Data from: Effects of inversions on within- and between-species recombination and divergence

Chromosomal inversions disrupt recombination in heterozygotes by both reducing crossing over within inverted regions and increasing it elsewhere in the genome. The reduction of recombination in inverted regions facilitates the maintenance of hybridizing species, as outlined by various models of chromosomal speciation. We present a comprehensive comparison of the effects of inversions on recombination rates and on nucleotide divergence. Within an inversion differentiating Drosophila pseudoobscura and D. persimilis, we detected one double-recombinant among 9739 progeny from F1 hybrids screened, consistent with published double crossover frequencies observed within species. Despite similar rates of exchange within and between species, we found no sequence-based evidence of ongoing gene exchange between species within this inversion, but significant exchange was inferred within species. We also observed greater differentiation at regions near inversion breakpoints between species vs. within species. Moreover, we observed strong 'interchromosomal effect' (higher recombination in inversion heterozygotes between species) with up to 9-fold higher recombination rates along collinear segments of chromosome two in hybrids. Further, we observed that regions most susceptible to changes in recombination rates corresponded to regions with lower recombination rates in homokaryotypes. Finally, we showed that interspecies nucleotide divergence is lower in regions with greater increases in recombination rate, potentially resulting from greater interspecies exchange. Overall, we have identified several similarities and differences between inversions segregating within vs. between species in their effects on recombination and divergence. We conclude that these differences are most likely due to lower frequency of heterokaryotypes and to fitness consequences from the accumulation of various incompatibilities between species. Additionally, we have identified possible effects of inversions on interspecies gene exchange that had not been considered previously.ScriptsScripts used to calculate average pairwise differences between all 6 pairwise combinations along the XR chromosome between Drosophila pseudoobscura, Drosophila persimilis, Sex-Ratio Drosophila persimilis, and Drosophila miranda. These output file can then be used to calculate RND between D pseudoobscura, D persimilis, and SR D persimilis in another program such as Microsoft Excel. All scripts are written in Perl. Author: Kenneth Hoehn. Date: May-5-2011. Sections: 1. Constructing the combined, raw input file from PILEUP outputs (skip if combined input file is provided); 2. Necessary input files for final analysis; 3. Editing combined input file and calculating average pairwise differences; 4. Calculating RND; 5. Double checking output; 6. Simple window writing script. See README.txt for more details.Multiple genome alignment of XRThis document contains the multiple genome alignment file associated with this publication. A total of four XR chromosome sequences were used for this study – one D. miranda, one D. pseudoobscura, and two D. persimilis.XR_PsPerMir_combined_g1g2_MSH39.tx