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  • 1
    Publication Date: 2013-06-19
    Description: Inferring a realistic demographic model from genetic data is an important challenge to gain insights into the historical events during the speciation process and to detect molecular signatures of selection along genomes. Recent advances in divergence population genetics have reported that speciation in face of gene flow occurred more frequently than theoretically expected, but the approaches used did not account for genome-wide heterogeneity (GWH) in introgression rates. Here, we investigate the impact of GWH on the inference of divergence with gene flow between two cryptic species of the marine model Ciona intestinalis by analyzing polymorphism and divergence patterns in 852 protein-coding sequence loci. These morphologically similar entities are highly diverged molecular-wise, but evidence of hybridization has been reported in both laboratory and field studies. We compare various speciation models and test for GWH under the approximate Bayesian computation framework. Our results demonstrate the presence of significant extents of gene flow resulting from a recent secondary contact after 〉3 My of divergence in isolation. The inferred rates of introgression are relatively low, highly variable across loci and mostly unidirectional, which is consistent with the idea that numerous genetic incompatibilities have accumulated over time throughout the genomes of these highly diverged species. A genomic map of the level of gene flow identified two hotspots of introgression, that is, large genome regions of unidirectional introgression. This study clarifies the history and degree of isolation of two cryptic and partially sympatric model species and provides a methodological framework to investigate GWH at various stages of speciation process.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
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  • 2
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1999-01-08
    Description: The G+C nucleotide content of ribosomal RNA (rRNA) sequences is strongly correlated with the optimal growth temperature of prokaryotes. This property allows inference of the environmental temperature of the common ancestor to all life forms from knowledge of the G+C content of its rRNA sequences. A model of sequence evolution, assuming varying G+C content among lineages and unequal substitution rates among sites, was devised to estimate ancestral base compositions. This method was applied to rRNA sequences of various species representing the major lineages of life. The inferred G+C content of the common ancestor to extant life forms appears incompatible with survival at high temperature. This finding challenges a widely accepted hypothesis about the origin of life.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Galtier, N -- Tourasse, N -- Gouy, M -- New York, N.Y. -- Science. 1999 Jan 8;283(5399):220-1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratoire de Biometrie, Genetique et Biologie des Populations, Universite C. Bernard Lyon 1, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9880254" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Composition ; Base Sequence ; Computer Simulation ; Confidence Intervals ; Cytosine/*analysis ; *Evolution, Molecular ; Guanine/*analysis ; Hot Temperature ; Likelihood Functions ; Markov Chains ; Models, Chemical ; *Origin of Life ; Phylogeny ; RNA, Archaeal/chemistry ; RNA, Bacterial/chemistry ; RNA, Ribosomal/*chemistry ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2009-02-07
    Description: Prabhakar et al. (Reports, 5 September 2008, p. 1346) argued that the conserved noncoding sequence HACNS1 has undergone positive selection and contributed to human adaptation. However, the pattern of substitution in HACNS1 is more consistent with the neutral process of biased gene conversion (BGC). The reported human-specific gain of function is likely due to the accumulation of deleterious mutations driven by BGC, not positive selection.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Duret, Laurent -- Galtier, Nicolas -- New York, N.Y. -- Science. 2009 Feb 6;323(5915):714; author reply 714. doi: 10.1126/science.1165848.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Universite de Lyon, Universite Lyon 1, CNRS, UMR5558, Laboratoire de Biometrie et Biologie Evolutive, F-69622, Villeurbanne, France. duret@biomserv.univ-lyon1.fr〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19197042" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Conserved Sequence ; *Enhancer Elements, Genetic ; Evolution, Molecular ; *Gene Conversion ; Humans ; Mutation ; Recombination, Genetic ; Selection, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2014-08-21
    Description: Genetic diversity is the amount of variation observed between DNA sequences from distinct individuals of a given species. This pivotal concept of population genetics has implications for species health, domestication, management and conservation. Levels of genetic diversity seem to vary greatly in natural populations and species, but the determinants of this variation, and particularly the relative influences of species biology and ecology versus population history, are still largely mysterious. Here we show that the diversity of a species is predictable, and is determined in the first place by its ecological strategy. We investigated the genome-wide diversity of 76 non-model animal species by sequencing the transcriptome of two to ten individuals in each species. The distribution of genetic diversity between species revealed no detectable influence of geographic range or invasive status but was accurately predicted by key species traits related to parental investment: long-lived or low-fecundity species with brooding ability were genetically less diverse than short-lived or highly fecund ones. Our analysis demonstrates the influence of long-term life-history strategies on species response to short-term environmental perturbations, a result with immediate implications for conservation policies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Romiguier, J -- Gayral, P -- Ballenghien, M -- Bernard, A -- Cahais, V -- Chenuil, A -- Chiari, Y -- Dernat, R -- Duret, L -- Faivre, N -- Loire, E -- Lourenco, J M -- Nabholz, B -- Roux, C -- Tsagkogeorga, G -- Weber, A A-T -- Weinert, L A -- Belkhir, K -- Bierne, N -- Glemin, S -- Galtier, N -- England -- Nature. 2014 Nov 13;515(7526):261-3. doi: 10.1038/nature13685. Epub 2014 Aug 20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] UMR 5554, Institute of Evolutionary Sciences, University Montpellier 2, Centre national de la recherche scientifique, Place E. Bataillon, 34095 Montpellier, France [2] Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland. ; 1] UMR 5554, Institute of Evolutionary Sciences, University Montpellier 2, Centre national de la recherche scientifique, Place E. Bataillon, 34095 Montpellier, France [2] UMR 7261, Institut de Recherches sur la Biologie de l'Insecte, Centre national de la recherche scientifique, Universite Francois-Rabelais, 37200 Tours, France. ; UMR 5554, Institute of Evolutionary Sciences, University Montpellier 2, Centre national de la recherche scientifique, Place E. Bataillon, 34095 Montpellier, France. ; Aix-Marseille Universite, Institut Mediterraneen de Biodiversite et d'Ecologie marine et continentale (IMBE) - CNRS - IRD - UAPV, 13007 Marseille, France. ; Department of Biology, University of South Alabama, Mobile, Alabama 36688-0002, USA. ; UMR 5558, Laboratoire de Biometrie et Biologie Evolutive, Universite Lyon 1, CNRS, 69622 Lyon, France. ; 1] UMR 5554, Institute of Evolutionary Sciences, University Montpellier 2, Centre national de la recherche scientifique, Place E. Bataillon, 34095 Montpellier, France [2] The School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK. ; 1] UMR 5554, Institute of Evolutionary Sciences, University Montpellier 2, Centre national de la recherche scientifique, Place E. Bataillon, 34095 Montpellier, France [2] Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25141177" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Ecology ; *Evolution, Molecular ; Genetic Variation/*genetics ; *Genetics, Population ; Genome/*genetics ; *Genomics ; *Phylogeny
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2006-04-29
    Description: Within-species genetic diversity is thought to reflect population size, history, ecology, and ability to adapt. Using a comprehensive collection of polymorphism data sets covering approximately 3000 animal species, we show that the widely used mitochondrial DNA (mtDNA) marker does not reflect species abundance or ecology: mtDNA diversity is not higher in invertebrates than in vertebrates, in marine than in terrestrial species, or in small than in large organisms. Nuclear loci, in contrast, fit these intuitive expectations. The unexpected mitochondrial diversity distribution is explained by recurrent adaptive evolution, challenging the neutral theory of molecular evolution and questioning the relevance of mtDNA in biodiversity and conservation studies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bazin, Eric -- Glemin, Sylvain -- Galtier, Nicolas -- New York, N.Y. -- Science. 2006 Apr 28;312(5773):570-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉CNRS UMR 5171-Genome, Populations, Interactions, Adaptation-Universite Montpellier 2 34095 Montpellier Cedex 5, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/16645093" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptation, Biological ; Animals ; *Biological Evolution ; Body Size ; DNA/genetics ; DNA, Mitochondrial/*genetics ; Ecosystem ; Evolution, Molecular ; *Genes, Mitochondrial ; Genetic Markers ; *Genetic Variation ; Genetics, Population ; Invertebrates/*genetics ; Isoenzymes/genetics ; Mutation ; *Polymorphism, Genetic ; Population Density ; Recombination, Genetic ; Selection, Genetic ; Vertebrates/*genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 979 (1989), S. 46-52 
    ISSN: 0005-2736
    Keywords: (Corn root plasmalemma) ; ATPase, Mg^2^+- ; Electrostatic interaction ; Ionic effect ; Vanadate inhibition
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 1995-11-21
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 8
    Publication Date: 2015-08-20
    Description: Because mating systems affect population genetics and ecology, they are expected to impact the molecular evolution of species. Self-fertilizing species experience reduced effective population size, recombination rates, and heterozygosity, which in turn should decrease the efficacy of natural selection, both adaptive and purifying, and the strength of meiotic drive processes such as GC-biased gene conversion. The empirical evidence is only partly congruent with these predictions, depending on the analyzed species, some, but not all, of the expected effects have been observed. One possible reason is that self-fertilization is an evolutionary dead-end, so that most current selfers recently evolved self-fertilization, and their genome has not yet been strongly impacted by selfing. Here, we investigate the molecular evolution of two groups of freshwater snails in which mating systems have likely been stable for several millions of years. Analyzing coding sequence polymorphism, divergence, and expression levels, we report a strongly reduced genetic diversity, decreased efficacy of purifying selection, slower rate of adaptive evolution, and weakened codon usage bias/GC-biased gene conversion in the selfer Galba compared with the outcrosser Physa , in full agreement with theoretical expectations. Our results demonstrate that self-fertilization, when effective in the long run, is a major driver of population genomic and molecular evolutionary processes. Despite the genomic effects of selfing, Galba truncatula seems to escape the demographic consequences of the genetic load. We suggest that the particular ecology of the species may buffer the negative consequences of selfing, shedding new light on the dead-end hypothesis.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
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  • 9
    Publication Date: 2015-01-24
    Description: Mammalian and avian genomes are characterized by a substantial spatial heterogeneity of GC-content, which is often interpreted as reflecting the effect of local GC-biased gene conversion (gBGC), a meiotic repair bias that favors G and C over A and T alleles in high-recombining genomic regions. Surprisingly, the first fully sequenced nonavian sauropsid (i.e., reptile), the green anole Anolis carolinensis , revealed a highly homogeneous genomic GC-content landscape, suggesting the possibility that gBGC might not be at work in this lineage. Here, we analyze GC-content evolution at third-codon positions (GC3) in 44 vertebrates species, including eight newly sequenced transcriptomes, with a specific focus on nonavian sauropsids. We report that reptiles, including the green anole, have a genome-wide distribution of GC3 similar to that of mammals and birds, and we infer a strong GC3-heterogeneity to be already present in the tetrapod ancestor. We further show that the dynamic of coding sequence GC-content is largely governed by karyotypic features in vertebrates, notably in the green anole, in agreement with the gBGC hypothesis. The discrepancy between third-codon positions and noncoding DNA regarding GC-content dynamics in the green anole could not be explained by the activity of transposable elements or selection on codon usage. This analysis highlights the unique value of third-codon positions as an insertion/deletion-free marker of nucleotide substitution biases that ultimately affect the evolution of proteins.
    Electronic ISSN: 1759-6653
    Topics: Biology
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  • 10
    Publication Date: 2012-08-31
    Description: Phylogenomics has revealed the existence of fast-evolving animal phyla in which the amino acid substitution rate, averaged across many proteins, is consistently higher than in other lineages. The reasons for such differences in proteome-wide evolutionary rates are still unknown, largely because only a handful of species offer within-species genomic data from which molecular evolutionary processes can be deduced. In this study, we use next-generation sequencing technologies and individual whole-transcriptome sequencing to gather extensive polymorphism sequence data sets from Ciona intestinalis . Ciona is probably the best-characterized member of the fast-evolving Urochordata group (tunicates), which was recently identified as the sister group of the slow-evolving vertebrates. We introduce and validate a maximum-likelihood framework for single-nucleotide polymorphism and genotype calling, based on high-throughput short-read typing. We report that the C. intestinalis proteome is characterized by a high level of within-species diversity, efficient purifying selection, and a substantial percentage of adaptive amino acid substitutions. We conclude that the increased rate of amino acid sequence evolution in tunicates, when compared with vertebrates, is the consequence of both a 2–6 times higher per-year mutation rate and prevalent adaptive evolution.
    Electronic ISSN: 1759-6653
    Topics: Biology
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