Fig. 1: Study design to test the fitness effects of chromosomal inversions in two salinity treatments.

A For each chromosomal inversion, three independent F1 families were generated. B For the F2 generation, three crosses were generated from three unique pairs of females and males taken from each independent F1 family, for a total of nine crosses per inversion. The progeny of each cross was equally divided between the freshwater and saltwater treatments. C The three crosses for one family per inversion are shown. For the inversion on chromosome XI, two crosses with its respective tanks in freshwater and saltwater were sampled, whereas for the inversions on chromosome I and XXI, two crosses plus the saltwater tank from the third cross were sampled. An X indicates the crosses that were sampled. This sampling procedure was equally done across the three independent families for each chromosomal inversion.