Aim: The Pleistocene glacial cycles play a prominent role in shaping phylogeographicalpatterns of organisms, while few studies have focused on the regional difference ofglacial effects. By acquiring comprehensive knowledge of the origin, diversification andhistorical demography of an intensively studied passerine species complex, Great Tit,we aim to test the regional variation of the Late Pleistocene glaciation impacts on thiswidely distributed bird lineage.

Location: Eurasia and associated peninsulas and archipelagos.

Taxa: Parus major species complex.

Methods: Phylogeny, divergence times and demographic dynamics were estimatedwith Bayesian methods. Population structure, genetic diversity and correlation betweengenetic and physical distances were estimated based on mtDNA variation.Glacial-to-present distributional changes were assessed via ecological niche modelling(ENM).

Results: Five major clades (Central Asia, Eastern Asia, Eastern Himalaya, Northern and Western Eurasia and Southern Asia) were detected, with divergence timesranging 1.57–0.50 million years ago. Genetic diversity values and Bayesian skylineplots suggest that the three eastern clades had a deeper population history. A morecomplex geographic structure was observed in East Asia. Demographic expansionduring the last glacial cycle was indicated for all five clades. ENM results showed broad conservatism of traits related to climate tolerances, and generally broader andmore continuous distributional patterns under glacial conditions.

Main Conclusions: The Great Tit complex probably originated in Southeast Asia.Geographic barriers, such as the deserts of Central Asia and the Qinghai–TibetPlateau appear to be related to the lineage divergence. Late Pleistocene climate cyclesinfluenced both demographic dynamics and divergence, especially in terms ofeast–west differences in relation to geographic complexity.