Fig 6. Correlation between individual variation in BDNF expression level and species-biased song structures in F₁ hybrids.

(A) Individual variation of BDNF mRNA expression level and ASE ratio between F₁ hybrids. (B) Individual variation of learned songs in F₁ hybrids that were tutored with ZF and OF songs. Orange solid and blue dotted lines represent the motif and repetitive structure of syllables, respectively. (C) Heatmaps showing the correlation of p-values between the BDNF expression level or ASE ratio and species-biased song phenotypes in F₁ hybrids. (D) Correlations between BDNF mRNA expression in HVC and species-biased song structures (syllable duration, entropy variance, motif, and repetition) among F₁ hybrid individuals. Relevant data values are included in S5 Data. ASE, allele-specific expression; BDNF, brain-derived neurotrophic factor; F₁, first-generation; OF, owl finch; OZ, F₁ hybrid offspring between OF♀ and ZF♂; RA, robust nucleus of the arcopallium; RPKM, reads per kilobase of transcript per million reads mapped; ZF, zebra finch; ZO, F₁ hybrid offspring between ZF♀ and OF♂.