Gene trees, species trees and E arth history combine to shed light on the evolution of migration in a model avian system

The evolution of migration in birds has fascinated biologists for centuries. In this study, we performed phylogenetic‐based analyses of C atharus thrushes, a model genus in the study of avian migration, and their close relatives. For these analyses, we used both mitochondrial and nuclear genes, and the resulting phylogenies were used to trace migratory traits and biogeographic patterns. Our results provide the first robust assessment of relationships within C atharus and relatives and indicate that both mitochondrial and autosomal genes contribute to overall support of the phylogeny. Measures of phylogenetic informativeness indicated that mitochondrial genes provided more signal within C atharus than did nuclear genes, whereas nuclear loci provided more signal for relationships between C atharus and close relatives than did mitochondrial genes. Insertion and deletion events also contributed important support across the phylogeny. Across all taxa included in the study, and for C atharus , possession of long‐distance migration is reconstructed as the ancestral condition, and a N orth A merican (north of M exico) ancestral area is inferred. Within C atharus , sedentary behaviour evolved after the first speciation event in the genus and is geographically and temporally correlated with C entral A merican distributions and the final closure of the C entral A merican S eaway. Migratory behaviour subsequently evolved twice in C atharus and is geographically and temporally correlated with a recolonization of N orth A merica in the late P leistocene. By temporally linking speciation events with changes in migratory condition and events in E arth history, we are able to show support for several competing hypotheses relating to the geographic origin of migration.