79 resultados para morph
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The hypothesis that ornaments can honestly signal quality only if their expression is condition-dependent has dominated the study of the evolution and function of colour traits. Much less interest has been devoted to the adaptive function of colour traits for which the expression is not, or is to a low extent, sensitive to body condition and the environment in which individuals live. The aim of the present paper is to review the current theoretical and empirical knowledge of the evolution, maintenance and adaptive function of colour plumage traits for which the expression is mainly under genetic control. The finding that in many bird species the inheritance of colour morphs follows the laws of Mendel indicates that genetic colour polymorphism is frequent. Polymorphism may have evolved or be maintained because each colour morph facilitates the exploitation of alternative ecological niches as suggested by the observation that individuals are not randomly distributed among habitats with respect to coloration. Consistent with the hypothesis that different colour morphs are linked to alternative strategies is the finding that in a majority of species polymorphism is associated with reproductive parameters, and behavioural, life-history and physiological traits. Experimental studies showed that such covariations can have a genetic basis. These observations suggest that colour polymorphism has an adaptive function. Aviary and field experiments demonstrated that colour polymorphism is used as a criterion in mate-choice decisions and dominance interactions confirming the claim that conspecifics assess each other's colour morphs. The factors favouring the evolution and maintenance of genetic variation in coloration are reviewed, but empirical data are virtually lacking to assess their importance. Although current theory predicts that only condition-dependent traits can signal quality, the present review shows that genetically inherited morphs can reveal the same qualities. The study of genetic colour polymorphism will provide important and original insights on the adaptive function of conspicuous traits.
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Abstract Phenotypic polymorphism is an ideal system to study natural selection in wild populations, because it allows tracking population genetic changes by means of phenotypic changes. A wide variety of polymorphic traits have been studied in numerous animals and plants, as for example colour patterns in moths, snails and birds, human laterality, male reproductive strategies, plant morphology or mating systems. This thesis focused on Dactylorhiza sarnbucina, a rewardless European orchid species, showing a striking flower colour polymorphism, with either yellow or red flowered individuals co-occurring in natural populations. Several studies have investigated its evolutionary ecology since Nilsson's seminal paper in 1980, with a particular emphasis in the evolution and maintenance of its colour polymorphism. One of the main selective forces proposed to maintain this colour polymorphism was pollinator driven negative frequency-dependent selection (NFDS), when each morph is advantaged when rare, and comparatively disadvantaged when common. However, other investigators have recently questioned the occurrence of NFDS, and proposed alternatively that fluctuating selection may maintain this colour polymorphism. In this thesis, we aimed at reviewing and synthesizing these different studies, and also brought our contribution on D. sambucina reproductive ecology. Because numerous hypotheses have still to be tested, we concluded by saying that we are a long way from understanding the evolution and dynamics of colour polymorphism in natural D. sambucina populations. Beside the debated question of colour polymorphism maintenance, one question remained to be tested: what are the consequences of polymorphism per se. We experimentally addressed this question using artificial populations of D. sambucina, and found no relationship between population phenotypic diversity and orchid pollination success. This finding suggest that polymorphism itself was not an advantage for deceptive species such D sambucina, contrarily to the expectations. Finally, we suggest potential research perspectives that could allow a better understanding of the evolutionary ecology of this species. Résumé Le polymorphisme phénotypique est un système biologique idéal pour étudier l'action de la sélection en populations naturelles, grâce à la possibilité de suivre les changements génétiques de la population en étudiant les phénotypes des individus. De très nombreuses études ont montré du polymorphisme phénotypique chez les animaux, par exemple la latéralité chez l'Homme, la coloration des escargots ou des oiseaux. Dans le règne végétal, le polymorphisme est souvent associé à des traits du système de reproduction. Cette thèse est centrée sur une espèce d'orchidée Européenne qui ne produit pas de nectar, Dactylorhiza sambucina. Cette espèce présente des individus à fleurs jaunes et des individus à fleurs rouge, généralement présents en mélange dans les populations naturelles. Plusieurs études ont investigué l'écologie évolutive de cette espèce depuis 25 ans, avec comme thème central l'évolution et le maintien de ce polymorphisme. La principale force sélective proposée pour maintenir ce polymorphisme de couleur est la sélection fréquence-dépendante, exercée par le comportement des pollinisateurs. Chacun des deux variants de couleur est favorisé quand il est rare, et défavorisé quand il devient commun. Bien que ce mécanisme semble agir, certains auteurs doutent de son importance, et ont proposé que les variations temporelles ou spatiales des forces de sélection puisse maintenir le polymorphisme de couleur chez D. sambucina. Dans cette thèse, nous avons voulu résumer et synthétiser les résultats de ces différentes études, et aussi présenter des données nouvelles concernant la reproduction de cette espèce. À la vue de ces résultats, il apparait que de nombreux points nécessitent des expériences complémentaires, et que la compréhension de ce système biologique est encore fragmentaire. Nous nous sommes également intéressés à une question laissée en suspens dans la littérature: le polymorphisme de couleur en soit confère-t-il un avantage à l'espèce, comme proposé par certains auteurs? En construisant des populations artificielles de D. sambucina, nous avons pu montrer que le polymorphisme de couleur n'augmente pas le succès reproducteur de l'espèce. Nous terminons ce travail de recherche en proposant plusieurs axes de recherche pouvant conduire à une meilleure compréhension de l'écologie et de l'évolution de cette espèce.
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[spa]El presente trabajo culmina un proyecto dedicado al estudio de cuatro láminas de plomo con escritura ibérica procedentes del área ilergeta, que habñian sido extraídas de forma irregular de forma irregular a principios de la década de los años 80 del pasado siglo y que acabaron en el Instituto de Estudios Ilerdenses. En 2005 se dio a conocer el plomo de Olriols (Sant Esteve de Llitera), en 2009 los plomos 1 y 2 de Monteró (Camarasa) y ahora finalmente el plomo del Tossal del Mor (Tárrega). Este texto es muy corto, sólo consta de cuatro segmentos, todos posiblemete antropónimos sin ningún morfo añadido. Desde el punto de vista paleográfico, es significativo que por primera vez se documente un signo dual ko complejo en la zona ilergeta. Mientras que del léxico, cabe destacar que en uno de los antroponimos se documenta por primera vez con claridad en una inscripción ibérica el elemento iber. Independientemente de su significado parece plausible su relación con el etnónimo o con el río con los que antiguos griegos y romanos identificaban a los íberos. [eng]This work is the culmination of a project dedicated to the study of four sheets of lead with Iberian writing from the Ilerget area that had been extracted without authorisation in the early 1980s and that found way to the Institut d"Estudis Ilerdencs (Lleida). In 2005, the lead from Olriols (Sant Esteve de Llitera) was presented, as were lead sheets 1 and 2 from Monteró (Camarasa) in 2009 and now finally the lad piece from Tossal del Mor (Tàrrega). The text is very short, with only four segments, all possibly anthroponyms without any added morph. From the palaeographic point of view, it is significant that, for the first time, a complex dual ko sign is documented in the Ilerget area. Regarding the lexis, it is of note that in one of the anthroponyms the element ibeŕ is documented clearly for the first time in an Iberian inscription. Independently of its meaning, it seems plausible to link it to the ethnonym or the river with which the ancient Greeks and Romans identified the Iberians.
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BACKGROUND: The presence of intraspecific color polymorphism can have multiple impacts on the ecology of a species; as a consequence, particular color morphs may be strongly selected for in a given habitat type. For example, the asp viper (Vipera aspis) shows a high level of color polymorphism. A blotched morph (cryptic) is common throughout its range (central and western Europe), while a melanistic morph is frequently found in montane populations, presumably for thermoregulatory reasons. Besides, rare atypical uniformly colored individuals are known here and there. Nevertheless, we found in a restricted treeless area of the French Alps, a population containing a high proportion (>50%) of such specimens. The aim of the study is to bring insight into the presence and function of this color morph by (i) studying the genetic structure of these populations using nine microsatellite markers, and testing for (ii) a potential local diversifying selection and (iii) differences in dispersal capacity between blotched and non-blotched vipers. RESULTS: Our genetic analyses support the occurrence of local diversifying selection for the non-blotched phenotype. In addition, we found significant color-biased dispersal, blotched individuals dispersing more than atypical individuals. CONCLUSION: We hypothesize that, in this population, the non-blotched phenotype possess an advantage over the typical one, a phenomenon possibly due to a better background matching ability in a more open habitat. In addition, color-biased dispersal might be partly associated with the observed local diversifying selection, as it can affect the genetic structure of populations, and hence the distribution of color morphs.
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Variants of the melanocortin-1 receptor (MC1R) gene result in abrupt, naturally selected colour morphs. These genetic variants may differentially affect sexual dimorphism if one morph is naturally selected in the two sexes but another morph is naturally or sexually selected only in one of the two sexes (e.g. to confer camouflage in reproductive females or confer mating advantage in males). Therefore, the balance between natural and sexual selections can differ between MC1R variants, as suggest studies showing interspecific correlations between sexual dimorphism and the rate of nonsynonymous vs. synonymous amino acid substitutions at the MC1R. Surprisingly, how MC1R is related to within-species sexual dimorphism, and thereby to sex-specific selection, has not yet been investigated. We tackled this issue in the barn owl (Tyto alba), a species showing pronounced variation in the degree of reddish pheomelanin-based coloration and in the number and size of black feather spots. We found that a valine (V)-to-isoleucine (I) substitution at position 126 explains up to 30% of the variation in the three melanin-based colour traits and in feather melanin content. Interestingly, MC1R genotypes also differed in the degree of sexual colour dimorphism, with individuals homozygous for the II MC1R variant being 2 times redder and 2.5 times less sexually dimorphic than homozygous individuals for the VV MC1R variant. These findings support that MC1R interacts with the expression of sexual dimorphism and suggest that a gene with major phenotypic effects and weakly influenced by variation in body condition can participate in sex-specific selection processes.
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ABSTRACT This study investigates the flowering and pollinators of the floral morphs of three co-occurring distylous species, Psychotria conjugens Müll, P. hastisepala Müll. Arg. and P. sessilis Vell., in two consecutive flowering seasons in an Atlantic Forest fragment in southeastern Brazil. The species have diurnal, cream-colored, tubular, nectariferous flowers and their flowering occurs in the rainy season, from September to April, with little or no overlapping between species, characterizing a staggered flowering. The flowering of the long-and short-styled floral morphs of each species was synchronous, but the number of open flowers per day per morph tended to vary in each flowering season. These numbers were higher in P. sessilis and P. conjugens and, probably, resulted in higher total numbers of visits on its flowers (up to 1084 visits in P. sessilis and 756 in P. conjugens), compared to that observed in P. hastisepala (up to 71). There was a higher frequency of visits to long-styled flowers of all species. The bee Ariphanarthra palpalis was a common pollinator to all species. This bee is native to Brazil, solitary, considered relatively rare and its host plants were unknown. Other native bees (Melipona spp.) also visited the flowers of the Psychotria species. The availability of flowers with similar floral features over eight months, the staggered flowering and common pollinators appear to be part of a strategy to attract floral visitors, minimizing the competition for pollinators and then favoring the legitimate pollination of these plants.
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Psychotria ipecacuanha is a perennial, medicinal herb that grows in clusters in the understory of humid, shady areas of the Atlantic Rain Forest of southeastern Brazil. The present study characterized the variation in floral traits among 35 clusters from three natural populations of this plant species. Field observations showed that the clusters are isomorphic, that is, a given cluster will either set long-styled or short-styled flowers. Stigmas and anthers are reciprocally placed in each morph, a dimorphism characteristic of distyly. The populations are isoplethic, that is, a given population exhibits an equilibrium 1:1 ratio of floral morphs. Morphometric analyses revealed that anther length, stigma length, corolla diameter, and pollen grain diameter were consistently greater in short-styled flowers, regardless of the population investigated. Significant differences for floral traits in the short-styled morph were found among populations. Floral traits in the long-styled morph also showed some significant differences among populations, but not for stigma height and corolla length. Controlled pollinations carried out in natural populations showed that fruit production was higher after inter-morph pollination. Nevertheless, observations of pollen tube growth in style, and also fruit production after spontaneous self-pollination and intra-morph pollination, indicated partial intramorph compatibility in this plant species.
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The thesis deals with our studies on the synthesis and elucidation of structure of some metal complexes of dithio ligands, such as the dithiocarbamates, xanthates and 2-aminocyclopent-1-ene-1-dithiocarboxylate and its N-alkyl derivatives.2-Aminocyclopent-1-ene-1-dithiocarboxylate (ACDA) is an interesting ligand, because of its potential dual capability of bonding between the metal and the ligand. Since the earlier reports on the complexes of ACDA contain contradictory ideas on the nature of its bonding, it was thought worthwhile to undertake a detailed and systematic study of these type of complexes. As the ACDA complexes have very low solubilities in solvents like chloroform, we have used the isopropyl derivative of ACDA as the ligand. The increased solubility of these complexes have made it possible to investigate their NMR and solution electronic spectra.The complexes of this ligand have not yet been reported in the literature.We have synthesised some new mixed ligand complexes of dithiocarbamates by reacting bis(dithiocarbamato)-µ-dichloro dicopper complexes (obtained by the reaction of mixed benzoic dithiocarbamic anhydride and copper(II) chloride) with ACDA or its N-alkyl derivatives.Interactions of metal halides with the mixed anhydrides formed from benzoylchloride and xanthates have also been investigated. Novel complexes of the type, [Cu2(RXant)CI] (R=i-Bu, i-Pr, n-Bu or n-Pr)) have been isolated from the reaction of copper(II) chloride and the mixed anhydride, and these reactions appear to be like the clock reactions reported in the literature.It also deal with the characterisation of the complexes of the type [Hg(R2d t c )X] (X=Cl, Br or 1),[Cu3(R2dtc)6][Cu2Br6] and [Cu(R2dtc)Cl2](R2=Me2,Et2,Pip,Morph or Pyrr)respectively, synthesised by simple and novel routes, different from those reported earlier.
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The white paper ‘Pharmacy in England’ advocates establishing a new pharmacy regulator, building leadership and integrating undergraduate education.[1] Students must morph into competent pharmacists with the skills, expertise and confidence to lead the profession to 2020 and beyond.[2] One way individuals are encouraged to ‘professionalise’ is through participation in personal/professional development schemes. The British Pharmaceutical Students’ Association (BPSA) and the College of Pharmacy Practice have operated a professional development certificate (PDC) scheme since 2001. The scheme rewards students with a joint certificate for evidence of participation in five accredited activities in one academic year. Although the scheme is relevant to development of students, less than 2% of BPSA members take part annually. We wanted to understand the reasons for the low uptake. Our primary objectives were to examine the portrayal of the scheme and to investigate what it signifies to individuals. We describe our attempts to apply social marketing techniques[3] to the PDC, and we use ‘logical levels of change’[4] to highlight a paradox with personal identity.
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Despite theoretical predictions, dishonest signalling has rarely been observed in aggressive interactions. We present evidence of such signalling in the nonpollinating. g wasp Philotrypesis sp. A ex Ficus rubiginosa. First, morphometric data indicated that an alternative 'atypical' male morph (17.8% of individuals) exists that tends to be larger in body size and has longer mandibles for a given body size than other 'typical' males. Second, behavioural observations suggested that males use mandible gape width (which depends on mandible length) as a cue to assess opponents before fights and retreat without escalating if they are unlikely to win, and, probably because their greater mandible gape width causes more opponents to retreat without escalating, that atypical males engaged in fewer fights than typical males for a given body size but had higher mating success. Third, atypical males were less likely to win fights than typical males of similar mandible length relative to opponents. In addition, we found that atypical males incur more injuries (greater receiver-dependent signal costs) than typical males of similar body size relative to rivals. We discuss the implications of our findings for future work on dishonest signalling. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
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A series of self-assembling terminally blocked tripeptides (containing coded amino acids) form gels in various aromatic solvents including benzene, toluene, xylenes at low concentrations. However these tripeptides do not form gels in aliphatic hydrocarbons like n-hexane, cyclohexane, n-decane etc. Morphological studies of the dried gel indicate the presence of an entangled fibrous network, which is responsible for gelation. Differential scanning calorimetric (DSC) studies of the gels produced by peptide 1 clearly demonstrates thermoreversible nature of the gel and tripeptide-solvent complex may be produced during gel formation. FT-IR and H-1 NMR studies of the gels demonstrate that an intermolecular hydrogen-bonding network is formed during gelation. Single crystal X-ray diffraction studies for peptides 1, 2 and 3 have been performed to investigate the molecular arrangement that might be responsible for forming the fibrous network of these self-assembling peptide gelators. It has been found that the morph responsible for gelation of peptides 1, 2 and 3 in benzene is somewhat different from that of its xerogel.
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Background Atypical self-processing is an emerging theme in autism research, suggested by lower self-reference effect in memory, and atypical neural responses to visual self-representations. Most research on physical self-processing in autism uses visual stimuli. However, the self is a multimodal construct, and therefore, it is essential to test self-recognition in other sensory modalities as well. Self-recognition in the auditory modality remains relatively unexplored and has not been tested in relation to autism and related traits. This study investigates self-recognition in auditory and visual domain in the general population and tests if it is associated with autistic traits. Methods Thirty-nine neurotypical adults participated in a two-part study. In the first session, individual participant’s voice was recorded and face was photographed and morphed respectively with voices and faces from unfamiliar identities. In the second session, participants performed a ‘self-identification’ task, classifying each morph as ‘self’ voice (or face) or an ‘other’ voice (or face). All participants also completed the Autism Spectrum Quotient (AQ). For each sensory modality, slope of the self-recognition curve was used as individual self-recognition metric. These two self-recognition metrics were tested for association between each other, and with autistic traits. Results Fifty percent ‘self’ response was reached for a higher percentage of self in the auditory domain compared to the visual domain (t = 3.142; P < 0.01). No significant correlation was noted between self-recognition bias across sensory modalities (τ = −0.165, P = 0.204). Higher recognition bias for self-voice was observed in individuals higher in autistic traits (τ AQ = 0.301, P = 0.008). No such correlation was observed between recognition bias for self-face and autistic traits (τ AQ = −0.020, P = 0.438). Conclusions Our data shows that recognition bias for physical self-representation is not related across sensory modalities. Further, individuals with higher autistic traits were better able to discriminate self from other voices, but this relation was not observed with self-face. A narrow self-other overlap in the auditory domain seen in individuals with high autistic traits could arise due to enhanced perceptual processing of auditory stimuli often observed in individuals with autism.
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Background. Leopards Panthera pardus show genetically determined colour variation. Erythristic (strawberry) morphs, where individuals are paler and black pigment in the coat is replaced by a red-brown colour, are exceptionally rare in the wild. Historically, few records exist, with only five putative records from India known. Objectives. To record the presence of erythristic leopards in our study site (Thabo Thalo Wilderness Reserve, Mpumalanga), and to collate records from across South Africa. Method. A network of camera traps was used to record individual leopards at Thabo Thalo. We also surveyed local experts, searched the popular South African press and used social media to request observations. Results. Two out of 27 individual leopards (7.1%) recorded in our study site over three years were of this colour morph. We obtained records of five other erythristic leopards in the Waterberg and Mpumalanga region, with no reports outside of this population. Conclusions. Erythristic leopards are widely dispersed across north-west South Africa, predominantly in the Lydenburg region. The presence of this rare colour morph may reflect the consequences of population fragmentation.
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Intense male-male competition for females may drive the evolution of male morphological dimorphism, which is frequently associated with alternative mating tactics. Using modern techniques for the detection of discontinuous allometries, we describe male dimorphism in the Neotropical harvestman Longiperna concolor, the males of which use their elongated, sexually dimorphic legs IV in fights for the possession of territories where females lay eggs. We also tested three predictions related to the existence of alternative mating tactics: (1) if individuals with relatively longer legs IV (majors) are more likely to monopolize access to reproductive resources, they are expected to remain close to stable groups of females more than individuals with relatively shorter legs IV (minors) do; (2) if minors achieve fertilization by moving between territories, they are expected to be less faithful to specific sites; and (3) majors should be observed in aggressive interactions more often. We individually marked all the individuals from a population of Longiperna during the reproductive season and recorded the location of each sighting for males and females as well as the identity of males involved in fights. Majors were more likely to have harems, and large majors were even more likely to do so. Majors were more philopatric and all males involved in fights belonged to this morph. These results strongly suggest that the mating tactic of the majors is based on resource defense whereas that of the minors probably relies on sneaking into the territories of the majors and furtively copulating with females.
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In arthropods, most cases of morphological dimorphism within males are the result of a conditional evolutionarily stable strategy (ESS) with status-dependent tactics. In conditionally male-dimorphic species, the status` distributions of male morphs often overlap, and the environmentally cued threshold model (ET) states that the degree of overlap depends on the genetic variation in the distribution of the switchpoints that determine which morph is expressed in each value of status. Here we describe male dimorphism and alternative mating behaviors in the harvestman Serracutisoma proximum. Majors express elongated second legs and use them in territorial fights; minors possess short second legs and do not fight, but rather sneak into majors` territories and copulate with egg-guarding females. The static allometry of second legs reveals that major phenotype expression depends on body size (status), and that the switchpoint underlying the dimorphism presents a large amount of genetic variation in the population, which probably results from weak selective pressure on this trait. With a mark-recapture study, we show that major phenotype expression does not result in survival costs, which is consistent with our hypothesis that there is weak selection on the switchpoint. Finally, we demonstrate that switchpoint is independent of status distribution. In conclusion, our data support the ET model prediction that the genetic correlation between status and switchpoint is low, allowing the status distribution to evolve or to fluctuate seasonally, without any effect on the position of the mean switchpoint.