Browsing by Subject "selection"

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  • Skytthe, Axel; Harris, Jennifer R.; Czene, Kamila; Mucci, Lorelei; Adami, Hans-Olov; Christensen, Kaare; Hjelmborg, Jacob; Holm, Niels V.; Nilsen, Thomas S.; Kaprio, Jaakko; Pukkala, Eero (2019)
    The Nordic countries have comprehensive, population-based health and medical registries linkable on individually unique personal identity codes, enabling complete long-term follow-up. The aims of this study were to describe the NorTwinCan cohort established in 2010 and assess whether the cancer mortality and incidence rates among Nordic twins are similar to those in the general population. We analyzed approximately 260,000 same-sexed twins in the nationwide twin registers in Denmark, Finland, Norway and Sweden. Cancer incidence was determined using follow-up through the national cancer registries. We estimated standardized incidence (SIR) and mortality (SMR) ratios with 95% confidence intervals (CI) across country, age, period, follow-up time, sex and zygosity. More than 30,000 malignant neoplasms have occurred among the twins through 2010. Mortality rates among twins were slightly lower than in the general population (SMR 0.96; CI 95% [0.95, 0.97]), but this depends on information about zygosity. Twins have slightly lower cancer incidence rates than the general population, with SIRs of 0.97 (95% CI [0.96, 0.99]) in men and 0.96 (95% CI [0.94, 0.97]) in women. Testicular cancer occurs more often among male twins than singletons (SIR 1.15; 95% CI [1.02, 1.30]), while cancers of the kidney (SIR 0.82; 95% CI [0.76, 0.89]), lung (SIR 0.89; 95% CI [0.85, 0.92]) and colon (SIR 0.90; 95% CI [0.87, 0.94]) occur less often in twins than in the background population. Our findings indicate that the risk of cancer among twins is so similar to the general population that cancer risk factors and estimates of heritability derived from the Nordic twin registers are generalizable to the background populations.
  • Michel, Matthieu (Helsingin yliopisto, 2020)
    Hybrid wheat has been the focus of much research for its potential high yield, high protein content and better resistance to biotic and abiotic stresses. Nowadays, only CHA (Chemical Hybridizing Agent) method is used to induce male sterility at a commercial scale. However, this technique is hard to implement on a large production scale and other methods have been investigated for several years. CMS (Cytoplasmic Male Sterility) has been shown to be a promising way to develop hybrid wheat. However, one downside of the technique is the challenging breeding stage step and the associated conversion and restoration process. To fully express the potential gain in yield, the restoration of the cytoplasmic sterility must be complete for the F1 to be fully fertile. In this study, we investigated different methods to assess fertility restoration in nursery and compared the results with the trial notations. The collected data were also used to feed a genomic selection model to predict the behavior of untested hybrids. The results showed a high experimental error of the bagging method originated mostly from human manipulation. The visual scoring showed higher repeatability but was poorly correlated with trial score. A deeper study of the trial scoring revealed an interesting effect coming from the female and an expression of sterility for commercial lines and CHA hybrid checks. Good prediction accuracies were found for genomic selection on both methods, however deeper studies and cross prediction are needed. The multilocation trials remained the best option to score fertility restoration
  • Monzon-Argueello, Catalina; Consuegra, Sofia; Gajardo, Gonzalo; Marco-Rius, Francisco; Fowler, Daniel M.; De Faveri, Jacquelin; de Leaniz, Carlos Garcia (2014)
  • Ostrander, E.A.; Lohi, H.; Dog10K Consortium (2019)
    Dogs are the most phenotypically diverse mammalian species, and they possess more known heritable disorders than any other non-human mammal. Efforts to catalog and characterize genetic variation across well-chosen populations of canines are necessary to advance our understanding of their evolutionary history and genetic architecture. To date, no organized effort has been undertaken to sequence the world's canid populations. The Dog10K Consortium (http://www.dog10kgenomes.org) is an international collaboration of researchers from across the globe who will generate 20× whole genomes from 10 000 canids in 5 years. This effort will capture the genetic diversity that underlies the phenotypic and geographical variability of modern canids worldwide. Breeds, village dogs, niche populations and extended pedigrees are currently being sequenced, and de novo assemblies of multiple canids are being constructed. This unprecedented dataset will address the genetic underpinnings of domestication, breed formation, aging, behavior and morphological variation. More generally, this effort will advance our understanding of human and canine health. © 2019 The Author(s) 2019. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.
  • Velling, Pirkko; Tigerstedt, P. M. A. (Suomen metsätieteellinen seura, 1984)
  • Weissenberg, Kim von (Suomen metsätieteellinen seura, 1973)
  • Kulmuni, Jonna; Nouhaud, Pierre; Pluckrose, Lucy; Satokangas, Ina; Dhaygude, Kishor; Butlin, Roger K. (2020)
    Speciation underlies the generation of novel biodiversity. Yet, there is much to learn about how natural selection shapes genomes during speciation. Selection is assumed to act against gene flow at barrier loci, promoting reproductive isolation. However, evidence for gene flow and selection is often indirect and we know very little about the temporal stability of barrier loci. Here we utilize haplodiploidy to identify candidate male barrier loci in hybrids between two wood ant species. As ant males are haploid, they are expected to reveal recessive barrier loci, which can be masked in diploid females if heterozygous. We then test for barrier stability in a sample collected 10 years later and use survival analysis to provide a direct measure of natural selection acting on candidate male barrier loci. We find multiple candidate male barrier loci scattered throughout the genome. Surprisingly, a proportion of them are not stable after 10 years, natural selection apparently switching from acting against to favouring introgression in the later sample. Instability of the barrier effect and natural selection for introgressed alleles could be due to environment-dependent selection, emphasizing the need to consider temporal variation in the strength of natural selection and the stability of the barrier effect at putative barrier loci in future speciation work.
  • Nichols, Johanna (2018)
    An attractor, in complex systems theory, is any state that is more easily or more often entered or acquired than departed or lost; attractor states therefore accumulate more members than non-attractors, other things being equal. In the context of language evolution, linguistic attractors include sounds, forms, and grammatical structures that are prone to be selected when sociolinguistics and language contact make it possible for speakers to choose between competing forms. The reasons why an element is an attractor are linguistic (auditory salience, ease of processing, paradigm structure, etc.), but the factors that make selection possible and propagate selected items through the speech community are non-linguistic. This paper uses the consonants in personal pronouns to show what makes for an attractor and how selection and diffusion work, then presents a survey of several language families and areas showing that the derivational morphology of pairs of verbs like fear and frighten, or Turkish korkmak 'fear, be afraid' and korkutmak 'frighten, scare', or Finnish istua 'sit' and istutta 'seat (someone)', or Spanish sentarse 'sit down' and sentar 'seat (someone)' is susceptible to selection. Specifically, the Turkish and Finnish pattern, where 'seat' is derived from 'sit by addition of a suffix – is an attractor and a favored target of selection. This selection occurs chiefly in sociolinguistic contexts of what is defined here as linguistic symbiosis, where languages mingle in speech, which in turn is favored by certain demographic, sociocultural, and environmental factors here termed frontier conditions. Evidence is surveyed from northern Eurasia, the Caucasus, North and Central America, and the Pacific and from both modern and ancient languages to raise the hypothesis that frontier conditions and symbiosis favor causativization.
  • Teacher, Amber G. F.; Andre, Carl; Jonsson, Per R.; Merila, Juha (2013)
  • Kosunen, Sonja; Bernelius, Venla; Seppänen, Piia; Porkka, Miina (2020)
    We explore the interconnections of pupil admission and school choice with the socioeconomic composition of schools in the city of Espoo, Finland. We analyze pupil enrollment from residential areas, and compare the schools' expected and actual socioeconomic profiles using GIS software (MapInfo). Social-diversification mechanisms within urban comprehensive schooling emerged: Distinctive choices of language and selective classes are made predominantly by pupils from residential blocks with higher socioeconomic profiles. The role of urban segregation in school choice seems to be stronger than predicted. As mechanisms of educational distinction accompanied with grouping policies, choice leads to socioeconomic segregation across and within schools.
  • Morozov, Sergey; Leinonen, Tuomas; Merilä, Juha; McCairns, R. J. Scott (2018)
    Conspecifics inhabiting divergent environments frequently differ in morphology, physiology, and performance, but the interrelationships amongst traits and with Darwinian fitness remains poorly understood. We investigated population differentiation in morphology, metabolic rate, and swimming performance in three-spined sticklebacks (Gasterosteus aculeatus L.), contrasting a marine/ancestral population with two distinct freshwater morphotypes derived from it: the typical low-plated morph, and a unique small-plated morph. We test the hypothesis that similar to plate loss in other freshwater populations, reduction in lateral plate size also evolved in response to selection. Additionally, we test how morphology, physiology, and performance have evolved in concert as a response to differences in selection between marine and freshwater environments. We raised pure-bred second-generation fish originating from three populations and quantified their lateral plate coverage, burst- and critical swimming speeds, as well as standard and active metabolic rates. Using a multivariate Q(ST)-F-ST framework, we detected signals of directional selection on metabolic physiology and lateral plate coverage, notably demonstrating that selection is responsible for the reduction in lateral plate coverage in a small-plated stickleback population. We also uncovered signals of multivariate selection amongst all bivariate trait combinations except the two metrics of swimming performance. Divergence between the freshwater and marine populations exceeded neutral expectation in morphology and in most physiological and performance traits, indicating that adaptation to freshwater habitats has occurred, but through different combinations of traits in different populations. These results highlight both the complex interplay between morphology, physiology and performance in local adaptation, and a framework for their investigation.
  • Konijnendijk, Nellie; Shikano, Takahito; Daneels, Dorien; Volckaert, Filip A. M.; Raeymaekers, Joost A. M. (2015)
    Local adaptation is often obvious when gene flow is impeded, such as observed at large spatial scales and across strong ecological contrasts. However, it becomes less certain at small scales such as between adjacent populations or across weak ecological contrasts, when gene flow is strong. While studies on genomic adaptation tend to focus on the former, less is known about the genomic targets of natural selection in the latter situation. In this study, we investigate genomic adaptation in populations of the three-spined stickleback Gasterosteus aculeatus L. across a small-scale ecological transition with salinities ranging from brackish to fresh. Adaptation to salinity has been repeatedly demonstrated in this species. A genome scan based on 87 microsatellite markers revealed only few signatures of selection, likely owing to the constraints that homogenizing gene flow puts on adaptive divergence. However, the detected loci appear repeatedly as targets of selection in similar studies of genomic adaptation in the three-spined stickleback. We conclude that the signature of genomic selection in the face of strong gene flow is weak, yet detectable. We argue that the range of studies of genomic divergence should be extended to include more systems characterized by limited geographical and ecological isolation, which is often a realistic setting in nature.