Winter moth adaptation to climate change

Timing of winter moth egg hatching shows rapid genetic adaptation to climate change. The reaction norm of egg development rate versus temperature has shifted up compared to 10 years ago. This later hatching for a given temperature has led to a better match with timing of their food source, young oak leaves. To identify the genes underlying the genetic adaptation of winter moth egg hatching, we used an evo-eco-devo approach: eggs collected from the field were used in a split-brood experiment. At different times during development, we measured embryonic development in, and obtained transcriptomes of, eggs before and after transfer to a colder or warmer temperature compared to a baseline. Stages of embryonic development in the winter moth were determined by imagining eggs using epifluorescence microscopy. These images were then used to map the thermal sensitivity of winter moth embryonic development over time, enabling us to focus on the transcriptomes taken during thermally sensitive stages of development. Ultimately, we aim to compare the genes identified this way with genes that show changes in allele frequency over the past 20 years, using our DNA record of four natural populations that adapted to climate change. As winter moths are one of the few species showing genetic adaptation under climate change, this study of winter moth embryonic development can advance our understanding of the genetic basis of adaptive evolutionary change in a natural population.