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fitness landscape

Ana-Hermina Ghenu, Alexandre Blanckaert, Roger K Butlin, Jonna Kulmuni, Claudia Bank
In many diploid species the sex chromosomes play a special role in mediating reproductive isolation. In haplodiploids, where females are diploid and males haploid, the whole genome behaves similarly to the X/Z chromosomes of diploids. Therefore, haplodiploid systems can serve as a model for the role of sex chromosomes in speciation and hybridization. A previously described population of Finnish Formica wood ants displays genome-wide signs of ploidally and sexually antagonistic selection resulting from hybridization...
January 12, 2018: Molecular Ecology
Pavel Khromov, Constantin D Malliaris, Alexandre V Morozov
In considering evolution of transcribed regions, regulatory sequences, and other genomic loci, we are often faced with a situation in which the number of allelic states greatly exceeds the size of the population. In this limit, the population eventually adopts a steady state characterized by mutation-selection-drift balance. Although new alleles continue to be explored through mutation, the statistics of the population, and in particular the probabilities of seeing specific allelic configurations in samples taken from the population, do not change with time...
2018: PloS One
D R Schoolmaster, C L Stagg
A trade-off between competitive ability and stress tolerance has been hypothesized and empirically supported to explain the zonation of species across stress gradients for a number of systems. Since stress often reduces plant productivity, one might expect a pattern of decreasing productivity across the zones of the stress gradient. However, this pattern is often not observed in coastal wetlands that show patterns of zonation along a salinity gradient. To address the potentially complex relationship between stress, zonation and productivity in coastal wetlands, we developed a model of plant biomass as a function of resource competition and salinity stress...
January 8, 2018: Ecology
Raymond H Y Louie, Kevin J Kaczorowski, John P Barton, Arup K Chakraborty, Matthew R McKay
HIV is a highly mutable virus, and over 30 years after its discovery, a vaccine or cure is still not available. The isolation of broadly neutralizing antibodies (bnAbs) from HIV-infected patients has led to renewed hope for a prophylactic vaccine capable of combating the scourge of HIV. A major challenge is the design of immunogens and vaccination protocols that can elicit bnAbs that target regions of the virus's spike proteins where the likelihood of mutational escape is low due to the high fitness cost of mutations...
January 8, 2018: Proceedings of the National Academy of Sciences of the United States of America
Nathan J Kleist, Robert P Guralnick, Alexander Cruz, Christopher A Lowry, Clinton D Francis
Anthropogenic noise is a pervasive pollutant that decreases environmental quality by disrupting a suite of behaviors vital to perception and communication. However, even within populations of noise-sensitive species, individuals still select breeding sites located within areas exposed to high noise levels, with largely unknown physiological and fitness consequences. We use a study system in the natural gas fields of northern New Mexico to test the prediction that exposure to noise causes glucocorticoid-signaling dysfunction and decreases fitness in a community of secondary cavity-nesting birds...
January 8, 2018: Proceedings of the National Academy of Sciences of the United States of America
Jinping Liu, Hien Dang, Xin Wei Wang
Genomic analyses of primary liver cancer samples reveal a complex mutational landscape with vast intertumor and intratumor heterogeneity. Different primary liver tumors and subclones within each tumor display striking molecular and biological variations. Consequently, tumor molecular heterogeneity contributes to drug resistance and tumor relapse following therapy, which poses a substantial obstruction to improving outcomes of patients with liver cancer. There is an urgent need to the compositional and functional understanding of tumor heterogeneity...
January 5, 2018: Experimental & Molecular Medicine
Monique Nouailhetas Simon, Gabriel Marroig
The theory of morphological integration and modularity predicts that if functional correlations among traits are relevant to mean population fitness, the genetic basis of development will be molded by stabilizing selection to match functional patterns. Yet, how much functional interactions actually shape the fitness landscape is still an open question. We used the anuran skull as a model of a complex phenotype for which we can separate developmental and functional modularity. We hypothesized that functional modularity associated to functional demands of the adult skull would overcome developmental modularity associated to bone origin at the larval phase because metamorphosis would erase the developmental signal...
December 2017: Ecology and Evolution
Philip A Fay, Michael J Aspinwall, Harold P Collins, Anne E Gibson, Richard H Gill, Robert B Jackson, Virginia L Jin, Albina R Khasanova, Lara G Reichmann, H Wayne Polley
Continuing enrichment of atmospheric CO2 may change plant community composition, in part by altering the availability of other limiting resources including soil water, nutrients, or light. The combined effects of CO2 enrichment and altered resource availability on species flowering remain poorly understood. We quantified flowering culm and ramet production and biomass allocation to flowering culms/ramets for ten years in C4 dominated grassland communities on contrasting soils along a CO2 concentration gradient spanning pre-industrial to expected mid-21st century levels (250 - 500 μL L-1 )...
December 28, 2017: Global Change Biology
Kath Maguire, Nicky Britten
Patient and public involvement in health research and care has been repeatedly theorised using the metaphor of spaces, knowledge spaces and participatory citizenship spaces. Drawing on data from a three year qualitative study of people involved in health research with organisations across England, this article explores where these spaces fit in a wider social, political and historical landscape. It outlines a theme recurring frequently in the study data: a unified public/patient/service-user perspective in opposition to a professional/clinical/academic view...
December 27, 2017: Sociology of Health & Illness
Kristina Crona, Alex Gavryushkin, Devin Greene, Niko Beerenwinkel
Darwinian fitness is a central concept in evolutionary biology. In practice, however, it is hardly possible to measure fitness for all genotypes in a natural population. Here, we present quantitative tools to make inferences about epistatic gene interactions when the fitness landscape is only incompletely determined due to imprecise measurements or missing observations. We demonstrate that genetic interactions can often be inferred from fitness rank orders, where all genotypes are ordered according to fitness, and even from partial fitness orders...
December 20, 2017: ELife
Aidin Rashidi, Christopher L Wirth
This article describes the simulated Brownian motion of a sphere comprising hemispheres of unequal zeta potential (i.e., "Janus" particle) very near a wall. The simulation tool was developed and used to assist in the methodology development for applying Total Internal Reflection Microscopy (TIRM) to anisotropic particles. Simulations of the trajectory of a Janus sphere with cap density matching that of the base particle very near a boundary were used to construct 3D potential energy landscapes that were subsequently used to infer particle and solution properties, as would be done in a TIRM measurement...
December 14, 2017: Journal of Chemical Physics
Diane C Wiernasz, Blaine J Cole
A fundamental decision that an organism must make is how to allocate resources to offspring, with respect to both size and number. The two major theoretical approaches to this problem, optimal offspring size and optimistic brood size models, make different predictions that may be reconciled by including how offspring fitness is related to size. We extended the reasoning of Trivers and Willard (1973) to derive a general model of how parents should allocate additional resources with respect to the number of males and females produced, and among individuals of each sex, based on the fitness payoffs of each...
January 2018: American Naturalist
Ivain Martinossi-Allibert, Uroš Savković, Mirko Đorđević, Göran Arnqvist, Biljana Stojković, David Berger
Whether sexual selection generally promotes or impedes population persistence remains an open question. Intralocus sexual conflict (IaSC) can render sexual selection in males detrimental to the population by increasing the frequency of alleles with positive effects on male reproductive success but negative effects on female fecundity. Recent modelling based on fitness landscape theory, however, indicates that the relative impact of IaSC may be reduced in maladapted populations and that sexual selection therefore might promote adaptation when it is most needed...
December 14, 2017: Evolution; International Journal of Organic Evolution
George L Peabody V, Hao Li, Katy C Kao
Sexual recombination and mutation rate are theorized to play different roles in adaptive evolution depending on the fitness landscape; however, direct experimental support is limited. Here we examine how these factors affect the rate of adaptation utilizing a "genderless" strain of Escherichia coli capable of continuous in situ sexual recombination. The results show that the populations with increased mutation rate, and capable of sexual recombination, outperform all the other populations. We further characterize two sexual and two asexual populations with increased mutation rate and observe maintenance of beneficial mutations in the sexual populations through mutational sweeps...
December 13, 2017: Nature Communications
María Laura Miserendino, Cecilia Brand, Luis B Epele, Cecilia Y Di Prinzio, Guillermo H Omad, Miguel Archangelsky, Oscar Martínez, Adriana M Kutschker
Patagonia is by far the largest glacierized area in South America. However, little is known about ecology, functioning and biodiversity of glacier-fed streams facing global warming. We investigated changes in environmental features and macroinvertebrate communities along a longitudinal gradient of glacier influence of two Patagonian systems that differ in glacier cover magnitude and the spatial sequence of lotic and lentic phases. Both glaciers, Torrecillas (~5.5km2, Torrecillas system) and Cónico (~0.44km2, Baggilt system), are retreating...
December 3, 2017: Science of the Total Environment
Wei-Jen Chung, Anneleen Daemen, Jason H Cheng, Jason E Long, Jonathan E Cooper, Bu-Er Wang, Christopher Tran, Mallika Singh, Florian Gnad, Zora Modrusan, Oded Foreman, Melissa R Junttila
KRAS mutant tumors are largely recalcitrant to targeted therapies. Genetically engineered mouse models (GEMMs) of Kras mutant cancer recapitulate critical aspects of this disease and are widely used for preclinical validation of targets and therapies. Through comprehensive profiling of exomes and matched transcriptomes of >200 KrasG12D-initiated GEMM tumors from one lung and two pancreatic cancer models, we discover that significant intratumoral and intertumoral genomic heterogeneity evolves during tumorigenesis...
December 4, 2017: Proceedings of the National Academy of Sciences of the United States of America
Craig R Miller, James T Van Leuven, Holly A Wichman, Paul Joyce
Fitness landscapes map genotypes to organismal fitness. Their topographies depend on how mutational effects interact-epistasis-and are important for understanding evolutionary processes such as speciation, the rate of adaptation, the advantage of recombination, and the predictability versus stochasticity of evolution. The growing amount of data has made it possible to better test landscape models empirically. We argue that this endeavor will benefit from the development and use of meaningful basic models against which to compare more complex models...
November 30, 2017: Theoretical Population Biology
M Szűcs, M L Vahsen, B A Melbourne, C Hoover, C Weiss-Lehman, R A Hufbauer
Colonization and expansion into novel landscapes determine the distribution and abundance of species in our rapidly changing ecosystems worldwide. Colonization events are crucibles for rapid evolution, but it is not known whether evolutionary changes arise mainly after successful colonization has occurred, or if evolution plays an immediate role, governing the growth and expansion speed of colonizing populations. There is evidence that spatial evolutionary processes can speed range expansion within a few generations because dispersal tendencies may evolve upwards at range edges...
November 28, 2017: Proceedings of the National Academy of Sciences of the United States of America
Jonathan Salerno, Noam Ross, Ria Ghai, Michael Mahero, Dominic A Travis, Thomas R Gillespie, Joel Hartter
Fevers of unknown origin complicate treatment and prevention of infectious diseases and are a global health burden. We examined risk factors of self-reported fever-categorized as "malarial" and "nonmalarial"-in households adjacent to national parks across the Ugandan Albertine Rift, a biodiversity and emerging infectious disease hotspot. Statistical models fitted to these data suggest that perceived nonmalarial fevers of unknown origin were associated with more frequent direct contact with wildlife and with increased distance from parks where wildlife habitat is limited to small forest fragments...
December 2017: EcoHealth
John Maciejowski, Marcin Imielinski
Cancer genome sequences contain footprints of somatic mutational processes, whose analysis in large tumor sequencing datasets has revealed novel mutational signatures, correlative features of variant topography, and complex events. Many of these analytic results have yet to reconciled with decades of mechanistic genome integrity research performed in controlled model systems. However, a new generation of genome-integrity experiments combining computational modeling, data analytics, and high-throughput sequencing are emerging to link mechanisms to patterns...
February 2017: Current Opinion in Systems Biology
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