Eric Bandou - Academia.edu (original) (raw)
Papers by Eric Bandou
Levels of genetic diversity were estimated for 8 forest trees of French Guiana which were selecte... more Levels of genetic diversity were estimated for 8 forest trees of French Guiana which were selected because of their contrasting life history traits. Multilocus methods are used as RAPDs or AFLPs in order to assess genetic diversity at the whole genome level. However these markers suffer from a major drawback: they behave generally as dominant markers. Theoretical calculations were made to compare two different methods to assess genetic diversity with dominant markers, the phenotypic diversity (Hp) that considers presence and absence of fragments versus the genotypic diversity (Hg) that considers the alleles responsible for the presence or the absence of the bands. It is shown that these values (Hp and Hg) can only be compared in a limited number of cases, according to the frequency of the bands. The genetic monitoring of gene diversity is based on a two step sampling procedure: (i) the intra-locus sampling, e.g. sampling of trees and populations and (ii) the inter-locus sampling, e....
Forestry Sciences, 2001
The small scale spatial genetic structure of six tropical tree species (Carapa procera, Chrysophy... more The small scale spatial genetic structure of six tropical tree species (Carapa procera, Chrysophyllum sanguinolentum, Dicorynia guianensis, Eperua grandiflora, Virola michelii, Vouacapoua americana) was studied for populations located within a sylvicultural trial in French Guiana. The analysed species have different biological and ecological characteristics with respect to spatial distribution, sexual system, pollen and seed dispersal agents, flowering phenology, and they differ in their environmental demands. The spatial position of trees and at least one data set on the genetic information for allozymes, cp-DNA marker, RAPDs and AFLPs served as basis for the analysis. As estimator for spatial genetic structure, Moran’s index was computed for allozymes and cp-DNA markers, while for RAPDs and AFLPs mean Tanimoto distances between pairs of trees in different spatial distance classes were calculated. Each species showed significant spatial structure for at least one type of gene marker. The expansion of significant spatial genetic structures was relatively large and varied between 60m up to 800m. The strongest spatial autocorrelation was found for maternally inherited cp-DNA marker. Due to distinctly higher level of genetic variation, AFLPs and RAPDs were more sensitive to detect spatial structure than allozymes. Relations between the spatial genetic structures and the species’ life characteristics are discussed.
Molecular Ecology, 2004
Outcrossing rates, pollen dispersal and male mating success were assessed in Dicorynia guianensis... more Outcrossing rates, pollen dispersal and male mating success were assessed in Dicorynia guianensis Amshoff, a neotropical tree endemic to the Guiana shield. All adult trees within a continuous area of 40 ha (n = 157) were mapped, and were genotyped with six microsatellite loci. In addition, progenies were genotyped from 22 mature trees. At the population level, the species was mostly outcrossing (t m = 0.89) but there was marked variation among individuals. One tree exhibited mixed mating, confirming earlier results obtained with isozymes that D. guianensis can tolerate selfing. A Bayesian extension of the fractional paternity method was used for paternity analysis, and was compared with the neighbourhood method used widely for forest trees. Both methods indicated that pollen dispersal was only weakly related to distance between trees within the study area, and that the majority (62%) of pollen came from outside the study stand. Using maximum likelihood, male potential population size was estimated to be 1119, corresponding to a neighbourhood size of 560 hectares. Male mating success was, however, related to the diameter of the stem and to flowering intensity assessed visually. The mating behaviour of D. guianensis is a combination of long-distance pollen flow and occasional selfing. The species can still reproduce when it is extremely rare, either by selfing or by dispersing pollen at long distances. These results, together with the observation that male mating success was correlated with the size of the trees, could be implemented in management procedures aiming at regenerating the species.
Heredity, 2003
Dicorynia guianensis is a canopy tree, endemic to the tropical rain forest of French Guiana. We c... more Dicorynia guianensis is a canopy tree, endemic to the tropical rain forest of French Guiana. We compared generational and spatial genetic structure for maternally and biparentally inherited markers in two cohorts (adult and seedling) in order to infer processes shaping the distribution of genetic diversity. The study was conducted on a 40 ha study plot located at Paracou near Kourou, where 172 adults trees and 375 saplings were sampled. Aggregation of trees was therefore suggested at different distances, ranging from 100 to 400 m. There was a strong link between demographic and genetic spatial structures at small distances (less than 100 m) that is likely to be the consequence of restricted seed dispersal. Genetic differentiation was more pronounced between spatial aggregates than between cohorts. Despite the spatial differentiation, the species was able to maintain high levels of diversity for maternal genomes, suggesting rapid turnover of aggregates. Spatial autocorrelation was larger for chloroplast than nuclear markers indicating a strong asymmetry between pollen and seed flow. Fixation indices indicated a lower heterozygote deficiency for the adults, maybe because of gradual elimination of selfed trees. Genetic relatedness at lower distances was higher in adult trees than in saplings, as a result of generation overlapping in the adult cohort. Overall, our results confirm earlier biological knowledge about the dispersion mechanisms of the species, and lead to an enhanced role of spatial processes in the dynamics of genetic diversity of D. guianensis.
Direct measures of gene flow in forest. Gene flow through seeds and pollen are major processes sh... more Direct measures of gene flow in forest. Gene flow through seeds and pollen are major processes shaping genetic diversity in plants. In this project we studied gene flow in five tree species of contrasting life history traits: social species (oaks), scattered species (wild service tree, ash tree, angelique), introduced species (cedar), monoecious and dioecious species, species from temperate and tropical forests. For each species, we performed a parentage analysis in order to assign male and female parents to saplings sampled in the stands. We used codominant or dominant molecular markers and the same analytical methods for parentage studies (FaMoz software). Our ability to reconstruct parent-offspring relationships inside stands and to estimate the gene flow stemming from outside the studied area differed markedly among species. Observed dispersions were always shorter than expected at random, reduced gene flow inside the stands was thus favoured. Contrasted results between male (pollen) and female (seeds) dispersions are likely due to particular pollination systems and diverse seed dispersion mechanisms. gene flow / markers / forest trees / parentage Résumé-Les flux de gènes par graines et par pollen sont à l'origine de la dynamique de l'évolution de la diversité végétale. Nous avons étudié cinq espèces de biologie et d'histoire contrastées : espèce sociale (chênes), espèces dispersées (alisier, frêne, angélique), espèce introduite (cèdre), espèces monoïque ou dioïque, espèces des forêts tempérées et tropicales. Pour chacune de ces espèces, nous avons mis en
Major target Additional target Research programme Systems research on natural capital and the hum... more Major target Additional target Research programme Systems research on natural capital and the human environment Tools for sustainable development Key action Strategies for rural productivity; ecosystem management for sustainability (b.i) Technologies for sustainable crop and animal production: building blocks for improvement. Cash crops and forestry (c.ii-1) Region code LAM Contract Number Project number: ICA4-CT-2001-10101 Project homepage http://www.edinburgh.ceh.ac.uk/geneo Sustainable management of Neo-Tropical Tree Genetic Resources: Combining molecular and modelling methods to understand the structure and dynamics of gene diversity GENEO-TROPECO
Molecular Ecology Notes, 2002
Dicorynia guianensis is a canopy tree endemic to French Guyana and the first to be exploited as t... more Dicorynia guianensis is a canopy tree endemic to French Guyana and the first to be exploited as timber wood. To investigate levels of diversity and dynamics of gene flow in a 40-ha study plot, highly polymorphic microsatellite markers were developed. An enriched microsatellite library was constructed and seven microsatellite primer pairs were developed. Total genomic DNA was extracted and amplified from cambium tissue from 172 adult individuals. The level of genetic diversity was found to be low. A large heterozygote deficiency was found at one locus. This was resolved by redesigning the primer set.
![Research paper thumbnail of Viral treasure hunt in European outermost territories: how metagenomics boosts the discovery of novel viral species in tropical and sub-tropical crops germplasm. [O.18]](https://attachments.academia-assets.com/101363154/thumbnails/1.jpg)
](A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) wa... more A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) was performed on 6 tropical and subtropical crops (banana, garlic, sugarcane, sweet potato, vanilla and yam) originating from the Azores, Guadeloupe, Madeira and Reunion. Roche 454-based sequencing of purified dsRNA and virion-associated nucleic acids (VANA) proved the best strategies for recovering plant virus sequences following a first screening performed on a set of 96 plant samples. These two metagenomics approaches were further used on a total of 740 plant samples of the 6 targeted crops. Following demultiplexing, reads were either mapped against viral references or assembled into contigs and annotated using Blast analyses, leading to the identification and molecular characterization of 5 new viral species in garlic, 10 in yams, 7 in sugarcane, and 3 in vanilla. Sequences hinting at the possible presence of additional novel agents were also identified. In addition, a systematic searc...
![Research paper thumbnail of Viral treasure hunt in European outermost territories: how metagenomics boosts the discovery of novel viral species in tropical and sub-tropical crops germplasm. [O.18]](https://attachments.academia-assets.com/101363151/thumbnails/1.jpg)
](A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) wa... more A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) was performed on 6 tropical and subtropical crops (banana, garlic, sugarcane, sweet potato, vanilla and yam) originating from the Azores, Guadeloupe, Madeira and Reunion. Roche 454-based sequencing of purified dsRNA and virion-associated nucleic acids (VANA) proved the best strategies for recovering plant virus sequences following a first screening performed on a set of 96 plant samples. These two metagenomics approaches were further used on a total of 740 plant samples of the 6 targeted crops. Following demultiplexing, reads were either mapped against viral references or assembled into contigs and annotated using Blast analyses, leading to the identification and molecular characterization of 5 new viral species in garlic, 10 in yams, 7 in sugarcane, and 3 in vanilla. Sequences hinting at the possible presence of additional novel agents were also identified. In addition, a systematic searc...
![Research paper thumbnail of Viral treasure hunt in European outermost territories: how metagenomics boosts the discovery of novel viral species in tropical and sub-tropical crops germplasm. [O.18]](https://attachments.academia-assets.com/101363150/thumbnails/1.jpg)
](A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) wa... more A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) was performed on 6 tropical and subtropical crops (banana, garlic, sugarcane, sweet potato, vanilla and yam) originating from the Azores, Guadeloupe, Madeira and Reunion. Roche 454-based sequencing of purified dsRNA and virion-associated nucleic acids (VANA) proved the best strategies for recovering plant virus sequences following a first screening performed on a set of 96 plant samples. These two metagenomics approaches were further used on a total of 740 plant samples of the 6 targeted crops. Following demultiplexing, reads were either mapped against viral references or assembled into contigs and annotated using Blast analyses, leading to the identification and molecular characterization of 5 new viral species in garlic, 10 in yams, 7 in sugarcane, and 3 in vanilla. Sequences hinting at the possible presence of additional novel agents were also identified. In addition, a systematic searc...
13èmes Rencontres de virologie végétale (RVV 2011), Aussois, France, 16-20 janvier 2011, 2011
Ectomycorrhizal Symbioses in Tropical and Neotropical Forests, 2014
Mycorrhiza, 2006
The purpose of this study was to test the capacity of the ectomycorrhizal (ECM) fungus, Scleroder... more The purpose of this study was to test the capacity of the ectomycorrhizal (ECM) fungus, Scleroderma bermudense, to alleviate saline stress in seagrape (Coccoloba uvifera L.) seedlings. Plants were grown over a range (0, 200, 350 and 500 mM) of NaCl levels for 12 weeks, after 4 weeks of non-saline pre-treatment under greenhouse conditions. Growth and mineral nutrition of the seagrape seedlings were stimulated by S. bermudense regardless of salt stress. Although ECM colonization was reduced with increasing NaCl levels, ECM dependency of seagrape seedlings increased. Tissues of ECM plants had significantly increased concentrations of P and K but lower Na and Cl concentrations than those of non-ECM plants. Higher K concentrations in the leaves of ECM plants suggested a higher osmoregulating capacity of these plants. Moreover, the water status of ECM plants was improved despite their higher evaporative leaf surface. The results suggest that the reduction in Na and Cl uptake together with a concomitant increase in P and K absorption and a higher water status in ECM plants may be important salt-alleviating mechanisms for seagrape seedlings growing in saline soils.
Molecular Ecology, 2000
The level and the spatial organization of chloroplast DNA polymorphism were investigated in Dicor... more The level and the spatial organization of chloroplast DNA polymorphism were investigated in Dicorynia guianensis Hamshoff (Caesalpiniaceae) at different spatial and temporal scales. D. guianensis is a canopy tree of the rain forest that is distributed throughout the Guiana plateau in small aggregates. Twelve different haplotypes were identified using restriction analysis of polymerase chain reaction (PCR) amplified fragments of the chloroplast genome. When populations from different areas of French Guiana were compared, a clear geographical pattern of haplotype frequencies was identified along the Atlantic coast. This pattern is most likely the result of the restriction-expansion dynamics of the tropical forest during the Quaternary. At the local level, D. guianensis was characterized by a high level of within population diversity. Maintenance of within population diversity results from the dynamics of the aggregates; stochastic demography associated with the turnover of aggregates generates genetic differentiation among them. At the stand level, a strong spatial aggregation of haplotypes persisted from the adult to the seedling cohort indicating limited seed flow. There was also a strong difference in levels of diversity between the cohorts which suggested that recruitment over several years is needed in order to maintain genetic diversity during regeneration.
Levels of genetic diversity were estimated for 8 forest trees of French Guiana which were selecte... more Levels of genetic diversity were estimated for 8 forest trees of French Guiana which were selected because of their contrasting life history traits. Multilocus methods are used as RAPDs or AFLPs in order to assess genetic diversity at the whole genome level. However these markers suffer from a major drawback: they behave generally as dominant markers. Theoretical calculations were made to compare two different methods to assess genetic diversity with dominant markers, the phenotypic diversity (Hp) that considers presence and absence of fragments versus the genotypic diversity (Hg) that considers the alleles responsible for the presence or the absence of the bands. It is shown that these values (Hp and Hg) can only be compared in a limited number of cases, according to the frequency of the bands. The genetic monitoring of gene diversity is based on a two step sampling procedure: (i) the intra-locus sampling, e.g. sampling of trees and populations and (ii) the inter-locus sampling, e....
Forestry Sciences, 2001
The small scale spatial genetic structure of six tropical tree species (Carapa procera, Chrysophy... more The small scale spatial genetic structure of six tropical tree species (Carapa procera, Chrysophyllum sanguinolentum, Dicorynia guianensis, Eperua grandiflora, Virola michelii, Vouacapoua americana) was studied for populations located within a sylvicultural trial in French Guiana. The analysed species have different biological and ecological characteristics with respect to spatial distribution, sexual system, pollen and seed dispersal agents, flowering phenology, and they differ in their environmental demands. The spatial position of trees and at least one data set on the genetic information for allozymes, cp-DNA marker, RAPDs and AFLPs served as basis for the analysis. As estimator for spatial genetic structure, Moran’s index was computed for allozymes and cp-DNA markers, while for RAPDs and AFLPs mean Tanimoto distances between pairs of trees in different spatial distance classes were calculated. Each species showed significant spatial structure for at least one type of gene marker. The expansion of significant spatial genetic structures was relatively large and varied between 60m up to 800m. The strongest spatial autocorrelation was found for maternally inherited cp-DNA marker. Due to distinctly higher level of genetic variation, AFLPs and RAPDs were more sensitive to detect spatial structure than allozymes. Relations between the spatial genetic structures and the species’ life characteristics are discussed.
Molecular Ecology, 2004
Outcrossing rates, pollen dispersal and male mating success were assessed in Dicorynia guianensis... more Outcrossing rates, pollen dispersal and male mating success were assessed in Dicorynia guianensis Amshoff, a neotropical tree endemic to the Guiana shield. All adult trees within a continuous area of 40 ha (n = 157) were mapped, and were genotyped with six microsatellite loci. In addition, progenies were genotyped from 22 mature trees. At the population level, the species was mostly outcrossing (t m = 0.89) but there was marked variation among individuals. One tree exhibited mixed mating, confirming earlier results obtained with isozymes that D. guianensis can tolerate selfing. A Bayesian extension of the fractional paternity method was used for paternity analysis, and was compared with the neighbourhood method used widely for forest trees. Both methods indicated that pollen dispersal was only weakly related to distance between trees within the study area, and that the majority (62%) of pollen came from outside the study stand. Using maximum likelihood, male potential population size was estimated to be 1119, corresponding to a neighbourhood size of 560 hectares. Male mating success was, however, related to the diameter of the stem and to flowering intensity assessed visually. The mating behaviour of D. guianensis is a combination of long-distance pollen flow and occasional selfing. The species can still reproduce when it is extremely rare, either by selfing or by dispersing pollen at long distances. These results, together with the observation that male mating success was correlated with the size of the trees, could be implemented in management procedures aiming at regenerating the species.
Heredity, 2003
Dicorynia guianensis is a canopy tree, endemic to the tropical rain forest of French Guiana. We c... more Dicorynia guianensis is a canopy tree, endemic to the tropical rain forest of French Guiana. We compared generational and spatial genetic structure for maternally and biparentally inherited markers in two cohorts (adult and seedling) in order to infer processes shaping the distribution of genetic diversity. The study was conducted on a 40 ha study plot located at Paracou near Kourou, where 172 adults trees and 375 saplings were sampled. Aggregation of trees was therefore suggested at different distances, ranging from 100 to 400 m. There was a strong link between demographic and genetic spatial structures at small distances (less than 100 m) that is likely to be the consequence of restricted seed dispersal. Genetic differentiation was more pronounced between spatial aggregates than between cohorts. Despite the spatial differentiation, the species was able to maintain high levels of diversity for maternal genomes, suggesting rapid turnover of aggregates. Spatial autocorrelation was larger for chloroplast than nuclear markers indicating a strong asymmetry between pollen and seed flow. Fixation indices indicated a lower heterozygote deficiency for the adults, maybe because of gradual elimination of selfed trees. Genetic relatedness at lower distances was higher in adult trees than in saplings, as a result of generation overlapping in the adult cohort. Overall, our results confirm earlier biological knowledge about the dispersion mechanisms of the species, and lead to an enhanced role of spatial processes in the dynamics of genetic diversity of D. guianensis.
Direct measures of gene flow in forest. Gene flow through seeds and pollen are major processes sh... more Direct measures of gene flow in forest. Gene flow through seeds and pollen are major processes shaping genetic diversity in plants. In this project we studied gene flow in five tree species of contrasting life history traits: social species (oaks), scattered species (wild service tree, ash tree, angelique), introduced species (cedar), monoecious and dioecious species, species from temperate and tropical forests. For each species, we performed a parentage analysis in order to assign male and female parents to saplings sampled in the stands. We used codominant or dominant molecular markers and the same analytical methods for parentage studies (FaMoz software). Our ability to reconstruct parent-offspring relationships inside stands and to estimate the gene flow stemming from outside the studied area differed markedly among species. Observed dispersions were always shorter than expected at random, reduced gene flow inside the stands was thus favoured. Contrasted results between male (pollen) and female (seeds) dispersions are likely due to particular pollination systems and diverse seed dispersion mechanisms. gene flow / markers / forest trees / parentage Résumé-Les flux de gènes par graines et par pollen sont à l'origine de la dynamique de l'évolution de la diversité végétale. Nous avons étudié cinq espèces de biologie et d'histoire contrastées : espèce sociale (chênes), espèces dispersées (alisier, frêne, angélique), espèce introduite (cèdre), espèces monoïque ou dioïque, espèces des forêts tempérées et tropicales. Pour chacune de ces espèces, nous avons mis en
Major target Additional target Research programme Systems research on natural capital and the hum... more Major target Additional target Research programme Systems research on natural capital and the human environment Tools for sustainable development Key action Strategies for rural productivity; ecosystem management for sustainability (b.i) Technologies for sustainable crop and animal production: building blocks for improvement. Cash crops and forestry (c.ii-1) Region code LAM Contract Number Project number: ICA4-CT-2001-10101 Project homepage http://www.edinburgh.ceh.ac.uk/geneo Sustainable management of Neo-Tropical Tree Genetic Resources: Combining molecular and modelling methods to understand the structure and dynamics of gene diversity GENEO-TROPECO
Molecular Ecology Notes, 2002
Dicorynia guianensis is a canopy tree endemic to French Guyana and the first to be exploited as t... more Dicorynia guianensis is a canopy tree endemic to French Guyana and the first to be exploited as timber wood. To investigate levels of diversity and dynamics of gene flow in a 40-ha study plot, highly polymorphic microsatellite markers were developed. An enriched microsatellite library was constructed and seven microsatellite primer pairs were developed. Total genomic DNA was extracted and amplified from cambium tissue from 172 adult individuals. The level of genetic diversity was found to be low. A large heterozygote deficiency was found at one locus. This was resolved by redesigning the primer set.
A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) wa... more A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) was performed on 6 tropical and subtropical crops (banana, garlic, sugarcane, sweet potato, vanilla and yam) originating from the Azores, Guadeloupe, Madeira and Reunion. Roche 454-based sequencing of purified dsRNA and virion-associated nucleic acids (VANA) proved the best strategies for recovering plant virus sequences following a first screening performed on a set of 96 plant samples. These two metagenomics approaches were further used on a total of 740 plant samples of the 6 targeted crops. Following demultiplexing, reads were either mapped against viral references or assembled into contigs and annotated using Blast analyses, leading to the identification and molecular characterization of 5 new viral species in garlic, 10 in yams, 7 in sugarcane, and 3 in vanilla. Sequences hinting at the possible presence of additional novel agents were also identified. In addition, a systematic searc...
A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) wa... more A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) was performed on 6 tropical and subtropical crops (banana, garlic, sugarcane, sweet potato, vanilla and yam) originating from the Azores, Guadeloupe, Madeira and Reunion. Roche 454-based sequencing of purified dsRNA and virion-associated nucleic acids (VANA) proved the best strategies for recovering plant virus sequences following a first screening performed on a set of 96 plant samples. These two metagenomics approaches were further used on a total of 740 plant samples of the 6 targeted crops. Following demultiplexing, reads were either mapped against viral references or assembled into contigs and annotated using Blast analyses, leading to the identification and molecular characterization of 5 new viral species in garlic, 10 in yams, 7 in sugarcane, and 3 in vanilla. Sequences hinting at the possible presence of additional novel agents were also identified. In addition, a systematic searc...
A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) wa... more A comparative assay of 8 viral metagenomic protocols based on next generation sequencing (NGS) was performed on 6 tropical and subtropical crops (banana, garlic, sugarcane, sweet potato, vanilla and yam) originating from the Azores, Guadeloupe, Madeira and Reunion. Roche 454-based sequencing of purified dsRNA and virion-associated nucleic acids (VANA) proved the best strategies for recovering plant virus sequences following a first screening performed on a set of 96 plant samples. These two metagenomics approaches were further used on a total of 740 plant samples of the 6 targeted crops. Following demultiplexing, reads were either mapped against viral references or assembled into contigs and annotated using Blast analyses, leading to the identification and molecular characterization of 5 new viral species in garlic, 10 in yams, 7 in sugarcane, and 3 in vanilla. Sequences hinting at the possible presence of additional novel agents were also identified. In addition, a systematic searc...
13èmes Rencontres de virologie végétale (RVV 2011), Aussois, France, 16-20 janvier 2011, 2011
Ectomycorrhizal Symbioses in Tropical and Neotropical Forests, 2014
Mycorrhiza, 2006
The purpose of this study was to test the capacity of the ectomycorrhizal (ECM) fungus, Scleroder... more The purpose of this study was to test the capacity of the ectomycorrhizal (ECM) fungus, Scleroderma bermudense, to alleviate saline stress in seagrape (Coccoloba uvifera L.) seedlings. Plants were grown over a range (0, 200, 350 and 500 mM) of NaCl levels for 12 weeks, after 4 weeks of non-saline pre-treatment under greenhouse conditions. Growth and mineral nutrition of the seagrape seedlings were stimulated by S. bermudense regardless of salt stress. Although ECM colonization was reduced with increasing NaCl levels, ECM dependency of seagrape seedlings increased. Tissues of ECM plants had significantly increased concentrations of P and K but lower Na and Cl concentrations than those of non-ECM plants. Higher K concentrations in the leaves of ECM plants suggested a higher osmoregulating capacity of these plants. Moreover, the water status of ECM plants was improved despite their higher evaporative leaf surface. The results suggest that the reduction in Na and Cl uptake together with a concomitant increase in P and K absorption and a higher water status in ECM plants may be important salt-alleviating mechanisms for seagrape seedlings growing in saline soils.
Molecular Ecology, 2000
The level and the spatial organization of chloroplast DNA polymorphism were investigated in Dicor... more The level and the spatial organization of chloroplast DNA polymorphism were investigated in Dicorynia guianensis Hamshoff (Caesalpiniaceae) at different spatial and temporal scales. D. guianensis is a canopy tree of the rain forest that is distributed throughout the Guiana plateau in small aggregates. Twelve different haplotypes were identified using restriction analysis of polymerase chain reaction (PCR) amplified fragments of the chloroplast genome. When populations from different areas of French Guiana were compared, a clear geographical pattern of haplotype frequencies was identified along the Atlantic coast. This pattern is most likely the result of the restriction-expansion dynamics of the tropical forest during the Quaternary. At the local level, D. guianensis was characterized by a high level of within population diversity. Maintenance of within population diversity results from the dynamics of the aggregates; stochastic demography associated with the turnover of aggregates generates genetic differentiation among them. At the stand level, a strong spatial aggregation of haplotypes persisted from the adult to the seedling cohort indicating limited seed flow. There was also a strong difference in levels of diversity between the cohorts which suggested that recruitment over several years is needed in order to maintain genetic diversity during regeneration.