References of "Bizoux, Jean-Philippe"
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See detailForest refugia revisited: nSSRs and cpDNA sequences support historical isolation in a wide-spread African tree with high colonization capacity, Milicia excelsa (Moraceae)
Daïnou, Kasso ULg; Bizoux, Jean-Philippe ULg; Doucet, Jean-Louis ULg et al

in Molecular Ecology (2010), 19

The impact of the Pleistocene climate oscillations on the structure of biodiversity in tropical regions remains poorly understood. In this study, the forest refuge theory is examined at the molecular ... [more ▼]

The impact of the Pleistocene climate oscillations on the structure of biodiversity in tropical regions remains poorly understood. In this study, the forest refuge theory is examined at the molecular level in Milicia excelsa, a dioecious tree with a continuous range throughout tropical Africa. Eight nuclear microsatellites (nuSSRs) and two sequences and one microsatellite from chloroplast DNA (cpDNA) showed a deep divide between samples from Benin and those from Lower Guinea. This suggests both that these populations were isolated in separate geographical regions, probably for several glacial cycles of the Pleistocene, and a poor mixture of gene pools despite M. excelsa’s wind-pollination syndrome. The divide can also be related to seed dispersal patterns, which should be largely determined by the migration behaviour of M. excelsa's main seed disperser, the frugivorous bat Eidolon helvum. Within Lower Guinea, a north-south divide, observed with both markers despite weak genetic structure (nuSSRs: FST=0.035, cpDNA: GST=0.506), suggested the existence of separate Pleistocene refugia in Cameroon and the Gabon/Congo region. We inferred a pollen-to-seed dispersal distance ratio of 1.76, consistent with wide-ranging gene dispersal by both wind and bats. Simulations in an Approximate Bayesian Computation framework suggested low nuSSR and cpDNA mutation rates but imprecise estimates of other demographic parameters, probably due to a substantial gene flow between the Lower Guinean gene pools. The decline of genetic diversity detected in some Gabonese populations could be a consequence of the relatively recent establishment of a closed canopy forest which may negatively affect M. excelsa's reproductive system. [less ▲]

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See detailGenetic Diversity of Andean Tuber Crop Species in the in situ Microcenter of Huanuco, Peru
Malice, Marie ULg; Bizoux, Jean-Philippe ULg; Blas, Raul et al

in Crop Science (2010), 50(5), 1915-1923

Andean tuber crop species oca (Oxalis tuberosa Molina), ulluco (Ullucus tuberosus Caldas), and mashua (Tropaeolum tuberosum Ruiz & Pav.) play major roles in Andean communities. These species show high ... [more ▼]

Andean tuber crop species oca (Oxalis tuberosa Molina), ulluco (Ullucus tuberosus Caldas), and mashua (Tropaeolum tuberosum Ruiz & Pav.) play major roles in Andean communities. These species show high variability but are threatened with genetic erosion. To study the management of genetic resources of neglected vegetatively propagated crop species, we studied genetic diversity and structure of these species in an in situ diversity microcenter (Huanuco, Peru). A sample of 15 varieties of oca, 15 of ulluco, and 26 of mashua was analyzed with the inter simple sequence repeats (ISSR) molecular markers. Mean genetic distances and global genetic diversities were high for the three species, with higher values for mashua than for oca and ulluco. Assignment technique divided both oca and ulluco samples into two genetic clusters; the mashua sample probably belongs to a single genetic cluster. Inter simple sequence repeats (ISSR) technique showed intravarietal genetic variability for most varieties, suggesting an underestimation of the in situ genetic variability. These results are discussed considering how variation in breeding systems and farmers' practice influenced patterns of genetic diversity. Our findings confirm the hypothesis of a considerable amount of variability found in neglected Andean tubers and are essential to deserve adequate conservation strategies and to maintain genetic resources of neglected Andean tuber crop species under a threat of genetic erosion. [less ▲]

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See detailColonization Credit in Restored Wet Heathlands
Cristofoli, Sara ULg; Piqueray, Julien ULg; Dufrêne, Marc ULg et al

in Restoration Ecology (2010), 18(5), 645-655

Although human-driven landscape modification is generally characterized by habitat destruction and fragmentation, it may also result in the creation of new habitat patches, providing conditions conducive ... [more ▼]

Although human-driven landscape modification is generally characterized by habitat destruction and fragmentation, it may also result in the creation of new habitat patches, providing conditions conducive to spontaneous colonization. In this article, we propose the concept of ‘‘colonization credit’’ (i.e., the number of species yet to colonize a patch, following landscape changes) as a framework to evaluate the success of colonization, in terms of species richness, in new/restored habitats, taking into account the spatial structure of landscapes. The method mirrors similar approaches used to estimate extinction debt in the context of habitat fragmentation, that is, comparisons, between old and new habitat patches, of the relationships among spatial patch metrics and patch species richness. We applied our method to the case of spontaneous colonization of newly created habitat patches suitable for wet heathland plant communities in South Belgium. Colonization credit was estimated for the total species richness, the specialist species richness, and the species richness of three emergent groups (EGs) of specialist species, delineated on the basis of dispersal traits. No significant colonization credit was identified either in patches created 25–55 years ago or in those created within the past 25 years, with the exception of species from our first EG (mostly anemochorous species with long-term persistent seed bank). However, the differential response of species in that first EG could not be explained through their characteristic life history traits. The results of this study are encouraging and suggest that deliberate, directed restoration activities could yield positive developments in a relatively short period of time. [less ▲]

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See detailSpatial genetic structure in Milicia excelsa (Moraceae) indicates extensive gene dispersal in a low-density wind-pollinated tropical tree
Bizoux, Jean-Philippe ULg; Daïnou, Kasso ULg; Bourland, Nils ULg et al

in Molecular Ecology (2009), 18

In this study, we analysed spatial genetic structure (SGS) patterns and estimated dispersal distances in Milicia excelsa (Welw.) C.C. Berg (Moraceae), a threatened windpollinated dioecious African tree ... [more ▼]

In this study, we analysed spatial genetic structure (SGS) patterns and estimated dispersal distances in Milicia excelsa (Welw.) C.C. Berg (Moraceae), a threatened windpollinated dioecious African tree, with typically low density ( 10 adults ⁄km2). Eight microsatellite markers were used to type 287 individuals in four Cameroonian populations characterized by different habitats and tree densities. Differentiation among populations was very low. Two populations in more open habitat did not display any correlation between genetic relatedness and spatial distance between individuals, whereas significant SGS was detected in two populations situated under continuous forest cover. SGS was weak with a maximum Sp-statistic of 0.006, a value in the lower quartile of SGS estimates for trees in the literature. Using a stepwise approach with Bayesian clustering methods, we demonstrated that SGS resulted from isolation by distance and not colonization by different gene pools. Indirect estimates of gene dispersal distances ranged from rg = 1 to 7.1 km, one order of magnitude higher than most estimates found in the literature for tropical tree species. This result can largely be explained by life-history traits of the species. Milicia excelsa exhibits a potentially wideranging wind-mediated pollen dispersal mechanism as well as very efficient seed dispersal mediated by large frugivorous bats. Estimations of gene flow suggested no major risk of inbreeding because of reduction in population density by exploitation. Different strategy of seed collection may be required for reforestation programmes among populations with different extent of SGS. [less ▲]

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See detailFitness And Genetic Variation Of Viola Calaminaria, An Endemic Metallophyte: Implications Of Population Structure And History
Bizoux, Jean-Philippe ULg; Daïnou, Kasso ULg; Raspe, O. et al

in Plant Biology (2008), 10(6), 684-693

We investigated variations in genetic diversity and plant fitness in a rare endemic metallophyte of calamine soils, Viola calaminaria, in relation to population size, population connectivity and ... [more ▼]

We investigated variations in genetic diversity and plant fitness in a rare endemic metallophyte of calamine soils, Viola calaminaria, in relation to population size, population connectivity and population history in order to evaluate and discuss potential conservation strategies for the species. Mean population genetic diversity (Hs = 0.25) of V. calaminaria was similar to endemic non-metallophyte taxa. Twenty-one per cent of the genetic variation was partitioned among populations and a low (9%) but significant differentiation was found among geographical regions. Our results did not support the hypothesis that the acquisition of metal tolerance may result in reduced genetic diversity, and suggested that strict metallophytes do not exhibit higher inter-population differentiation resulting from scattered habitats. There were no relationships between population genetic diversity and population size. Significant correlations were found between plant fitness and (i) population size and (ii) connectivity index. Recently-founded populations exhibited the same level of genetic diversity as ancient populations and also possessed higher plant fitness. There was no indication of strong founder effects in recently-established populations. The results suggest that the creation of habitats through human activities could provide new opportunities for conservation of this species. [less ▲]

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See detailGenetic Structure Of Quinoa (Chenopodium Quinoa Willd.) From The Bolivian Altiplano As Revealed By Rapd Markers
Del Castillo, C.; Winkel, T.; Mahy, Grégory ULg et al

in Genetic Resources and Crop Evolution (2007), 54(4), 897-905

Quinoa (Chenopodium quinoa Willd.) is a pseudocereal originated from the Andes important for small farmers’ food security as well as for commercial production. Recently, it has been claimed that in ... [more ▼]

Quinoa (Chenopodium quinoa Willd.) is a pseudocereal originated from the Andes important for small farmers’ food security as well as for commercial production. Recently, it has been claimed that in Bolivia genetic erosion could result from the marginalization of the crop in the north and from its commercial standardization in the south. The aim of this study was to quantify the hierarchical structure of the genetic variation present in eight quinoa field populations, consisting of cultivated and weedy individuals, representative of the altiplano and interandean valleys of Bolivia. Randomly amplified polymorphic DNA markers show that quinoa has a strong population structure and a high intra-population variation. An effect of geographical structure of the populations was highlighted, due to population isolation, not simply linked to distance but more probably to climatic and orographic barriers present in the studied zone. The population structure is also reinforced by the limited seed exchanges among farmers as revealed by field interviews. This population structure appears related to three major biogeographic zones: the northern and central altiplano, the interandean valley, and the southern Salar. Intrapopulation genetic diversity was higher than that expected for a mainly autogamous species, and higher than that reported in anterior studies based on germplasm collections. These results are commented in view of current knowledge on phylogeny and reproductive biology of the species, and their implications regarding genetic resources management are discussed. [less ▲]

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See detailHybridization And Morphogenetic Variation In The Invasive Alien Fallopia (Polygonaceae) Complex In Belgium
Tiebre, Ms.; Bizoux, Jean-Philippe ULg; Hardy, Oj. et al

in American Journal of Botany (2007), 94(11), 1900-1910

The invasive alien knotweeds, Fallopia spp. (Polygonaceae), are some of the most troublesome invasive species in Europe and North America. Invasive success in Fallopia may be enhanced by multiple ... [more ▼]

The invasive alien knotweeds, Fallopia spp. (Polygonaceae), are some of the most troublesome invasive species in Europe and North America. Invasive success in Fallopia may be enhanced by multiple hybridization events. We examined the pattern of hybridization and its evolutionary consequences in Belgium with a concerted analysis of ploidy levels (chromosome counts and flow cytometry), morphological variation, and genetic variation (RAPDs). At least four taxa with different ploidy levels were part of the pattern of invasion in Belgium. Hybrid F.3bohemica with various chromosome numbers restored the genotypic diversity that was lacking in the parental species. Hybrid genotypes were mainly assigned to a specific genetic pool and not to a mixture between the genetic pools of the putative parental species as would be expected for hybrids. Parental species and hexaploid hybrids differed significantly for a set of well-defined morphological characters, enabling future researchers to distinguish these taxa. On the basis of our results, the importance of hybridization has probably been underestimated in large parts of the adventive range of alien Fallopia species, pointing to the need for concerted molecular and morphological analyses in the study of the evolutionary consequences of hybridization. [less ▲]

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See detailWithin-Population Genetic Structure And Clonal Diversity Of A Threatened Endemic Metallophyte, Viola Calaminaria (Violaceae)
Bizoux, Jean-Philippe ULg; Mahy, Grégory ULg

in American Journal of Botany (2007), 94(5), 887-895

We studied the within-population genetic structure and the clonality extent of Viola calaminaria, a rare endemic species of calamine soils, by means of RAPD markers in two populations (one recent and one ... [more ▼]

We studied the within-population genetic structure and the clonality extent of Viola calaminaria, a rare endemic species of calamine soils, by means of RAPD markers in two populations (one recent and one ancient) with expected harsh and heterogeneous heavy-metal stress. At a very local scale (0.2 3 m), clonal propagation was detected in both populations, but the levels of clonal diversity were high (number of genets/number of ramets sampled ¼ 0.9 [recent] and 0.76 [ancient]) and the maximal observed extension of the clones was 0.4 m. This indicated that clonality is not, for the species, an important mode of propagation and that clonal growth cannot be interpreted as a strategy for propagating or perpetuating adapted genotypes under harsh ecological constraints. Spatial autocorrelations revealed a significant (P , 0.001) negative value of correlogram slope in the two populations even when a single individual per clone was considered (i.e., analysis at the genet level). We conclude that spatial genetic structure at a very local scale reflects limited gene flow due to restricted seed dispersal rather than variation in clonal pattern in response to environmental heterogeneity. At a larger scale (2–30 m), spatial autocorrelations revealed a positive (P , < 0.001) correlation at , 3 m and a random pattern at larger distances for the two populations. This suggested a patchy distribution of the genetically linked individuals associated with a disrupted pattern at a longer distance probably due to gene flow by pollen dispersal and a seed bank effect. The implications for the conservation of V. calaminaria are discussed. [less ▲]

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See detailInfluence of human activities on the metallic trace elements status in soils
Colinet, Gilles ULg; Bizoux, Jean-Philippe ULg; Bock, Laurent ULg

Conference (2006)

The total concentrations of trace elements in soils results from natural and anthropic factors. Knowledge of natural distribution (e.g. bio-geochemical background) helps assessing the impacts of human ... [more ▼]

The total concentrations of trace elements in soils results from natural and anthropic factors. Knowledge of natural distribution (e.g. bio-geochemical background) helps assessing the impacts of human activities in terms of contaminations. But the processes generated by the modifications of the soil environment may also affect the form of a trace element, that is its distribution through various pools. We investigated the chemical speciation of some metallic trace elements (Cu, Zn, Cr, Ni, Pb, Co, Cd) in soils from various land-use environment: “natural” soils under forest, “typical” cultivated soils, kitchen-garden soils, soils developped on geogenic anomalies and on contaminated areas. The analysis protocol aims at identifying different pools from their reaction to various extraction phases, ordered by increasing intensity in a single sequence. The different fractions are so-called soluble, linked to carbonates, to organic matter, to manganese oxides, to weakly cristallized Fe-Al oxides, to well-cristallized oxides, and residual. The “available” and total fractions have also been measured. The results stress the fact that the comparisons are difficult from one situation to another because each one represents a particular case of human activity without a common logic. The relationships with the classical pedological parameters are therefore difficult to generalize. However some relationships between elements have been found inside the various types of land use, which could be usefull in the risk assesment of transfers from soils to plants. [less ▲]

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See detailViola calaminaria: genetic diversity and occurrence in Belgium.
Bizoux, Jean-Philippe ULg; Brevers, florence; Mahy, Grégory ULg

Conference (2006)

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See detailGenetic variation of Viola calaminaria, an endemic metallophyte
Bizoux, Jean-Philippe ULg; Mahy, Grégory ULg

in Proceedings of the GfÖ: Lanscapes, ecosystems and populations: dynamics, functions and conservation (2005)

The zinc violet, Viola calaminaria (DC) Lej., is a rare threatened species in Belgium which is endemic to metalliferous sites. Yours aims were to assess the genetic structure of the species at the scale ... [more ▼]

The zinc violet, Viola calaminaria (DC) Lej., is a rare threatened species in Belgium which is endemic to metalliferous sites. Yours aims were to assess the genetic structure of the species at the scale of its distribution range, including differentiation with related taxa Viola guesphalica and to examine the influence of population size and recent colonisation events on population genetic structure in order to identify conservation priorities. The analysis of genetic variation (Amova) showed a strong population differentiation (Fst = 0.26) with a regional group differentiation. The V. guestfalica population exhibits the larger differentiation (Fst = 0.19). The levels of population genetic diversity (Hs) varied from 0.21 to 0.29. Mean genetic differentiation among ancient populations (Fst =0.26) is higher than genetic differentiation among recent populations (Fst =0.18) while any difference appears on genetic diversity. This strong population differentiation suggests a low gene flow between populations but sufficient within population to maintain high level of diversity. For management, the result implies a hierarchical conservation strategy including small population. New populations had as much genetically importance than old populations. No foundation effects were detected in the recent populations. These populations probably result from multiple colonization effects from more than one source population. Finally, even if some V. calaminaria populations exhibit a similar level of genetic differentiation of V. guestfalica population, this one appeared as a particular genetic pool. [less ▲]

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