Repeated Transitions in Migratory Behavior Across a Songbird Radiation Are Not Driven by Selection on Shared Variation in Candidate Genes

In the parulid warbler radiation (n = 101), candidate-gene variation and signals of positive selection do not show a clear association with migratory propensity, despite repeated gains and losses.

• Why it matters: The study addresses whether repeated evolution of migration is driven by selection acting on shared genetic variation, a mechanism still unclear for behavioral traits.
• What they did: Using a phylogenomic comparison of candidate gene tree topologies to the parulid warbler species tree, the authors tested discordance and then modeled coding-sequence evolution to find elevated dN/dS in five candidate genes.
• The result: Discordance reflected differences in informative sites rather than genetic similarity tied to shared migratory strategies, and no recurrent selection was detected across lineages where migration transitions likely occurred.

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