Data from: Gene expression correlates of social evolution in coral reef butterflyfishes

Animals display remarkable variation in social behavior. 
However, outside of rodents, little is known about the neural mechanisms
of social variation, and whether they are shared across species and sexes,
limiting our understanding of how sociality evolves. Using coral reef
butterflyfishes, we examined gene expression correlates of social
variation (i.e., pair bonding vs. solitary living) within and between
species and sexes.  In several brain regions, we quantified gene
expression of receptors important for social variation in mammals:
oxytocin (OTR), arginine vasopressin (V1aR), dopamine (D1R, D2R), and
mu-opioid (MOR). We found that social variation across individuals of the
oval butterflyfish, Chaetodon lunulatus, is linked to differences in
OTR,V1aR, D1R, D2R, and MOR gene expression within several forebrain
regions in a sexually dimorphic manner. However, this contrasted with
social variation among six species representing a single evolutionary
transition from pair bonded to solitary living. Here, OTR expression
within the supracommissural part of the ventral telencephalon was higher
in pair bonded than solitary species, specifically in males. These results
contribute to the emerging idea that nonapeptide, dopamine, and opioid
signaling is a central theme to the evolution of sociality across
individuals, although the precise mechanism may be flexible across sexes
and species.