Experimental test of the fitness effects of divergent marine-freshwater chromosomal inversions in stickleback under different salinity conditions

Chromosomal inversions are a type of structural variant that have long interested evolutionary biologists because of their potential role in local adaptation and speciation. However, direct experimental evidence for the fitness consequences of inversions is rare, limiting our ability to dissect the evolutionary forces associated with the spread and maintenance of inversions in natural populations. We tackle this knowledge gap by studying the fitness effects of three chromosomal inversions that consistently differ between marine and freshwater populations of threespine sticklebacks (Gasterosteus aculeatus). Using controlled laboratory crosses, we tested whether inversion genotype influences fitness (measured as survival, standard length, and body condition) across two salinity treatments (freshwater vs saltwater). In both the freshwater and the saltwater treatments, there were no deviations from Mendelian ratios at any of the three inversions. This suggests that there are no intrinsic de..., , # Experimental test of the fitness effects of divergent marine-freshwater chromosomal inversions in stickleback under different salinity conditions

Dataset DOI: [10.5061/dryad.76hdr7t7c](10.5061/dryad.76hdr7t7c)

## Description of the data and file structure

This data was collected based on lethal sampling of experimental crosses from a marine population of threespine sticklebacks. For each individual, measurements of body size, which correspond to standard length and weight, were determined. Additionally, individuals were genotyped to determine the orientation at the chromosomal inversion of interest (i.e., chromosome I, chromosome XI, or chromosome XXI) and sex. 

### Files and variables

#### File: cross_data_stickleback_F2.csv

**Description:** This file includes information about the F2 crosses, which are used for the analysis.

##### Variables

* parent.cross: F1 cross from where a female and male were used to generate an F2 cross
* tank.parents: Tank where the F1 parents were h...,