Winter moth adaptation to climate change:Genetic changes in thermal plasticity of embryonic development rate

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

Winter moth (<i>Operophtera brumata</i>) adaptation to climate change::Embryonic response to temperature

Climate change influences the seasonal timing of many organisms, but at different rates such that mismatches can occur between trophic levels. Increased winter temperatures caused winter moth egg hatching to advance, leading to a mismatch in timing between winter moth caterpillars and their food source young oak leaves. In response, winter moth egg development has genetically adapted to climate change. Eggs now need higher temperatures to complete development at a given time compared to 10 years ago, leading to a better match with oak bud burst. To investigate how and when temperature influences embryonic development, an experiment was carried out. The aim of the experiment is two-fold, to determine (1) which stages of winter moth embryonic development can be distinguished, and (2) the effect of temperature in- or decreases on developmental rate in these different stages of development. In a split-brood design, sub-clutches of eggs were transferred from a baseline temperature of 10 degrees to a colder or warmer temperature for two weeks at different times during development. Before transfer and two weeks after transfer, eggs were fixated and imaged using confocal fluorescence imaging. Here we present the first glimpses of winter moth embryonic development, a moth with an unusually long development of multiple months, and one of the few species that has been able to rapidly adapt to climate change

Winter moth adaptation to climate change:Genetic changes in thermal plasticity of embryonic development rate

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