Biology subjects

van de Zande, L.

Publications and source records attributed to van de Zande, L..

5 recordsLinked to original sources

bioRxiv2020

A single QTL with large effect is associated with female functional virginity in an asexual parasitoid wasp

During the transition from sexual to asexual reproduction, a suite of reproduction-related sexual traits become superfluous, and may be selected against if costly. Female functional virginity refers to asexual females resisting to mate or not fertilizing eggs after mating. These traits appear to be among the first that evolve during the gradual transition from sexual to asexual reproduction. The genetic basis of female functional virginity remains elusive. Previously, we reported that female functional virginity segregates as a single recessive locus in the asexual parasitoid wasp Asobara japonica. Here, we investigate the genetic basis of this trait by quantitative trait loci (QTL) mapping and candidate gene analyses. Consistent with the segregation of phenotypes, a single QTL of large effect was found spanning over 4.23 Mb and comprising at least 131 protein-coding genes, of which 15 featured sex-biased expression in the related sexual Asobara tabida. We speculate that two of these 15 genes may be of particular interest: CD151 antigen and nuclear pore complex protein Nup50. Overall, our results are consistent with a single gene or a cluster of linked genes underlying rapid evolution of female functional virginity in the transition to asexuality. Once a mutation for rejection to mate has swept through a population, the region comprising the gene(s) does not get smaller due to lack of recombination in asexuals.

evolutionary biology↗

bioRxiv2020

Sexually dimorphic traits and male-specific differentiation are actively regulated by Doublesex during specific developmental windows in Nasonia vitripennis

Sexually dimorphic traits in insects are rapidly evolving due to sexual selection which can ultimately lead to speciation. However, our knowledge of the underlying sex-specific molecular mechanisms is still scarce. Here we show that the highly conserved gene, Doublesex (Dsx), regulates rapidly diverging sexually dimorphic traits in the model parasitoid wasp Nasonia vitripennis (Hymenoptera: Pteromalidae). We present here the revised full Dsx gene structure with an alternative first exon, and two additional male NvDsx isoforms, which gives important insights into the evolution of the sex-specific oligomerization domains and C-termini. We show the sex-specific NvDsx expression throughout development, and demonstrate that transient NvDsx silencing in different male developmental stages dramatically shifts the morphology of two sexually dimorphic traits from male to female, with the effect being dependent on the timing of silencing. In addition, transient silencing of NvDsx in early male larvae affects male genitalia tissue growth but not morphology. This indicates that male NvDsx is actively required to suppress female-specific traits and to promote male-specific traits during specific developmental windows. These results also strongly suggest that in N. vitripennis most sex-specific tissues fully differentiate in the embryonic stage and only need the input of NvDsx for growth afterwards. This provides a first insight into the regulatory activity of Dsx in the Hymenoptera and will help to better understand the evolutionary and molecular mechanisms involved in sex-specific development in this parasitoid wasp, which can eventually lead to the development of new synthetic genetics-based tools for biological pest control by parasitoid wasps. Significance StatementIn insects, male and female differentiation is regulated by the highly conserved transcription factor Doublesex (Dsx). The role of Dsx in regulating rapidly evolving sexually dimorphic traits has received less attention, especially in wasps and bees. Here, we mainly focused on Dsx regulation of two sexually dimorphic traits and male genitalia morphology in the parasitoid wasp, Nasonia vitripennis. We demonstrate that Dsx actively regulates male-specific tissue growth and morphology during specific developmental windows. These findings will help to better understand the molecular mechanisms underlying the rapid evolution of sexual differentiation and sexually dimorphic traits in insects, but may also be the starting point for the development of new tools for biological control of pest insects by parasitoid wasps.

developmental biology↗

bioRxiv2020

Genomics of sex allocation in the parasitoid wasp Nasonia vitripennis

BackgroundWhilst adaptive facultative sex allocation has been widely studied at the phenotypic level across a broad range of organisms, we still know remarkably little about its genetic architecture. Here, we explore the genome-wide basis of sex ratio variation in the parasitoid wasp Nasonia vitripennis, perhaps the best studied organism in terms of sex allocation, and well known for its response to local mate competition (LMC). ResultsWe performed a genome-wide association study (GWAS) for single foundress sex ratios using iso-female lines derived from the recently developed outbred N. vitripennis laboratory strain HVRx. The iso-female lines capture a sample of the genetic variation in HVRx and we present them as the first iteration of the Nasonia vitripennis Genome Reference Panel (NVGRP 1.0). This panel provides an assessment of the standing genetic variation for sex ratio in the study population. Using the NVGRP, we discovered a cluster of 18 linked SNPs, encompassing 9 annotated loci associated with sex ratio variation. Furthermore, we found evidence that sex ratio has a shared genetic basis with clutch size on three different chromosomes. ConclusionsOur approach provides a thorough description of the quantitative genetic basis of sex ratio variation in Nasonia at the genome level and reveals a number of inter-related candidate loci underlying sex allocation regulation.

evolutionary biology↗

bioRxiv2019

Genetic architecture of male courtship behavior differences in the parasitoid wasp genus Nasonia (Hymenoptera; Pteromalidae)

Very little is known about the genetic basis of behavioral variation in courtship behavior, which can contribute to speciation by prezygotic isolation of closely related species. Here, we analyze the genetic basis and architecture of species differences in the male courtship behavior of two closely related parasitoid wasps Nasonia vitripennis and N. longicornis. Both species occur microsympatrically in parts of their ranges and have been found in the same host pupae. Despite strong postzygotic isolation mechanisms between these two Nasonia species, viable hybrid females can be produced in the laboratory if both species are cured of their Wolbachia endosymbionts. We used haploid F2 hybrid males derived from virgin F1 hybrid females of two independent mapping populations to study the genetic architecture of five quantitative and two qualitative components of their courtship behavior. A total of 14 independent Quantitative Trait Loci (QTL) were found in the first mapping population (320 males), which explained 4-25% of the observed phenotypic variance. Ten of these QTL were confirmed by a second independent mapping population (112 males) and no additional ones were found. A genome-wide scan for two-loci interactions revealed many unique but mostly additive interactions explaining an additional proportion of the observed phenotypic variance. Courtship QTL were found on all five chromosomes and four loci were associated with more than one QTL, indicating either possible pleiotropic effects of individual QTL or individual loci contributing to multiple courtship components. Our results indicate that these two evolutionary young species have rapidly evolved multiple significant phenotypic differences in their courtship behavior that have a polygenic and highly interactive genetic architecture. Based on the location of the QTL and the published Nasonia genome sequence we were able to identify a series of candidate genes for further study.

genetics↗

bioRxiv2019

Latitudinal variation in circadian rhythmicity in Nasonia vitripennis

Many physiological processes of living organisms show circadian rhythms, governed by an endogenous clock. This clock has a genetic basis and is entrained by external cues such as light and temperature. Other physiological processes exhibit seasonal rhythms, that are also responsive to light and temperature. We previously reported a natural latitudinal cline of photoperiodic diapause induction in the parasitic wasp Nasonia vitripennis in Europe and a correlated haplotype frequency for the circadian clock gene period (per). To evaluate if this correlation is reflected in circadian behaviour, we investigated circadian locomotor activity of seven populations from the cline. We found that the proportion of rhythmic males is higher than females in constant darkness, and that mating decreased rhythmicity of both sexes. Only for virgin females, the free running period ({tau}) increased weakly with latitude. Wasps from the most southern locality had an overall shorter free running rhythm and earlier onset, peak and offset of activity during the 24 h period, than wasps from the northernmost locality. We evaluate this variation in rhythmicity as a function of period haplotype frequencies in the populations and discuss its functional significance in the context of local adaptation.

evolutionary biology↗