Sex-biased cooperation among immature peers: It matters who helps whom

Our understanding of sex-biased helping has progressed from a historical emphasis on relatedness differences caused by haplodiploidy to an understanding of the role played by the rarer-sex effect. Theory to date typically assumes that offspring help their mother. We show that an alternative, peer-to-peer cooperation, can shed light on the interaction of helpers and the recipients of help. In pine sawfly (Diprion pini) larvae, larval peer-to-peer cooperation takes the form of collective, and individually costly, antipredator behaviour. Larvae typically occur in mixed-sex groups, but females can lay unfertilized eggs that develop into haploid males, which produce male-only broods. Female-biased sex ratios typically select for female-biased helping, and our model here matches empirical findings. Alternative scenarios provide insight too: (1) if genetic constraints permit no sex-specificity in behaviour beyond haploid males expressing all alleles while helping in females can be recessive or..., , # Data from: Sex-biased cooperation among immature peers: It matters who helps whom

Dataset DOI: [10.5061/dryad.3xsj3txvb](10.5061/dryad.3xsj3txvb)

## Description of the data and file structure

This dataset contains simulation and analysis code used to study an alternative, peer-to-peer cooperation, which can shed light on the interaction of helpers and the recipients of help. The models track the proportion of defenders among males, females, and the total population under different genetic assumptions. Code used to generate the `.csv` data files and analysis notebooks is included, along with supplementary data from pine sawfly populations. Detailed information about all the parameters of the model are present in the supplementary.

### Files and variables

#### File: Closed_model.m

**Description:** MATLAB script for a **closed model** for the coevolution of sex ratio and sex-specific defence. This model is included in the supplementary analyses.

#### File: Model_1_datagen.ipynb

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