Data from: Flight loss linked to faster molecular evolution in insects

The loss of flight ability has occurred thousands of times independently
during insect evolution. Flight loss may be linked to higher molecular
evolutionary rates because of reductions in effective population sizes
(Ne) and relaxed selective constraints. Reduced dispersal ability
increases population subdivision, may decrease geographical range size and
increases (sub)population extinction risk, thus leading to an expected
reduction in Ne. Additionally, flight loss in birds has been linked to
higher molecular rates of energy-related genes, probably owing to relaxed
selective constraints on energy metabolism. We tested for an association
between insect flight loss and molecular rates through comparative
analysis in 49 phylogenetically independent transitions spanning multiple
taxa, including moths, flies, beetles, mayflies, stick insects,
stoneflies, scorpionflies and caddisflies, using available nuclear and
mitochondrial protein-coding DNA sequences. We estimated the rate of
molecular evolution of flightless (FL) and related flight-capable lineages
by ratios of non-synonymous-to-synonymous substitutions (dN/dS) and
overall substitution rates (OSRs). Across multiple instances of flight
loss, we show a significant pattern of higher dN/dS ratios and OSRs in FL
lineages in mitochondrial but not nuclear genes. These patterns may be
explained by relaxed selective constraints in FL ectotherms relating to
energy metabolism, possibly in combination with reduced Ne.