Recurrent adaptation to industrial pollution: ancestral diversity and ecological succession

Natural populations adapt to novel environments via phenotypic variation that has its origins either in contemporary mutation events or in pre-existing ancestral variation, or both. Understanding the significance of these modes of evolution in real ecological settings is central to predicting the speed of adaptation to novel challenges, and thus to informed population management intervention in the face of environmental change - but we lack suitable empirical studies. Industrial melanism in the peppered moth (Biston betularia) has emerged as a top candidate for such a study. In Britain, the black (carbonaria) form is due to a singular recent mutation, whereas in continental Europe, preliminary data suggests a surprising diversity of mutations, some of which may be adapted to a pre-industrial and pre-agricultural, forest-dominated landscape. Thus, the celebrated British case may not be generally representative of the evolutionary origins of industrial melanism across the species' range. Natural heterogeneity in resting backgrounds, associated with successional turnover and extensive mature forests, may be the unrecognised factor maintaining the striking diversity of melanic forms in this species. By revealing the identity of the mutations causing melanism in continental European populations, estimating their age, and evaluating non-industrial environmental factors maintaining melanism, this project will resolve a major puzzle in this influential evolutionary biology case study, whilst at the same time providing a novel illustration of how the interplay between genomic architecture, ecology, and geographic isolation influences mechanisms of evolution.