Unravelling the developmental origins of parallel evolution

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The diversity of life may seem endless. Yet, a closer look reveals that evolution often is on repeat. This is most striking when the same suite of characters evolves over and over again. One explanation for such parallel evolution is that development produces some phenotypes readily and frequently, while others are rare or impossible. Evolution must go where development leads. I have identified a rare opportunity to put the role of development in adaptive evolution to the test. At least six species of wall lizards have repeatedly evolved a complex syndrome, including striking coloration, stout bodies, large heads, and aggressive behaviour. All these traits develop from the same cell type, neural crest cells. I propose that this developmental coupling allows seemingly unrelated traits – colours, morphologies and behaviours – to vary together. As a result, variation is channelled down particular routes, resulting in parallel evolution. I will test this hypothesis by establishing ‘Evo-Devo 2.0’ – merging evolutionary and developmental biology in a comparative framework. Firstly, I will reveal if independent origins of the syndrome share the same transcriptional and epigenetic modifications of neural crest cells. Secondly, I will identify how parallelism at the phenotypic level is mirrored at the genomic level. Thirdly, I will use gene editing to functionally validate the results and reconstruct the evolutionary steps at the origin of the syndrome. If my hypothesis is correct, my insights will demonstrate that understanding development enables us to make evolution more predictable. Failure to attend to the arrival of the fittest has left us poorly equipped to predict how invasive species evolve, or if species will adapt to environmental challenges. My research will fill this explanatory gap by showing that it is possible to understand the rules by which individuals vary, and use this insight to explain why evolution proceeds some ways rather than others.