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Auswahl der wissenschaftlichen Literatur zum Thema „Cryptic variation“
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Zeitschriftenartikel zum Thema "Cryptic variation"
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Gibson, Greg, und Laura K. Reed. „Cryptic genetic variation“. Current Biology 18, Nr. 21 (November 2008): R989—R990. http://dx.doi.org/10.1016/j.cub.2008.08.011.
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Gibson, Greg, und Ian Dworkin. „Uncovering cryptic genetic variation“. Nature Reviews Genetics 5, Nr. 9 (September 2004): 681–90. http://dx.doi.org/10.1038/nrg1426.
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Burgess, Darren J. „An eye for cryptic variation“. Nature Reviews Genetics 15, Nr. 2 (24.12.2013): 64. http://dx.doi.org/10.1038/nrg3660.
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Zheng, Jia, Joshua L. Payne und Andreas Wagner. „Cryptic genetic variation accelerates evolution by opening access to diverse adaptive peaks“. Science 365, Nr. 6451 (25.07.2019): 347–53. http://dx.doi.org/10.1126/science.aax1837.
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Cryptic genetic variation can facilitate adaptation in evolving populations. To elucidate the underlying genetic mechanisms, we used directed evolution in Escherichia coli to accumulate variation in populations of yellow fluorescent proteins and then evolved these proteins toward the new phenotype of green fluorescence. Populations with cryptic variation evolved adaptive genotypes with greater diversity and higher fitness than populations without cryptic variation, which converged on similar genotypes. Populations with cryptic variation accumulated neutral or deleterious mutations that break the constraints on the order in which adaptive mutations arise. In doing so, cryptic variation opens paths to adaptive genotypes, creates historical contingency, and reduces the predictability of evolution by allowing different replicate populations to climb different adaptive peaks and explore otherwise-inaccessible regions of an adaptive landscape.
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McGuigan, Katrina, und Carla M. Sgrò. „Evolutionary consequences of cryptic genetic variation“. Trends in Ecology & Evolution 24, Nr. 6 (Juni 2009): 305–11. http://dx.doi.org/10.1016/j.tree.2009.02.001.
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Paaby, Annalise B., und Matthew V. Rockman. „Cryptic genetic variation: evolution's hidden substrate“. Nature Reviews Genetics 15, Nr. 4 (11.03.2014): 247–58. http://dx.doi.org/10.1038/nrg3688.
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Paaby, Annalise, und Greg Gibson. „Cryptic Genetic Variation in Evolutionary Developmental Genetics“. Biology 5, Nr. 2 (13.06.2016): 28. http://dx.doi.org/10.3390/biology5020028.
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Omland, Kevin E., Cheryl L. Tarr, William I. Boarman, John M. Marzluff und Robert C. Fleischer. „Cryptic genetic variation and paraphyly in ravens“. Proceedings of the Royal Society of London. Series B: Biological Sciences 267, Nr. 1461 (22.12.2000): 2475–82. http://dx.doi.org/10.1098/rspb.2000.1308.
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Hodgkinson, Alan, Emmanuel Ladoukakis und Adam Eyre-Walker. „Cryptic Variation in the Human Mutation Rate“. PLoS Biology 7, Nr. 2 (03.02.2009): e1000027. http://dx.doi.org/10.1371/journal.pbio.1000027.
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Titus, Robert. „Cryptic variation and its manifestation in the Lower Trentonian Rafinesquina lineage (Ordovician, New York State)“. Paleontological Society Special Publications 6 (1992): 292. http://dx.doi.org/10.1017/s2475262200008522.
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Species populations commonly carry a great deal of genetic variation which is not expressed in individual phenotypes. Cryptic variation can be carried in recessive alleles, in cases of heterosis, or where modifier genes inhibit expression of the hidden trait. Other genetic and ecological factors also allow cryptic variation. Stabilizing selection prevents the expression of hidden traits; normalizing selection weeds out the deviants and canalizing selection suppresses their traits. Together the two keep the species near the top of the adaptive peak. Cryptic variation balances a species' need to be well-adapted to its environment and also for it to maintain a reserve of variation for potential environmental change. Expression of cryptic traits is rare and is usually associated with times of greatly reduced natural selection and rapid population growth, when the lower slopes of the adaptive peak are exposed.A possible example of the manifestation of cryptic traits occurs within the lower Trentonian Rafinesquina lineage of New York State. The two most commonly reported species of the genus have been reappraised in terms of cryptic variation. Extensive collections of Rafinesquina “lennoxensis” reveal far more intergrading morphotypes than had hitherto been recognized. The form which Salmon (1942) described is broadly U-shaped with sulcate margins. It grades into very convex forms as well as sharply-defined or convexly geniculate types. Of great importance, all forms grade into the flat, U-shaped, alate R. trentonensis, which is, by far, the most common and widespread lower Trentonian member of the genus. The R. “lennoxensis” assemblage has a very narrow biostratigraphy, being confined to a few locations in the upper Napanee Limestone. This places it in a quiet, protected, low stress, lagoonal setting behind the barrier shoal facies of the Kings Falls Limestone.The R. “lennoxensis” assemblage does not constitute a natural biologic species; it is reinterpreted as an assemblage of phenodeviants occupying a low stress, low natural selection lagoon facies. All such forms should be included within R. trentonensis. Given the evolutionary plasticity of this genus, extensive cryptic variation is not surprising.
Dissertationen zum Thema "Cryptic variation"
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KIssane, Kelly C. „Geographic variation and cryptic species evidence from natural populations of the fishing spider Dolomedes triton /“. abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3275834.
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Moeser, Andrew A. „Genetic analyses of sympatric cryptic species in the Neotropical catfish, Pimelodella chagresi“. Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82294.
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I used microsatellite markers to assess reproductive isolation between cryptic, sympatric lineages of a freshwater catfish (Pimelodella chagresi ). These are "cryptic" lineages because they cannot be distinguished visually on the basis of morphological characters, and currently they are recognized as a single species. Previous analyses utilizing mitochondrial DNA (mtDNA) indicated that two highly divergent lineages are present in lower Central America, and that these lineages are the result of independent colonization events from South American source populations. I isolated eight dinucleotide repeats from P. chagresi and designed primers to amplify these microsatellite loci. I sampled fishes from four Panamanian watersheds. The congruence of microsatellite data with mtDNA indicated that these taxa are reproductively isolated and should be considered as separate species despite the lack of morphological differentiation. Both lineages exhibit a high degree of divergence among populations inhabiting isolated freshwater drainages, but the lineages differ in their intra-watershed population structure.
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Tri, Baskoro T. S. „Cryptic species within Anopheles barbirostris Van der Wulp, 1884 : inferred from nuclear and mitochondrial gene sequence variation“. Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250419.
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Van, Leeuwen Travis Edward. „Variation in metabolic rate between individuals and species : cryptic physiological tradeoffs underlying habitat partitioning and life history strategies of juvenile salmonids“. Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/28689.
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Physiological traits such as standard metabolic rate have been shown to vary up to half an order of magnitude between individuals and species and influence key life history tradeoffs in juvenile salmonids (e.g. smolt timing).
The purpose of my thesis research was to examine the relationship between food consumption, dominance and disproportionate feeding on physiological traits and adaptive strategies of juvenile salmonids.
Results show that SMR is positively correlated with food consumption and growth in juvenile coho salmon which showed a reduction in SMR under low food and an elevation in SMR under high food (Chapter 2).
Comparisons between hatchery and wild juvenile steelhead and coho salmon revealed no difference in Stnadard metabolic rate between wild coho and wild steelhead but a significant difference in the hatchery fish, with hatchery steelhead being higher. In both wild and hatchery populations I found a marked difference in maximal metabolic rate between steelhead and coho, leading to a greater aerobic scope and swim performance in wild steelhead but no difference in the hatchery fish. This result is consistent with a steelhead energy maximizing strategy, habitat partitioning and trade-offs between elevated SMR at higher growth and decreased swim performance. Interestingly, wild steelhead with higher maximum growth, swim performance, and maximum food consumption do not appear to tradeoff increased growth against lower swim performance, as commonly observed for high growth strains. Instead steelhead appear to be trading off higher growth for lower food consumption efficiency; highlighting potential differences in food consumption and digestion strategies as cryptic adaptations that have received little attention.
In experiments conducted in semi-natural stream channels, I found that dominant coho salmon were able to achieve higher absolute growth rates compared to smaller subordinates, at high food ration but suffered significantly lower absolute growth at low food ration as larger dominant fish approached the capacity of their habitat (Chapter 4).
Overall I demonstrated that the relationship between physiological traits, life history strategy and dominance rank depended on per capita food consumption rates, habitat characteristics (pools vs riffles) and the absolute size of individuals in a dominance hierarchy.
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Bazzano, Jason. „Differences in Sexual Dimorphism and Influences of Sexual Dichromatism on Crypsis Among Populations of the Jumping Spider Habronattus oregonensis“. PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/272.
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Crypsis can be an important mechanism of predator avoidance for organisms. However, many species exhibit sexual dichromatism, in which the males possess a suite of colorations in order to attract female attention. The resulting differences in crypsis between the males and females can provide insight into the relative strengths of the sexually and naturally selective forces shaping the coloration of the organism, as well as clues regarding potential sensory biases of the selecting sex. In this study, I examine variation in the coloration of four Pacific Northwest populations of the sexually dimorphic and dichromatic polygynous species of jumping spider Habronattus oregonensis and compare the coloration of different body regions of the spiders to their habitats. I also investigate differences in relative size of a male sexual ornament, the enlarged first leg tibia. Field work for this study was conducted in June and July of 2009. The three main foci of this study are 1) to compare the degree of color matching of females and their habitat to the degree of color matching of males and their habitat, evaluating whether sexual selection on males has reduced their degree of crypsis relative to that of females, 2) if there is indeed a difference in crypsis between the sexes, to gauge whether there are similar divergences from crypsis among the populations - both in the quantitative amount of divergences as well as the colorimetric direction of such divergences, and 3) whether there is any variation in sexual ornament size among populations. Male first leg tibia size is a sexual character that is presumably not influenced by habitat coloration; differences in male tibia allometry among populations would provide supporting evidence for the hypothesis that sexual selection is indeed maintaining phenotypic differences among the populations, regardless of habitat location and color. I found a high degree of conformity of hue and chroma between male and female spiders and their habitats, with three notable exceptions. The most extreme difference in coloration between spider and habitat was that of the Gorge and Siskiyou population male anteriors. The anteriors had proportionally less green and more ultraviolet reflectance than their habitat. Second, the Mt. Hood and Tillamook population male abdomens diverged from their habitat in a similar, although less pronounced manner to that of the Gorge and Siskiyou population male anteriors: they had proportionally less green and more UV reflectance. Third, female abdomens of all populations were highly variable in chroma, despite having hues that generally matched their habitat. Tibia area relative to body size of Gorge and Siskiyou population males was significantly smaller than that of Mt. Hood and Tillamook population males. The lower level of background hue matching among males compared to females implies that sexual selection has directly conflicted with natural selection, resulting in impaired crypsis. While the reduced crypsis of the Gorge and Siskiyou population males is centered on their anterior (the primary body region presented to the females during courtship), the deviations from crypsis in the Mt. Hood and Tillamook population males are highest on their abdomen, although the degree of contrast is lower than that of the Gorge and Siskiyou population anteriors. These differences in coloration between the Mt. Hood and Tillamook population male abdomens and their habitats are in the same colorimetric direction as those of the Gorge and Siskiyou population anteriors and their habitat; this may indicate a sensory bias of the females, conserved in all four populations, selecting for male reflectance with a higher UV to green ratio. The fact that Mt. Hood and Tillamook population male abdomens have a more modest reduction in background matching compared to Gorge and Siskiyou population male anteriors may be due to the search methods of flying predators (e.g., spider wasps); the dorsum would presumably be more conspicuous to predators than the anterior, and would thus be subject to more intense selection for crypsis despite sexual selection to the contrary. The variability of abdomen coloration of females of both morphs may indicate that selection for crypsis is less strong among females than among males. One possible reason for this would be if females spent less time in the exposed courtship habitat than males, a conclusion implied by a highly male-skewed sex ratio encountered during field collections. Like the differences in coloration between different males of different populations, the significant differences in male tibia size also imply variability in the intensity of sexual selection. Relative importance of male coloration and tibia size may be weighted differently among populations, operating under similar constraints on reductions in survival accrued by developing these characters. The high degree of variation found among the populations implies that there is a degree of reproductive isolation among the chromatically and morphologically dissimilar populations. However, the similarity of the environments in which the populations existed, the close geographic proximity of some of the dissimilar populations, and the lack of any substantial geographic boundaries between the populations imply that this isolation is not maintained through extrinsic factors. Rather, it would seem that the interpopulational diversity is maintained by sexual selection. However, evidence from morphology and coloration suggest that the generation of this diversity is not evolving exclusively under sexual selection pressure, but rather is constrained to a degree by natural selection.
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Aissaoui, Cherifa. „Les mollusques du Golfe de Gabès (Méditerranée sud-orientale) : néo-endemisme ou variations écophénotypiques ?“ Thesis, Paris, Muséum national d'histoire naturelle, 2016. http://www.theses.fr/2016MNHN0014/document.
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L’originalité du golfe de Gabès (Sud de la Tunisie) a été reconnue par les malacologistes depuis le19ème siècle mais reste mal définie. Les espèces de cette région présentent des caractères morphologiques qui ont conduit à l’établissement de variétés, sous-espèces et espèces faiblement caractérisées. Certains auteurs les traitent comme des taxons endémiques tandis que d'autres les considèrent comme de simples variants locaux d'espèces à large répartition méditerranéenne. Le manque d’information concernant la valeur taxonomique de ces caractères morphologiques ne permet pas de traiter de façon robuste la question de l’endémisme dans le golfe de Gabès. Le premier objectif est de réviser le statut taxonomique des mollusques du golfe de Gabès en s’appuyant sur une approche de taxonomie moléculaire. La confrontation des différents caractères a permis d’identifier ceux qui discriminent correctement les individus en espèces, d’éliminer à l’inverse ceux qui ne remplissent pas cette fonction et d’en redéfinir de nouveaux. Le deuxième objectif est de relier les particularités faunistiques du Golfe à ses caractéristiques océanographiques et de discuter les phénomènes de spéciation qui pourraient être à l’origine de l’endémisme. Nos analyses ont porté sur six genres: Jujubinus (Trochidae), Diodora (Fissurellidae), Ocinebrina, Muricopsis (Muricidae), Aplus (Buccinidae) et Tritia (Nassariidae). L’approche intégrative utilisée a permis de proposer des hypothèses de délimitation d’espèces que nous avons ensuite confrontées aux données morphologiques et géographiques. Au final, l’endémisme est confirmé dans certains cas mais l’hypothèse qu’une partie des espèces décrites du golfe de Gabès ne sont que des variétés éco phénotypiques est également attestée. Notre approche moléculaire a mis aussi en évidence l’existencede nouvelles espèces et d’espèces cryptiques insoupçonnées dans la Méditerranée. Finalement l’hypothèse que le golfe de Gabès est un centre de spéciation est retenue. Plus de données moléculaires (reliées à des données fossiles) d’autres groupes provenant de différentes localités (spécialement du golfe de Syrte) apparaissent toutefois nécessairesThe present Mediterranean marine fauna is the result of a history going back to the Messinian Salinity Crisis, with current biogeographical patterns mostly reflecting Quaternary to modern oceanographic conditions. The Gulf of Gabès, in southern Tunisia, is remarkable for its extreme ecological characteristics that distinguish it from "ambiant" Mediterranean conditions. Starting with the work of malacologists at the turn of the 19th-20th centuries, the molluscs of the Gulf of Gabès have been recognized as exhibiting morphological characters that set them apart from more typical forms that occur in the rest of the Mediterranean. At present, 6% of the species of the overall Gulf of Gabès mollusc fauna are treated as valid local endemics. Using an integrative taxonomy approach, combining molecular and morphological data, the objective of the study is to re-evaluate the status of these Gulf of Gabès local forms: are they valid, endemic species or do they represent ecophenotypic variation? Given the young geological age (6-8 ka) of the Gulf, where would local endemics have originated? The gastropod genera Jujubinus (Trochidae), Diodora (Fissurellidae), Tritia (Nassariidae) Ocinebrina (Muricidae), Muricopsis (Muricidae) and Aplus (Buccinidae) all have in common non-planktotrophic larval development. Our integrative approach confirms the validity of some of the endemic taxa, but also infirm that others are not valid species; molecular data also reveal unsuspected cryptic lineages both within and outside the Gulf. Regarding the question of the origin of the endemic species, various hypotheses have been proposed, one of them being that the Gulf of Gabès is a “speciation factory”. To formally test this hypothesis, more molecular data (coupled with fossil record data) are needed from other species groups and from other localities in the Mediterranean (specifically the Gulf of Syrte)
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Colson-Proch, Céline. „Écophysiologie évolutive en milieu aquatique souterrain : influence des variations de température sur la distribution de Niphargus rhenorhodanensis et Proasellus valdensis“. Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10195.
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La température est le paramètre abiotique qui influence de façon majoritaire les traits d’histoire de vie des espèces ectothermes. Pour appréhender les relations entre physiologie, environnement et histoire évolutive et leur influence respective sur la délimitation des aires de distribution des espèces, ce travail exploite les caractéristiques thermiques du milieu souterrain. Les résultats réfutent l’hypothèse de sténothermie des deux organismes hypogés étudiés Niphargus rhenorhodanensis et Proasellus valdensis et prouvent que l’histoire évolutive, la dispersion ou la compétition sont des paramètres importants dans l’établissement des aires de distribution des espèces souterraines. En outre, ce travail caractérise pour la première fois chez des organismes souterrains, un gène codant pour des protéines de choc thermique et montre l’importante sensibilité cellulaire de N. rhenorhodanensis face à une augmentation de températureTemperature is the abiotic factor that most influences the life-history traits of ectothermic organisms. In order to study the relationships between physiology, environment and evolutionary history and their respective role in the determination of species distribution areas, this work takes advantage of the thermal caracteristics of subterranean aquatic biotopes. Our results refuted stenothermy in both studied hypogean organisms Niphargus rhenorhodanensis and Proasellus valdensis and they showed that evolutionary history, dispersal and competition are important factors that determine the distribution of subterranean species. Moreover, this work characterized for the first time in subterranean organisms a gene encoding heat shock proteins and demonstrated the high cellular sensitivity of N. rhenorhodanensis to increased water temperature
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Cunche, Mathieu. „Codes AL-FEC hautes performances pour les canaux à effacements : variations autour des codes LDPC“. Phd thesis, Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00451336.
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Nous assistons au développement rapide des solutions de diffusion de contenus sur des systèmes, où en plus des traditionnelles corruptions de l'information dans les couches basses, se pose le problème des pertes de paquets d'informations. Le besoin de fiabiliser ces systèmes de transmission a conduit à l'émergence de codes correcteurs d'effacements, qui grâce à l'ajout d'informations redondantes, permettent de reconstruire l'information perdue. Dans cette thèse nous abordons le problème de la conception de codes à effacements ayant de bonnes capacités de correction et dont les algorithmes de décodage possèdent une complexité permettant d'atteindre des débits élevés. Pour cela, nous avons choisi de travailler conjointement sur les codes et sur leur implémentation au sein d'un codec logiciel, et plus particulièrement sur les algorithmes de décodage. La première partie de nos travaux montre que des solutions basées sur les codes “Low-Density Parity-Check” (LDPC) permettent d'obtenir d'excellents résultats. En particulier lorsque ces codes sont décodés avec un décodeur hybride IT/ML qui permet d'obtenir des capacités de corrections proches de l'optimal, tout en conservant une complexité acceptable. De plus, nous montrons que grâce à l'utilisation de codes LDPC structurés la complexité du décodage ML peut être largement réduite. Nous étudions ensuite le développement de systèmes combinant un code à effacements et des fonctionnalités cryptographiques. Les systèmes résultants permettent de réduire la complexité globale du système tout en garantissant un niveau de sécurité élevé. Finalement, nous présentons une technique de tolérance aux fautes basée sur des codes correcteurs pour des applications de multiplications matricielles. Cette technique nous permet de construire un système de calcul distribué sur plateforme P2P tolérant efficacement aussi bien les pannes franches que les erreurs malicieuses.
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Smith, Geneviève Kathleen. „The coexistence of ecologically similar species“. 2013. http://hdl.handle.net/2152/23186.
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The biological diversity on planet Earth is astounding. Understanding the origins of this diversity, and how it is maintained, are the twin goals of ecology and evolutionary biology. An early and oft-repeated insight in this investigation is that that similar organisms cannot coexist indefinitely. Theory predicts that individuals and species will compete for limited resources and whichever has even a slight advantage will drive all others extinct in a process known as ‘competitive exclusion’. By diversifying, species avoid competition, thereby ‘stabilizing’ their coexistence. Yet natural systems often display levels of diversity that are surprisingly high, given this theory and investigations of how the similarity of coexisting species is maintained have received much less attention. Using a combination of field studies and experiments I demonstrate that highly similar species of freshwater amphipods may compete for resources without resulting in competitive exclusion. These findings suggest that there exist a range of interactions among Hyalella amphipods, ranging from strong stabilizing effects due to ecological trade-offs, to weakly stabilizing effects, to a total lack of stabilizing effects among various pairs of species in this system. These findings demonstrate how the relative strength of stabilizing forces may vary among coexisting species.
Although much effort has been dedicated to enumerating and classifying the ways in which ecological and evolutionary forces promote diversity among species, there has been far less attention paid to mechanisms such as convergent evolution, habitat filtering, competition for non-substitutable resources, and non-ecological speciation, among others. I surveyed current theory that may explain the high levels of similarity among species often found in natural systems. I describe how several ecological and evolutionary mechanisms may operate to promote the coexistence of similar species and present results from new theoretical combinations of mechanisms to demonstrate how they may further act in concert with one another.text
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Zhang, Bing. „Habitat selection, cryptic diversity, phylogeny, and phylogeography of the European Lepidocyrtus lanuginosus species group (Collembola: Entomobryidae)“. Doctoral thesis, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E58C-1.
Der volle Inhalt der QuelleBücher zum Thema "Cryptic variation"
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Fabris, Flavia. Waddington’s Processual Epigenetics and the Debate over Cryptic Variability. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198779636.003.0012.
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This chapter reappraises Waddington’s processual theory of epigenetics and examines its implications for contemporary evolutionary biology. It focuses in particular on the ontological difference between two conflicting assumptions that have been conflated in the recent debate over the nature of cryptic variability: a substance view that is consistent with the modern synthesis and construes variability as a preexisting pool of random genetic variation; and a processual view, which derives from Waddington’s conception of developmental canalization and understands variability as an epigenetic process. The chapter also discusses how these opposing interpretations fare in their capacity to explain the genetic assimilation of acquired characters.
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Minelli, Alessandro. Evolvability and Its Evolvability. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199377176.003.0007.
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No universally accepted notion of evolvability is available, focus being alternatively put onto either genetic or phenotypic change. The heuristic power of this concept is best found when considering the intricacies of the genotype→phenotype map, which is not necessarily predictable, expression of variation depending on the structure of gene networks and especially on the modularity and robustness of developmental systems. We can hardly ignore evolvability whenever studying the role of cryptic variation in evolution, the often pervious boundary between phenotypic plasticity and the expression of a genetic polymorphism, the major phenotypic leaps that the mechanisms of development can produce based on point mutations, or the morphological stasis that reveals how robust a developmental process can be in front of genetic change. Evolvability is subject itself to evolution, but it is still uncertain to what extent there is positive selection for enhanced evolvability, or for evolvability biased in a specific direction.
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Sherratt, Thomas N., und Changku Kang. Anti-predator behavior. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198797500.003.0009.
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Insects have evolved a wide range of behavioral traits to avoid predation. Frequently, these behaviors are deployed to augment the effectiveness of a primary defence such as crypsis or mimicry, but they are also sometimes elicited as a secondary defence when a primary defence fails. Anti-predator behaviors in insects include adaptations to avoid being detected by predators, adaptations rendering the insect unattractive to consume, warning behaviors, and behaviors to enhance the effectiveness of mimicry. This chapter reviews many of these behavioral anti-predator adaptations, emphasizing when they are elicited and highlighting their adaptive significance. We argue that some of the inter-specific variation in behavioral defences can be explained in terms of defensive portfolios: if a physical defence is sufficient, then behaviour to augment or back-up this defence is unnecessary. As the use of comparative methods increases, researchers will be better placed to understand variation in the suites of defences that evolve.
Buchteile zum Thema "Cryptic variation"
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Pavan, Márcio G., Gustavo B. S. Rivas, Fernando B. S. Dias und Rodrigo Gurgel-Gonçalves. „Looks Can be Deceiving: Cryptic Species and Phenotypic Variation in Rhodnius spp., Chagas Disease Vectors“. In Evolutionary Biology: Biodiversification from Genotype to Phenotype, 345–72. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-19932-0_18.
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Krämer, Martin. „Crypto-Variation in Italian Velar Palatalisation“. In Romance Linguistics 2007, 193–208. Amsterdam: John Benjamins Publishing Company, 2009. http://dx.doi.org/10.1075/cilt.304.13kra.
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de Jonge, Wiebren, und David Chaum. „Some Variations on RSA Signatures & their Security“. In Advances in Cryptology — CRYPTO’ 86, 49–59. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/3-540-47721-7_4.
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Dworkin, Ian. „Canalization, Cryptic Variation, and Developmental Buffering“. In Variation, 131–58. Elsevier, 2005. http://dx.doi.org/10.1016/b978-012088777-4/50010-7.
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„11. Phenotypic Traits, Cryptic Variation, and Human Diseases“. In Robustness and Evolvability in Living Systems, 161–74. Princeton: Princeton University Press, 2013. http://dx.doi.org/10.1515/9781400849383.161.
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Margurran, Anne E. „The Causes and Consequences of Geographic Variation in Antipredator Behavior: Perspectives from Fish Populations“. In Geographic Variation in Behavior. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195082951.003.0011.
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Predators are extremely effective agents of selection. After all, if an individual member of a prey species does not survive long enough to reproduce, it will have lost its chance (kin selection considerations apart) to bequeath its genes to future generations. It is not surprising, therefore, that many cases of population difference have been attributed to geographic variation in risk. These population differences can take a variety of forms and may, for example, involve modifications to morphology or to life-history traits. The correlation between armor and predation in the three-spined stickleback, Gasterosteus aculeatus, is one case that has been well documented (see Reimchen 1994 for a review and discussion), while another is the association between reproductive allotment and risk (Reznick and Endler 1982) and male color pattern and risk (Endler 1980) in the Trinidadian guppy, Poecilia reticulata. However, such adaptations can be futile if they are not accompanied by effective antipredator behavior. For instance, a cryptic color pattern confers no advantage if its holder chooses the “wrong” background or behaves in a conspicuous manner. Behavior is also flexible in a way that life histories or morphology may not be, and it allows moment-to-moment changes in response as risk increases or decreases. Because it is such an important weapon in the evolutionary arms race, antipredator behavior provides important insights into the causes and consequences of natural selection. Some of the best examples of geographically variable antipredator responses occur in populations of freshwater fish (see, e.g., Bell and Foster 1994). The predation regime of these populations is relatively easy to classify—at least in terms of the presence and absence of predatory species—and the distribution of key predators can explain much of the documented variation in antipredator behavior (see p. 140). Covariance in predation regime and antipredator responses is compelling evidence for natural selection. Moreover, because predation regimes can change (or be manipulated) over relatively short periods of time, there is an opportunity to record heritable changes in antipredator responses—in other words, to watch evolution in action.
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„Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals“. In Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals, herausgegeben von Edward J. Heist. American Fisheries Society, 1999. http://dx.doi.org/10.47886/9781888569155.ch12.
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<em>Abstract.</em> —This manuscript summarizes the results of seven studies of population genetics in sharks and several other studies that estimated levels of genetic variation in sharks. Investigations of population genetics in sharks are rare relative to studies in other fishes, and no analyses have been performed on any member of most orders of chondrichthyans. Allozymes and mitochondrial DNA typically reveal low levels of genetic variation within sharks, perhaps due in part to the demographic characteristics of sharks. Levels of genetic variation are significantly lower than those in marine teleosts. Sharks exhibit little genetic heterogeneity across wide geographic ranges; however, some stock structure has been detected both within and between oceans. Molecular characters have been used to confirm the presence of cryptic species and to support the synonymization of allopatric populations under a single species name.
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„8.2 Intraspecific Variation in Cryptic Female Choice Criteria and Sexual Selection Theory“. In Female Control, 384–86. Princeton: Princeton University Press, 1996. http://dx.doi.org/10.1515/9780691207209-070.
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Wagner, Günter P. „Developmental Mechanisms for Evolutionary Novelties“. In Homology, Genes, and Evolutionary Innovation. Princeton University Press, 2014. http://dx.doi.org/10.23943/princeton/9780691156460.003.0006.
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This chapter examines the developmental mechanisms underlying evolutionary novelties. It first considers the role of the environment in evolutionary innovations, with particular emphasis on how environmental perturbations result in the release of cryptic genetic variation. It then explores where the positional information for novel characters comes from before explaining derived mechanical stimuli and the origin of novelties in the avian hind limb skeleton. It also discusses the origin of character identity networks and the evolution of novel signaling centers, focusing on two novel morphological characters: the butterfly eyespot and the turtle carapace. Finally, it reflects on the developmental biology of novelties, emphasizing the complex and multifaceted nature of the evolutionary changes in the developmental mechanisms that contribute to the origin of novel body parts.
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Weitz, Joshua S. „Evolutionary Dynamics of Viruses or Microbes, but Not Both“. In Quantitative Viral Ecology. Princeton University Press, 2016. http://dx.doi.org/10.23943/princeton/9780691161549.003.0004.
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This chapter discusses the evolutionary dynamics of viruses. Preexisting variation in host phenotypes include variants with different levels of susceptibility to viruses, including complete resistance. Formative studies of the basis of the mutation rate relied upon virus–host interactions and the possibility of the evolution of resistance to infection. Viruses represent a strong selective pressure and can induce evolution among hosts. Host evolution, as induced by viruses, includes novel forms of ecological dynamics, including cryptic dynamics. Infection of hosts represents a strong selective pressure for viruses. Viruses that differ in their life history traits vary in their fitness and can invade and replace existing viral strains. The latent period represents a model trait for the further study of the evolution of intermediate phenotypes. Evolution among other traits is also possible, including who infects whom.
Konferenzberichte zum Thema "Cryptic variation"
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Mills, Penelope J. „Chromosomal variation and cryptic species in theApiomorpha minorspecies complex“. In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.115289.
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Tan, Denise. „Exploring COI variation in EcuadorianHermeuptychia butterflies: The first step in an integrative approach to resolving species limits in this widely distributed and cryptic genus“. In 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.115041.
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Engler, Adam J. „Probing Mechanisms of Mechano-Sensitive Differentiation in Mesenchymal Stem Cells“. In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19184.
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Adult mesenchymal stem cells (MSCs) have recently been shown to be responsive to the properties of their adjacent extracellular niche, most notably physical parameters such as topography and elasticity. Elasticity varies dramatically between tissues that MSCs inhibit, which drives elasticity-based differentiation into neurons, muscle, bone, etc. However within tissues, distinct elasticity gradients, brought on by pathological conditions, e.g. myocardial infarction ∼ 8.67 ± 1.50 kPa/mm, or through normal tissue variation, e.g. 0.58 ± 0.88 kPa/mm, could drive MSC migration. In fact, MSCs appear to undergo directed migration up elasticity gradients, or “durotax,” as shallow as 0.96 kPa/mm, indicating a ‘differentiation hierarchy’ since when given the choice, MSCs will durotax into the stiffest regions of the niche and then differentiate based on niche elasticity. As cells move up the gradient, they do so by deforming their niche to determine it’s elasticity, but the molecular mechanism that converts this biophysical signal into a biochemical one which the nucleus can interpret is yet unresolved. We have identified several focal adhesion-related proteins may be capable of force-induced conformational changes, e.g. vinculin. Upon the application of different amounts of traction stress in situ by MSCs, an appropriate amount of stretching results in the exposure of cryptic MAPK binding sites within vinculin and suggests that vinculin, among other focal adhesion proteins, may be sensitive to physical ECM properties and thus able to relay information leading to differentiation of stem cells.
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Wang, Junfeng, Chunlei Liang und Charles A. Garris. „Two-Dimensional Discontinous Galerkin Simulations of Crypto-Steady Supersonic Pressure Exchange“. In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65818.
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This paper reports the development of a third-order discontinuous Galerkin (DG) method for supersonic inviscid flow on a moving grid, as well as simulations of a simple model of crypto-steady supersonic pressure exchange (CSSPE) by solving 2D inviscid Euler equations. A total variation bounded (TVB) limiter is implemented for shock capturing. The third-order DG method is firstly validated using a case of supersonic vortex flow. Subsequently, the method is successfully employed to predict the crypto-steady supersonic flat-plate flow under various pressure ratios. In particular, at high pressure ratios between primary gas and secondary gas, a detached shock away from the trailing edge of the flat plate is accurately predicted. This study is our first step in approaching to developing a 3D numerical tool and modeling a novel pressure-exchange ejector.
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Pannekoek, H., M. Linders, J. Keijer, H. Veerman, H. Van Heerikhuizen und D. J. Loskutoff. „THE STRUCTURE OF THE HUMAN ENDOTHELIAL PLASMINOGEN ACTIVATOR INHIBITOR (PAI-1) GENE: NON-RANDOM POSITIONING OF INTRONS“. In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644767.
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The endothelium plays a crucial role in the regulation of the fibrinolytic process, since it synthesizes and secretes tissue-type plasminogen activator (t-PA) as well as the fast-acting plasminogen activator inhibitor (PAI-1). Molecular cloning of full-length PAI-1 cDNA, employing a human endothelial cDNA expression library, and a subsequent determination of the complete nucleotide sequence, allowed a prediction of the amino-acid sequence of the PAI-1 glycoprotein. It was observed that the amino-acid sequence is significantly homologous to those of members of the serine protease inhibitor ("Serpin") family, e.g. αl-antitrypsin and antithrombin III. Serpins are regulators of various processes, such as coagulation, inflammatory reactions, complement activation and share a common functional principle and a similar structure, indicative for a common primordial gene. The intron-exon arrangement of Serpin genes may provide a record for the structure of a primordial gene. A comparison of the location of introns among members of the Serpin family reveals that some introns are indeed present at identical or almost identical positions, however in many other cases there is no correspondence between the intron positions among different Serpin genes.Obviously, more data on the chromosomal gene structure of members of this family are required to formulate a scheme for the evolutionary creation of the Serpins. To that end, we have established the number and the precise location of the introns in the PAI-1 gene and have compared these data with those reported on other Serpin genes. For that purpose a human genomic cosmid DNA library of about 340.000 independent colonies was screened with radiolabelled full-length PAI-1 cDNA as probe. Two clones were found which contain the entire PAI-1 gene. Restriction site mapping, electron microscopic inspection of heteroduplexes and nucleotide sequence analysis demonstrate that the PAI-1 gene comprises about 12.2kilo basepairs and consists of nine exons and eight introns. Intron-exon boundaries are all in accord with the "GT-AG" rule, including a cryptic acceptor splice site found in intron 7. Furthermore, it is observed that intron 3 of the PAI-1 gene occupies an identical position as intron E of chicken ovalbumin and intron E of the ovalbumin-related gene Y. The location of the other seven introns is unrelated to the known location of introns in the genes encoding the Serpins, rat angiotensin, chicken ovalbumin (and gene Y), human antithrombin III and human al-antitrypsin. The 3' untranslated region of the PAI-1 gene is devoid of introns, indicating that the two mRNA species detected in cultured endothelial cells which share an identical 5' untranslated segment and codogenic region, but differ in the length of the 3' untranslated region, arise by alternative polyadenylation. An extrapolation of the position of the introns to the amino-acid sequence of PAI-1, and adaption of the view that the subdomain structure of the Serpins is analogous, shows that the introns of PAI-1 are non-randomly distributed. Except for intron 7, the position of the other seven introns corresponds with randon-coil regions of the protein or with the borders of β-sheets and a-helices. Extrapolation of the position of introns in the genes of other Serpins to their respective amino-acid sequences and subdomain structures also reveals a preference for random-coil regions and borders of subdomains. These observations are reminiscent of an evolutionary model, called "intron sliding", that accounts for variations in surface loops of the same protein in different species by aberrant splicing (Craik et al., Science 220 (1983) 1125). The preferential presence of introns in gene segments, encoding these variable regions, and absence in regions determining the general folding of these proteins would explain conservation of the structure during the evolution of those genes.