50]. The emerging scenario unambiguously indicates Southern Europe to have hosted a mosaic of refugia for the persistence of tree species during the Quaternary [28,51], with white oak populations exhibiting complex patterns of genetic variation.…”