Comparative analysis of gene expressions among avian brains: a molecular approach to the evolution of vocal learning.

Among avian species, three families of birds (songbirds, parrots, and hummingbirds) learn songs. In the brain of these vocal learners, there are neural networks called 'song systems' that specialize in song learning and production. To explore the evolution of the molecular basis of vocal learning, we conducted a comparative analysis of gene expression in vocal learners (Bengalese finches and budgerigars) and non-learners (quails and pigeons). The expression of one gene is similar in vocal learners, but that of other genes is highly diverse. In non-learners, by contrast, no nuclei-specific expression exists. These results suggest that songbirds and parrots acquired their song systems through both similar and different molecular mechanisms.