Environmental gradients and the establishment of chromosomal inversions

Along continuous environmental gradients, a rare chromosomal inversion’s establishment rate follows universal profiles after rescaling by cline width, with total establishment increasing monotonically with dispersal.

• Why it matters: Theory for inversion establishment along environmental gradients has been limited to continent–island and two-deme settings, leaving clinal mechanisms hard to quantify from data.
• What they did: The authors combine classical cline theory, quasi-linkage equilibrium, and spatial branching processes to derive growth rate, establishment probability, and total establishment rate, then validate with stochastic simulations.
• The result: At a sharp environmental transition, local inversion growth equals selection on captured alleles, but establishment probability is about one tenth of that value; establishment can be estimated from observable allele-frequency clines.