Extensive transcriptomic profiling of pupal diapause in a butterfly reveals a dynamic phenotype.

Diapause is a common adaptation for overwintering in insects that is characterized by arrested development and increased tolerance to stress and cold. While the expression of specific candidate genes during diapause have been investigated, there is no general understanding of the dynamics of the transcriptional landscape as a whole during the extended diapause phenotype. Such a detailed temporal insight is important, as diapause is a vital aspect of life cycle timing. Here we performed a time-course experiment using RNA-Seq on the head and abdomen in the butterfly Pieris napi. In both body parts, comparing diapausing and non-diapausing siblings, differentially expressed genes are detected from the first day of pupal development and onwards, varying dramatically across these formative stages. During diapause there are strong gene expression dynamics present, revealing a pre-programmed transcriptional landscape that is active during the winter. Different biological processes appear to be active in the two body parts. Finally, adults emerging from either the direct or diapause pathways do not show large transcriptomic differences, suggesting the adult phenotype is strongly canalized.