Biology subjects

Dopman, E. B.

Publications and source records attributed to Dopman, E. B..

4 recordsLinked to original sources

bioRxiv2024

The period gene alters daily and seasonal timing in Ostrinia nubilalis

The timing of insects daily (feeding, movement) and seasonal (diapause, migration) rhythms affects their population dynamics and distribution. Yet, despite their implications for insect conservation and pest management, the genetic mechanisms underlying variation in timing are poorly understood. Prior research in the European corn borer moth (Ostrinia nubilalis) associated ecotype differences in seasonal diapause and daily activity with genetic variation at the circadian clock gene period (per). Here, we demonstrate that populations with divergent allele frequencies at per exhibit differences in daily behavior, seasonal development, and the expression of circadian clock genes. Specifically, later daily activity and shortened diapause were associated with a reduction and delay in the abundance of cycling per mRNA. CRISPR/Cas9-mediated mutagenesis revealed that per and/or an intact circadian clock network were essential for the appropriate timing of daily behavior and seasonal responsiveness. Furthermore, a reduction of per gene dosage in per heterozygous mutants (per -/+) pleiotropically decreased the diapause incidence, shortened post-diapause development, and delayed the timing of daily behavior, in a manner phenotypically reminiscent of wild-type individuals. Altogether, this combination of observational and experimental research strongly suggests that per is a master regulator of biological rhythms and may contribute to the observed life cycle differences between bivoltine (two generation) and univoltine (one generation) O. nubilalis. HighlightsO_LINatural ecotypes with divergent period (per) genotypes differ in their daily and seasonal responses to photoperiod C_LIO_LILater daily activity, reduced diapause incidence, and shorter post-diapause development is associated with reduced per mRNA abundance C_LIO_LIper is essential for short-day recognition and daily timing C_LIO_LIReduced per gene dosage shortened post-diapause development and delayed locomotor activity C_LI

evolutionary biology↗

bioRxiv2022

Partial reuse of circadian clock genes along parallel clines of diapause in two moth species

Understanding the molecular basis of repeated evolution is essential for improving our ability to predict evolution. Genes repeatedly used in independent cases of adaptation to similar environments are strong candidates for predicting adaptation across phylogeny. The Asian corn borer (Ostrinia furnacalis; ACB) and the European corn borer (Ostrinia nubilalis; ECB) are two closely related moths that display remarkable adaptability to a wide range of climate on two separate continents, largely manifesting as changes in the timing of diapause (dormancy), but the genetic basis of parallel clinal responses remains to be characterized. We extensively sampled the ACB cline in China in a genome-wide association study (GWAS) using pooled sequencing data (Pool-seq). We characterized the genetic basis of clinal diapause response in ACB and showed that genes involved in circadian rhythm were over-represented among the candidate genes under spatially varying selection. Comparing with previous results from ECB, we found that the circadian clock gene period (per), but not pigment-dispersing factor receptor (Pdfr), was repeatedly used, but the alleles were not shared between the species. The corn borers shared adaptability is likely based in per but seemingly through independent mutational paths.

evolutionary biology↗

bioRxiv2021

Consequences of coupled barriers to gene flow for the build-up of genomic differentiation

Theory predicts that when different barriers to gene flow become coincident, their joint effects enhance reproductive isolation and genomic divergence beyond their individual effects, but empirical tests of this coupling hypothesis are rare. Here, we analyze patterns of gene exchange among populations of European corn borer moths that vary in the number of acting barriers, allowing for comparisons of genomic variation when barrier traits or loci are in coincident or independent states. We find that divergence is mainly restricted to barrier loci when populations differ by a single barrier, whereas the coincidence of temporal and behavioral barriers is associated with divergence of two chromosomes harboring barrier loci. Furthermore, differentiation at temporal barrier loci increases in the presence of behavioral divergence and differentiation at behavioral barrier loci increases in the presence of temporal divergence. Our results demonstrate how the joint action of coincident barrier effects leads to levels of genomic differentiation that far exceed those of single barriers acting alone, consistent with theory arguing that coupling allows indirect selection to combine with direct selection and thereby lead to a stronger overall barrier to gene flow. Thus, the state of barriers - independent or coupled - strongly influences the accumulation of genomic differentiation.

evolutionary biology↗

bioRxiv2019

Genomic basis of circannual rhythm in the European corn borer moth

Genetic variation in life-history timing allows populations to synchronize with seasonal cycles but little is known about the molecular mechanisms that produce differences in circannual rhythm in nature. Changes in diapause timing in the European corn borer moth (Ostrinia nubilalis) have facilitated rapid response to shifts in winter length encountered during range expansion and from climate change, with some populations emerging from diapause earlier to produce an additional generation per year. We identify genomic variation associated with changes in the time spent in winter diapause and show evidence that the circadian clock genes period (per) and pigment dispersing factor receptor (Pdfr) interact to underlie this adaptive polymorphism in circannual rhythm. Per and Pdfr are located within two epistatic QTL, strongly differ in allele frequency among individuals that pupate earlier or later, have the highest linkage disequilibrium among gene pairs in the QTL regions despite separation by > 4 megabases, and possess amino-acid changes likely to affect function. One per mutation in linkage disequilibrium with Pdfr creates a novel putative clock-cycle binding site found exclusively in populations that pupate later. We find associated changes in free-running daily circadian rhythm, with longer daily rhythms in individuals that end diapause early. These results support a modular connection between circadian and circannual timers and provide testable hypotheses about the physiological role of the circadian clock in seasonal synchrony. Winter length is expected to continually shorten from climate warming and we predict these gene candidates will be targets of selection for future adaptation and population persistence.

evolutionary biology↗