Does sexual dimorphism reflect sexual antagonism? Covariation of female fitness with brothers’ sexual traits and their female homologues in neriid flies

Alleles favoured by sexual selection in males can reduce fitness when expressed in females, resulting in intralocus sexual conflict. It remains unclear whether such conflict is fully resolved by the evolution of sexual dimorphism. If conflict persists, then female reproductive performance might covary negatively with the expression of secondary sexual traits in male relatives, and potentially with the expression of homologous traits in females themselves. However, because secondary sexual traits often exhibit strong condition dependence, a resource-poor developmental environment could weaken the covariance between female fitness and the expression of such traits. We tested these predictions using a split-brood experiment in which neriid flies (Telostylinus angusticollis) were reared on nutrient-rich or nutrient-poor larval diets, resulting in high (rich diet) and low (poor diet) adult sexual dimorphism. Consistent with predictions, in families reared on the rich larval diet, we found th..., Experiment set-up
Approximately 30 neriid fly (Telostylinus angusticollis) individuals were collected from a natural population in Fred Hollows Reserve (33°54 44.04S 151°14 52.14E), Sydney, Australia, and mixed with stock flies (around 20 individuals) that had originated from the same location and had been reared in the lab for several generations. The flies were maintained in an 8L container with a mesh top and a layer of cocopeat on the bottom in a controlled-temperature room (~25 °C, 12 h light/dark cycle). The flies were supplied with food (sugar and yeast) ad libitum and watered periodically. To collect eggs, we provided oviposition medium in a large petri dish. The oviposition medium was prepared using rich larval food (described below) that was kept in a room at 25 °C for approximately seven days to allow mould growth, and watered and mixed periodically. From this lab population, 430 eggs were collected and raised on a standard larval diet in 500mL containers, with ~40 eggs per 2..., # Data from: Does sexual dimorphism reflect sexual antagonism? Covariation of female fitness with brothers’ sexual traits and their female homologues in neriid flies

Dataset DOI: [10.5061/dryad.9s4mw6mtq](10.5061/dryad.9s4mw6mtq)

## Description of the data and file structure

A split-brood larval diet manipulation experiment was carried out using the neriid fly Telostylinus angusticollis. Families from each larval diet treatment were ranked by the relative expression of male secondary sexual traits (head length relative to body size). From families with the largest and smallest male relative head length, focal females were randomly selected for fitness assays. The analysis tests for covariation between female fitness and the expression of females' own morphology (relative head length) and their brothers' morphology (relative head length).  
### Files and variables

#### File: Script.R

**Description:** R script to run the analyses

#### File: female\_performance.csv

**Description:** ...,