| dc.description.abstract | The current geographic distribution and genetic structure of plant species have been greatly affected by the Quaternary climatic oscillations. The alternating glacial and interglacial periods resulted in cycles of populations expansion and contraction that have provided opportunities for contacts and hybridization between advancing populations, as well as for differentiation due to long-lasting geographic isolation and/or adaptation to different environments. Here, I first focused on the genetic differentiation, structure and the patterns of hybridization between the native British oak species Q. robur and Q. petraea, using whole genome sequence data of 386 oak individuals sampled across four managed British parklands environments. Additionally, I reconstructed these species demographic histories in view of paleoclimatic events and searched the Q. robur genome for signatures of recent positive selection. I then explored chloroplast DNA variation and compared it with data from other studies of oaks in ancient woodlands across Europe, to assess whether the parklands populations sampled derive from native and local seed stock. Secondly, I explored the genetic structure and diversity of Asian white Birch (B. platyphylla) in China and its hybridization with the closely related silver birch, B. pendula, across Eurasia, based on whole genome sequencing data of 83 B. platyphylla individuals sampled across 74 natural Chinese populations and B. pendula whole sequencing data from a previous Eurasian study. I developed ecological niche models to define the present habitat and predict the future distribution of this species in China. Furthermore, I explored the genetic structure and evolution of B. platyphylla Chinese populations and performed genome-environment association (GEA) analyses to detect signals of local adaptation in China. I used the identified adaptive genetic loci to assess the degree of maladaptation of these populations to future climatic conditions and highlight regions of China where this species may be particularly threatened by climate change. | en_US |
