Pale, speckled peppered moths are cryptic against lichen-covered bark. In nineteenth-century industrial Britain, soot killed the lichen and darkened surfaces, and a near-black form named carbonaria rose from rarity to dominance in polluted regions within a few decades. After clean air legislation the frequency of the dark form fell again. Predation experiments, some criticised on methodological grounds and later repeated more carefully, support differential bird predation as the main selective agent.
The genetics arrived much later. Work published in 2016 identified the carbonaria mutation as a large transposable element inserted into an intron of the gene cortex, which affects wing pigmentation patterning in butterflies and moths. Statistical dating of the insertion from recombination around it placed its origin around the 1810s to 1820s, some decades before the first recorded black specimen in 1848.
The episode is often overstated in both directions. It is not proof of speciation, and the moths do not usually rest on exposed trunks as early photographs suggested. But the selective mechanism, the field evidence and now the mutation itself are all documented.