Biology subjects

Duneau, D.

Publications and source records attributed to Duneau, D..

3 recordsLinked to original sources

bioRxiv2018

Signatures of insecticide selection in the genome of Drosophila melanogaster.

Resistance to insecticides has evolved in multiple insect species, leading to increased application rates and even control failures. Understanding the genetic basis of insecticide resistance is fundamental for mitigating its impact on crop production and disease control. We performed a GWAS approach with the Drosophila Genetic Reference Panel (DGRP) to identify the mutations involved in resistance to two widely used classes of insecticides: organophosphates (OPs, parathion) and pyrethroids (deltamethrin). Most variation in parathion resistance was associated with mutations in the target gene Ace, while most variation in deltamethrin resistance was associated with mutations in Cyp6a23, a gene encoding a detoxification enzyme never previously associated with resistance. A \"nested GWAS\" further revealed the contribution of other loci: Dscam1 and trpl were implicated in resistance to parathion, but only in lines lacking Wolbachia. Cyp6a17, the paralogous gene of Cyp6a23, and CG7627, an ATP-binding cassette transporter, were implicated in deltamethrin resistance. We observed signatures of recent selective sweeps at all of these resistance loci and confirmed that the soft sweep at Ace is indeed driven by the identified resistance mutations. Analysis of allele frequencies in additional population samples revealed that most resistance mutations are segregating across the globe, but that frequencies can vary substantially among populations. Altogether, our data reveal that the widely used OP and pyrethroid insecticides imposed a strong selection pressure on natural insect populations. However, it remains unclear why, in Drosophila, resistance evolved due to changes in the target site for OPs, but due to a detoxification enzyme for pyrethroids.\n\nArticle summaryInsecticides are widely used to control pests and insect vectors of disease. In response to the strong selection pressure exerted by insecticides, resistance has evolved in most insect species. We identified few genes present in several Drosophila melanogaster natural populations implicated in the evolution of resistance against two insecticides widely used today. We identified primary and secondary genes involved in the resistance. Surprisingly, resistance evolved in the target site for one insecticide, but was associated to changes in a novel detoxification enzyme for the other insecticide.

evolutionary biology↗

bioRxiv2018

Genetic basis of thermal plasticity variation in Drosophila melanogaster body size

Body size is a quantitative trait that is closely associated to fitness and under the control of both genetic and environmental factors. While developmental plasticity for this and other traits is heritable and under selection, little is known about the genetic basis for variation in plasticity that can provide the raw material for its evolution. We quantified genetic variation for body size plasticity in Drosophila melanogaster by measuring thorax and abdomen length of females reared at two temperatures from a panel representing naturally segregating alleles, the Drosophila Genetic Reference Panel (DGRP). We found variation between genotypes for the levels and direction of thermal plasticity in size of both body parts. We then used a Genome-Wide Association Study (GWAS) approach to unravel the genetic basis of inter-genotype variation in body size plasticity, and used different approaches to validate selected QTLs and to explore potential pleiotropic effects. We found mostly \"private QTLs\", with little overlap between the candidate loci underlying variation in plasticity for thorax versus abdomen size, for different properties of the plastic response, and for size versus size plasticity. We also found that the putative functions of plasticity QTLs were diverse and that alleles for higher plasticity were found at lower frequencies in the target population. Importantly, a number of our plasticity QTLs have been targets of selection in other populations. Our data sheds light onto the genetic basis of inter-genotype variation in size plasticity that is necessary for its evolution.\n\nSignificance StatementThe environmental conditions under which development takes place can affect developmental outcomes and lead to the production of phenotypes adjusted to the environment adults will live in. This developmental plasticity, which can help organisms cope with environmental heterogeneity, is heritable and under selection. Plasticity can itself evolve, a process that will be partly dependent on the available genetic variation for this trait. Using a wild-derived D. melanogaster panel, we identified DNA sequence variants associated to variation in thermal plasticity for body size. We found that these variants correspond to a diverse set of gene functions. Furthermore, their effects differ between body parts and properties of the thermal response, which can, therefore, evolve independently. Our results shed new light onto a number of key questions about the long discussed genes for plasticity.

evolutionary biology↗

bioRxiv2017

Complex effects of day and night temperature fluctuations on thermally plastic traits in an experimental model of adaptive seasonal plasticity.

BackgroundChanges in development in response to seasonally variable environments can produce phenotypes adjusted to fluctuating seasonal conditions and help organisms cope with temporal heterogeneity. In contrast to what happens in natural situations, experimental studies of developmental plasticity typically use environmental factors held constant during development, precluding assessment of potential environment-by-environment interaction effects.\n\nResultsWe tested effects of circadian fluctuations in temperature on a series of thermally plastic traits in a model of adaptive seasonal plasticity, the butterfly Bicyclus anynana. Comparing phenotypes from individuals reared under two types of fluctuations (warmer days with cooler nights, and cooler days with warmer nights) and those reared under a constant temperature of the same daily average allowed us to identify complex patterns of response to day and night temperatures. We found evidence of additive-like effects (for body size), but also different types of \"dominance\"-type effects where one particular period of the light cycle (for development time) or one particular extreme temperature (for eyespot size) had a relatively larger contribution to phenotype expression. We also gathered evidence against the hypothesis that thermal plasticity in development time drives thermal plasticity in other traits.\n\nConclusionsCombined effects of fluctuating day and night temperatures include additive-like effects as well as different types of environmental-dominance interaction effects. Differences between plastic traits reveal independent responses to temperature, and possible independent assessment of temperature conditions. Our study underscores the importance of understanding how organisms integrate complex environmental information towards a complete understanding of natural phenotypic variation and of the potential impact of environmental change thereon.

evolutionary biology↗