PhD defence Tianhao Zhao
Phenotypic and genetic differences of migratory landbirds in East-Central Asian flyways
his thesis investigates the ecology and evolution of migration in Asian landbirds along the East–Central Asian flyways, with a focus on the Qinghai–Tibet Plateau (QTP) as a potential geographic barrier. Using individual tracking and genomic re-sequencing, it examines two taxa, Calliope and Saxicola, to address major knowledge gaps in Asian migration ecology. Tracking of Siberian Rubythroats (Calliope calliope) from Qinghai revealed loop migration, with autumn routes detouring east of the QTP and more direct spring routes. Migration speed was higher in spring due to shorter stopovers, while flight altitude remained consistent across seasons. Limited data from other populations suggest similar detoured routes, but broader comparisons were constrained. In contrast, Asian stonechats (Saxicola spp.) showed greater variation in migratory strategies. A migratory divide between Siberian and Amur stonechats was confirmed, with evidence of an intermediate route crossing the QTP. Tibetan stonechats exhibited loop migration over the QTP involving trans-Himalayan flights. Genomic analyses revealed strong differentiation of Tibetan stonechats and extensive hybridization within the migratory divide between Siberian and Amur stonechats, though links between genotype and migration route remain unresolved. Migration timing varied among populations and was associated with environmental cues such as day length and breeding habitat vegetation phenology. Notably, Qinghai populations showed distinct phenological patterns, potentially linked to their migration routes and evolutionary divergence. At a global scale, population genomics of the stonechat complex identified four major clades and suggested repeated evolution of migration and high-altitude adaptation. The dataset provides a foundation for a Genoscape method and genotype–phenotype association studies. With an expansion from a conservation perspective on anthropogenic threats this thesis overall highlights significant knowledge gaps in Asian flyways, emphasizing the need for expanded data collection and international collaboration.