Browsing by Subject "QUANTITATIVE TRAIT LOCI"

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  • Rastas, Pasi; Calboli, Federico C. F.; Guo, Baocheng; Shikano, Takahito; Merilä, Juha (2016)
    High-density linkage maps are important tools for genome biology and evolutionary genetics by quantifying the extent of recombination, linkage disequilibrium, and chromosomal rearrangements across chromosomes, sexes, and populations. They provide one of the best ways to validate and refine de novo genome assemblies, with the power to identity errors in assemblies increasing with marker density. However, assembly of high-density linkage maps is still challenging due to software limitations. We describe Lep-MAP2, a software for ultradense genome-wide linkage map construction. Lep-MAP2 can handle various family structures and can account for achiasmatic meiosis to gain linkage map accuracy. Simulations show that Lep-MAP2 outperforms other available mapping software both in computational efficiency and accuracy. When applied to two large F-2-generation recombinant crosses between two nine-spined stickleback (Pungitius pungitius) populations, it produced two high-density (similar to 6 markers/cM) linkage maps containing 18,691 and 20,054 single nucleotide polymorphisms. The two maps showed a high degree of synteny, but female maps were 1.5-2 times longer than male maps in all linkage groups, suggesting genome-wide recombination suppression in males. Comparison with the genome sequence of the three-spined stickleback (Gasterosteus aculeatus) revealed a high degree of interspecific synteny with a low frequency (
  • Mikkola, Lea; Holopainen, Saila; Pessa-Morikawa, Tiina; Lappalainen, Anu K.; Hytönen, Marjo K.; Lohi, Hannes; Iivanainen, Antti (2019)
    Background Hip dysplasia and osteoarthritis continue to be prevalent problems in veterinary and human medicine. Canine hip dysplasia is particularly problematic as it massively affects several large-sized breeds and can cause a severe impairment of the quality of life. In Finland, the complex condition is categorized to five classes from normal to severe dysplasia, but the categorization includes several sub-traits: congruity of the joint, Norberg angle, subluxation degree of the joint, shape and depth of the acetabulum, and osteoarthritis. Hip dysplasia and osteoarthritis have been proposed to have separate genetic etiologies. Results Using Federation Cynologique Internationale -standardized ventrodorsal radiographs, German shepherds were rigorously phenotyped for osteoarthritis, and for joint incongruity by Norberg angle and femoral head center position in relation to dorsal acetabular edge. The affected dogs were categorized into mild, moderate and severe dysplastic phenotypes using official hip scores. Three different genome-wide significant loci were uncovered. The strongest candidate genes for hip joint incongruity were noggin (NOG), a bone and joint developmental gene on chromosome 9, and nanos C2HC-type zinc finger 1 (NANOS1), a regulator of matrix metalloproteinase 14 (MMP14) on chromosome 28. Osteoarthritis mapped to a long intergenic region on chromosome 1, between genes encoding for NADPH oxidase 3 (NOX3), an intriguing candidate for articular cartilage degradation, and AT-rich interactive domain 1B (ARID1B) that has been previously linked to joint laxity. Conclusions Our findings highlight the complexity of canine hip dysplasia phenotypes. In particular, the results of this study point to the potential involvement of specific and partially distinct loci and genes or pathways in the development of incongruity, mild dysplasia, moderate-to-severe dysplasia and osteoarthritis of canine hip joints. Further studies should unravel the unique and common mechanisms for the various sub-traits.
  • Saastamoinen, Marjo Anna Kaarina; Bocedi, Greta; Cote, Julien; Legrand, Dephine; Guillaume, Fredric; Wheat, Christopher West; Fronhofer, Emanuel A.; Garcia, Cristina; Henry, Roslyn; Husby, Arild; Baguette, Michelle; Bonte, Dries; Coulon, Aurelie; Kokko, Hanna; Matthysen, Erik; Niitepöld, Kristjan; Nonaka, Etsuko; Stevens , Virginie M.; Travis, Justin MJ; Donohue, Kathlin; Bullock, James M.; del Mar Delgado, Maria (2018)
    Dispersal is a process of central importance for the ecological and evolutionary dynamics of populations and communities, because of its diverse consequences for gene flow and demography. It is subject to evolutionary change, which begs the question, what is the genetic basis of this potentially complex trait? To address this question, we (i) review the empirical literature on the genetic basis of dispersal, (ii) explore how theoretical investigations of the evolution of dispersal have represented the genetics of dispersal, and (iii) discuss how the genetic basis of dispersal influences theoretical predictions of the evolution of dispersal and potential consequences. Dispersal has a detectable genetic basis in many organisms, from bacteria to plants and animals. Generally, there is evidence for significant genetic variation for dispersal or dispersal-related phenotypes or evidence for the micro-evolution of dispersal in natural populations. Dispersal is typically the outcome of several interacting traits, and this complexity is reflected in its genetic architecture: while some genes of moderate to large effect can influence certain aspects of dispersal, dispersal traits are typically polygenic. Correlations among dispersal traits as well as between dispersal traits and other traits under selection are common, and the genetic basis of dispersal can be highly environment-dependent. By contrast, models have historically considered a highly simplified genetic architecture of dispersal. It is only recently that models have started to consider multiple loci influencing dispersal, as well as non-additive effects such as dominance and epistasis, showing that the genetic basis of dispersal can influence evolutionary rates and outcomes, especially under non-equilibrium conditions. For example, the number of loci controlling dispersal can influence projected rates of dispersal evolution during range shifts and corresponding demographic impacts. Incorporating more realism in the genetic architecture of dispersal is thus necessary to enable models to move beyond the purely theoretical towards making more useful predictions of evolutionary and ecological dynamics under current and future environmental conditions. To inform these advances, empirical studies need to answer outstanding questions concerning whether specific genes underlie dispersal variation, the genetic architecture of context-dependent dispersal phenotypes and behaviours, and correlations among dispersal and other traits.
  • Baison, John; Vidalis, Amaryllis; Zhou, Linghua; Chen, Zhi-Qiang; Li, Zitong; Sillanpää, Mikko J.; Bernhardsson, Carolina; Scofield, Douglas; Forsberg, Nils; Grahn, Thomas; Olsson, Lars; Karlsson, Bo; Wu, Harry; Ingvarsson, Pär K.; Lundqvist, Sven-Olof; Niittylae, Totte; Garcia-Gil, M. Rosario (2019)
    Norway spruce is a boreal forest tree species of significant ecological and economic importance. Hence there is a strong imperative to dissect the genetics underlying important wood quality traits in the species. We performed a functional genome-wide association study (GWAS) of 17 wood traits in Norway spruce using 178 101 single nucleotide polymorphisms (SNPs) generated from exome genotyping of 517 mother trees. The wood traits were defined using functional modelling of wood properties across annual growth rings. We applied a Least Absolute Shrinkage and Selection Operator (LASSO-based) association mapping method using a functional multilocus mapping approach that utilizes latent traits, with a stability selection probability method as the hypothesis testing approach to determine a significant quantitative trait locus. The analysis provided 52 significant SNPs from 39 candidate genes, including genes previously implicated in wood formation and tree growth in spruce and other species. Our study represents a multilocus GWAS for complex wood traits in Norway spruce. The results advance our understanding of the genetics influencing wood traits and identifies candidate genes for future functional studies.
  • Li, Zitong; Kemppainen, Petri; Rastas, Pasi; Merilä, Juha (2018)
    Genomewide association studies (GWAS) aim to identify genetic markers strongly associated with quantitative traits by utilizing linkage disequilibrium (LD) between candidate genes and markers. However, because of LD between nearby genetic markers, the standard GWAS approaches typically detect a number of correlated SNPs covering long genomic regions, making corrections for multiple testing overly conservative. Additionally, the high dimensionality of modern GWAS data poses considerable challenges for GWAS procedures such as permutation tests, which are computationally intensive. We propose a cluster-based GWAS approach that first divides the genome into many large nonoverlapping windows and uses linkage disequilibrium network analysis in combination with principal component (PC) analysis as dimensional reduction tools to summarize the SNP data to independent PCs within clusters of loci connected by high LD. We then introduce single- and multilocus models that can efficiently conduct the association tests on such high-dimensional data. The methods can be adapted to different model structures and used to analyse samples collected from the wild or from biparental F-2 populations, which are commonly used in ecological genetics mapping studies. We demonstrate the performance of our approaches with two publicly available data sets from a plant (Arabidopsis thaliana) and a fish (Pungitius pungitius), as well as with simulated data.
  • Mobley, Kenyon B.; Aykanat, Tutku; Czorlich, Yann; House, Andrew; Kurko, Johanna; Miettinen, Antti; Moustakas-Verho, Jacqueline; Salgado, Andres; Sinclair-Waters, Marion; Verta, Jukka-Pekka; Primmer, Craig R. (2021)
    Over the past decades, Atlantic salmon (Salmo salar, Salmonidae) has emerged as a model system for sexual maturation research, owing to the high diversity of life history strategies, knowledge of trait genetic architecture, and their high economic value. The aim of this synthesis is to summarize the current state of knowledge concerning maturation in Atlantic salmon, outline knowledge gaps, and provide a roadmap for future work. We summarize the current state of knowledge: 1) maturation in Atlantic salmon takes place over the entire life cycle, starting as early as embryo development, 2) variation in the timing of maturation promotes diversity in life history strategies, 3) ecological and genetic factors influence maturation, 4) maturation processes are sex-specific and may have fitness consequences for each sex, 5) genomic studies have identified large-effect loci that influence maturation, 6) the brain-pituitary-gonadal axis regulates molecular and physiological processes of maturation, 7) maturation is a key component of fisheries, aquaculture, conservation, and management, and 8) climate change, fishing pressure, and other anthropogenic stressors likely have major effects on salmon maturation. In the future, maturation research should focus on a broader diversity of life history stages, including early embryonic development, the marine phase and return migration. We recommend studies combining ecological and genetic approaches will help disentangle the relative contributions of effects in different life history stages to maturation. Functional validation of large-effect loci should reveal how these genes influence maturation. Finally, continued research in maturation will improve our predictions concerning how salmon may adapt to fisheries, climate change, and other future challenges.
  • Alexandersson, Erik; Keinanen, Markku; Chawade, Aakash; Himanen, Kristiina (2018)
    Plant phenomics refers to the systematic study of plant phenotypes. Together with closely monitored, controlled climates, it provides an essential component for the integrated analysis of genotype-phenotype-environment interactions. Currently, several plant growth and phenotyping facilities are under establishment globally, and numerous facilities are already in use. Alongside the development of the research infrastructures, several national and international networks have been established to support shared use of the new methodology. In this review, an overview is given of the Nordic plant phenotyping and climate control facilities. Since many areas of phenomics such as sensor-based phenotyping, image analysis and data standards are still developing, promotion of educational and networking activities is especially important. These facilities and networks will be instrumental in tackling plant breeding and plant protection challenges. They will also provide possibilities to study wild species and their ecological interactions under changing Nordic climate conditions.
  • Hoggart, Clive J.; Venturini, Giulia; Mangino, Massimo; Gomez, Felicia; Ascari, Giulia; Zhao, Jing Hua; Teumer, Alexander; Winkler, Thomas W.; Tsernikova, Natalia; Luan, Jian'an; Mihailov, Evelin; Ehret, Georg B.; Zhang, Weihua; Lamparter, David; Esko, Tonu; Mace, Aurelien; Rueeger, Sina; Bochud, Pierre-Yves; Barcella, Matteo; Dauvilliers, Yves; Benyamin, Beben; Evans, David M.; Hayward, Caroline; Lopez, Mary F.; Franke, Lude; Russo, Alessia; Heid, Iris M.; Salvi, Erika; Vendantam, Sailaja; Arking, Dan E.; Boerwinkle, Eric; Chambers, John C.; Fiorito, Giovanni; Grallert, Harald; Guarrera, Simonetta; Homuth, Georg; Huffman, Jennifer E.; Porteous, David; Moradpour, Darius; Iranzo, Alex; Hebebrand, Johannes; Kemp, John P.; Lammers, Gert J.; Aubert, Vincent; Heim, Markus H.; Martin, Nicholas G.; Montgomery, Grant W.; Peraita-Adrados, Rosa; Santamaria, Joan; Generation Scotland Consortium; LifeLines Cohort Study; GIANT Consortium; Lokki, Marja-Liisa (2014)
  • Mikkola, Lea; Holopainen, Saila; Lappalainen, Anu; Pessa-Morikawa, Tiina; Pulikotial Augustine, Thomas; Arumilli, Meharji; Hytönen, Marjo Kristiina; Hakosalo, Osmo Topi Valtteri; Lohi, Hannes; Iivanainen, Antti (2019)
    Canine hip dysplasia is a common, non-congenital, complex and hereditary disorder. It can inflict severe pain via secondary osteoarthritis and lead to euthanasia. An analogous disorder exists in humans. The genetic background of hip dysplasia in both species has remained ambiguous despite rigorous studies. We aimed to investigate the genetic causes of this disorder in one of the high-risk breeds, the German Shepherd. We performed genetic analyses with carefully phenotyped case-control cohorts comprising 525 German Shepherds. In our genome-wide association studies we identified four suggestive loci on chromosomes 1 and 9. Targeted resequencing of the two loci on chromosome 9 from 24 affected and 24 control German Shepherds revealed deletions of variable sizes in a putative enhancer element of the NOG gene. NOG encodes for noggin, a well-described bone morphogenetic protein inhibitor affecting multiple developmental processes, including joint development. The deletion was associated with the healthy controls and mildly dysplastic dogs suggesting a protective role against canine hip dysplasia. Two enhancer variants displayed a decreased activity in a dual luciferase reporter assay. Our study identifies novel loci and candidate genes for canine hip dysplasia, with potential regulatory variants in the NOG gene. Further research is warranted to elucidate how the identified variants affect the expression of noggin in canine hips, and what the potential effects of the other identified loci are.
  • Gerwin, Jan; Urban, Sabine; Meyer, Axel; Kratochwil, Claudius F. (2021)
    Abstract Understanding the origins of phenotypic diversity among closely related species remains an important largely unsolved question in evolutionary biology. With over 800 species, Lake Malawi haplochromine cichlid fishes are a prominent example of extremely fast evolution of diversity including variation in coloration. Previously, a single major effect gene, agrp2 (asip2b), has been linked to evolutionary losses and gains of horizontal stripe patterns in cichlids, but it remains unknown what causes more fine-scale variation in the number and continuity of the stripes. Also, the genetic basis of the most common color pattern in African cichlids, vertical bars, and potential interactions between the two color patterns remain unknown. Based on a hybrid cross of the horizontally striped Lake Malawi cichlid Pseudotropheus cyaneorhabdos and the vertically barred species Chindongo demasoni we investigated the genetic basis of both color patterns. The distribution of phenotypes in the F2 generation of the cross indicates that horizontal stripes and vertical bars are independently inherited patterns that are caused by two sets of genetic modules. While horizontal stripes are largely controlled by few major effect loci, vertical bars are a highly polygenic trait. Horizontal stripes show substantial variation in the F2 generation that, interestingly, resemble naturally occurring phenotypes found in other Lake Malawi cichlid species. Quantitative trait loci (QTL) mapping of this cross reveals known (agrp2) and unknown loci underlying horizontal stripe patterns. These findings provide novel insights into the incremental fine-tuning of an adaptive trait that diversified through the evolution of additional modifier loci.
  • Pritchard, Victoria L.; Viitaniemi, Heidi M.; McCairns, R. J. Scott; Merila, Juha; Nikinmaa, Mikko; Primmer, Craig R.; Leder, Erica H. (2017)
    Much adaptive evolutionary change is underlain by mutational variation in regions of the genome that regulate gene expression rather than in the coding regions of the genes themselves. An understanding of the role of gene expression variation in facilitating local adaptation will be aided by an understanding of underlying regulatory networks. Here, we characterize the genetic architecture of gene expression variation in the threespine stickleback (Gasterosteus aculeatus), an important model in the study of adaptive evolution. We collected transcriptomic and genomic data from 60 half-sib families using an expression microarray and genotyping-by-sequencing, and located expression quantitative trait loci (eQTL) underlying the variation in gene expression in liver tissue using an interval mapping approach. We identified eQTL for several thousand expression traits. Expression was influenced by polymorphism in both cis- and trans-regulatory regions. Transe-QTL clustered into hotspots. We did not identify master transcriptional regulators in hotspot locations: rather, the presence of hotspots may be driven by complex interactions between multiple transcription factors. One observed hotspot colocated with a QTL recently found to underlie salinity tolerance in the threespine stickleback. However, most other observed hotspots did not colocate with regions of the genome known to be involved in adaptive divergence between marine and freshwater habitats.