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1
Moore, William S., i Walter D. Koenig. "Comparative Reproductive Success of Yellow-Shafted, Red-Shafted, and Hybrid Flickers across a Hybrid Zone". Auk 103, nr 1 (1.01.1986): 42–51. http://dx.doi.org/10.1093/auk/103.1.42.
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Abstract Alternative hypotheses of hybrid zones make specific predictions about reproductive components of fitness in the hybrids. The dynamic-equilibrium and reinforcement hypotheses are premised on reduced hybrid fitness, which should be apparent as reduced clutch or brood size or as increased embryonic mortality. The hybrid-superiority and introgression hypotheses predict normal clutch and brood size and embryonic mortality. Reproductive success was measured at four study sites on a transect across the hybrid zone between the Yellow- (Colaptes auratus auratus) and Red-shafted (C. a. cafer) subspecies of the Northern Flicker. Two additional clutch size samples representing pure Yellow- and Red-shafted flickers were obtained from museum egg collections. Mean clutch size did not differ significantly among the six samples. Factorial ANOVAs showed that early clutches and broods are larger than late clutches and broods, but no significant difference was detected between hybrid and parental study sites. Analyses of the effect of phenotype (yellow-shafted, red-shafted, hybrid) also suggest that neither clutch size nor brood size is affected, with the exception that hybrid males sired significantly smaller broods. Finally, there were no significant effects of type of cross (red-shafted male × hybrid female, etc.) on the ratio brood-size/clutch-size. The only evidence for reduced hybrid fitness was in the test where males with hybrid phenotypes appear to have sired small broods. This may indicate that abnormal behavior of hybrid males affects female fecundity, but it is also plausible that this marginally significant result is a type I statistical error. The overall lack of evidence for reduced hybrid fitness is inconsistent with either the dynamic-equilibrium or reinforcement models. Of the two remaining alternatives, the bounded hybrid-superiority model appears the more likely explanation of the Northern Flicker hybrid zone because earlier work (Moore and Buchanan 1985) showed that the hybrid zone is not becoming broader, as predicted by the introgression model.
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Natcheva, Rayna, i Nils Cronberg. "What do we know about hybridization among bryophytes in nature?" Canadian Journal of Botany 82, nr 12 (1.12.2004): 1687–704. http://dx.doi.org/10.1139/b04-139.
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Despite being recognized as a widespread and evolutionary important phenomenon among vascular plants, interspecific hybridization among bryophytes has been strongly underestimated. In the present review, we summarize knowledge about bryophyte hybrids that are found in nature. Mechanisms of reproductive isolation in bryophytes are compared with those in vascular plants. The morphological and genetic features of sporophytic hybrids and their gametophytic progeny are discussed, as well as some inferences about hybrid fitness. The data available indicate that spontaneous hybridization among bryophytes is not uncommon and has an important, though still not completely understood, evolutionary significance. The existence of many allopolyploid taxa supports this conclusion. Finally we suggest some methods for further investigation of hybridization among bryophytes in nature.Key words: hybridization, bryophytes, isolating mechanisms, evolution, hybrid fitness, hybrid features.
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Power, Jeffrey J., Fernanda Pinheiro, Simone Pompei, Viera Kovacova, Melih Yüksel, Isabel Rathmann, Mona Förster, Michael Lässig i Berenike Maier. "Adaptive evolution of hybrid bacteria by horizontal gene transfer". Proceedings of the National Academy of Sciences 118, nr 10 (1.03.2021): e2007873118. http://dx.doi.org/10.1073/pnas.2007873118.
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Horizontal gene transfer (HGT) is an important factor in bacterial evolution that can act across species boundaries. Yet, we know little about rate and genomic targets of cross-lineage gene transfer and about its effects on the recipient organism's physiology and fitness. Here, we address these questions in a parallel evolution experiment with two Bacillus subtilis lineages of 7% sequence divergence. We observe rapid evolution of hybrid organisms: gene transfer swaps ∼12% of the core genome in just 200 generations, and 60% of core genes are replaced in at least one population. By genomics, transcriptomics, fitness assays, and statistical modeling, we show that transfer generates adaptive evolution and functional alterations in hybrids. Specifically, our experiments reveal a strong, repeatable fitness increase of evolved populations in the stationary growth phase. By genomic analysis of the transfer statistics across replicate populations, we infer that selection on HGT has a broad genetic basis: 40% of the observed transfers are adaptive. At the level of functional gene networks, we find signatures of negative, positive, and epistatic selection, consistent with hybrid incompatibilities and adaptive evolution of network functions. Our results suggest that gene transfer navigates a complex cross-lineage fitness landscape, bridging epistatic barriers along multiple high-fitness paths.
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Arnold, Michael L., i Noland H. Martin. "Hybrid fitness across time and habitats". Trends in Ecology & Evolution 25, nr 9 (wrzesień 2010): 530–36. http://dx.doi.org/10.1016/j.tree.2010.06.005.
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Wolinska, Justyna, Barbara Keller, Kerstin Bittner, Sandra Lass i Piet Spaak. "Do parasites lower Daphnia hybrid fitness?" Limnology and Oceanography 49, nr 4part2 (31.01.2004): 1401–7. http://dx.doi.org/10.4319/lo.2004.49.4_part_2.1401.
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Wool, David, i Orna Bergerson. "Random environmental variation and inbreeding: effects on pure-strain and hybrid populations of flour beetles (Tribolium)". Canadian Journal of Genetics and Cytology 28, nr 6 (1.12.1986): 889–98. http://dx.doi.org/10.1139/g86-124.
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The effect of inbreeding and of random environmental variation on fitness characters was studied in small populations derived from 10 inbred laboratory strains of Tribolium castaneum (I) and in 18 hybrids (IH) populations, obtained by crossing six mutant to three wild-type strains. Replicate population of each type were held in a constant (C) and a randomly varying (V) environment. Each replicate population was founded by a single pair of adults and one pair of sibs founded each subsequent generation. Thus four groups of inbreeding populations were created: IC, IV, IHC, and IHV. Outbred hybrid populations were held in the varying environment (OV). Several fitness characters were measured. The results confirmed that inbreeding populations exposed to random environmental variation had lower fitness than similar populations in the constant environment populations, as expected (IHC > IHV, IC > IV for each fitness trait). The environmental stress did not result in selection for individuals with higher fitness. In the hybrid populations, consistent and significant differences in fitness between populations having different wild-type (female) ancestors persisted for several generations. No such differences were found among populations grouped by their mutant ancestor. Within each environment, inbreeding had a pronounced effect on fitness. The order of magnitude of the fitness characters was IHC > IC, OV > IHV > IV, parallel to the level of inbreeding. Directional changes in relative (rank) magnitude of fitness characters among populations suggested that their genetic composition was changing temporally.Key words: Tribolium, selection, fitness, inbreedig, population.
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Gramlich, Susanne, i Elvira Hörandl. "Fitness of natural willow hybrids in a pioneer mosaic hybrid zone". Ecology and Evolution 6, nr 21 (5.10.2016): 7645–55. http://dx.doi.org/10.1002/ece3.2470.
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Li, Meng Jian, i Wei Dong Geng. "Evaluation Fitness of Footwear Using Hybrid Simulation". Applied Mechanics and Materials 462-463 (listopad 2013): 1055–61. http://dx.doi.org/10.4028/www.scientific.net/amm.462-463.1055.
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This research is trying to develop a process for identifying comfortable shoe last for human feet. A hybrid of geometric model and physics based model is proposed to simulate the procedure of fitting foot into footwear. The system implemented is able to construct all meaningful slicing planes used in footwear industry. And all kinds of dimensions are measured for fitness check, especially the most important three girth of human feet and shoe last, i.e., ball girth, waist girth, and instep girth. Quantified Fitness range, known as dimensional difference (DD), is updated according to positive and negative samples. Result shows that comparing with geometric based method, our method significantly improves the percentage of comfortable shoes among all shoes that are guided by former fitness evaluation method.
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Dybdahl, Mark F., Jukka Jokela, Lynda F. Delph, Britt Koskella i Curtis M. Lively. "Hybrid Fitness in a Locally Adapted Parasite". American Naturalist 172, nr 6 (grudzień 2008): 772–82. http://dx.doi.org/10.1086/592866.
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Dagilis, Andrius J., Mark Kirkpatrick i Daniel I. Bolnick. "The evolution of hybrid fitness during speciation". PLOS Genetics 15, nr 5 (6.05.2019): e1008125. http://dx.doi.org/10.1371/journal.pgen.1008125.
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Potts, BM. "Population Dynamics and Regeneration of a Hybrid Zone Between Eucalyptus risdonii Hook-F and E amygdalina Labill". Australian Journal of Botany 34, nr 3 (1986): 305. http://dx.doi.org/10.1071/bt9860305.
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Regeneration of a hybrid zone between E. amygdalina and E. risdonii and pure species stands following wildfire is reported, as well as the reproductive and vegetative fitness of parental and hybrid phenotypes. E. risdonii phenotypes dominated the seed rain and seedling cohort and there was clearly a marked fitness differential between E. amygdalina and E. risdonii at their boundary. When the F1 type hybrid is in competition with both parental types it is generally reproductively the least fit, although frequently vegetatively vigorous. Reduced fitness appears to extend to advanced generations as hybrid phenotypes tending.toward either species are, on average, less fit than the corresponding parental type. The pattern of phenotypic fitness suggests that the species' boundary is in disequilibrium and it is argued that E. risdonii is invading the range of E. amygdalina by both pollen and seed migration. There is an asymmetric distribution of F1 type hybrids across the boundary and the hybrid swarm examined is being invaded by E. risdonii genes. It is suggested that hybridization may be associated with natural disequilibrium and, where seed migration is limited, boundary movements may be preceded by a wave of hybridization due partly to pollen swamping of the least fit species. Hybrid swarms may develop but, at the boundary of large stands, are probably transitory. There is a marked inertia in the population response to the prevailing selective regime due to the extremely slow population turnover and limited dispersal potential. This is discussed in the broader context of non-equilibrium models where it is argued that dispersal may be the factor limiting population response to perturbation of a shallow environmental gradient. This is due to large geographical shifts in the position of the null point and would be accentuated in a patchy environment where migration as a front is prevented.
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Parris, Matthew J. "Hybridization in leopard frogs (Rana pipiens complex): terrestrial performance of newly metamorphosed hybrid and parental genotypes in field enclosures". Canadian Journal of Zoology 79, nr 9 (1.09.2001): 1552–58. http://dx.doi.org/10.1139/z01-119.
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Terrestrial ecology has been largely neglected in the study of amphibian life histories because it is difficult to manipulate most species during the terrestrial stage. I examined the terrestrial performance of Rana blairi, Rana sphenocephala, and four hybrid (two F1 and two advanced generation) genotypes in replicated experimental enclosures to test for differences in traits related to juvenile terrestrial fitness. I produced all genotypes by means of artificial fertilizations using frogs collected from natural populations in central Missouri, and juvenile frogs were obtained from larvae reared in experimental ponds. Following metamorphosis, froglets were raised in single-genotype groups in terrestrial enclosures through the first overwintering. The proportion surviving did not vary among genotypes, but the power to detect significant differences was low. F1 hybrid genotypes BS and SB demonstrated significantly higher growth rates than either parental species or advanced-generation hybrid genotypes. Observation of growth rates of advanced-generation hybrids equal to those of the parental species, and heterosis in F1 hybrids for growth rate, suggests that natural hybridization between R. blairi and R. sphenocephala can produce novel and relatively fit hybrid genotypes. Direct measurement of multiple fitness components for hybrid and parental genotypes is critical for assessing the evolutionary potential of natural hybridization in organisms with complex life cycles.
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Hewitt, Sarah K., Kobchai Duangrattanalert, Tim Burgis, Leo A. H. Zeef, Samina Naseeb i Daniela Delneri. "Plasticity of Mitochondrial DNA Inheritance and its Impact on Nuclear Gene Transcription in Yeast Hybrids". Microorganisms 8, nr 4 (31.03.2020): 494. http://dx.doi.org/10.3390/microorganisms8040494.
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Mitochondrial DNA (mtDNA) in yeast is biparentally inherited, but colonies rapidly lose one type of parental mtDNA, thus becoming homoplasmic. Therefore, hybrids between the yeast species possess two homologous nuclear genomes, but only one type of mitochondrial DNA. We hypothesise that the choice of mtDNA retention is influenced by its contribution to hybrid fitness in different environments, and the allelic expression of the two nuclear sub-genomes is affected by the presence of different mtDNAs in hybrids. Saccharomyces cerevisiae/S. uvarum hybrids preferentially retained S. uvarum mtDNA when formed on rich media at colder temperatures, while S. cerevisiae mtDNA was primarily retained on non-fermentable carbon source, at any temperature. Transcriptome data for hybrids harbouring different mtDNA showed a strong environmentally dependent allele preference, which was more important in respiratory conditions. Co-expression analysis for specific biological functions revealed a clear pattern of concerted allelic transcription within the same allele type, which supports the notion that the hybrid cell works preferentially with one set of parental alleles (or the other) for different cellular functions. Given that the type of mtDNA retained in hybrids affects both nuclear expression and fitness, it might play a role in driving hybrid genome evolution in terms of gene retention and loss.
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Nilsson, P. Anders, Kaj Hulthén, Ben B. Chapman, Lars-Anders Hansson, Jakob Brodersen, Henrik Baktoft, Jerker Vinterstare, Christer Brönmark i Christian Skov. "Species integrity enhanced by a predation cost to hybrids in the wild". Biology Letters 13, nr 7 (lipiec 2017): 20170208. http://dx.doi.org/10.1098/rsbl.2017.0208.
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Species integrity can be challenged, and even eroded, if closely related species can hybridize and produce fertile offspring of comparable fitness to that of parental species. The maintenance of newly diverged or closely related species therefore hinges on the establishment and effectiveness of pre- and/or post-zygotic reproductive barriers. Ecological selection, including predation, is often presumed to contribute to reduced hybrid fitness, but field evidence for a predation cost to hybridization remains elusive. Here we provide proof-of-concept for predation on hybrids being a postzygotic barrier to gene flow in the wild. Cyprinid fishes commonly produce fertile, viable hybrid offspring and therefore make excellent study organisms to investigate ecological costs to hybrids. We electronically tagged two freshwater cyprinid fish species (roach Rutilus rutilus and bream Abramis brama ) and their hybrids in 2005. Tagged fish were returned to their lake of origin, exposing them to natural predation risk from apex avian predators (great cormorant, Phalacrocorax carbo ). Scanning for regurgitated tags under cormorant roosts 3–4 years later identified cormorant-killed individual fish and allowed us to directly test for a predation cost to hybrids in the wild. Hybrid individuals were found significantly more susceptible to cormorant predation than individuals from either parental species. Such ecological selection against hybrids contributes to species integrity, and can enhance species diversification.
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Ålund, Murielle, Simone Immler, Amber M. Rice i Anna Qvarnström. "Low fertility of wild hybrid male flycatchers despite recent divergence". Biology Letters 9, nr 3 (23.06.2013): 20130169. http://dx.doi.org/10.1098/rsbl.2013.0169.
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Postzygotic isolation may be important for maintaining species boundaries, particularly when premating barriers are incomplete. Little is known about the course of events leading from minor environmental mismatches affecting hybrid fitness to severe genetic incompatibilities causing sterility or inviability. We investigated whether reduced reproductive success of hybrid males was caused by suboptimal sperm traits or by more severe genetic incompatibilities in a hybrid zone of pied ( Ficedula hypoleuca ) and collared flycatchers ( F. albicollis ) on the island of Öland, Sweden. About 4 per cent hybridization is observed in this population and all female hybrids are sterile. We found no sperm in the ejaculates of most sampled hybrid males, and sperm with abnormal morphology in two hybrids. Furthermore, none of the hybrids sired any offspring because of high levels of hatching failure and extra-pair paternity in their nests. These results from a natural hybrid zone suggest that the spermatogenesis of hybrid males may become disrupted despite little genetic divergence between the parental species.
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Wade, M. J., N. A. Johnson i G. Wardle. "Analysis of autosomal polygenic variation for the expression of Haldane's rule in flour beetles." Genetics 138, nr 3 (1.11.1994): 791–99. http://dx.doi.org/10.1093/genetics/138.3.791.
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Abstract Haldane's rule states that, in interspecific crosses, when hybrid viability or fertility is diminished more in one sex of the hybrids than in the other, the heterogametic sex is more adversely affected. We used quantitative genetic methods to investigate the genetic basis of variation for the expression of the viability aspect of Haldane's rule when Tribolium castaneum males are crossed to Tribolium freemani females. Using a half-sib design, we found significant genetic variance for the expression of Haldane's rule, i.e., variation among T. castaneum sires in the hybrid sex ratios produced by their sons. We also derived 23 independent lineages from the same base population by 8 generations of brother-sister mating. From the same experiments, we also found heritable variation among surviving hybrid males in the incidence of antennal deformities. Upon inbreeding, the variance of both traits (hybrid sex ratio and proportion deformities) increased substantially but the means changed little. Because fitness within T. castaneum lineages declined substantially with inbreeding, we infer that hybrid male viability may have a different genetic basis than viability fitness within species. Deleterious recessive alleles held within species by mutation/selection balance appear not to be a major contributor to hybrid incompatibility.
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Healy, Timothy M., i Ronald S. Burton. "Strong selective effects of mitochondrial DNA on the nuclear genome". Proceedings of the National Academy of Sciences 117, nr 12 (10.03.2020): 6616–21. http://dx.doi.org/10.1073/pnas.1910141117.
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Oxidative phosphorylation, the primary source of cellular energy in eukaryotes, requires gene products encoded in both the nuclear and mitochondrial genomes. As a result, functional integration between the genomes is essential for efficient adenosine triphosphate (ATP) generation. Although within populations this integration is presumably maintained by coevolution, the importance of mitonuclear coevolution in key biological processes such as speciation and mitochondrial disease has been questioned. In this study, we crossed populations of the intertidal copepodTigriopus californicusto disrupt putatively coevolved mitonuclear genotypes in reciprocal F2hybrids. We utilized interindividual variation in developmental rate among these hybrids as a proxy for fitness to assess the strength of selection imposed on the nuclear genome by alternate mitochondrial genotypes. Developmental rate varied among hybrid individuals, and in vitro ATP synthesis rates of mitochondria isolated from high-fitness hybrids were approximately two-fold greater than those of mitochondria isolated from low-fitness individuals. We then used Pool-seq to compare nuclear allele frequencies for high- or low-fitness hybrids. Significant biases for maternal alleles were detected on 5 (of 12) chromosomes in high-fitness individuals of both reciprocal crosses, whereas maternal biases were largely absent in low-fitness individuals. Therefore, the most fit hybrids were those with nuclear alleles that matched their mitochondrial genotype on these chromosomes, suggesting that mitonuclear effects underlie individual-level variation in developmental rate and that intergenomic compatibility is critical for high fitness. We conclude that mitonuclear interactions can have profound impacts on both physiological performance and the evolutionary trajectory of the nuclear genome.
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Crowley, SE, IR Bradbury, AM Messmer, SJ Duffy, SS Islam i IA Fleming. "Common-garden comparison of relative survival and fitness-related traits of wild, farm, and hybrid Atlantic salmon Salmo salar parr in nature". Aquaculture Environment Interactions 14 (3.03.2022): 35–52. http://dx.doi.org/10.3354/aei00425.
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When escapee farmed Atlantic salmon Salmo salar interbreed with wild fish, the introgression of maladaptive genes can lower wild population productivity and alter key life history traits. To date, only a few European studies have compared wild, farm, and hybrid salmon under common conditions in the wild, isolating the influence of genetics on survival and fitness-related traits. Here, we examined the performance of experimentally derived Atlantic salmon fry from 4 cross types (wild, farm, and reciprocal F1 hybrids) during the first summer of growth at 3 locations in southern Newfoundland. Overall survival was high, with the cross type rank order consistent across sites (mean percent recaptured: wild-mother hybrids 26.2% ≈ wild 26.0% > farm 19.2% > farm-mother hybrids 12.8%). Wild fish were smaller than wild-mother hybrids and farm fish, though differed less in size from farm-mother hybrids. At 2 out of 3 sites, wild-mother hybrids were larger than wild and farm-mother hybrid fish but had only a small size advantage over farm fish. Shape differences were small and mainly related to body depth, with the largest differences between wild and farm fish. Wild-mother hybrids had fewer parr marks than other cross types at a single site, and though differences in the size of marks were minimal, farm fish tended to have the narrowest marks. Overall, these results show that genetic differences exist for fitness-related traits among wild, farm, and hybrid juveniles, even over short temporal scales and under favourable environmental conditions, and may contribute to patterns of reduced farm-mother hybrid and feral farm survival in the wild.
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Hatfield, Todd, i Dolph Schluter. "Ecological Speciation in Sticklebacks: Environment-Dependent Hybrid Fitness". Evolution 53, nr 3 (czerwiec 1999): 866. http://dx.doi.org/10.2307/2640726.
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Rhode, Jennifer M., i Mitchell B. Cruzan. "Contributions of Heterosis and Epistasis to Hybrid Fitness". American Naturalist 166, nr 5 (listopad 2005): E124—E139. http://dx.doi.org/10.1086/491798.
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Hatfield, Todd, i Dolph Schluter. "ECOLOGICAL SPECIATION IN STICKLEBACKS: ENVIRONMENT-DEPENDENT HYBRID FITNESS". Evolution 53, nr 3 (czerwiec 1999): 866–73. http://dx.doi.org/10.1111/j.1558-5646.1999.tb05380.x.
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Arnold, M. L., R. S. Cornman i N. H. Martin. "Hybridization, hybrid fitness and the evolution of adaptations". Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology 142, nr 1 (marzec 2008): 166–71. http://dx.doi.org/10.1080/11263500701873018.
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Miller, Charles J. J., i Daniel R. Matute. "The Effect of Temperature on Drosophila Hybrid Fitness". G3: Genes|Genomes|Genetics 7, nr 2 (2.12.2016): 377–85. http://dx.doi.org/10.1534/g3.116.034926.
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Freeman, Patrick. "Navigating Hybrid Communication Successfully as a Fitness Manager". ACSM'S Health & Fitness Journal 26, nr 1 (styczeń 2022): 52–54. http://dx.doi.org/10.1249/fit.0000000000000730.
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Markula, Pirkko. "Barre Matters: Hybrid Formations of Ballet and Group Fitness". Somatechnics 11, nr 2 (sierpień 2021): 191–210. http://dx.doi.org/10.3366/soma.2021.0351.
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Employing a variety of theoretical approaches, feminist researchers have critiqued the fitness industry of its singular emphasis on the impossible, narrowly defined feminine body ideal that is likely to cause more mental (e.g., body dissatisfaction) and physical ill health (eating disorders, injuries) than improve fitness. With the focus on social construction of gendered identities, there has been less problematisation of the materiality of the fitness practices and their impact on the cultural production of the moving body. In this article, I adopt a Latourian approach to seek for a more complete account of the body in motion and how it matters in the contemporary world. A barre class as a popular group exercise class that combines ballet and exercise modalities offers a location for such an examination due to the centrality of a non-human object, the barre, that distinguishes it from other group exercise classes. I consider how exercise practices may be constituted in relation to a material object, the barre, and how the physical and material intersect, historically, with the cultural politics of fitness and dance from where the barre originates. To do this, I trace the journey of the barre from ballet training to the fitness industry to illustrate how human and non-human associations create a hybrid collective.
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Shivaramu, S., D. T. Vuong, M. Havelka, H. Šachlová, I. Lebeda, V. Kašpar i M. Flajšhans. "Influence of interspecific hybridization on fitness-related traits in Siberian sturgeon and Russian sturgeon". Czech Journal of Animal Science 64, No. 2 (13.02.2019): 78–88. http://dx.doi.org/10.17221/165/2018-cjas.
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Polyploidy in sturgeons makes them highly susceptible to interspecific hybridization, and these interspecific hybrids have been described in nature as well as in captivity. Nevertheless, the fitness-related traits between sturgeon hybrids and pure species have been poorly compared as yet. In the present study, we compared the reproductive parameters such as fertilization rate and hatching rate, growth traits and genetic polymorphism in the artificially produced hybrids of the Siberian sturgeon (Acipenser baerii) and Russian sturgeon (A. gueldenstaedtii) with their purebreds. Fertilization and hatching rates were found to be significantly higher in Siberian sturgeon (♀) × Russian sturgeon (♂) hybrid group compared to purebreds. The highest cumulative survival rate was determined in purebred groups until 151 days post-hatch (dph); however, this trend changed and Russian sturgeon purebred showed the lowest cumulative survival rate (0.21%) by 913 dph. Similarly, the lowest average body weight was recorded in Russian sturgeon purebred group (264 g). In contrast, the highest average body weight was recorded in Russian sturgeon (♀) × Siberian sturgeon (♂) hybrids (435.3 g) and the highest cumulative survival rate was recorded in Siberian sturgeon (♀) × Russian sturgeon (♂) hybrids (12.32%) by 913 dph. No significant differences were found at heterozygosity levels among studied crosses. Our results showed that studied sturgeon hybrids had higher survival and growth if compared with the purebreds under provided hatchery conditions.
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Shivaramu, Sahana, Ievgen Lebeda, Vojtěch Kašpar i Martin Flajšhans. "Intraspecific Hybrids Versus Purebred: A Study of Hatchery-Reared Populations of Sterlet Acipenser ruthenus". Animals 10, nr 7 (7.07.2020): 1149. http://dx.doi.org/10.3390/ani10071149.
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Hatchery-reared sterlet originating from the Danube and Volga river basins that showed population-discriminatory alleles on at least one microsatellite locus were used to produce purebred (within-population) and hybrid crosses to evaluate intraspecific hybridization with respect to the genetic polymorphism and physiological fitness of fish for commercial aquaculture and, conservation programs. Reciprocal crossing assessed the effect of parent position. The fish were reared in indoor and outdoor tanks and monitored over 504 days for growth traits. The highest final mean body weight (144.9 ± 59.5 g) was recorded in the Danube (♀) × Volga (♂) hybrid and the highest survival in the Volga (♀) × Danube (♂) hybrid. The Volga purebred exhibited the lowest mean body weight (124.8 ± 57.6 g). A set of six microsatellites was used to evaluate the heterozygosity. The mean number of alleles was highest in the Danube (♀) × Volga (♂) hybrid and lowest in the Volga purebred, suggesting an influence of the parent position in the hybridization matrix. The higher level of genetic polymorphism, as in the Danube (♀) × Volga (♂) hybrid, may confer greater fitness in a novel environment. Our analysis revealed that the intraspecific hybrids performed better than the purebred fish in the controlled and suboptimal rearing conditions.
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Masello, Juan F., Petra Quillfeldt, Edson Sandoval-Castellanos, Rachael Alderman, Luciano Calderón, Yves Cherel, Theresa L. Cole i in. "Additive Traits Lead to Feeding Advantage and Reproductive Isolation, Promoting Homoploid Hybrid Speciation". Molecular Biology and Evolution 36, nr 8 (26.04.2019): 1671–85. http://dx.doi.org/10.1093/molbev/msz090.
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Abstract Speciation through homoploid hybridization (HHS) is considered extremely rare in animals. This is mainly because the establishment of reproductive isolation as a product of hybridization is uncommon. Additionally, many traits are underpinned by polygeny and/or incomplete dominance, where the hybrid phenotype is an additive blend of parental characteristics. Phenotypically intermediate hybrids are usually at a fitness disadvantage compared with parental species and tend to vanish through backcrossing with parental population(s). It is therefore unknown whether the additive nature of hybrid traits in itself could lead successfully to HHS. Using a multi-marker genetic data set and a meta-analysis of diet and morphology, we investigated a potential case of HHS in the prions (Pachyptila spp.), seabirds distinguished by their bills, prey choice, and timing of breeding. Using approximate Bayesian computation, we show that the medium-billed Salvin’s prion (Pachyptila salvini) could be a hybrid between the narrow-billed Antarctic prion (Pachyptila desolata) and broad-billed prion (Pachyptila vittata). Remarkably, P. salvini’s intermediate bill width has given it a feeding advantage with respect to the other Pachyptila species, allowing it to consume a broader range of prey, potentially increasing its fitness. Available metadata showed that P. salvini is also intermediate in breeding phenology and, with no overlap in breeding times, it is effectively reproductively isolated from either parental species through allochrony. These results provide evidence for a case of HHS in nature, and show for the first time that additivity of divergent parental traits alone can lead directly to increased hybrid fitness and reproductive isolation.
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Houde, Aimee Lee S., Dylan J. Fraser i Jeffrey A. Hutchings. "Fitness-related consequences of competitive interactions between farmed and wild Atlantic salmon at different proportional representations of wild–farmed hybrids". ICES Journal of Marine Science 67, nr 4 (10.12.2009): 657–67. http://dx.doi.org/10.1093/icesjms/fsp272.
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Abstract Houde, A. S., Fraser, D. J., and Hutchings, J. A. 2010. Fitness-related consequences of competitive interactions between farmed and wild Atlantic salmon at different proportional representations of wild–farmed hybrids. – ICES Journal of Marine Science, 67: 657–667. Escaped farmed fish possess heritable characteristics that may give them and their wild–farmed hybrid offspring a competitive advantage over wild fish. Limited research has examined whether the results of wild vs. farmed pairwise behavioural contests can predict the change in fitness-related traits of wild fish when exposed to wild–farmed hybrids, or to different proportions of such hybrids, within stream environments. Pairwise aggression tests on North American Atlantic salmon (Salmo salar) revealed that regional farmed salmon and wild–farmed hybrids (F1, F2, and wild backcrosses) were more competitive than wild fish from two divergent populations. The ranking by which hybrids differed in competitive ability from wild fish also depended on the wild population. However, the magnitude of change in fitness-related traits of wild fish, such as mortality, size, and condition, from the same two populations could not be predicted from pairwise test results when replicate groups of wild fish were exposed to different proportions of hybrids (wild:hybrid ratios of 50:50, 70:30, and 85:15) in semi-natural stream environments. Notably, there was greater mortality of both wild and hybrid fish in treatments containing 30% hybrids for both populations; at a composition of 50% hybrids, the mortality of wild fish in one population increased more than it did in the other. The results suggest that for the life stage examined and provided the rate of farmed intrusion and wild–farmed interbreeding remains low (i.e. ≤15% hybrids), the effects of competitive interaction with their farmed counterparts may have comparatively little effect on the mortality of wild populations.
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Latour, Yasmin, Marco Perriat-Sanguinet, Pierre Caminade, Pierre Boursot, Carole M. Smadja i Guila Ganem. "Sexual selection against natural hybrids may contribute to reinforcement in a house mouse hybrid zone". Proceedings of the Royal Society B: Biological Sciences 281, nr 1776 (7.02.2014): 20132733. http://dx.doi.org/10.1098/rspb.2013.2733.
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Sexual selection may hinder gene flow across contact zones when hybrid recognition signals are discriminated against. We tested this hypothesis in a unimodal hybrid zone between Mus musculus musculus and Mus musculus domesticus where a pattern of reinforcement was described and lower hybrid fitness documented. We presented mice from the border of the hybrid zone with a choice between opposite sex urine from the same subspecies versus hybrids sampled in different locations across the zone. While no preference was evidenced in domesticus mice, musculus males discriminated in favour of musculus signals and against hybrid signals. Remarkably, the pattern of hybrid unattractiveness did not vary across the hybrid zone. Moreover, allopatric populations tested in the same conditions did not discriminate against hybrid signals, indicating character displacement for signal perception or preference. Finally, habituation–discrimination tests assessing similarities between signals pointed out that hybrid signals differed from the parental ones. Overall, our results suggest that perception of hybrids as unattractive has evolved in border populations of musculus after the secondary contact with domesticus . We discuss the mechanisms involved in hybrid unattractiveness, and the potential impact of asymmetric sexual selection on the hybrid zone dynamics and gene flow between the two subspecies.
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Barreto, Felipe S., i Ronald S. Burton. "Elevated oxidative damage is correlated with reduced fitness in interpopulation hybrids of a marine copepod". Proceedings of the Royal Society B: Biological Sciences 280, nr 1767 (22.09.2013): 20131521. http://dx.doi.org/10.1098/rspb.2013.1521.
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Aerobic energy production occurs via the oxidative phosphorylation pathway (OXPHOS), which is critically dependent on interactions between the 13 mitochondrial DNA (mtDNA)-encoded and approximately 70 nuclear-encoded protein subunits. Disruptive mutations in any component of OXPHOS can result in impaired ATP production and exacerbated oxidative stress; in mammalian systems, such mutations are associated with ageing as well as numerous diseases. Recent studies have suggested that oxidative stress plays a role in fitness trade-offs in life-history evolution and functional ecology. Here, we show that outcrossing between populations with divergent mtDNA can exacerbate cellular oxidative stress in hybrid offspring. In the copepod Tigriopus californicus , we found that hybrids that showed evidence of fitness breakdown (low fecundity) also exhibited elevated levels of oxidative damage to DNA, whereas those with no clear breakdown did not show significantly elevated damage. The extent of oxidative stress in hybrids appears to be dependent on the degree of genetic divergence between their respective parental populations, but this pattern requires further testing using multiple crosses at different levels of divergence. Given previous evidence in T. californicus that hybridization disrupts nuclear/mitochondrial interactions and reduces hybrid fitness, our results suggest that such negative intergenomic epistasis may also increase the production of damaging cellular oxidants; consequently, mtDNA evolution may play a significant role in generating postzygotic isolating barriers among diverging populations.
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Brucker, Robert M., i Seth R. Bordenstein. "The Hologenomic Basis of Speciation: Gut Bacteria Cause Hybrid Lethality in the Genus Nasonia". Science 341, nr 6146 (18.07.2013): 667–69. http://dx.doi.org/10.1126/science.1240659.
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Although the gut microbiome influences numerous aspects of organismal fitness, its role in animal evolution and the origin of new species is largely unknown. Here we present evidence that beneficial bacterial communities in the guts of closely related species of the genus Nasonia form species-specific phylosymbiotic assemblages that cause lethality in interspecific hybrids. Bacterial constituents and abundance are irregular in hybrids relative to parental controls, and antibiotic curing of the gut bacteria significantly rescues hybrid survival. Moreover, feeding bacteria to germ-free hybrids reinstates lethality and recapitulates the expression of innate immune genes observed in conventionally reared hybrids. We conclude that in this animal complex, the gut microbiome and host genome represent a coadapted “hologenome” that breaks down during hybridization, promoting hybrid lethality and assisting speciation.
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Rice, Amber M., i Michael A. McQuillan. "Maladaptive learning and memory in hybrids as a reproductive isolating barrier". Proceedings of the Royal Society B: Biological Sciences 285, nr 1879 (30.05.2018): 20180542. http://dx.doi.org/10.1098/rspb.2018.0542.
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Selection against hybrid offspring, or postzygotic reproductive isolation, maintains species boundaries in the face of gene flow from hybridization. In this review, we propose that maladaptive learning and memory in hybrids is an important, but overlooked form of postzygotic reproductive isolation. Although a role for learning in premating isolation has been supported, whether learning deficiencies can contribute to postzygotic isolation has rarely been tested. We argue that the novel genetic combinations created by hybridization have the potential to impact learning and memory abilities through multiple possible mechanisms, and that any displacement from optima in these traits is likely to have fitness consequences. We review evidence supporting the potential for hybridization to affect learning and memory, and evidence of links between learning abilities and fitness. Finally, we suggest several avenues for future research. Given the importance of learning for fitness, especially in novel and unpredictable environments, maladaptive learning and memory in hybrids may be an increasingly important source of postzygotic reproductive isolation.
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Zhang, Zebin, Devin P. Bendixsen, Thijs Janzen, Arne W. Nolte, Duncan Greig i Rike Stelkens. "Recombining Your Way Out of Trouble: The Genetic Architecture of Hybrid Fitness under Environmental Stress". Molecular Biology and Evolution 37, nr 1 (13.09.2019): 167–82. http://dx.doi.org/10.1093/molbev/msz211.
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Abstract Hybridization between species can either promote or impede adaptation. But we know very little about the genetic basis of hybrid fitness, especially in nondomesticated organisms, and when populations are facing environmental stress. We made genetically variable F2 hybrid populations from two divergent Saccharomyces yeast species. We exposed populations to ten toxins and sequenced the most resilient hybrids on low coverage using ddRADseq to investigate four aspects of their genomes: 1) hybridity, 2) interspecific heterozygosity, 3) epistasis (positive or negative associations between nonhomologous chromosomes), and 4) ploidy. We used linear mixed-effect models and simulations to measure to which extent hybrid genome composition was contingent on the environment. Genomes grown in different environments varied in every aspect of hybridness measured, revealing strong genotype–environment interactions. We also found selection against heterozygosity or directional selection for one of the parental alleles, with larger fitness of genomes carrying more homozygous allelic combinations in an otherwise hybrid genomic background. In addition, individual chromosomes and chromosomal interactions showed significant species biases and pervasive aneuploidies. Against our expectations, we observed multiple beneficial, opposite-species chromosome associations, confirmed by epistasis- and selection-free computer simulations, which is surprising given the large divergence of parental genomes (∼15%). Together, these results suggest that successful, stress-resilient hybrid genomes can be assembled from the best features of both parents without paying high costs of negative epistasis. This illustrates the importance of measuring genetic trait architecture in an environmental context when determining the evolutionary potential of genetically diverse hybrid populations.
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Ali, Zain Anwar, i Han Zhangang. "Multi-unmanned aerial vehicle swarm formation control using hybrid strategy". Transactions of the Institute of Measurement and Control 43, nr 12 (19.04.2021): 2689–701. http://dx.doi.org/10.1177/01423312211003807.
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This study proposes a novel hybrid strategy for formation control of a swarm of multiple unmanned aerial vehicles (UAVs). To enhance the fitness function of the formation, this research offers a three-dimensional formation control for a swarm using particle swarm optimization (PSO) with Cauchy mutant (CM) operators. We use CM operators to enhance the PSO algorithm by examining the varying fitness levels of the local and global optimal solutions for UAV formation control. We establish the terrain and the fixed-wing UAV model. Furthermore, it also models different control parameters of the UAV as well. The enhanced hybrid algorithm not only quickens the convergence rate but also improves the solution optimality. Lastly, we carry out the simulations for the multi-UAV swarm under terrain and radar threats and the simulation results prove that the hybrid method is effective and gives better fitness function.
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Schäfle, Tobias Rainer, Marcel Mitschke i Naoki Uchiyama. "Generation of Optimal Coverage Paths for Mobile Robots Using Hybrid Genetic Algorithm". Journal of Robotics and Mechatronics 33, nr 1 (20.02.2021): 11–23. http://dx.doi.org/10.20965/jrm.2021.p0011.
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This paper presents new optimal offline approaches to solve the coverage path planning problem. A novel hybrid genetic algorithm (HGA), which uses, the turn-away starting point and backtracking spiral algorithms for performing local search, is proposed for grid-based environmental representations. The HGA algorithm is validated using the following three different fitness functions: the number of cell visits, traveling time, and a new energy fitness function based on experimentally acquired energy values of fundamental motions. Computational results show that compared to conventional methods, HGA improves paths up to 38.4%; moreover, HGAs have a consistent fitness for different starting positions in an environment. Furthermore, experimental results prove the validity of the fitness function.
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Kelly, John K., i Mohamed A. F. Noor. "Speciation by Reinforcement: A Model Derived from Studies of Drosophila". Genetics 143, nr 3 (1.07.1996): 1485–97. http://dx.doi.org/10.1093/genetics/143.3.1485.
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Abstract Reinforcement is an increase in premating reproductive isolation between taxa resulting from selection against hybrids. We present a model of reinforcement with a novel type of selection on female mating behavior. Previous models of reinforcement have focused on the divergence of female mating preferences between nascent species. We suggest that an increase in the level of female mating discrimination can yield reinforcement without further divergence of either male characters or female preferences. This model indicates that selection on mating discrimination is a viable mechanism for reinforcement and may allow speciation under less stringent conditions than selection on female preference. This model also incorporates empirical results from genetic studies of hybrid fitness determination in Drosophila species. We find that the details of inheritance, which include sex-linked transmission, sex-limited fertility reduction, and X-autosome epistasis, have important effects on the likelihood of reinforcement. In particular, X-autosome epistasis for hybrid fitness determination facilitates reinforcement when hybrid fertility reduction occurs in males, but hinders the process when it occurs in females. Haldane's rule indicates that hybrid sterility will generally evolve in males prior to females within nascent species. Thus, Haldane's rule and X-autosome epistasis provide conditions that are surprisingly favorable for reinforcement in Drosophila.
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Voice, D. G., i R. B. Chapman. "Imported insecticide resistance in diamondback moth". New Zealand Plant Protection 53 (1.08.2000): 83–86. http://dx.doi.org/10.30843/nzpp.2000.53.3617.
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Laboratory experiments were conducted to determine whether resistance in an Australian population of diamondback moth could be conferred to a local susceptible population of diamondback moth (Plutella xylostella) Bioassays with larvae showed a 715fold difference in response at the LC50 to alphacypermethrin between the resistant imported and local susceptible populations The response of a hybrid strain from these populations displayed a lower level of resistance and a backcross of hybrids with the parents an even lower level of resistance The hybrid strain did not suffer any fitness disadvantage when compared with the parents
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Lu, Yuan, Angel Sandoval, Sarah Voss, Zhao Lai, Susanne Kneitz, Will Boswell, Mikki Boswell i in. "Oncogenic allelic interaction inXiphophorushighlights hybrid incompatibility". Proceedings of the National Academy of Sciences 117, nr 47 (9.11.2020): 29786–94. http://dx.doi.org/10.1073/pnas.2010133117.
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Mixing genomes of different species by hybridization can disrupt species-specific genetic interactions that were adapted and fixed within each species population. Such disruption can predispose the hybrids to abnormalities and disease that decrease the overall fitness of the hybrids and is therefore named as hybrid incompatibility. Interspecies hybridization between southern platyfish and green swordtails leads to lethal melanocyte tumorigenesis. This occurs in hybrids with tumor incidence following progeny ratio that is consistent with two-locus interaction, suggesting melanoma development is a result of negative epistasis. Such observations makeXiphophorusone of the only two vertebrate hybrid incompatibility examples in which interacting genes have been identified. One of the two interacting loci has been characterized as a mutant epidermal growth factor receptor. However, the other locus has not been identified despite over five decades of active research. Here we report the localization of the melanoma regulatory locus to a single gene,rab3d, which shows all expected features of the long-sought oncogene interacting locus. Our findings provide insights into the role ofegfrregulation in regard to cancer etiology. Finally, they provide a molecular explainable example of hybrid incompatibility.
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Markula, Pirkko. "“Tuning into One’s Self:” Foucault’s Technologies of the Self and Mindful Fitness". Sociology of Sport Journal 21, nr 3 (wrzesień 2004): 302–21. http://dx.doi.org/10.1123/ssj.21.3.302.
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This article explores the application of Michel Foucault’s technologies of the self—practices of freedom that are characterized by ethics of self-care, critical awareness, and aesthetic self-stylization. Foucault’s argument states that the technologies of self can act as practices of freedom from disciplinary, discursive body practices. Based on ethnographic fieldwork, this study examines the intersections of Foucault’s theory with commercial fitness practices to identify possibilities for changing the dominant, feminine body discourse. The focus is on fitness practices collectively defined as mindful fitness and specifically one hybrid mindfulfitness form that combines Pilates, yoga, and Tai Chi with western strength training. Through in-depth interviews with the instructors of this hybrid form, this study analyzes the possibilities for mindful fitness to act as a practice of freedom by detailing what can be meant by critically aware, self-stylized fitness professionals for whom ethical care of the self translates to ethical care of the others.
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Mehta, Ridhima. "Hybrid Fuzzy-Genetic Model for Fitness-Based Performance Optimization in Wireless Networks". International Journal of Computational Intelligence and Applications 20, nr 01 (22.01.2021): 2150008. http://dx.doi.org/10.1142/s1469026821500085.
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In recent times, the application of autonomic soft computing techniques for design and optimization of wireless access networks is progressively becoming prevalent. These computational learning techniques are capable of handling uncertain and imprecise networking information while driving toward the optimal solution set in the problem search space. The approach proposed by this paper presents the application of the fuzzy logic inference combined with the evolutionary genetic algorithm to optimize the performance parameters in wireless networks. In particular, we consider optimal bit rate allocation and transmission power consumption through the joint design of fuzzy-genetic modeling framework. The sample training data generated through simulations of IEEE 802.11 wireless access network are analyzed for optimization by supplying it to the expert hybrid model comprising of the conjunctive design of both the computational intelligent techniques. Specifically, we contemplate the binary encoding scheme, single-point crossover, reversing mutation, and two fitness functions for executing the binary genetic operations of crossover and mutation. It is generally observed that the proposed hybrid model with polynomial fitness function yields better performance with scalable network datasets than the logarithmic fitness function in terms of higher objective value. Moreover, the results obtained through simulation experiments exhibit significant throughput gains and power efficiency for the deployed fitness functions with the evolving size of training dataset. Compared with the existing methods, our hybrid learning model demonstrates performance enhancement with higher expected fitness measure, improved throughput and power efficiency.
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BARTON, N. H., i M. SHPAK. "The effect of epistasis on the structure of hybrid zones". Genetical Research 75, nr 2 (kwiecień 2000): 179–98. http://dx.doi.org/10.1017/s0016672399004334.
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Within hybrid zones that are maintained by a balance between selection and dispersal, linkage disequilibrium is generated by the mixing of divergent populations. This linkage disequilibrium causes selection on each locus to act on all other loci, thereby steepening clines, and generating a barrier to gene flow. Diffusion models predict simple relations between the strength of linkage disequilibrium and the dispersal rate, σ, and between the barrier to gene flow, B, and the reduction in mean fitness, W¯. The aim of this paper is to test the accuracy of these predictions by comparison with an exact deterministic model of unlinked loci (r = 0·5). Disruptive selection acts on the proportion of alleles from the parental populations (p, q): W = exp[−S(4 pq)β], such that the least fit genotype has fitness e−S. Where β [Lt ] 1, fitness is reduced for a wide range of intermediate genotypes; where β [Gt ] 1, fitness is only reduced for those genotypes close to p = 0·5. Even with strong epistasis, linkage disequilibria are close to σ2p′ip′j/ rij, where p′i, p′j are the gradients in allele frequency at loci i, j. The barrier to gene flow, which is reflected in the steepening of neutral clines, is given byformula herewhere r¯, the harmonic mean recombination rate between the neural and selected loci, is here 0·5. This is a close approximation for weak selection, but underestimates B for strong selection. The barrier is stronger for small β, because hybrid fitness is then reduced over a wider range of p. The widths of the selected clines are harder to predict: though simple approximations are accurate for β = 1, they become inaccurate for extreme β because, then, fitness changes sharply with p. Estimates of gene number, made from neutral clines on the assumption that selection acts against heterozygotes, are accurate for weak selection when β = 1; however, for strong selection, gene number is overestimated. For β > 1, gene number is systematically overestimated and, conversely, when β < 1, it is underestimated.
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Xia, Xuewen, Lei Tong, Yinglong Zhang, Xing Xu, Honghe Yang, Ling Gui, Yuanxiang Li i Kangshun Li. "NFDDE: A novelty-hybrid-fitness driving differential evolution algorithm". Information Sciences 579 (listopad 2021): 33–54. http://dx.doi.org/10.1016/j.ins.2021.07.082.
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Semlitsch, Raymond D., Joyce Pickle, Matthew J. Parris i Richard D. Sage. "Jumping performance and short-term repeatability of newly metamorphosed hybrid and parental leopard frogs ( Rana sphenocephala and Rana blairi )". Canadian Journal of Zoology 77, nr 5 (1.10.1999): 748–54. http://dx.doi.org/10.1139/z99-036.
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Differential fitness between hybrid and parental genotypes plays a critical role in explaining the maintenance of natural hybrid zones as well as the production of novel genetic variation that may lead to diversification. Because locomotor performance is a reliable and practical measure of potential fitness related to morphological variation, we tested for differences in jumping performance among parental and hybrid genotypes of newly metamorphosed leopard frogs (Rana sphenocephala and Rana blairi). Tadpoles of the parental species and primary and backcross hybrid tadpoles, generated from artificial crosses (a total of five genotypes), were reared at two initial larval densities. Locomotor performance of newly metamorphosed frogs, as measured by jumping ability, was tested three times over 6 days in the laboratory at 24-25°C. Maximum and average jump lengths were greater for metamorphs reared at low larval density than for those reared at high density. Regression analyses indicated that 70-79% of the variation in jump length was due to body mass. When reared at low density, metamorphs of two F1 backcross genotypes (HB and HS) and one primary hybrid genotype (SB) jumped shorter distances than either parental species. When reared at high density, hybrid performance was indistinguishable from that of the parentals, except for one backcross hybrid (HB). Moderately high short-term repeatabilities (0.47-0.66) of metamorphs reared at the high density indicate that measures of performance in newly metamorphosed frogs can be predictive. We suggest that, owing to poor jumping performance, some hybrid frogs would be at a selective disadvantage relative to their parental species in the terrestrial environment and thus would partially reinforce mechanisms of reproductive isolation in this leopard frog system. Yet equivalent performance of some hybrids relative to the parentals, at least when reared at low density, suggests that hybrid lineages also have the potential to evolve independently in some environments.
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Setiawan, Anas, Panca Mudjirahardjo i Wijono . "Automatic Voltage Regulator (AVR) Optimization Based on PID Using the Hybrid Grey Wolf Optimization - Genetic Algorithm (HGWGA) Method". International Journal of Computer Applications Technology and Research 10, nr 6 (czerwiec 2021): 136–41. http://dx.doi.org/10.7753/ijcatr1006.1002.
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In the generator set (genset), the voltage stability system is affected by the excitation system controlled by control circuit called AVR (Automatic Voltage Regulator). One of the important components in the AVR system is the algorithm of the controller. The application of the PID control method has been widely used in the design of AVR controllers. This study applies the GWO-GA (Grey Wolf Optimization - Genetic Algorithm) hybrid method on PID parameters setting. The best transient automatic voltage regulator (AVR) response results were obtained when using the hybrid genetic algorithm - grey wolf optimization (HGAGW) method with a fitness score of 4.3039, the Grey wolf optimization (GWO) method with a fitness score of 4.5059, and the genetic algorithm (GA) method with a fitness score of 6.0214.
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Saingamsook, Jassada, Jintana Yanola, Nongkran Lumjuan, Catherine Walton i Pradya Somboon. "Investigation of Relative Development and Reproductivity Fitness Cost in Three Insecticide-Resistant Strains of Aedes aegypti from Thailand". Insects 10, nr 9 (22.08.2019): 265. http://dx.doi.org/10.3390/insects10090265.
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Knockdown resistance (kdr) and detoxification enzymes are major resistance mechanisms in insecticide-resistant Aedes aegypti throughout the world. Persistence of the resistance phenotype is associated with high fitness of resistance alleles in the absence of insecticide pressure. This study determined the relative fitness cost of three insecticide-resistant strains of Aedes aegypti—PMD, PMD-R, and UPK-R—and a hybrid under similar laboratory conditions in the absence of insecticide. The PMD strain is resistant to DDT with no kdr alleles; the PMD-R is resistant to DDT and permethrin with 1534C homozygous kdr alleles; and UPK-R is resistant to DDT, permethrin, and deltamethrin with 989P + 1016G homozygous alleles. The DDT-resistant PMD strain had the highest fitness compared with the two DDT/pyrethroid-resistant strains (PMD-R and UPK-R) and hybrid. Consistent fitness costs were observed in the DDT/pyrethroid-resistant strains and hybrid, including shorter wing length, reduced egg hatchability, shorter female lifespan, and shorter viability of eggs after storage, whereas no effect was observed on blood feeding rate. In addition, reduced egg production was observed in the PMD-R strain and prolonged developmental time was seen in the UPK-R strain. The corresponding hybrid that is heterozygous for kdr alleles was fitter than either of the homozygous mutant genotypes. This is in accordance with the high frequency of heterozygous genotypes observed in natural populations of Ae. aegypti in Chiang Mai city.
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Trucco, Federico, Tatiana Tatum, Kenneth R. Robertson, A. Lane Rayburn i Patrick J. Tranel. "Characterization of Waterhemp (Amaranthus tuberculatus) × Smooth Pigweed (A. hybridus) F1Hybrids". Weed Technology 20, nr 1 (marzec 2006): 14–22. http://dx.doi.org/10.1614/wt-05-018r.1.
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In the state of Illinois, waterhemp and smooth pigweed are among the worst agricultural weeds. Previous research shows high potential for hybridization between these two species. However, the actual occurrence of hybrids in natural settings is still uncertain. Morphological similarity between hybrids and waterhemp makes field surveys of hybrids difficult to conduct. The main purpose of this study was to characterize the morphology of waterhemp × smooth pigweed F1hybrids, emphasizing evaluation of characters that may allow for hybrid discrimination in fieldAmaranthuscommunities. Concurrently, the study characterized hybrid reproductive fitness, chromosome number, and DNA content. To accomplish this, hybrids were obtained from field crosses. A species-specific polymorphism in theALSgene was used to verify hybrid identity. Significant differences (α = 0.05) between hybrids and individuals of the parental species were observed for five staminate and five carpellate characters. Of these, five characters differentiated hybrids from waterhemp. However, clustering analyses using these characters indicated that morphological differences were not reliable enough, by themselves, for unambiguous hybrid identification. Also, hybrid homoploidy (2n= 32) with respect to parental species excluded chromosome counts in hybridity determinations. However, DNA content analysis may be used for such purpose. Hybrids had an average of 1.21 pg of DNA per 2C nucleus, a value intermediate to that of parental species. Hybrids produced 3.3 or 0.7% the seed output of parental and sibling waterhemp individuals, respectively. Percent micropollen in hybrids was 95-times greater than in parental species. Hybrid sterility appears to be the most reliable feature for hybrid discrimination when conducting field surveys. However, molecular and cytogenetic analyses as employed in this study may be desired for ultimate identity corroboration.
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Kyan, Akira, Minoru Takakura i Masaya Miyagi. "Does Physical Fitness Affect Academic Achievement among Japanese Adolescents? A Hybrid Approach for Decomposing Within-Person and Between-Persons Effects". International Journal of Environmental Research and Public Health 15, nr 9 (1.09.2018): 1901. http://dx.doi.org/10.3390/ijerph15091901.
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Positive association between physical fitness and academic achievement in adolescents has been suggested yet the causal effect of physical fitness on academic achievement remains unclear. This study examined if longitudinal changes in physical fitness were associated with changes in academic achievement among junior high school students. Analyses were based on a two-year with three time-point data of 567 students (aged 12–13 years old at the baseline-point; 303 boys) who entered in five Japanese junior high schools in 2015. Academic achievement was evaluated using the student’s overall grade point average. Comprehensive physical fitness score was summed up from eight fitness tests: 50-m sprint, standing broad jump, repeated side-steps, sit and reach, sit-ups, hand-grip strength, handball throw, and 20-m shuttle run or endurance run. The hybrid regression model was applied to examine the impact of change in physical fitness on change in academic achievement using multiple imputation to account for non-response at follow-up. The changes in fitness score within-person and the differences in average of fitness score of three-time points between-person were associated with change in overall grade point average for boys. No significant association between fitness score and overall grade point average was observed in girls. Opportunities for increased physical fitness may be important to support academic achievement, particularly in junior high school boys.
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Hora, Katerina H., František Marec, Peter Roessingh i Steph B. J. Menken. "Limited intrinsic postzygotic reproductive isolation despite chromosomal rearrangements between closely related sympatric species of small ermine moths (Lepidoptera: Yponomeutidae)". Biological Journal of the Linnean Society 128, nr 1 (24.06.2019): 44–58. http://dx.doi.org/10.1093/biolinnean/blz090.
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Abstract In evolutionarily young species and sympatric host races of phytophagous insects, postzygotic incompatibility is often not yet fully developed, but reduced fitness of hybrids is thought to facilitate further divergence. However, empirical evidence supporting this hypothesis is limited. To assess the role of reduced hybrid fitness, we studied meiosis and fertility in hybrids of two closely related small ermine moths, Yponomeuta padella and Yponomeuta cagnagella, and determined the extent of intrinsic postzygotic reproductive isolation. We found extensive rearrangements between the karyotypes of the two species and irregularities in meiotic chromosome pairing in their hybrids. The fertility of reciprocal F1 and, surprisingly, also of backcrosses with both parental species was not significantly decreased compared with intraspecific offspring. The results indicate that intrinsic postzygotic reproductive isolation between these closely related species is limited. We conclude that the observed chromosomal rearrangements are probably not the result of an accumulation of postzygotic incompatibilities preventing hybridization. Alternative explanations, such as adaptation to new host plants, are discussed.
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Suri, Shelza, i Ritu Vijay. "A Bi-objective Genetic Algorithm Optimization of Chaos-DNA Based Hybrid Approach". Journal of Intelligent Systems 28, nr 2 (24.04.2019): 333–46. http://dx.doi.org/10.1515/jisys-2017-0069.
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Abstract The paper implements and optimizes the performance of a currently proposed chaos-deoxyribonucleic acid (DNA)-based hybrid approach to encrypt images using a bi-objective genetic algorithm (GA) optimization. Image encryption is a multi-objective problem. Optimizing the same using one fitness function may not be a good choice, as it can result in different outcomes concerning other fitness functions. The proposed work initially encrypts the given image using chaotic function and DNA masks. Further, GA uses two fitness functions – entropy with correlation coefficient (CC), entropy with unified average changing intensity (UACI), and entropy with number of pixel change rate (NPCR) – simultaneously to optimize the encrypted data in the second stage. The bi-objective optimization using entropy with CC shows significant performance gain over the single-objective GA optimization for image encryption.