Genetic Diversity and Differentiation of Pedunculate Oak (Quercus robur L.) Populations at the Southern Margin of Its Distribution Range—Implications for Conservation

Abstract

Understanding intraspecific genetic variation is one of the principal requirements for the evaluation of tree species capacity to cope with intensive climatic changes, as well as designing long-term conservation programs. Herein, we evaluated the genetic diversity and genetic structure of seven pedunculate oak (Quercus robur L.) populations, located at the southern margin of its distribution range on the Balkan Peninsula (Serbia). The objective of the study was to propose future in situ conservation measures aimed at protection of pedunculate oak adaptive and neutral genetic diversity at the species rear-edge. Genetic diversity and structure were estimated using twelve highly polymorphic simple sequence repeat (SSR) markers. The mean expected heterozygosity (He) was 0.769, allelic richness (AR) 9.63, and private allelic richness (pAR) 0.79, indicating high genetic diversity in the studied populations. Genetic differentiation among the populations was low (Fst = 0.032). Structure analysis, the unweighted pair group method with arithmetic mean (UPGMA) showed the existence of two gene pools unrelated to the populations’ area of occurrence. Taking into consideration the results of the current study and previous conservation activities on the pedunculate oak in Serbia, as well as the importance of rear-edge populations in the long-term conservation of the species genetic diversity, we suggested establishing three additional gene conservation units for securing long-term sustainability of the species.

The latitudinal trend in genetic diversity and distinctiveness ofQuercus roburrear edge forest remnants calls for new conservation priorities

“…However, the low levels of genetic differentiation we found in this area of ∼50,000 km 2 (450 km between MER and FAG, the most distant populations sampled in the Po Valley) were in line with several other studies reporting low to moderate levels of genetic differentiation at the regional scale (e.g. G ST = 0.003 in Burger et al 2021; F ST = 0.031 in Belletti et al 2005; F ST = 0.032 in Kesić et al 2021; F ST = 0.051 in Ballian et al 2010; F ST = 0.054 in Degen et al 2021). Q. robur is indeed a wind-pollinated tree, with a high potential for long-distance dispersal and extensive gene flow.…”

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

“…Likewise, the analysis of molecular variance for the two generations shows greater variability within populations (98%) than among populations (2%), which is commonly observed in pedunculate oaks (Gömöry et al 2001;Neophytou 2015;Kesić et al 2021). Furthermore, a comparison between Slavonian (A R = 6.26, H o = 0.504, H e = 0.542, F IS = 0.077) and indigenous (A R = 6.13, H o = 0.523, H e = 0.548, F IS = 0.055) old-growth stands and their natural regeneration (SLAV_NR: A R = 6.10, H o = 0.521, H e = 0.550, F IS = 0.055; IND_NR: A R = 5.54, H o = 0.528, H e = 0.541, F IS = 0.030) also revealed similar levels of genetic variation.…”

Demographic and genetic impacts of powdery mildew in a young oak cohort

“…The spatial, demographic, and genetic structure of oak populations (especially Q. robur and Q. petraea ) has nevertheless received much attention owing to the ecologic, cultural and economic importance of these species in Europe ( e.g. , Kremer & Petit 1993; Streiff et al 1998; Gömöry et al 2001; Vakkari et al 2006; Kesić et al 2021). Overall, oak populations exhibit a high level of genetic diversity, with no significant or little differences among cohorts of different ages in the same stand (Vranckx et al 2014a from adults to established seedlings; Gerzabek et al 2020 from emergence to 3-year old seedlings).…”