Fig. 3.

Equilibrium GC content inferred from new polymorphisms relative to actual GC content. GC4eq is the expected GC-content at 4-fold degenerate sites for a given species when based on new alleles introduced by recombination (left panel) and new alleles introduced by mutations (right panel). GC4eq values were normalized by the GC-contents at 4-fold degenerate sites for each species, and species with fewer than 50 polymorphic sites for any given category of allele were excluded. Points in shaded area below the diagonal denote species that are GC-rich relative to the input of polymorphisms by recombination or mutation.