In the Genes
How do genes correlate with behavior? How can we probe this relationship to better understand the migratory state? We used microarray analysis of 9,417 unique cDNA sequences in non-migrants, migrants, and reproductively active migrants (Zhu et al., 2009). Of those 9,417 sequences, gene expression profiles revealed a suite of 40 genes whose differential expression in the brain correlated with oriented flight behavior in individual migrants, independent of juvenile hormone activity—molecularly separating fall migrants from summer butterflies.
With the monarch genome, all 40 cDNAs have now been successfully annotated (see annotation of orientation genes).