Genomic Basis of Circannual Rhythm in the European Corn Borer Moth

• Published in: Current biology Vol. 29; no. 20; pp. 3501 - 3509.e5
• Main Authors: Kozak, Genevieve M., Wadsworth, Crista B., Kahne, Shoshanna C., Bogdanowicz, Steven M., Harrison, Richard G., Coates, Brad S., Dopman, Erik B.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 21.10.2019
• Subjects: air temperature; alleles; allochronic isolation; circadian clock; circadian clocks; climate change; diapause; epistasis; gene frequency; genetic polymorphism; genomics; Lepidoptera; linkage disequilibrium; moths; Ostrinia nubilalis; phenology; photoperiod; quantitative trait loci; seasonal timing; seasonal variation; speciation; spring; stress tolerance; winter; seasonal timing; epistasis; phenology; Lepidoptera; diapause; allochronic isolation; genomics; circadian clock; climate change; speciation
• ISSN: 0960-9822; 1879-0445; 1879-0445
• DOI: 10.1016/j.cub.2019.08.053

Synchronizing the annual timing of physiological, morphological, and behavioral transitions with seasons enables survival in temperate environments [1]. The capacity to adjust life history timing and track local seasonal cycles can facilitate geographic expansion [2], adaptation [3], and tolerance [4–6] during rapid environmental change. Understanding the proximate causes of variation in seasonal timing improves prediction of future response and persistence [7, 8]. However, relatively little is known about the molecular basis generating this diversity [9], particularly in Lepidoptera, a group with many species in decline [10, 11]. In insects, the stress-tolerant physiological state of diapause enables coping with seasonal challenges [1, 12–15]. Seasonal changes in photoperiod and temperature are used to synchronize diapause with winter, and timing of diapause transitions varies widely within and among species [9, 16]. Changes in spring diapause termination in the European corn borer moth (Ostrinia nubilalis) have allowed populations to respond to shorter winters and emerge ∼3 weeks earlier in the year [17]. Multiple whole-genome approaches suggest two circadian clock genes, period (per) and pigment-dispersing factor receptor (Pdfr), underlie this polymorphism. Per and Pdfr are within interacting quantitative trait loci (QTL) and differ in allele frequency among individuals that end diapause early or late, with alleles maintained in high linkage disequilibrium. Our results provide testable hypotheses about the physiological role of circadian clock genes in the circannual timer. We predict these gene candidates will be targets of selection for future adaptation under continued global climate change [18]. [Display omitted] •A shift in diapause termination is associated with different per and Pdfr alleles•per and Pdfr are within two quantitative trait loci mediating seasonal timing•Possible causal mutations include a novel putative CLOCK/CYCLE binding site at per•Longer daily rhythms are found in individuals ending diapause early The molecular basis of annual activity is poorly understood in animals. For a temperate species of moth, Kozak et al. find evidence of circadian clock gene control for the seasonal timing of diapause. Changes to daily and annual activity may be functionally intertwined in this species.