DNA Methylation and Sex Allocation in the Parasitoid WaspNasonia vitripennis

Abstract

Dryad data: http://dx.doi.org/10.5061/dryad.15nj0. abstract:The role of epigenetics in the control and evolution of behavior is being increasingly recognized. Here we test whether DNA methylation influences patterns of adaptive sex allocation in the parasitoid wasp Nasonia vitripennis. Female N. vitripennis allocate offspring sex broadly in line with local mate competition (LMC) theory. However, recent theory has highlighted how genomic conflict may influence sex allocation under LMC, conflict that requires parentof-origin information to be retained by alleles through some form of epigenetic signal. We manipulated whole-genome DNA methylation in N. vitripennis females using the hypomethylating agent 5-aza-2 0 -deoxycytidine. Across two replicated experiments, we show that disruption of DNA methylation does not ablate the facultative sex allocation response of females, as sex ratios still vary with cofoundress number as in the classical theory. However, sex ratios are generally shifted upward when DNA methylation is disrupted. Our data are consistent with predictions from genomic conflict over sex allocation theory and suggest that sex ratios may be closer to the optimum for maternally inherited alleles.

Genome-wide disruption of DNA methylation by 5-aza-2’-deoxycytidine in the parasitoid waspNasonia vitripennis

“…This subtle shift is as predicted by genomic conflict over sex allocation theory, which 121 requires some form of genomic imprinting (Wild and West 2008). Assuming that DNA methylation is 122 the mechanism by which parent-of-origin allelic information is carried in Nasonia (although see Wang 123 et al 2016), our data therefore provided the first (albeit indirect) evidence for genomic conflict 124 influencing sex allocation (Cook et al 2015a). Although patterns of methylation differ among eukaryotes, the epigenetic modification itself is 140 chemically identical.…”

Exposure to the neonicotinoid imidacloprid disrupts sex allocation cue use during superparasitism in the parasitoid wasp Nasonia vitripennis

“…However, research into the mechanisms involved in sex allocation in N. vitripennis is much less advanced, both in terms of the genetic basis of sex ratio and in terms of the underlying neuroscience. Quantitative genetic studies have revealed QTL associated with sex ratio variation (Pannebakker et al, 2011), transcriptomics studies have investigated gene expression patterns associated with sex allocation (Cook et al, 2015a), and a role for epigenetics, specifically DNA methylation, has also been inferred (Cook et al, 2015b). However, we still know virtually nothing of the neural substrates of sex allocation.…”

Sexual selection modulates genetic conflicts and patterns of genomic imprinting

“…It has often been suggested that genomic imprinting is absent outwith mammals and flowering plants, largely on account of lack of evidence from model organisms such as D. melanogaster (Chapman 2006;Spencer and Clark 2014;Yan et al 2014). Nevertheless, there is growing direct and indirect evidence of extensive methylation, and even genomic imprinting, in other insects, such as hymenoptera (Wang et al 2006;Kronforst et al 2008;Kucharski et al 2008;Herb et al 2012;Amarasinghe et al 2014;Oldroyd et al 2013;Yan et al 2014Yan et al , 2015Cook et al 2015;Galbraith et al 2016;Remnant et al 2016). Such taxa provide excellent opportunities for developing new theoretical and empirical avenues of genomic imprinting research (Queller 2003;Rautiala and Gardner 2016).…”