The grasshopper genome reveals long-term gene content conservation of the X Chromosome and temporal variation in X Chromosome evolution

Gene evolution rate between X Chromosome and autosomes. (A) Box plot of d_N/d_S values from different autosomal and X-linked categories. We classified genes in L. migratoria into five, partially overlapping, categories: X-conserved genes are X-linked in at least eight species from Figure 2, X-Lmig are X-linked only in L. migratoria and autosomal in all other species from Figure 2, X–X genes are X-linked in L. migratoria and only one other species, A–A genes are autosomal in L. migratoria and all other species, and A–X genes are autosomal in L. migratoria and X-linked in other species. Significant difference to the autosomal in the all-species (A–A) category shown. (****) P < 0.001. (B) The moving average values of d_N/d_S along the X Chromosome. (C) The moving average values of recombination rate (Rho) along the X Chromosome.