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Coniferous trees are of major economic and ecologic importance. Yet, they are genomically poorly studied, because their long generation times, their high levels of heterozygosity and their huge genomes impede the access to conifer genomic resources. The European silver fir (Abies alba MILL) is widely distributed across diverse habitats in mountainous areas of temperate Europe. The species is of high value for forestry due to its high quality timber and its ecosystem functions such as erosion control and landslide prevention. Using next-generation sequencing the first silver fir transcriptome was sequenced and annotated. The annotation protocol lead to the identification of 460 candidate genes that are putatively involved in environmental stress resistance. Additionally, the transcriptomes of twelve more individuals were sequenced. Subsequent SNP detection produced on average 24580 SNPs per individual. For the SNPs that lie on the annotated candidate genes, a KASP genotyping assay was designed that allows for the fast and cost efficient genotyping of many A. alba trees. In the Mediterranean Basin, A. alba occurs in isolated and comparatively small populations. Recently, strong die-off events were observed in these populations, likely as a result of severe droughts. In the course of climate change, droughts are predicted to increase further in frequency and severity endangering the persistence of Mediterranean A. alba populations. Particularly these populations may, however, be of special value for the adaptive potential of the whole species since they may harbor genetic resources preadapted to relatively xeric environments. There is an ongoing debate about assisted migration, i.e. the transplantation of Mediterranean A. alba populations to more northern population in order to use them as donors of drought adapted alleles. To elucidate the question whether the idea of assisted migration is practical, knowledge about the state of local adaptation, its molecular basis and its environmental drivers is needed. Here, 376 individuals from high and low elevational populations which are located along a 170 km eastwest transect across four mountains in the south-western Mediterranean pre-Alps of France were investigated at 267 SNP loci distributed across 175 candidate genes. The methodological framework of landscape genetics was applied. Results of Bayesian cluster analysis showed that the dominant genetic pattern coincides with an east-west isolation-by-distance genetic structure, likely a result of post-glacial recolonization movement. Fst-outlier tests revealed 16 SNPs under divergent selection. Significant associations of allele frequencies of eight SNPs and winter drought were detected suggesting that this variable is a strong driver of local adaptation. Correlations tests of genetic distance of a subset of outlier loci and environmental distance demonstrated that isolation-by-environment occurs along altitude. Reanalysis of published common garden phenotypic data using Qst-Fst comparisons revealed adaptive divergence of bud flush and growth rate at the coldest and most humid site. The thesis illustrates a complex pattern of genetic structure in ecologically marginal populations that is shaped by demography and natural selection. It highlights that local adaptation is site specific in terms of both the genes under selection and the environmental drivers. Hence, whether a population is suitable to be the subject of assisted migration would have to be answered individually. Since this is highly impractical, the thesis states that in-situ conservation of marginal populations is the best option to ensure the capacity of evolutionary change in A. alba and to support the species’ ability to cope with the challenges of a rapidly changing climate., Zu der Gruppe der Koniferen gehören einige ökonomisch und ökologisch wichtige Forstbäume. Trotzdem ist diese Gruppe genomisch nur wenig untersucht. Gründe dafür sind die langen Generationszyklen, das hohe Maß an Heterozygosität sowie die großen Genome von Koniferen, die den Zugang zu genomischen Ressourcen erschweren. Die Weißtanne (Abies alba MILL) ist weit über montane Habitate des temperaten und mediterranen Europas verbreitet. Die Art hat aufgrund ihres hochwertigen Holzes und ihrer bestandsstabilisierenden Funktion eine hohe Bedeutung in der Forstwirtschaft. Mittels next-generation-sequencing wurde das erste Weißtannentranskriptom sequenziert und annotiert. Das Annotationsprotokoll führte zur Identifizierung von 460 Kandidatengenen, denen eine Rolle in der Stressreaktion zukommt. Zusätzlich wurden die Transkriptome zwölf weiterer Tannen sequenziert und einem SNP-calling unterzogen, bei dem durchschnittlich 24580 SNPs pro Individuum detektiert wurden. Für diejenigen SNPs, die sich auf den annotierten Kandidatengenen befanden, wurde ein KASP Genotypisierungswerkzeug entworfen. Im mediterranen Becken kommt die Tanne in isolierten, vergleichsweise kleinen Populationen vor. Diese sind aktuell stark von Mortalität betroffen, was auf ausgeprägte Trockenperioden zurückgeführt wird. Im Zuge des Klimawandels wird eine noch stärkere Zunahme extremer Trockenheit erwartet, die die Existenz mediterraner Tannenpopulationen bedrohen könnte. Eben diese Populationen sind jedoch von besonderer Bedeutung für das adaptive Potential der gesamten Art, da sie schon jetzt über genetische Anpassungen an Trockenheit verfügen könnten. Zur Zeit entspannt sich eine Debatte über die Praktikabilität der sog. ‚assisted migration‘, d. h. über die Möglichkeit und Sinnhaftigkeit der Transplantation trockenadaptierter Tannen in nördlichere Populationen, in denen sie als Allele-Donoren fungieren sollen. Zur Erhellung der Debatte bedarf es erweiterter Kenntnisse über die tatsächliche lokale Anpassung mediterraner Tannen und ihrer molekularen Grundlage sowie über die Art der Umweltfaktoren, druch die die lokale Anpassung hervorgerufen wird. Mit den Methoden der Landschaftsgenetik wurden 376 Bäume an 267 SNP loci untersucht, die über 175 Kandidatengene verteilt waren. Die Bäume stammten von hoch und tief gelegenen Standorten, welche sich über vier Berge der süd-westlichen Voralpen in Frakreich entlang eines 170 km langen ost-west gerichteten Transekts erstreckten. Das Ergebnis einer Bayesischen Clusteranalyse zeigte, dass das übergeordnete genetische Muster einer isolation-by-distance Struktur folgt, welche wahrscheinlich von der Rekolonisationsbewegung der Art im Postglazial herrührt. Fst-outlier Tests förderten 16 SNPs zu Tage, die unter bidirektionaler Selektion stehen. Acht SNP loci waren signifikant mit Wintertrockenheit assoziiert. Korrelationstests der genetischen Distanz einiger Outlierloci und der Distanz von Umweltparametern ergaben, dass isolation-by-environment zwischen hoch- und tiefgelegenen Standorten auftritt. Die vergleichende Analyse von Qst und Fst Werten, zeigte das Auftreten von adaptiver Divergenz in Blattaustrieb und Wachstumsrate am kältesten und feuchtesten Standort. Die Arbeit beschreibt das komplexe Muster von Populationen an ökologischen Marginalstandorten, gleichsam geformt durch Demographie und Adaption. Die Arbeit betont, dass lokale Adaption im Bezug auf die unter Selektion stehenden Gene und die wirksamen Umweltfaktoren für jeden Standort spezifisch ist. So muss die Frage, ob eine Population zur Nutzung für assisted migration geeignet ist, für jeden Einzelfall neu beantwortet werden. Dieses ist in höchstem Maße unpraktikabel. Stattdessen erscheint der in-situ Schutz von Marginalpopulationen als die beste Möglichkeit die Fähigkeit der Tanne zur evolutiven Weiterentwicklung zu sichern und so ihr Potential sich den Herausforderungen des Klimawandels anzupassen zu stärken.

Coniferous trees are of major economic and ecologic importance. Yet, they are genomically poorly studied, because their long generation times, their high levels of heterozygosity and their huge genomes impede the access to conifer genomic resources. The European silver fir (Abies alba MILL) is widely distributed across diverse habitats in mountainous areas of temperate Europe. The species is of high value for forestry due to its high quality timber and its ecosystem functions such as erosion control and landslide prevention. Using next-generation sequencing the first silver fir transcriptome was sequenced and annotated. The annotation protocol lead to the identification of 460 candidate genes that are putatively involved in environmental stress resistance. Additionally, the transcriptomes of twelve more individuals were sequenced. Subsequent SNP detection produced on average 24580 SNPs per individual. For the SNPs that lie on the annotated candidate genes, a KASP genotyping assay was designed that allows for the fast and cost efficient genotyping of many A. alba trees. In the Mediterranean Basin, A. alba occurs in isolated and comparatively small populations. Recently, strong die-off events were observed in these populations, likely as a result of severe droughts. In the course of climate change, droughts are predicted to increase further in frequency and severity endangering the persistence of Mediterranean A. alba populations. Particularly these populations may, however, be of special value for the adaptive potential of the whole species since they may harbor genetic resources preadapted to relatively xeric environments. There is an ongoing debate about assisted migration, i.e. the transplantation of Mediterranean A. alba populations to more northern population in order to use them as donors of drought adapted alleles. To elucidate the question whether the idea of assisted migration is practical, knowledge about the state of local adaptation, its molecular basis and its environmental drivers is needed. Here, 376 individuals from high and low elevational populations which are located along a 170 km eastwest transect across four mountains in the south-western Mediterranean pre-Alps of France were investigated at 267 SNP loci distributed across 175 candidate genes. The methodological framework of landscape genetics was applied. Results of Bayesian cluster analysis showed that the dominant genetic pattern coincides with an east-west isolation-by-distance genetic structure, likely a result of post-glacial recolonization movement. Fst-outlier tests revealed 16 SNPs under divergent selection. Significant associations of allele frequencies of eight SNPs and winter drought were detected suggesting that this variable is a strong driver of local adaptation. Correlations tests of genetic distance of a subset of outlier loci and environmental distance demonstrated that isolation-by-environment occurs along altitude. Reanalysis of published common garden phenotypic data using Qst-Fst comparisons revealed adaptive divergence of bud flush and growth rate at the coldest and most humid site. The thesis illustrates a complex pattern of genetic structure in ecologically marginal populations that is shaped by demography and natural selection. It highlights that local adaptation is site specific in terms of both the genes under selection and the environmental drivers. Hence, whether a population is suitable to be the subject of assisted migration would have to be answered individually. Since this is highly impractical, the thesis states that in-situ conservation of marginal populations is the best option to ensure the capacity of evolutionary change in A. alba and to support the species’ ability to cope with the challenges of a rapidly changing climate.