Data from: An evolutionary loss of parental care in stickleback is associated with differences in the activity, but not the number, of neuropeptidergic neurons in the preoptic area

How can extensive diversity in social behaviour arise when behaviours
often depend on shared neural and hormonal mechanisms? In this study, we
discriminated between two ways conserved neural mechanisms might evolve to
generate differences in social behaviour: number or activity of neurons.
We compared two recently diverged ecotypes of threespine stickleback
(Gasterosteus aculeatus) in which males differ in the parental care they
provide. We quantified the number and activation of two types of
neuropeptidergic neurons in the preoptic area that affect parental care in
other species, galanin and oxytocin. Ecotypes did not differ in the
overall activation of the preoptic area or the number of galanin and
oxytocin neurons. However, ecotypes did differ in the activation of
galanin and oxytocin neurons. Activation of these neurons changed across
reproductive stages in the caring but not the non-caring ecotype,
suggesting that changes in the activation of these specific preoptic
neurons are required to transition to parenting. Our study provides
evidence that diversity in social behaviour can be generated via changes
in the activation of specific preoptic neuropeptidergic neurons.