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See detailEvolutionary conserved role of ptf1a in the specification of exocrine pancreatic fates
Zecchin, E.; Mavropoulos, A.; Filippi, A. et al

in Developmental Biology (2004), 268(1), 174-184

We have characterized and mapped the zebrafish ptf1a gene, analyzed its embryonic expression, and studied its role in pancreas development. In situ hybridization experiments show th at from the 12-somite ... [more ▼]

We have characterized and mapped the zebrafish ptf1a gene, analyzed its embryonic expression, and studied its role in pancreas development. In situ hybridization experiments show th at from the 12-somite stage to 48 hpf, ptf1a is dynamically expressed in the spinal cord, hindbrain, cerebellum, retina, and pancreas of zebrafish embryos. Within the endoderm, ptf1a is initially expressed at 32 hpf in the ventral portion of the pdx1 expression domain; ptf1a is expressed in a subset of cells located on the left side of the embryo posteriorly to the liver primordium and anteriorly to the endocrine islet that arises from the posterodorsal pancreatic anlage. Then the ptf1a expression domain buds giving rise to the anteroventral pancreatic anlage that grows posteriorly to eventually engulf the endocrine islet. By 72 hpf, ptf1a continues to be expressed in the exocrine compartment derived from the anteroventral anlage. Morpholino-induced ptf1a loss of function suppresses the expression of the exocrine markers, while the endocrine markers in the islet are unaffected. In mind bomb (mib) mutants, in which delta-mediated notch signalling is defective [Dev. Cell 4 (2003) 67], ptf1a is normally expressed. In addition, the slow-muscle-omitted (smu) mutants that lack expression of endocrine markers because of a defective hedgehog signalling [Curr. Biol. 11(2001) 1358] exhibit normal levels of ptf1a. This indicates that hedgehog signaling plays a different genetic role in the specification of the anteroventral (mostly exocrine) and posterodorsal (endocrine) pancreatic anlagen. (C) 2004 Elsevier Inc. All rights reserved. [less ▲]

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See detailEvolutionary ecology of facultative paedomorphosis in newts and salamanders
Denoël, Mathieu ULg; Joly, Pierre; Whiteman, Howard H.

in Biological Reviews (2005), 80(4), 663-671

Facultative paedomorphosis is an environmentally induced polymorphism that results in the coexistence of mature, gilled, and fully aquatic paedomorphic adults and transformed, terrestrial, metamorphic ... [more ▼]

Facultative paedomorphosis is an environmentally induced polymorphism that results in the coexistence of mature, gilled, and fully aquatic paedomorphic adults and transformed, terrestrial, metamorphic adults in the same population. This polymorphism has been of interest to scientists for decades because it occurs in a large number of caudate amphibian taxa as well as in a large diversity of habitats. Numerous experimental and observational studies have been conducted to explain the proximate and ultimate factors affecting these heterochronic variants in natural populations. The production of each alternative phenotype is based on a genotype x environment interaction and research suggests that differences in the environment can produce paedomorphs through several ontogenetic pathways. No single advantage accounts for the maintenance of this polymorphism. Rather, the interplay of different costs and benefits explains the success of the polyphenism across variable environments. Facultative paedomorphosis allows individuals to cope with habitat variation, to take advantage of environmental heterogeneity in the presence of open inches, and to increase their fitness. This process is expected to constitute a first step towards speciation events, and is also an example of biodiversity at the intraspecific level. The facultative paedomorphosis system is thus ripe for future studies encompassing ecology, evolution, behaviour, endocrinology, physiology, and conservation biology. Few other systems have been broad enough to provide varied research opportunities on topics as diverse as phenotypic plasticity, speciation, mating behaviour, and hormonal regulation of morphology. Further research on facultative paedomorphosis will provide needed insight into these and other important questions facing biologists. [less ▲]

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See detailEvolutionary ecology of paedomorphosis in the Alpine newt Triturus alpestris
Denoël, Mathieu ULg

Conference (2003)

Paedomorphosis, in which individuals retain ancestral characteristics in the adult stage, is widespread in newts and salamanders and is suspected to play an important role in evolution. In some species ... [more ▼]

Paedomorphosis, in which individuals retain ancestral characteristics in the adult stage, is widespread in newts and salamanders and is suspected to play an important role in evolution. In some species, paedomorphosis is facultative with some individuals skipping the metamorphic stage. Dimorphic populations of the Alpine newt inhabit a large variety of aquatic habitats such as permanent lakes and temporary ponds. The aim of this study was to determine the benefits of the alternatives in these different habitats. To this end, I focused on resource partitioning, energy intake, body condition and age structures in different populations composed of the two morphs. In deep lakes, there was a substantial trophic differentiation between morphs. Paedomorphs primarily preyed on plankton whereas metamorphs foraged on terrestrial invertebrates that fell to the water surface. By reducing competition, resource partitioning may contribute to the coexistence of the alternative morphs in heterogeneous habitats. On the contrary, in a small pond, resource use was similar in the two morphs. Maturity is reached earlier in the paedomorphs from this small pond than in metamorphs (progenetic process), favoring then a rapid turn-over of the population, while similar gonadal development was observed in one of the deep lakes (neotenic process). Body condition was generally higher in paedomorphs than in metamorphs in each studied population. These results show that facultative paedomorphosis is adaptive in varied habitats, but that different factors may favor it depending of the characteristics of the environment. Paedomorphic phenotypes can thus be selected in low altitude productive ponds and high altitude oligotrophic lakes. [less ▲]

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See detailEvolutionary history of Leopoldamys neilli, a karst endemic rodent in Southeast Asia, and implications for its conservation
Latinne, Alice ULg; Waengsothorn, Surachit; Michaux, Johan ULg

Conference (2013, August 15)

In this study, we have investigated the phylogeography of Leopoldamys neilli, a Murinae rodent species endemic to limestone karsts in Southeast Asia, on the basis of mitochondrial and nuclear markers ... [more ▼]

In this study, we have investigated the phylogeography of Leopoldamys neilli, a Murinae rodent species endemic to limestone karsts in Southeast Asia, on the basis of mitochondrial and nuclear markers. Both mitochondrial and nuclear markers support a large-scale population structure of four main groups within L. neilli and a strong finer structure within each of these groups. A deep genealogical divergence among geographically close lineages is observed and denotes a high population fragmentation. Our findings suggest that the current phylogeographic pattern of this species results from the fragmentation of a widespread ancestral population and that vicariance has played a significant role in the evolutionary history of L. neilli during Plio-Pleistocene. This study revealed an unexpected high level of intraspecific diversity within L. neilli. Consequently, the four main L. neilli population groups should be considered as four distinct Evolutionarily Significant Units (ESUs) and require appropriate management and conservation plans. [less ▲]

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See detailEvolutionary history of the bank vole Myodes glareolus: a morphometric perspective
Ledevin, Ronan; Michaux, Johan ULg; Deffontaine, Valerie et al

in Biological Journal of the Linnean Society (2010), 100(3), 681-694

The bank vole experienced a complex history during the Quaternary. Repeated isolation in glacial refugia led to the differentiation of several lineages in less than 300 000 years. We investigated if such ... [more ▼]

The bank vole experienced a complex history during the Quaternary. Repeated isolation in glacial refugia led to the differentiation of several lineages in less than 300 000 years. We investigated if such a recent differentiation led to a significant divergence of phenotypic characters between European lineages, which might provide insight into processes of intraspecific differentiation. The size and shape of the first and third upper molars, and first lower molar, of bank voles genetically attributed to different lineages were quantified using an outline analysis of their occlusal surface. The three teeth present similar trends of decreasing size towards high latitudes. This trend, the inverse of Bergmann's rule, is interpreted as the result of a balance between metabolic efficiency and food availability, favouring small body size in cold regions. Molar shape appeared to differ between lineages despite genetic evidence of suture zones. A mosaic pattern of evolution between the different teeth was evidenced. The analysis of such phenotypic features appears as a valuable complement to genetic analyses, providing a complementary insight into evolutionary processes, such as selective pressures, that have driven the differentiation of the lineages. It may further allow the integration of the paleontological dimension of the bank vole phylogeographic history. (C) 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 681-694. [less ▲]

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See detailEvolutionary history of the most speciose mammals: molecular phylogeny of muroid rodents.
Michaux, Johan ULg; Reyes, A.; Catzeflis, F.

in Molecular Biology and Evolution (2001), 18(11), 2017-31

Phylogenetic relationships between 32 species of rodents representing 14 subfamilies of Muridae and four subfamilies of Dipodidae were studied using sequences of the nuclear protein-coding genes Lecithin ... [more ▼]

Phylogenetic relationships between 32 species of rodents representing 14 subfamilies of Muridae and four subfamilies of Dipodidae were studied using sequences of the nuclear protein-coding genes Lecithin Cholesterol Acyl Transferase (LCAT) and von Willebrand Factor (vWF). An examination of some evolutionary properties of each data matrix indicates that the two genes are rather complementary, with lower rates of nonsynonymous substitutions for LCAT. Both markers exhibit a wide range of GC3 percentages (55%-89%), with several taxa above 70% GC3 for vWF, which indicates that those exonic regions might belong to the richest class of isochores. The primary sequence data apparently harbor few saturations, except for transitions on third codon positions for vWF, as indicated by comparisons of observed and expected pairwise values of substitutions. Phylogenetic trees based on 1,962 nucleotidic sites from the two genes indicate that the 14 Muridae subfamilies are organized into five major lineages. An early isolation leads to the clade uniting the fossorial Spalacinae and semifossorial Rhizomyinae with a strong robustness. The second lineage includes a series of African taxa representing nesomyines, dendromurines, cricetomyines, and the sole living member of mystromyines. The third one comprises only the mouselike hamster CALOMYSCUS: The fourth clade represents the cricetines, myospalacines, sigmodontines, and arvicolines, whereas the fifth one comprises four "traditional" subfamilies (Gerbillinae, Murinae, Otomyinae, and Acomyinae). Within these groups, we confirm the monophyly of almost all studied subfamilies, namely, Spalacinae, Rhizomyinae, Nesomyinae, Cricetomyinae, Arvicolinae, Sigmodontinae, Cricetinae, Gerbillinae, Acomyinae, and Murinae. Finally, we present evidence that the sister group of Acomyinae is Gerbillinae, and we confirm a nested position of Myospalacinae within Cricetinae and Otomyinae within Murinae. From a biogeographical point of view, the five main lineages spread and radiated from Asia with different degrees of success: the first three groups are now represented by a limited number of species and genera localized in some regions, whereas the last two groups radiated in a large variety of species and genera dispersed all over the world. [less ▲]

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See detailEvolutionary mechanisms in colonizing plant populations
Monty, Arnaud ULg

Conference (2012, November)

In a rapidly changing world, human activities offer opportunities for many plant species to colonize new areas. Increasingly, it is recognized that colonization can be accompanied by different ecological ... [more ▼]

In a rapidly changing world, human activities offer opportunities for many plant species to colonize new areas. Increasingly, it is recognized that colonization can be accompanied by different ecological and evolutionary processes, acting over relatively short periods of time. When populations colonize novel environments, individuals’ phenotypes will depend on a combination of different, non-exclusive processes, including phenotypic plasticity (PP), local adaptation (LA), environmental maternal effects (EME) and genetic drift (GD)(Monty and Mahy 2009b). Despite these processes have long been studied independently, few attempts have been made to simultaneously address the importance of those processes in plant colonization. Here, we present a set of related studies aiming at disentangling the role of PP, LA, EME and GD in Senecio inaequidens (Asteraceae) in southern France, where it was introduced at a single wool-processing site in the late 19th century. We used seeds from populations growing in contrasted climates to explore the phenotypic variation related to climate. We performed several common garden experiments (Monty et al. 2009, Monty and Mahy 2009a, 2010), as well as a reciprocal sowing experiment with gardens under Mediterranean and Pyrenean climates (Monty et al. in revision). We analyzed climatic phenotypic variation in germination, growth, reproduction, leaf physiology and survival. We characterized genetic structure in the studied populations using AFLP. We found consistent genetic differentiation in growth traits but no home-site advantage, thus weak support for LA to climatic conditions. In contrast, genetic differentiation showed a relationship to colonization history. PP in response to climate was observed for most traits, and it played a particularly important role in leaf trait variation. EME mediated by seed mass influenced all but leaf traits under harsh climate. Heavier, earlier-germinating seeds produced larger individuals that eventually produced more flower heads throughout the growing season. However in a milder climate, EME were negligible. Our different studies suggest that phenotypic variation in response to climate depends on various ecological and evolutionary processes associated with geographical zone and life history traits. Therefore, we argue that a “local adaptation vs. phenotypic plasticity” approach, as often considered in the literature, is not sufficient to fully understand what shapes phenotypic variation and genetic architecture of colonizing populations. References Monty, A., J.-P. Bizoux, J. Escarré, and G. Mahy. in revision. Rapid plant invasion in distinct climates involves different sources of phenotypic variation. PLoS ONE. submitted Monty, A., J. Lebeau, P. Meerts, and G. Mahy. 2009. An explicit test for the contribution of environmental maternal effects to rapid clinal differentiation in an invasive plant. Journal of Evolutionary Biology 22:917-926. Monty, A. and G. Mahy. 2009a. Clinal differentiation during invasion: Senecio inaequidens along altitudinal gradients in Europe. Oecologia 159:305-315. Monty, A. and G. Mahy. 2009b. Évolution des traits d’histoire de vie lors des invasions végétales. Biotechnologie, Agronomie, Société et Environnement 13:449-458. Monty, A. and G. Mahy. 2010. Evolution of dispersal traits along an invasion route in the wind-dispersed Senecio inaequidens (Asteraceae). Oikos 119:1563-1570. [less ▲]

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See detailEvolutionary mode, tempo, and phylogenetic association of continuous morphological traits in the aquatic moss genus Amblystegium
Vanderpoorten, Alain ULg; Jacquemart, A. L.

in Journal of Evolutionary Biology (2004), 17(2), 279-287

Evolutionary significance of morphological characters that have traditionally been used for species delineation in the aquatic moss genus Amblystegium was tested by partitioning the environmentally and ... [more ▼]

Evolutionary significance of morphological characters that have traditionally been used for species delineation in the aquatic moss genus Amblystegium was tested by partitioning the environmentally and genetically induced morphological variation and focusing on morphological evolution using comparative methods. Cultivation experiments under controlled condition showed that most of the morphological variation in nature resulted from plasticity. Information regarding genetically fixed morphological variation and genetic similarity derived from polymorphic inter-simple sequence repeat markers was combined into an explicit model of morphological evolution. Maximum likelihood estimates of the model parameters indicated that evolution of most characters tended to accelerate in the most recent taxa and was often independent from the phylogeny. Constraining the different characters to be independent from each other most often produced a less likely result than when the characters were free to evolve in a correlated fashion. Thus, the morphological characters that have traditionally been used to circumscribe different Amblystegium species lack the independence, diagnostic value for specific lineages, and stability that would be required for distinguishing different species. [less ▲]

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See detailEvolutionary potential of the Fallopia spp. complex in Europe
Vanderhoeven, Sonia ULg; Krebs, Christine; Schaffner, Urs et al

Conference (2009)

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See detailEvolutionary relationships among higher fungi inferred from small ribosomal subunit RNA sequence analysis
Wilmotte, Annick ULg; Van De Peer, Yves; Goris, Anne et al

in Systematic & Applied Microbiology (1993), 16

The primary structure of the small ribosomal subunit RNA (SSU rRNA) was determined for 13 species belonging to 10 ascomycete families and for the basidiomycetous anamorphic yeast Rhodotorula glutinis. The ... [more ▼]

The primary structure of the small ribosomal subunit RNA (SSU rRNA) was determined for 13 species belonging to 10 ascomycete families and for the basidiomycetous anamorphic yeast Rhodotorula glutinis. The sequences were fitted into an alignment of all hitherto published complete or nearly complete eukaryotic small subunit rRNA sequences. The evolutionary relationships within the fungi were examined by construction of a tree from 87 SSU rRNA sequences, corresponding to 71 different species, by means of a distance matrix method and bootstrap analysis. It confirms the early divergence of the zygomycetes and the classical division of the higher fungi into basidiomycetes and ascomycetes. The basidiomycetes are divided into true basidiomycetes and ustomycetes. Within the ascomycetes, the major subdivisions hemiascomycetes and euascomycetes can be recognized. However, Schizosaccharomyces pombe does not belong to the cluster of the hemiascomycetes, to which it is assigned in classical taxonomic schemes, but forms a distinct lineage. Among the euascomycetes, the plectomycetes and the pyrenomycetes can be distinguished. Within the hemiascomycetes, the polyphyly of genera like Pichia or Candida and of families like the Dipodascaceae and the Saccharomycetaceae can be observed. [less ▲]

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See detailEvolutionary significance and trade-offs in life-history traits associated to ecological specialization and mating systems in the liverwort genus Radula Dumort.
Laenen, Benjamin ULg; Devos, Nicolas; Renner, Matt et al

Poster (2011)

Shifts in mating systems are amongst the most common and important transitions in plants and are correlated with a suite of life-history traits. The evolution of mating systems and their relationships to ... [more ▼]

Shifts in mating systems are amongst the most common and important transitions in plants and are correlated with a suite of life-history traits. The evolution of mating systems and their relationships to gametophyte size, sexual reproduction, formation of asexual diaspores, and ecological specialization, is examined here in the leafy liverwort genus Radula.More specifically, we attempt to answer the following questions:(1)What is the ancestral mating system in Radula? (2)Are shifts from one mating system to another directional or random? (3)How does the evolution of mating systems correlate with the evolution of other related life history traits and, in particular, the specialization to temporary habitats? (4)What are the contingence relationships and order of acquisitionof those traits? [less ▲]

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See detailEvolutionary trends of swimbladder sound mechanisms in some teleost fishes
Parmentier, Eric ULg; Diogo, Rui

in Ladich, F.; Collin, S. P.; Moller, P. (Eds.) et al Fish Communication (2006)

Many teleosts are able to emit sounds with their swimbladder. This chapter reviews the various sonic mechanisms involving the swimbladder and the intrinsic and extrinsic muscles, comparing them from a ... [more ▼]

Many teleosts are able to emit sounds with their swimbladder. This chapter reviews the various sonic mechanisms involving the swimbladder and the intrinsic and extrinsic muscles, comparing them from a morphological, biochemical, morphofunctional and physiological point of view. Close attention is paid to the Siluriformes and Ophidiiformes in which different cases of parallelism and/or convergence are examined. [less ▲]

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See detailLes évolutions de l’offre en logement : de la désurbanisation au renouvellement urbain
Halleux, Jean-Marie ULg

Conference given outside the academic context (2003)

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See detailLes évolutions du phénomène urbain : précision des concepts et modélisation
Halleux, Jean-Marie ULg

Conference (2001, February 28)

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See detailEvolutions et changement de paradigme dans la fonction publique fédérale belge
Piron, Damien ULg

in Revue de la Faculté de Droit de l'Université de Liège (2012), 4

Detailed reference viewed: 51 (7 ULg)