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  • 1
    Publication Date: 2013-08-24
    Description: Sexual selection, through intra-male competition or female choice, is assumed to be a source of strong and sustained directional selection in the wild. In the presence of such strong directional selection, alleles enhancing a particular trait are predicted to become fixed within a population, leading to a decrease in the underlying genetic variation. However, there is often considerable genetic variation underlying sexually selected traits in wild populations, and consequently, this phenomenon has become a long-discussed issue in the field of evolutionary biology. In wild Soay sheep, large horns confer an advantage in strong intra-sexual competition, yet males show an inherited polymorphism for horn type and have substantial genetic variation in their horn size. Here we show that most genetic variation in this trait is maintained by a trade-off between natural and sexual selection at a single gene, relaxin-like receptor 2 (RXFP2). We found that an allele conferring larger horns, Ho(+), is associated with higher reproductive success, whereas a smaller horn allele, Ho(P), confers increased survival, resulting in a net effect of overdominance (that is, heterozygote advantage) for fitness at RXFP2. The nature of this trade-off is simple relative to commonly proposed explanations for the maintenance of sexually selected traits, such as genic capture ('good genes') and sexually antagonistic selection. Our results demonstrate that by identifying the genetic architecture of trait variation, we can determine the principal mechanisms maintaining genetic variation in traits under strong selection and explain apparently counter-evolutionary observations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Johnston, Susan E -- Gratten, Jacob -- Berenos, Camillo -- Pilkington, Jill G -- Clutton-Brock, Tim H -- Pemberton, Josephine M -- Slate, Jon -- Biotechnology and Biological Sciences Research Council/United Kingdom -- England -- Nature. 2013 Oct 3;502(7469):93-5. doi: 10.1038/nature12489. Epub 2013 Aug 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK. Susan.Johnston@ed.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23965625" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Female ; *Genetic Variation ; Genotype ; *Horns ; Male ; Mating Preference, Animal/*physiology ; Phenotype ; Polymorphism, Genetic ; Receptors, G-Protein-Coupled/genetics ; Reproduction/genetics ; Selection, Genetic ; Survival Analysis
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2015-11-05
    Description: Males and females share many traits that have a common genetic basis; however, selection on these traits often differs between the sexes, leading to sexual conflict. Under such sexual antagonism, theory predicts the evolution of genetic architectures that resolve this sexual conflict. Yet, despite intense theoretical and empirical interest, the specific loci underlying sexually antagonistic phenotypes have rarely been identified, limiting our understanding of how sexual conflict impacts genome evolution and the maintenance of genetic diversity. Here we identify a large effect locus controlling age at maturity in Atlantic salmon (Salmo salar), an important fitness trait in which selection favours earlier maturation in males than females, and show it is a clear example of sex-dependent dominance that reduces intralocus sexual conflict and maintains adaptive variation in wild populations. Using high-density single nucleotide polymorphism data across 57 wild populations and whole genome re-sequencing, we find that the vestigial-like family member 3 gene (VGLL3) exhibits sex-dependent dominance in salmon, promoting earlier and later maturation in males and females, respectively. VGLL3, an adiposity regulator associated with size and age at maturity in humans, explained 39% of phenotypic variation, an unexpectedly large proportion for what is usually considered a highly polygenic trait. Such large effects are predicted under balancing selection from either sexually antagonistic or spatially varying selection. Our results provide the first empirical example of dominance reversal allowing greater optimization of phenotypes within each sex, contributing to the resolution of sexual conflict in a major and widespread evolutionary trade-off between age and size at maturity. They also provide key empirical evidence for how variation in reproductive strategies can be maintained over large geographical scales. We anticipate these findings will have a substantial impact on population management in a range of harvested species where trends towards earlier maturation have been observed.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barson, Nicola J -- Aykanat, Tutku -- Hindar, Kjetil -- Baranski, Matthew -- Bolstad, Geir H -- Fiske, Peder -- Jacq, Celeste -- Jensen, Arne J -- Johnston, Susan E -- Karlsson, Sten -- Kent, Matthew -- Moen, Thomas -- Niemela, Eero -- Nome, Torfinn -- Naesje, Tor F -- Orell, Panu -- Romakkaniemi, Atso -- Saegrov, Harald -- Urdal, Kurt -- Erkinaro, Jaakko -- Lien, Sigbjorn -- Primmer, Craig R -- England -- Nature. 2015 Dec 17;528(7582):405-8. doi: 10.1038/nature16062. Epub 2015 Nov 4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, NO-1432 As, Norway. ; Department of Biology, University of Turku, FI-20014, Finland. ; Norwegian Institute for Nature Research (NINA), NO-7485 Trondheim, Norway. ; Nofima - Norwegian Institute of Food, Fisheries and Aquaculture Research, NO-1431 As, Norway. ; Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3FL, UK. ; AquaGen, NO-7462 Trondheim, Norway. ; Natural Resources Institute Finland, Oulu, FI-90014, Finland. ; Radgivende Biologer, NO-5003 Bergen, Norway.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26536110" target="_blank"〉PubMed〈/a〉
    Keywords: Aging/*genetics ; Animals ; Biological Evolution ; Body Size/*genetics ; Female ; Fish Proteins/*genetics/metabolism ; Genetic Variation/*genetics ; Genome-Wide Association Study ; Growth/*genetics ; Humans ; Male ; Models, Biological ; Phenotype ; Reproduction/genetics/physiology ; Salmo salar/*genetics ; *Sex Characteristics ; Transcription Factors/genetics/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2015-09-24
    Description: Several theories exist to explain the source of the bright, millisecond duration pulses known as fast radio bursts (FRBs). If the progenitors of FRBs are non-cataclysmic, such as giant pulses from pulsars, pulsar–planet binaries, or magnetar flares, FRB emission may be seen to repeat. We have undertaken a survey of the fields of eight known FRBs from the High Time Resolution Universe survey to search for repeating pulses. Although no repeat pulses were detected the survey yielded the detection of a new FRB, described in Petroff et al. ( 2015a ). From our observations we rule out periodic repeating sources with periods P  ≤ 8.6 h and rule out sources with periods 8.6 〈  P  〈 21 h at the 90 per cent confidence level. At P  ≥ 21 h our limits fall off as ~1/ P . Dedicated and persistent observations of FRB source fields are needed to rule out repetition on longer time-scales, a task well-suited to next generation wide-field transient detectors.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 4
    Publication Date: 2011-02-01
    Description: The rocks at Chimney Mountain provide a rare glimpse into primary intrusive relations and exceptionally well-preserved pre-Shawinigan metasedimentary rocks in the Adirondack Highlands despite a strong Ottawan thermal overprint. A near vertical contact between granite (ca. 1172 Ma) and a shallowly dipping and structurally intact sequence of quartzose to calc-silicate metasedimentary rocks is exposed on the southern flank of Chimney Mountain in the Central Adirondacks. The contact is marked by foliation truncation and a metasomatic aureole with randomly orientated porphyroblasts of enstatite rimmed by anthophyllite (max. 5 cm) and phlogopite (max. 2 cm), and a zone of granular, quartz-rich rock. The granite is non- to weakly foliated and has a shallow, north-plunging, mineral lineation as do the metasedimentary rocks. Zircons separated from a diopside-bearing quartzite (82% SiO2; 0.75 m thick) are of variable size (up to 400 {micro}m), equant, and contain, on average, 〉1000 ppm uranium. Scanning electron microscope investigation indicates that there is little variation in a uniformly dark cathodoluminescence response, no discernible cores or rims, few inclusions, and partially faceted to round morphologies. Zircon U-Pb sensitive high-resolution ion microprobe (SHRIMP II) ages of 1042 {+/-} 4 Ma and 1073 {+/-} 15 Ma are coincident with Ottawan metamorphic ages from the Adirondack Highlands. Zircons from the intrusive granite yield large cores with typical anorthosite-mangerite-charnockite-granite (AMCG) ages (ca. 1171.6 {+/-} 6.3 Ma) and sparse, thin younger rims (ca. 1060-1090 Ma) readily distinguishable by cathodoluminescence. Despite the younger zircon ages, the metasedimentary rocks and their fabric must predate the crosscutting granite. The thermal effect of the Ottawan event was likely enhanced by volatile fluxing and resulted in recrystallization and resetting of zircons in the metasedimentary rocks. However, it had limited effects on zircons in the granite and produced only thin metamorphic rims emphasizing the importance of local geochemical conditions to the response of zircon to metamorphism. Elzevirian or Shawinigan fabrics are preserved as the dominant foliation; the lineation and folding is likely late (post-1170 Ma) Shawinigan or Ottawan (ca. 1050 Ma). Titanites from the same metasedimentary sequence yield a range of 238U/206Pb ages from 969 to 1077 Ma, with a maximum probability age of 1035 Ma, similar to other titanites in the Adirondack Highlands. Ottawan paleotemperatures, estimated by zirconium in titanite thermometry, range from 787 to 818 {degrees}C.
    Electronic ISSN: 1553-040X
    Topics: Geosciences
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  • 5
    Publication Date: 2019
    Description: 〈p〉A long-held, but poorly tested, assumption in natural populations is that individuals that disperse into new areas for reproduction are at a disadvantage compared to individuals that reproduce in their natal habitat, underpinning the eco-evolutionary processes of local adaptation and ecological speciation. Here, we capitalize on fine-scale population structure and natural dispersal events to compare the reproductive success of local and dispersing individuals captured on the same spawning ground in four consecutive parent-offspring cohorts of wild Atlantic salmon (〈i〉Salmo salar〈/i〉). Parentage analysis conducted on adults and juvenile fish showed that local females and males had 9.6 and 2.9 times higher reproductive success than dispersers, respectively. Our results reveal how higher reproductive success in local spawners compared to dispersers may act in natural populations to drive population divergence and promote local adaptation over microgeographic spatial scales without clear morphological differences between populations.〈/p〉
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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  • 6
    Publication Date: 2018-07-03
    Description: Recombination is a fundamental feature of sexual reproduction, ensuring proper disjunction, preventing mutation accumulation and generating new allelic combinations upon which selection can act. However it is also mutagenic, and breaks up favorable allelic combinations previously built up by selection. Identifying the genetic drivers of recombination rate variation is a key step in understanding the causes and consequences of this variation, how loci associated with recombination are evolving and how they affect the potential of a population to respond to selection. However, to date, few studies have examined the genetic architecture of recombination rate variation in natural populations. Here, we use pedigree data from ~ 2,600 individuals genotyped at ~ 38,000 SNPs to investigate the genetic architecture of individual autosomal recombination rate in a wild population of red deer ( Cervus elaphus ). Female red deer exhibited a higher mean and phenotypic variance in autosomal crossover counts (ACC). Animal models fitting genomic relatedness matrices showed that ACC was heritable in females ( $${h}^{2}$$ = 0.12) but not in males. A regional heritability mapping approach showed that almost all heritable variation in female ACC was explained by a genomic region on deer linkage group 12 containing the candidate loci REC8 and RNF212B , with an additional region on linkage group 32 containing TOP2B approaching genome-wide significance. The REC8/RNF212B region and its paralogue RNF212 have been associated with recombination in cattle, mice, humans and sheep. Our findings suggest that mammalian recombination rates have a relatively conserved genetic architecture in both domesticated and wild systems, and provide a foundation for understanding the association between recombination loci and individual fitness within this population.
    Electronic ISSN: 2160-1836
    Topics: Biology
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  • 7
    Publication Date: 2017-09-15
    Description: Growing evidence suggests that microbes can influence the efficacy of cancer therapies. By studying colon cancer models, we found that bacteria can metabolize the chemotherapeutic drug gemcitabine (2',2'-difluorodeoxycytidine) into its inactive form, 2',2'-difluorodeoxyuridine. Metabolism was dependent on the expression of a long isoform of the bacterial enzyme cytidine deaminase (CDD L ), seen primarily in Gammaproteobacteria. In a colon cancer mouse model, gemcitabine resistance was induced by intratumor Gammaproteobacteria, dependent on bacterial CDD L expression, and abrogated by cotreatment with the antibiotic ciprofloxacin. Gemcitabine is commonly used to treat pancreatic ductal adenocarcinoma (PDAC), and we hypothesized that intratumor bacteria might contribute to drug resistance of these tumors. Consistent with this possibility, we found that of the 113 human PDACs that were tested, 86 (76%) were positive for bacteria, mainly Gammaproteobacteria.
    Keywords: Medicine, Diseases
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 2017-08-08
    Description: High-density linkage maps are an important tool to gain insight into the genetic architecture of traits of evolutionary and economic interest, and provide a resource to characterize variation in recombination landscapes. Here, we used information from the cattle genome and the 50 K Cervine Illumina BeadChip to inform and refine a high-density linkage map in a wild population of red deer ( Cervus elaphus ). We constructed a predicted linkage map of 38,038 SNPs and a skeleton map of 10,835 SNPs across 34 linkage groups. We identified several chromosomal rearrangements in the deer lineage relative to sheep and cattle, including six chromosome fissions, one fusion, and two large inversions. Otherwise, our findings showed strong concordance with map orders in the cattle genome. The sex-averaged linkage map length was 2739.7 cM and the genome-wide autosomal recombination rate was 1.04 cM/Mb. The female autosomal map length was 1.21 longer than that of males (2767.4 cM vs. 2280.8 cM, respectively). Sex differences in map length were driven by high female recombination rates in peri-centromeric regions, a pattern that is unusual relative to other mammal species. This effect was more pronounced in fission chromosomes that would have had to produce new centromeres. We propose two hypotheses to explain this effect: (1) that this mechanism may have evolved to counteract centromeric drive associated with meiotic asymmetry in oocyte production; and/or (2) that sequence and structural characteristics suppressing recombination in close proximity to the centromere may not have evolved at neo-centromeres. Our study provides insight into how recombination landscapes vary and evolve in mammals, and will provide a valuable resource for studies of evolution, genetic improvement, and population management in red deer and related species.
    Electronic ISSN: 2160-1836
    Topics: Biology
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  • 9
    Publication Date: 2008-11-05
    Print ISSN: 0018-067X
    Electronic ISSN: 1365-2540
    Topics: Biology
    Published by Springer Nature
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  • 10
    Publication Date: 2009-08-19
    Print ISSN: 0018-067X
    Electronic ISSN: 1365-2540
    Topics: Biology
    Published by Springer Nature
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