Drosophila simulans adaptive architecture
Ontology highlight
ABSTRACT:
PROVIDER: PRJEB39259 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| ERR4421060_1.fastq.gz | Fastqsanger.gz | |||
| ERR4421060_2.fastq.gz | Fastqsanger.gz | |||
| ERR4467210_1.fastq.gz | Fastqsanger.gz | |||
| ERR4467210_2.fastq.gz | Fastqsanger.gz | |||
| ERR4467750_1.fastq.gz | Fastqsanger.gz |
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Project description:Genomic divergence and adaptive convergence in Drosophila simulans from Evolution Canyon, Israel
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Project description:The genetic basis of adaptation to different environments has been of long-standing interest to evolutionary biologists. Dormancy is a well-studied adaptation to facilitate overwintering. In Drosophila melanogaster, a moderate number of genes with large effects have been described, which suggests a simple genetic basis of dormancy. On the other hand, genome-wide scans for dormancy suggest a polygenic architecture in insects. In D. melanogaster, the analysis of the genetic architecture of dormancy is complicated by the presence of cosmopolitan inversions. Here, we performed a genome-wide scan to characterize the genetic basis of this ecologically extremely important trait in the sibling species of D. melanogaster, D. simulans that lacks cosmopolitan inversions. We performed Pool-GWAS in a South African D. simulans population for dormancy incidence at 2 temperature regimes (10 and 12°C, LD 10:14). We identified several genes with SNPs that showed a significant association with dormancy (P-value < 1e-13), but the overall modest response suggests that dormancy is a polygenic trait with many loci of small effect. Our results shed light on controversies on reproductive dormancy in Drosophila and have important implications for the characterization of the genetic basis of this trait.
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Project description:Adaptive protein evolution is pervasive in Drosophila. Genomic studies, thus far, have analyzed each protein as a single entity. However, the targets of adaptive events may be localized to particular parts of proteins, such as protein domains or regions involved in protein folding. We compared the population genetic mechanisms driving sequence polymorphism and divergence in defined protein domains and non-domain regions. Interestingly, we find that non-domain regions of proteins are more frequent targets of directional selection. Protein domains are also evolving under directional selection, but appear to be under stronger purifying selection than non-domain regions. Non-domain regions of proteins clearly play a major role in adaptive protein evolution on a genomic scale and merit future investigations of their functional properties.
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Project description:A study evaluating the effect of stress resistance selection of Drosophila melanogaster. Abstract Here, we report a detailed analysis of changes in gene expression in Drosophila melanogaster selected for multiple eological relevant environmental stress resistance traits. We analyzed females from three biological replicates from seven selection regimes and one control regime using whole genome gene expression arrays. Replicated selection lines were selected for resistance to acute heat survival, high temperature knock down, constant 30°C during development, cold shock survival, desiccation and starvation, respectively. Additionally, a set of replicated lines was selected for increased longevity. When compared to gene expression profiles of control lines, we were able to detect consistent selection responses at the transcript level in each specific selection regime and also found a group of differentially expressed genes that were generally changed among all selected lines. Replicated selection lines clustered together, i.e. showed similar changes in gene expression (compared to controls) and thus showed that 10 generations of artificial selection gives a clear signal among gene expression profiles. The changes in gene expression in lines selected for increased longevity, desiccation and starvation resistance, respectively, showed high similarities. Cold resistance selected lines showed little differentiation from controls. Different methods of heat selection (heat survival, heat knock down and constant 30°C) showed little similarity verifying that different mechanism are involved in high temperature adaptation. The direction of change in gene expression in the selected lines showed a consistent pattern for each selection regime. For most selection regimes and in the comparison of all selected lines and controls exclusively up- or down regulation of gene expression among significant differentially expressed genes was found. The different responses to selection expressed in individual selection regimes and among all selected lines indicate that we have identified genes involved in stress specific and general stress response mechanisms. Keywords: control versus selected
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Project description:Biodiversity refugia formed by unique features of the Mediterranean arid landscape, such as the dramatic ecological contrast of "Evolution Canyon," provide a natural laboratory in which local adaptations to divergent microclimate conditions can be investigated. Significant insights have been provided by studies of Drosophila melanogaster diversifying along the thermal gradient in Evolution Canyon, but a comparative framework to survey adaptive convergence across sister species at the site has been lacking. To fill this void, we present an analysis of genomic polymorphism and evolutionary divergence of Drosophila simulans, a close relative of Drosophila melanogaster with which it co-occurs on both slopes of the canyon. Our results show even deeper interslope divergence in D. simulans than in D. melanogaster, with extensive signatures of selective sweeps present in flies from both slopes but enhanced in the population from the hotter and drier south-facing slope. Interslope divergence was enriched for genes related to electrochemical balance and transmembrane transport, likely in response to increased selection for dehydration resistance on the hotter slope. Both species shared genomic regions that underwent major selective sweeps, but the overall level of adaptive convergence was low, demonstrating no shortage of alternative genomic solutions to cope with the challenges of the microclimate contrast. Mobile elements were a major source of genetic polymorphism and divergence, affecting all parts of the genome, including coding sequences of mating behavior-related genes.
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Project description:Natural selection is expected to leave a characteristic footprint on neighboring nucleotide variation through the effects of genetic linkage. The size of the region affected is proportional to the strength of selection and greatly reduced with the recombinational distance from the selected site. Thus, the genomic footprint of selection is generally believed to be restricted to a small DNA stretch in normal and highly recombining regions. Here, we study the effect of selection on linked polymorphism (hitchhiking effect) by surveying nucleotide variation across a highly recombining approximately 88-kb genomic fragment in an African population of Drosophila simulans. We find a core region of up to 38 kb with a major haplotype at intermediate frequency. The extended haplotype structure that gradually vanishes until disappearing is unusual for a highly recombining region. Both the presence in the structured genomic domain of a single major haplotype depleted of variability and the detected spatial pattern of variation along the approximately 88-kb fragment are incompatible with neutral predictions in a panmictic population. A major role of demographic effects could also be discarded. The observed pattern of variation clearly provides evidence that directional selection has acted recently on this region, sweeping out variation around a strongly adaptive mutation. Our findings suggest a major role of positive selection in shaping DNA variability even in highly recombining regions.
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Project description:The compound eyes of insects exhibit striking variation in size, reflecting adaptation to different lifestyles and habitats. However, the genetic and developmental bases of variation in insect eye size is poorly understood, which limits our understanding of how these important morphological differences evolve. To address this, we further explored natural variation in eye size within and between four species of the Drosophila melanogaster species subgroup. We found extensive variation in eye size among these species, and flies with larger eyes generally had a shorter inter-ocular distance and vice versa We then carried out quantitative trait loci (QTL) mapping of intra-specific variation in eye size and inter-ocular distance in both D. melanogaster and D. simulans This revealed that different genomic regions underlie variation in eye size and inter-ocular distance in both species, which we corroborated by introgression mapping in D. simulans This suggests that although there is a trade-off between eye size and inter-ocular distance, variation in these two traits is likely to be caused by different genes and so can be genetically decoupled. Finally, although we detected QTL for intra-specific variation in eye size at similar positions in D. melanogaster and D. simulans, we observed differences in eye fate commitment between strains of these two species. This indicates that different developmental mechanisms and therefore, most likely, different genes contribute to eye size variation in these species. Taken together with the results of previous studies, our findings suggest that the gene regulatory network that specifies eye size has evolved at multiple genetic nodes to give rise to natural variation in this trait within and among species.
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Project description:In Drosophila, multiple lines of evidence converge in suggesting that beneficial substitutions to the genome may be common. All suffer from confounding factors, however, such that the interpretation of the evidence-in particular, conclusions about the rate and strength of beneficial substitutions-remains tentative. Here, we use genome-wide polymorphism data in D. simulans and sequenced genomes of its close relatives to construct a readily interpretable characterization of the effects of positive selection: the shape of average neutral diversity around amino acid substitutions. As expected under recurrent selective sweeps, we find a trough in diversity levels around amino acid but not around synonymous substitutions, a distinctive pattern that is not expected under alternative models. This characterization is richer than previous approaches, which relied on limited summaries of the data (e.g., the slope of a scatter plot), and relates to underlying selection parameters in a straightforward way, allowing us to make more reliable inferences about the prevalence and strength of adaptation. Specifically, we develop a coalescent-based model for the shape of the entire curve and use it to infer adaptive parameters by maximum likelihood. Our inference suggests that ∼13% of amino acid substitutions cause selective sweeps. Interestingly, it reveals two classes of beneficial fixations: a minority (approximately 3%) that appears to have had large selective effects and accounts for most of the reduction in diversity, and the remaining 10%, which seem to have had very weak selective effects. These estimates therefore help to reconcile the apparent conflict among previously published estimates of the strength of selection. More generally, our findings provide unequivocal evidence for strongly beneficial substitutions in Drosophila and illustrate how the rapidly accumulating genome-wide data can be leveraged to address enduring questions about the genetic basis of adaptation.
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Project description:A Saccharomyces cerevisiae population was cultured for many generations under conditions to which it is not optimally adapted. These experiments were designed to investigate adaptive evolution under natural selection. This study is described in more detail in Ferea TL, et al. 1999. Proc Natl Acad Sci USA 96:9721-6
2002-02-11 | E-GEOD-29 | biostudies-arrayexpress
Project description:Male sexual characters are often among the first traits to diverge between closely related species and identifying the genetic basis of such changes can contribute to our understanding of their evolutionary history. However, little is known about the genetic architecture or the specific genes underlying the evolution of male genitalia. The morphology of the claspers, posterior lobes, and anal plates exhibit striking differences between Drosophila mauritiana and D. simulans. Using QTL and introgression-based high-resolution mapping, we identified several small regions on chromosome arms 3L and 3R that contribute to differences in these traits. However, we found that the loci underlying the evolution of clasper differences between these two species are independent from those that contribute to posterior lobe and anal plate divergence. Furthermore, while most of the loci affect each trait in the same direction and act additively, we also found evidence for epistasis between loci for clasper bristle number. In addition, we conducted an RNAi screen in D. melanogaster to investigate if positional and expression candidate genes located on chromosome 3L, are also involved in genital development. We found that six of these genes, including components of Wnt signaling and male-specific lethal 3 (msl3), regulate the development of genital traits consistent with the effects of the introgressed regions where they are located and that thus represent promising candidate genes for the evolution these traits.
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