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Inversions are bigger on the X chromosome
- Cheng, Changde, Kirkpatrick, Mark
- Molecular ecology 2019 v.28 no.6 pp. 1238-1245
- Anopheles, Bayesian theory, Drosophila, X chromosome, genes, genetic models, insects
- In many insects, X‐linked inversions fix at a higher rate and are much less polymorphic than autosomal inversions. Here, we report that in Drosophila, X‐linked inversions also capture 67% more genes. We estimated the number of genes captured through an approximate Bayesian computational analysis of gene orders in nine species of Drosophila. X‐linked inversions fixed with a significantly larger gene content. Further, X‐linked inversions of intermediate size enjoy highest fixation rate, while the fixation rate of autosomal inversions decreases with size. A less detailed analysis in Anopheles suggests a similar pattern holds in mosquitoes. We develop a population genetic model that assumes the fitness effects of inversions scale with the number of genes captured. We show that the same conditions that lead to a higher fixation rate also produce a larger size for inversions on the X.