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 req..., , , # An evolutionary loss of parental care in stickleback is associated with differences in the activity, but not the number, of neuropeptidergic neurons

[https://doi.org/10.5061/dryad.3r2280grv](https://doi.org/10.5061/dryad.3r2280grv)

## Description of the data and file structure

Brains were collected from male threespine stickleback of two ecotypes - whites and commons - that differ in parental behaviour. Brains were sectioned and stained via double-label immunohistochemistry (IHC) to quantify the number of preoptic neurons labelled with pS6 (a marker for activated neurons), galanin (Gal), oxytocin (OXT), pS6 and Gal, and pS6 and OXT at three reproductive stages. Behavioural data were also collected on the same individuals to determine if reproductive behaviours were correlated with the activation of Gal or OXT neurons.

### Files and variables

#### File: metadata.csv

**Description:**

This file contains unique identifiers for each male and information about which reproductive sta...,