Diana Krajmerová

Adapting through glacial cycles: insights from a long-lived tree (Taxus baccata).

Despite the large body of research devoted to understanding the role of Quaternary glacial cycles in the genetic divergence of European trees, the differential contribution of geographic isolation and/or environmental adaptation in creating population genetic divergence remains unexplored. In this study, we used a long-lived tree (Taxus baccata) as a model species to investigate the impact of Quaternary climatic changes on genetic diversity via neutral (isolation-by-distance) and selective (isolation-by-adaptation) processes. We applied approximate Bayesian computation to genetic data to infer its demographic history, and combined this information with past and present climatic data to assess the role of environment and geography in the observed patterns of genetic structure. We found evidence that yew colonized Europe from the East, and that European samples diverged into two groups (Western, Eastern) at the beginning of the Quaternary glaciations, c. 2.2 Myr before present. Apart from the expected effects of geographical isolation during glacials, we discovered a significant role of environmental adaptation during interglacials at the origin of genetic divergence between both groups. This process may be common in other organisms, providing new research lines to explore the effect of Quaternary climatic factors on present-day patterns of genetic diversity.

Nucleotide polymorphisms associated with climate, phenology and physiological traits in European beech (Fagus sylvatica L.)

Although European beech (Fagus sylvatica L.) is one of the most widespread and ecologically and commercially most important deciduous trees in Europe, little is known about its adaptive genetic variation. We explored single-nucleotide polymorphism (SNP) variation in candidate genes for budburst and drought resistance in beech populations sampled across most of the distribution range, represented in an international provenance trial. SNP variation was monitored for six candidate genes, in 114 individuals from 19 natural populations. Population structure was deduced from the analysis of 20 nuclear microsatellite markers. Different methods to detect imprints of natural selection were used (FST-outlier, SNP-climate regression, association tests). The FST-outlier approach identified the COV gene with unambiguous signal of selection, which is an orthologue of Arabidopsis gene for a membrane protein previously reported as phenology-related. Based on environmental association analysis at the population level, the dehydrin gene was found associated with drought-related climatic variables. At the individual level, dehydrin gene also showed a significant association with chlorophyll fluorescence parameters, which are considered stress markers. The importance of the knowledge of physiological variation and geographical patterns of adaptive genetic variation for guiding reproductive materials transfer under climate change is stressed.

Voľba lesného reprodukčného materiálu v podmienkach klimatickej zmeny / Choice of forest reproductive material under conditions of climate change

Abstract Climate change may endanger not only yield and fulfilling the social functions of European forests, but even the survival of several tree species. The study emphasises the complexity of climatic factors and physiological mechanisms, which may potentially endanger the persistence of tree populations and which cannot be reduced to problems of drought and temperature increase. A substantial inter-population variation in traits associated with the response to climatic stress, observed in provenance experiments, is a prerequisite for the choice of proper forest reproductive material (FRM) in reforestation as a strategy of climate-change mitigation. Assisted migration, i.e., transfer of FRM from source regions, currently characterised by such climate characteristics, which are expected in the target regions in the future, requires knowledge of key stress factors (depending on the climate scenario), physiological processes associated with the adaptation to this stress, identification of genes and eventually epigenetic mechanisms, controlling adaptation processes, and finally mapping of genetic and/or epigenetic variation in key genes. For most tree species, such information is not yet available. Therefore, assisted migration under such information uncertainty needs to be complemented by in situ gene conservation measures to preserve the possibility of reversing the effects of eventual erroneous decisions on FRM transfer. Abstrakt Prebiehajúca klimatická zmena môže ohroziť nielen produkčné schopnosti európskych lesov a plnenie ich celospoločenských funkcií, ale aj samotné prežitie viacerých druhov drevín. Práca poukazuje na komplexnosť klimatických faktorov a fyziologických mechanizmov, ktoré môžu potenciálne ohrozovať prežitie drevín, a ktoré nemožno redukovať na problém sucha a zvýšenia teplôt. Značná medzipopulačná variabilita lesných drevín v znakoch súvisiacich s odozvou na klimatický stres, pozorovaná v provenienčných pokusoch, je predpokladom využitia voľby vhodného reprodukčného materiálu pri umelej obnove lesa ako stratégie adaptácie na klimatickú zmenu. Riadená migrácia, teda prenos lesného reprodukčného materiálu (LRM) zo zdrojových oblastí, ktoré v súčasnosti vykazujú klimatické charakteristiky, očakávané v cieľovej oblasti v budúcnosti, vyžaduje znalosť kľúčových stresových faktorov, závisiacich od klimatického scenára, fyziologických procesov, spojených s adaptáciou na tieto stresy, identifikáciu génov či epigenetických mechanizmov, kontrolujúcich adaptačné procesy a zmapovanie genetickej či epigenetickej variability kľúčových génov. Pri väčšine drevín tieto informácie zatiaľ nie sú k dispozícii. V podmienkach informačnej neistoty musí byť preto riadená migrácia doplnená opatreniami na zachovanie genofondu lesných drevín in situ, aby bolo možné v čo najväčšom rozsahu zvrátiť dôsledky prípadných chybných rozhodnutí pri prenose LRM.

Variation of cytosine methylation patterns in European beech ( Fagus sylvatica L.)

The role of epigenetic phenomena in plant adaptation is becoming widely recognized and the potential of epigenetics for forestry practice has been demonstrated as well. In this study, methylation-sensitive amplification polymorphism (MSAP) markers were investigated in 20 European beech (Fagus sylvatica L.) provenances that cover most of Europe and were planted in two climatically contrasting provenance trial plots. Correlations of cytosine-methylation patterns at five loci and overall DNA methylation with climatic conditions of the sites of population origin and budburst phenology were detected, suggesting that methylation at particular loci was influenced by the weather or photoperiod during embryogenesis or even earlier. Alternation of methylation patterns may also have been caused by genetic mutation. Frequencies of methylation patterns at three loci differed between the two trial locations, indicating that a climatically induced change of methylation during the ontogeny occurs as well. The results suggest that the rules for collection, transfer, and use of forest reproductive materials should also consider epigenetic effects.

Landscape genetics highlight the importance of sustainable management in European mountain spruce forests: a case study on Western capercaillie

The mountain spruce forests of the Western Carpathians have experienced a dramatic deterioration in the last decades increasing the landscape fragmentation. This considerably affected the Western capercaillie population recently surviving within small habitat patches surrounded by unfavourable habitats. Our study shows that the long-term isolation resulted in genetic differentiation with decreasing trend in allelic richness towards the most adjacent western subpopulations. We evaluated dispersal possibilities within the landscape and identified barriers and the most critical corridors between genetically distinct subpopulations. Landscape genetic analysis confirmed that the isolation by environmental features explains the observed genetic patterns better than straight geographical distance. We highlight the urgent need for an active conservation management in the critical habitats where dispersion might be constrained or “bottlenecked” in order to ensure gene flow within the fragmented capercaillie metapopulation of the Western Carpathian mountain forests.

Genetic variation in Tertiary relics: The case of eastern-Mediterranean Abies (Pinaceae)

Abstract The eastern‐Mediterranean Abies taxa, which include both widely distributed species and taxa with minuscule ranges, represent a good model to study the impacts of range size and fragmentation on the levels of genetic diversity and differentiation. To assess the patterns of genetic diversity and phylogenetic relationships among eastern‐Mediterranean Abies taxa, genetic variation was assessed by eight nuclear microsatellite loci in 52 populations of Abies taxa with a focus on those distributed in Turkey and the Caucasus. Both at the population and the taxon level, the subspecies or regional populations of Abies nordmanniana s.l. exhibited generally higher allelic richness, private allelic richness, and expected heterozygosity compared with Abies cilicica s.l. Results of both the structure analysis and distance‐based approaches showed a strong differentiation of the two A. cilicica subspecies from the rest as well as from each other, whereas the subspecies of A. nordmanniana were distinct but less differentiated. ABC simulations were run for a set of scenarios of phylogeny and past demographic changes. For A. ×olcayana, the simulation gave a poor support for the hypothesis of being a taxon resulting from a past hybridization, the same is true for Abies equi‐trojani: both they represent evolutionary branches of Abies bornmuelleriana.

Epigenetic memory effects in forest trees: a victory of “Michurinian biology”?

Abstract The study reviews trait inheritance, which is in contradiction with the rules of Mendelian genetics, and which was object of controversies among biologists (sometimes with grave political consequences) in the USSR and Sovietcontrolled countries in the 1930s-1960s. “Carryover” or “memory” effects of the climate, to which maternal trees are exposed during seed development, on phenological behavior and other adaptively relevant traits of their offspring in conifers are mentioned; similar effects are associated with the germination and early growth environment. Molecular mechanisms underlying these effects include covalent modifications of DNA or DNA-associated proteins (cytosine methylation, various types of histone modifications), micro-RNAs and small interfering RNAs. Tools for the identification of these modifications are reviewed with a focus on cytosine methylation, along with an overview of the hitherto knowledge on the occurrence of DNA modifications in forest trees. The practical implications of epigenetic inheritance in forest trees are discussed with the focus on the adaptation to climate change and legislation on forest reproductive materials.