Genus Guibourtia belongs to the family Fabaceae, subfamily of Caesalpinioideae . In Africa, it is... more Genus Guibourtia belongs to the family Fabaceae, subfamily of Caesalpinioideae . In Africa, it is composed of 13 species and includes taxa with a strong cultural and commercial value. Today, the pressure of logging combined with low densities would pose significant threats to some species. Understanding the determinants of species distribution is essential to the implementation of appropriate conservation strategies . A first component of this research was to identify climate determinants explaining the distribution of species. To this end, we combined static models (MaxEnt and logistic regression) with data from global climate model CNRM CM5 , based on the occurrence of these taxa between 1950 and 2000. As result, the species of the genus Guibourtia are sensitive to precipitating factors (69.2%) and thermal amplitude (74.3 %). In a second step, it will be used climate models geological eras past to infer the distribution of the species during the Quaternary, and to establish the li...
Ten microsatellite loci were used to investigate the impact of human activity on the spatial and ... more Ten microsatellite loci were used to investigate the impact of human activity on the spatial and temporal genetic structure of Vitellaria paradoxa (Sapotaceae), a parkland tree species in agroforestry systems in southern Mali. Two stands (forest and fallow) and three cohorts (adults, juveniles and natural regeneration) in each stand were studied to: (i) compare their levels of genetic diversity (gene diversity, HE; allelic richness, Rs; and inbreeding, FIS); (ii) assess their genetic differentiation (FST); and (iii) compare their levels of spatial genetic structuring. Gene diversity parameters did not vary substantially among stands or cohorts, and tests for bottleneck events were nonsignificant. The inbreeding coefficients were not significantly different from zero in most cases (FIS = -0.025 in forest and 0.045 in fallow), suggesting that the species is probably outbreeding. There was a weak decrease in F(IS) with age, suggesting inbreeding depression. Differentiation of stands wi...
ABSTRACT Scorodophloeus zenkeri is a tropical tree from mature rainforests of Central Africa, loc... more ABSTRACT Scorodophloeus zenkeri is a tropical tree from mature rainforests of Central Africa, locally threatened by overexploitation. Ten nuclear microsatellite markers, amplifiable in two multiplexed reactions, were developed and characterized in one population. The levels of polymorphism observed (3–15 alleles per locus, expected heterozygosity ranging from 0.198 to 0.905) point at the promising application of the markers for conservation purposes regarding the location of past forest refugia, assessment of mating system and evaluation of genetic diversity in isolated and threatened populations.
AFLP markers are often used to study patterns of population genetic variation and gene flow becau... more AFLP markers are often used to study patterns of population genetic variation and gene flow because they offer a good coverage of the nuclear genome, but the reliability of AFLP scoring is critical. To assess interspecific gene flow in two African rainforest liana species (Haumania danckelmaniana, H. liebrechtsiana) where previous evidence of chloroplast captures questioned the importance of hybridization and species boundaries, we developed new AFLP markers and a novel approach to select reliable bands from their degree of reproducibility. The latter is based on the estimation of the broad-sense heritability of AFLP phenotypes, an improvement over classical scoring error rates, which showed that the polymorphism of most AFLP bands was affected by a substantial nongenetic component. Therefore, using a quantitative genetics framework, we also modified an existing estimator of pairwise kinship coefficient between individuals correcting for the limited heritability of markers. Bayesian clustering confirms the recognition of the two Haumania species. Nevertheless, the decay of the relatedness between individuals of distinct species with geographic distance demonstrates that hybridization affects the nuclear genome. In conclusion, although we showed that AFLP markers might be substantially affected by nongenetic factors, their analysis using the new methods developed considerably advanced our understanding of the pattern of gene flow in our model species.
We simulated large mammal populations using an individual-based stochastic model under various se... more We simulated large mammal populations using an individual-based stochastic model under various sex-specific migration schemes and life history parameters from the blue whale and the Asian elephant. Our model predicts that genetic structure at nuclear loci is significantly more influenced by female than by male migration. We identified requisite comigration of mother and offspring during gravidity and lactation as the primary cause of this phenomenon. In addition, our model predicts that the common assumption that geographical patterns of mitochondrial DNA (mtDNA) could be translated into female migration rates (Nmf) will cause biased estimates of maternal gene flow when extensive male migration occurs and male mtDNA haplotypes are included in the analysis.
Genus Guibourtia belongs to the family Fabaceae, subfamily of Caesalpinioideae . In Africa, it is... more Genus Guibourtia belongs to the family Fabaceae, subfamily of Caesalpinioideae . In Africa, it is composed of 13 species and includes taxa with a strong cultural and commercial value. Today, the pressure of logging combined with low densities would pose significant threats to some species. Understanding the determinants of species distribution is essential to the implementation of appropriate conservation strategies . A first component of this research was to identify climate determinants explaining the distribution of species. To this end, we combined static models (MaxEnt and logistic regression) with data from global climate model CNRM CM5 , based on the occurrence of these taxa between 1950 and 2000. As result, the species of the genus Guibourtia are sensitive to precipitating factors (69.2%) and thermal amplitude (74.3 %). In a second step, it will be used climate models geological eras past to infer the distribution of the species during the Quaternary, and to establish the li...
Ten microsatellite loci were used to investigate the impact of human activity on the spatial and ... more Ten microsatellite loci were used to investigate the impact of human activity on the spatial and temporal genetic structure of Vitellaria paradoxa (Sapotaceae), a parkland tree species in agroforestry systems in southern Mali. Two stands (forest and fallow) and three cohorts (adults, juveniles and natural regeneration) in each stand were studied to: (i) compare their levels of genetic diversity (gene diversity, HE; allelic richness, Rs; and inbreeding, FIS); (ii) assess their genetic differentiation (FST); and (iii) compare their levels of spatial genetic structuring. Gene diversity parameters did not vary substantially among stands or cohorts, and tests for bottleneck events were nonsignificant. The inbreeding coefficients were not significantly different from zero in most cases (FIS = -0.025 in forest and 0.045 in fallow), suggesting that the species is probably outbreeding. There was a weak decrease in F(IS) with age, suggesting inbreeding depression. Differentiation of stands wi...
ABSTRACT Scorodophloeus zenkeri is a tropical tree from mature rainforests of Central Africa, loc... more ABSTRACT Scorodophloeus zenkeri is a tropical tree from mature rainforests of Central Africa, locally threatened by overexploitation. Ten nuclear microsatellite markers, amplifiable in two multiplexed reactions, were developed and characterized in one population. The levels of polymorphism observed (3–15 alleles per locus, expected heterozygosity ranging from 0.198 to 0.905) point at the promising application of the markers for conservation purposes regarding the location of past forest refugia, assessment of mating system and evaluation of genetic diversity in isolated and threatened populations.
AFLP markers are often used to study patterns of population genetic variation and gene flow becau... more AFLP markers are often used to study patterns of population genetic variation and gene flow because they offer a good coverage of the nuclear genome, but the reliability of AFLP scoring is critical. To assess interspecific gene flow in two African rainforest liana species (Haumania danckelmaniana, H. liebrechtsiana) where previous evidence of chloroplast captures questioned the importance of hybridization and species boundaries, we developed new AFLP markers and a novel approach to select reliable bands from their degree of reproducibility. The latter is based on the estimation of the broad-sense heritability of AFLP phenotypes, an improvement over classical scoring error rates, which showed that the polymorphism of most AFLP bands was affected by a substantial nongenetic component. Therefore, using a quantitative genetics framework, we also modified an existing estimator of pairwise kinship coefficient between individuals correcting for the limited heritability of markers. Bayesian clustering confirms the recognition of the two Haumania species. Nevertheless, the decay of the relatedness between individuals of distinct species with geographic distance demonstrates that hybridization affects the nuclear genome. In conclusion, although we showed that AFLP markers might be substantially affected by nongenetic factors, their analysis using the new methods developed considerably advanced our understanding of the pattern of gene flow in our model species.
We simulated large mammal populations using an individual-based stochastic model under various se... more We simulated large mammal populations using an individual-based stochastic model under various sex-specific migration schemes and life history parameters from the blue whale and the Asian elephant. Our model predicts that genetic structure at nuclear loci is significantly more influenced by female than by male migration. We identified requisite comigration of mother and offspring during gravidity and lactation as the primary cause of this phenomenon. In addition, our model predicts that the common assumption that geographical patterns of mitochondrial DNA (mtDNA) could be translated into female migration rates (Nmf) will cause biased estimates of maternal gene flow when extensive male migration occurs and male mtDNA haplotypes are included in the analysis.
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Papers by Olivier Hardy