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Heino Konrad - One of the best experts on this subject based on the ideXlab platform.
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Detection of Self Incompatibility Genotypes in Prunus africana: Characterization, Evolution and Spatial Analysis
PloS one, 2016Co-Authors: Judith Ssali Nantongo, Silvio Schueler, Gerald Eilu, Thomas Geburek, Heino KonradAbstract:In flowering plants, self-incompatibility is an effective genetic mechanism that prevents self-fertilization. Most Prunus tree species exhibit a homomorphic gametophytic self-incompatibility (GSI) system, in which the pollen phenotype is encoded by its own haploid genome. To date, no identification of S-alleles had been done in Prunus africana, the only member of the genus in Africa. To identify S-RNase alleles and hence determine S-genotypes in African cherry (Prunus africana) from Mabira Forest Reserve, Uganda, primers flanking the first and second intron were designed and these amplified two bands in most individuals. PCR bands on agarose indicated 26 and 8 different S-alleles for second and first intron respectively. Partial or full sequences were obtained for all these fragments. Comparison with published S-RNase data indicated that the amplified products were S-RNase alleles with very high interspecies homology despite the high intraspecific variation. Against expectations for a locus under balancing selection, frequency and spatial distribution of the alleles in a study plot was not random. Implications of the results to breeding efforts in the species are discussed, and mating experiments are strongly suggested to finally prove the functionality of SI in P. africana.
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GPS coordinates of all the Prunus africana trees that were sampled for analysis of S-alleles.
2016Co-Authors: Judith Ssali Nantongo, Silvio Schueler, Gerald Eilu, Thomas Geburek, Heino KonradAbstract:GPS coordinates of all the Prunus africana trees that were sampled for analysis of S-alleles.
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Patterns of genetic diversity of Prunus africana in Ethiopia: hot spot but not point of origin for range-wide diversity
Tree Genetics & Genomes, 2015Co-Authors: Z. Mihretie, Silvio Schueler, Heino Konrad, E. Bekele, Thomas GeburekAbstract:We studied the genetic pattern of 21 Ethiopian populations of Prunus africana by using six nuclear and five plastid microsatellites. In total, 89 alleles were found in the nuclear and 16 haplotypes in the plastid genome. High levels of diversity both in cpSSRs (h T = 0.703) and nSSR (H T = 0.725) were detected. Genetic differentiation among populations at the nuclear and plastid level was moderate (F ST = 0.122 vs. G ST = 0.478). While Ethiopian populations harbored the highest plastid haplotype diversity throughout Africa, the level of nuclear diversity was lower than in the remaining part of the species’ range. Ten of the observed 16 plastid haplotypes were unique to Ethiopia, suggesting an isolated plastid evolution. Remarkably, all plastid haplotypes found in Ethiopia belonged to one single lineage, while other populations from East Africa and Madagascar contain haplotypes from up to four more divergent lineages. This suggests that in contrast to previous expectations, the Horn of Africa is a hot spot of plastid diversity but not the ancestral origin for present populations of P. africana. The ratio between pollen to seed flow was estimated to be 7.1, indicating predominant gene flow by pollen. The exhaustive pollen flow also facilitated gene exchange with West African nuclear lineages probably in the early Holocene. The Ethiopian rift formed a genetic barrier resulting in population differentiation east and west of the rift; however, it was less effective in disrupting gene flow than the Eastern Rift in more southern parts of the East African range.
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Conservation Priorities for Prunus africana Defined with the Aid of Spatial Analysis of Genetic Data and Climatic Variables
PloS one, 2013Co-Authors: Barbara Vinceti, Silvio Schueler, Heino Konrad, Judy Loo, Hannes Gaisberger, C. A. C. Kadu, Maarten Van Zonneveld, Thomas GeburekAbstract:Conservation priorities for Prunus africana, a tree species found across Afromontane regions, which is of great commercial interest internationally and of local value for rural communities, were defined with the aid of spatial analyses applied to a set of georeferenced molecular marker data (chloroplast and nuclear microsatellites) from 32 populations in 9 African countries. Two approaches for the selection of priority populations for conservation were used, differing in the way they optimize representation of intra-specific diversity of P. africana across a minimum number of populations. The first method (S1) was aimed at maximizing genetic diversity of the conservation units and their distinctiveness with regard to climatic conditions, the second method (S2) at optimizing representativeness of the genetic diversity found throughout the species’ range. Populations in East African countries (especially Kenya and Tanzania) were found to be of great conservation value, as suggested by previous findings. These populations are complemented by those in Madagascar and Cameroon. The combination of the two methods for prioritization led to the identification of a set of 6 priority populations. The potential distribution of P. africana was then modeled based on a dataset of 1,500 georeferenced observations. This enabled an assessment of whether the priority populations identified are exposed to threats from agricultural expansion and climate change, and whether they are located within the boundaries of protected areas. The range of the species has been affected by past climate change and the modeled distribution of P. africana indicates that the species is likely to be negatively affected in future, with an expected decrease in distribution by 2050. Based on these insights, further research at the regional and national scale is recommended, in order to strengthen P. africana conservation efforts.
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Prunus africana populations of conservation priority based on the first selection method proposed (S1).
2013Co-Authors: Barbara Vinceti, C. A. C. Kadu, Silvio Schueler, Heino Konrad, Judy Loo, Hannes Gaisberger, Maarten J. Van Zonneveld, Thomas GeburekAbstract:A subset of 32 Prunus africana populations, from across 9 African countries is characterized by genetic data (number of individuals, haplotype richness, allelic richness, occurrence of locally common alleles, similarity in allelic composition) and climatic data. Haplotype/allelic richness and presence of locally common alleles are ranked, with highest ranking attributed to populations with the highest value of these parameters. Priority populations for conservation are highlighted in bold.
Katrin Böhning-gaese - One of the best experts on this subject based on the ideXlab platform.
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Fine-scale spatial genetic dynamics over the life cycle of the tropical tree Prunus africana
Heredity, 2014Co-Authors: Dana G Berens, Santiago C. González-martínez, R. Nathan, Eva Maria Griebeler, C Braun, Katrin Böhning-gaeseAbstract:Studying fine-scale spatial genetic patterns across life stages is a powerful approach to identify ecological processes acting within tree populations. We investigated spatial genetic dynamics across five life stages in the insect-pollinated and vertebrate-dispersed tropical tree Prunus africana in Kakamega Forest, Kenya. Using six highly polymorphic microsatellite loci, we assessed genetic diversity and spatial genetic structure (SGS) from seed rain and seedlings, and different sapling stages to adult trees. We found significant SGS in all stages, potentially caused by limited seed dispersal and high recruitment rates in areas with high light availability. SGS decreased from seed and early seedling stages to older juvenile stages. Interestingly, SGS was stronger in adults than in late juveniles. The initial decrease in SGS was probably driven by both random and non-random thinning of offspring clusters during recruitment. Intergenerational variation in SGS could have been driven by variation in gene flow processes, overlapping generations in the adult stage or local selection. Our study shows that complex sequential processes during recruitment contribute to SGS of tree populations.
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Does Forest Fragmentation and Selective Logging Affect Seed Predators and Seed Predation Rates of Prunus africana (Rosaceae)
Biotropica, 2007Co-Authors: Nina Farwig, Bärbel Bleher, Sabine Von Der Gönna, Katrin Böhning-gaeseAbstract:Forest fragmentation and selective logging can influence the life cycle of tropical tree species at several levels, e.g., by lowering pollination, by limiting seed dispersal, and by increasing seed predation. Understanding human-induced modifications in ecosystem processes such as seed predation is essential for conservation management of threatened species. We studied the impact of forest fragmentation and selective logging on seed predation of the endangered tree Prunus africana in the tropical rain forest of Kakamega, Kenya. We quantified the activity of seed predators in the main forest, forest fragments, and in sites of different logging intensity in the dry and rainy seasons of 2003 and 2006. Further, we performed predation experiments with single and groups of P. africana seeds in the same sites. We recorded a tendency toward higher activity of seed predators in the main forest compared to fragmented sites. Single seeds, in contrast to groups of seeds, had marginally significantly higher predation rates in intensively logged compared to moderately logged sites. Overall, predation rates showed little relationship to seed predator activity and were highly variable among years and seasons. Additional studies on seedling establishment and survival are needed to predict whether the endangered tree is able to maintain sustainable populations in Kakamega Forest. Only by studying all processes in the life cycle is it possible to develop sound management strategies for the species.
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Human disturbance reduces genetic diversity of an endangered tropical tree, Prunus africana (Rosaceae)
Conservation Genetics, 2007Co-Authors: Nina Farwig, Carsten Braun, Katrin Böhning-gaeseAbstract:Human activities such as fragmentation and selective logging of forests can threaten population via- bility by modification of ecological and genetic processes. Using six microsatellite markers, we examined the effects of forest fragmentation and local disturbance on the genetic diversity and structure of adult trees (N = 110) and seed- lings (N = 110) of Prunus africana in Kakamega Forest, western Kenya. Taking samples of adults and seedlings allowed for study of changes in genetic diversity and structure between generations. Thereby, adults reflect the pattern before and seedlings after intensive human impact. Overall, we found 105 different alleles in the six loci examined, 97 in adults and 88 in seedlings. Allelic richness and heterozygosity were significantly lower in seedlings than in adults. Inbreeding increased from adult tree to seedling populations. Genetic differentiation of adult trees was low (overall FST = 0.032), reflecting large population sizes and extensive gene flow in the past. Genetic differ- entiation of seedlings was slightly higher (overall FST = 0.044) with all of the 28 pairwise FST-values being sig- nificantly different from zero. These results suggest that human disturbance in Kakamega Forest has significantly reduced allelic richness and heterozygosity, increased inbreeding and slightly reduced gene flow in P. africana in the past 80-100 years.
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Enhanced seed dispersal of Prunus africana in fragmented and disturbed forests
Oecologia, 2005Co-Authors: Nina Farwig, Katrin Böhning-gaese, Bärbel BleherAbstract:Forest destruction and disturbance can have long-term consequences for species diversity and ecosystem processes such as seed dispersal. Understanding these consequences is a crucial component of conserving vulnerable ecosystems. In the heavily fragmented and disturbed Kakamega Forest, western Kenya, we studied seed dispersal of Prunus africana (Rosaceae). In the main forest, five forest fragments, and differently disturbed sites, we quantified the overall frugivore community as an indicator for species diversity. Furthermore, we determined the frugivores on 28 fruiting P. africana trees, estimated seed dispersal, crop size and the general fruit availability of surrounding trees. During the overall frugivore census we recorded 49 frugivorous species; 36 of them were observed visiting P. africana trees and feeding on their fruits. Although overall frugivore species richness was 1.1 times lower in fragments than in main forest sites and 1.02 times higher in highly disturbed than in less disturbed sites, P. africana experienced 1.1 times higher numbers of frugivores in fragments than in main forest sites and 1.5 times higher numbers of frugivores in highly disturbed than in less disturbed sites. Correspondingly, seed dispersal was 1.5 times higher in fragments than in main forest sites and 1.5 times higher in more disturbed than less disturbed sites. Fruit availability of surrounding trees and crop size influenced the number of visitors to some degree. Thus, the number of dispersed seeds seemed to be slightly higher in fragmented and highly disturbed sites. This indicates that loss of single species does not necessarily lead to a decrease of ecosystem services. However, loss of diversity could be a problem in the long term, as a multitude of species might act as buffer against future environmental change.
C. A. C. Kadu - One of the best experts on this subject based on the ideXlab platform.
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Conservation Priorities for Prunus africana Defined with the Aid of Spatial Analysis of Genetic Data and Climatic Variables
PloS one, 2013Co-Authors: Barbara Vinceti, Silvio Schueler, Heino Konrad, Judy Loo, Hannes Gaisberger, C. A. C. Kadu, Maarten Van Zonneveld, Thomas GeburekAbstract:Conservation priorities for Prunus africana, a tree species found across Afromontane regions, which is of great commercial interest internationally and of local value for rural communities, were defined with the aid of spatial analyses applied to a set of georeferenced molecular marker data (chloroplast and nuclear microsatellites) from 32 populations in 9 African countries. Two approaches for the selection of priority populations for conservation were used, differing in the way they optimize representation of intra-specific diversity of P. africana across a minimum number of populations. The first method (S1) was aimed at maximizing genetic diversity of the conservation units and their distinctiveness with regard to climatic conditions, the second method (S2) at optimizing representativeness of the genetic diversity found throughout the species’ range. Populations in East African countries (especially Kenya and Tanzania) were found to be of great conservation value, as suggested by previous findings. These populations are complemented by those in Madagascar and Cameroon. The combination of the two methods for prioritization led to the identification of a set of 6 priority populations. The potential distribution of P. africana was then modeled based on a dataset of 1,500 georeferenced observations. This enabled an assessment of whether the priority populations identified are exposed to threats from agricultural expansion and climate change, and whether they are located within the boundaries of protected areas. The range of the species has been affected by past climate change and the modeled distribution of P. africana indicates that the species is likely to be negatively affected in future, with an expected decrease in distribution by 2050. Based on these insights, further research at the regional and national scale is recommended, in order to strengthen P. africana conservation efforts.
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Divergent pattern of nuclear genetic diversity across the range of the Afromontane Prunus africana mirrors variable climate of African highlands
Annals of botany, 2012Co-Authors: C. A. C. Kadu, Silvio Schueler, Geoffrey M. Muluvi, Oscar Eyog-matig, Alice Muchugi, Vivienne L. Williams, Lolona Ramamonjisoa, Consolatha Kapinga, Heino Konrad, Bernard FoahomAbstract:† Background and Aims Afromontane forest ecosystems share a high similarity of plant and animal biodiversity, although they occur mainly on isolated mountain massifs throughout the continent. This resemblance has long provoked questions on former wider distribution of Afromontane forests. In this study Prunus africana (one of the character trees of Afromontane forests) is used as a model for understanding the biogeography of this vegetation zone. † Methods Thirty natural populations from nine African countries covering a large part of Afromontane regions were analysed using six nuclear microsatellites. Standard population genetic analysis as well as Bayesian and maximum likelihood models were used to infer genetic diversity, population differentiation, barriers to gene flow, and recent and all migration among populations. † Key Results Prunus africana exhibits strong divergence among five main Afromontane regions: West Africa, East Africa west of the Eastern Rift Valley (ERV), East Africa east of the ERV, southern Africa and Madagascar. The strongest divergence was evident between Madagascar and continental Africa. Populations from West Africa showed high similarity with East African populations west of the ERV, whereas populations east of the ERV are closely related to populations of southern Africa, respectively. † Conclusions The observed patterns indicate divergent population history across the continent most likely associated to Pleistocene changes in climatic conditions. The high genetic similarity between populations of West Africa with population of East Africa west of the ERV is in agreement with faunistic and floristic patterns and provides further evidence for a historical migration route. Contrasting estimates of recent and historical gene flow indicate a shift of the main barrier to gene flow from the Lake Victoria basin to the ERV, highlighting the dynamic environmental and evolutionary history of the region.
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Phylogeography of the Afromontane Prunus africana reveals a former migration corridor between East and West African highlands.
Molecular ecology, 2010Co-Authors: C. A. C. Kadu, Silvio Schueler, Geoffrey M. Muluvi, Oscar Eyog-matig, Alice Muchugi, Vivienne L. Williams, Lolona Ramamonjisoa, Consolatha Kapinga, Heino Konrad, Bernard FoahomAbstract:Scattered populations of the same tree species in montane forests through Africa have led to speculations on the origins of distributions. Here, we inferred the colonization history of the Afromontane tree Prunus africana using seven chloroplast DNA loci to study 582 individuals from 32 populations sampled in a range-wide survey from across Africa, revealing 22 haplotypes. The predominant haplotype, HT1a, occurred in 13 populations of eastern and southern Africa, while a second common haplotype, HT1m, occurred in populations of western Uganda and western Africa. The high differentiation observed between populations in East Africa was unexpected, with stands in western Uganda belonging with the western African lineage. High genetic differentiation among populations revealed using ordered alleles (NST = 0.840) compared with unordered alleles (GST = 0.735), indicated a clear phylogeographic pattern. Bayesian coalescence modelling suggested that ‘east’ and ‘west’ African types likely split early during southward migration of the species, while further more recent splitting events occurred among populations in the East of the continent. The high genetic similarity found between western Uganda and west African populations indicates that a former Afromontane migration corridor may have existed through Equatorial Africa.
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Transfer of microsatellite loci for the tropical tree Prunus africana (Hook. f.) Kalkman.
Silvae Genetica, 2009Co-Authors: Stephen Cavers, R. C. Munro, C. A. C. Kadu, Heino KonradAbstract:Using databases of previously published primers, we optimised six nuclear microsatellite markers for Prunus africana for the purposes of studying spatial genetic structure and gene flow. To assess variability, these and three previously transferred loci were screened in populations from Kenya and South Africa. Across both populations most loci were polymorphic, with the exception of a single locus which failed to amplify in the South African samples, exhibiting between 2 and 22 alleles and levels of expected heterozygosity (He) ranged from 0.059 to 0.932. Departures from Hardy–Weinberg equilibrium were detected for all loci but not for all populations. The estimated null allele frequency was very low to moderate and no evidence for linkage disequilibrium was detected.
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Genetic variation in the threatened medicinal tree Prunus africana in Cameroon and Kenya: implications For current management and evolutionary history
South African Journal of Botany, 2006Co-Authors: Alice Muchugi, Geoffrey M. Muluvi, C. A. C. Kadu, Ard G. Lengkeek, E.n.m. Njagi, Ian K. DawsonAbstract:Abstract Listed as vulnerable under Appendix II of CITES, populations of the commercially valuable African highland medicinal tree Prunus africana are threatened by over-exploitation in a number of countries. Here, random amplified polymorphic DNA (RAPD) analysis was used to assess patterns of genetic variation in the species in Cameroon and Kenya, two countries where exploitation has been particularly high and where information on genetic structure is a crucial input for developing the national management plans that are a requirement of CITES listing. Analysis of molecular variance (AMOVA), which employed 39 RAPD markers, indicated that a significantly greater proportion of total country variation partitioned among eight stands in Kenya than among nine stands in Cameroon (values of 55% and 24%, respectively), with important implications for conservation strategies. Kenyan stands appear to represent a particularly diverse resource for conservation, evaluation and domestication, although possible human movement of germplasm during cultivation raises integrity concerns. Data also shed light on the evolutionary history of P. africana stands. A genetic disjunction between western and central Kenyan populations was observed, with individuals from western Kenya more similar to geographically distant stands from Cameroon (> 2000 km) than to central Kenya (
Silvio Schueler - One of the best experts on this subject based on the ideXlab platform.
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Detection of Self Incompatibility Genotypes in Prunus africana: Characterization, Evolution and Spatial Analysis
PloS one, 2016Co-Authors: Judith Ssali Nantongo, Silvio Schueler, Gerald Eilu, Thomas Geburek, Heino KonradAbstract:In flowering plants, self-incompatibility is an effective genetic mechanism that prevents self-fertilization. Most Prunus tree species exhibit a homomorphic gametophytic self-incompatibility (GSI) system, in which the pollen phenotype is encoded by its own haploid genome. To date, no identification of S-alleles had been done in Prunus africana, the only member of the genus in Africa. To identify S-RNase alleles and hence determine S-genotypes in African cherry (Prunus africana) from Mabira Forest Reserve, Uganda, primers flanking the first and second intron were designed and these amplified two bands in most individuals. PCR bands on agarose indicated 26 and 8 different S-alleles for second and first intron respectively. Partial or full sequences were obtained for all these fragments. Comparison with published S-RNase data indicated that the amplified products were S-RNase alleles with very high interspecies homology despite the high intraspecific variation. Against expectations for a locus under balancing selection, frequency and spatial distribution of the alleles in a study plot was not random. Implications of the results to breeding efforts in the species are discussed, and mating experiments are strongly suggested to finally prove the functionality of SI in P. africana.
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GPS coordinates of all the Prunus africana trees that were sampled for analysis of S-alleles.
2016Co-Authors: Judith Ssali Nantongo, Silvio Schueler, Gerald Eilu, Thomas Geburek, Heino KonradAbstract:GPS coordinates of all the Prunus africana trees that were sampled for analysis of S-alleles.
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Patterns of genetic diversity of Prunus africana in Ethiopia: hot spot but not point of origin for range-wide diversity
Tree Genetics & Genomes, 2015Co-Authors: Z. Mihretie, Silvio Schueler, Heino Konrad, E. Bekele, Thomas GeburekAbstract:We studied the genetic pattern of 21 Ethiopian populations of Prunus africana by using six nuclear and five plastid microsatellites. In total, 89 alleles were found in the nuclear and 16 haplotypes in the plastid genome. High levels of diversity both in cpSSRs (h T = 0.703) and nSSR (H T = 0.725) were detected. Genetic differentiation among populations at the nuclear and plastid level was moderate (F ST = 0.122 vs. G ST = 0.478). While Ethiopian populations harbored the highest plastid haplotype diversity throughout Africa, the level of nuclear diversity was lower than in the remaining part of the species’ range. Ten of the observed 16 plastid haplotypes were unique to Ethiopia, suggesting an isolated plastid evolution. Remarkably, all plastid haplotypes found in Ethiopia belonged to one single lineage, while other populations from East Africa and Madagascar contain haplotypes from up to four more divergent lineages. This suggests that in contrast to previous expectations, the Horn of Africa is a hot spot of plastid diversity but not the ancestral origin for present populations of P. africana. The ratio between pollen to seed flow was estimated to be 7.1, indicating predominant gene flow by pollen. The exhaustive pollen flow also facilitated gene exchange with West African nuclear lineages probably in the early Holocene. The Ethiopian rift formed a genetic barrier resulting in population differentiation east and west of the rift; however, it was less effective in disrupting gene flow than the Eastern Rift in more southern parts of the East African range.
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Conservation Priorities for Prunus africana Defined with the Aid of Spatial Analysis of Genetic Data and Climatic Variables
PloS one, 2013Co-Authors: Barbara Vinceti, Silvio Schueler, Heino Konrad, Judy Loo, Hannes Gaisberger, C. A. C. Kadu, Maarten Van Zonneveld, Thomas GeburekAbstract:Conservation priorities for Prunus africana, a tree species found across Afromontane regions, which is of great commercial interest internationally and of local value for rural communities, were defined with the aid of spatial analyses applied to a set of georeferenced molecular marker data (chloroplast and nuclear microsatellites) from 32 populations in 9 African countries. Two approaches for the selection of priority populations for conservation were used, differing in the way they optimize representation of intra-specific diversity of P. africana across a minimum number of populations. The first method (S1) was aimed at maximizing genetic diversity of the conservation units and their distinctiveness with regard to climatic conditions, the second method (S2) at optimizing representativeness of the genetic diversity found throughout the species’ range. Populations in East African countries (especially Kenya and Tanzania) were found to be of great conservation value, as suggested by previous findings. These populations are complemented by those in Madagascar and Cameroon. The combination of the two methods for prioritization led to the identification of a set of 6 priority populations. The potential distribution of P. africana was then modeled based on a dataset of 1,500 georeferenced observations. This enabled an assessment of whether the priority populations identified are exposed to threats from agricultural expansion and climate change, and whether they are located within the boundaries of protected areas. The range of the species has been affected by past climate change and the modeled distribution of P. africana indicates that the species is likely to be negatively affected in future, with an expected decrease in distribution by 2050. Based on these insights, further research at the regional and national scale is recommended, in order to strengthen P. africana conservation efforts.
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Prunus africana populations of conservation priority based on the first selection method proposed (S1).
2013Co-Authors: Barbara Vinceti, C. A. C. Kadu, Silvio Schueler, Heino Konrad, Judy Loo, Hannes Gaisberger, Maarten J. Van Zonneveld, Thomas GeburekAbstract:A subset of 32 Prunus africana populations, from across 9 African countries is characterized by genetic data (number of individuals, haplotype richness, allelic richness, occurrence of locally common alleles, similarity in allelic composition) and climatic data. Haplotype/allelic richness and presence of locally common alleles are ranked, with highest ranking attributed to populations with the highest value of these parameters. Priority populations for conservation are highlighted in bold.
Alice Muchugi - One of the best experts on this subject based on the ideXlab platform.
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Divergent pattern of nuclear genetic diversity across the range of the Afromontane Prunus africana mirrors variable climate of African highlands
Annals of botany, 2012Co-Authors: C. A. C. Kadu, Silvio Schueler, Geoffrey M. Muluvi, Oscar Eyog-matig, Alice Muchugi, Vivienne L. Williams, Lolona Ramamonjisoa, Consolatha Kapinga, Heino Konrad, Bernard FoahomAbstract:† Background and Aims Afromontane forest ecosystems share a high similarity of plant and animal biodiversity, although they occur mainly on isolated mountain massifs throughout the continent. This resemblance has long provoked questions on former wider distribution of Afromontane forests. In this study Prunus africana (one of the character trees of Afromontane forests) is used as a model for understanding the biogeography of this vegetation zone. † Methods Thirty natural populations from nine African countries covering a large part of Afromontane regions were analysed using six nuclear microsatellites. Standard population genetic analysis as well as Bayesian and maximum likelihood models were used to infer genetic diversity, population differentiation, barriers to gene flow, and recent and all migration among populations. † Key Results Prunus africana exhibits strong divergence among five main Afromontane regions: West Africa, East Africa west of the Eastern Rift Valley (ERV), East Africa east of the ERV, southern Africa and Madagascar. The strongest divergence was evident between Madagascar and continental Africa. Populations from West Africa showed high similarity with East African populations west of the ERV, whereas populations east of the ERV are closely related to populations of southern Africa, respectively. † Conclusions The observed patterns indicate divergent population history across the continent most likely associated to Pleistocene changes in climatic conditions. The high genetic similarity between populations of West Africa with population of East Africa west of the ERV is in agreement with faunistic and floristic patterns and provides further evidence for a historical migration route. Contrasting estimates of recent and historical gene flow indicate a shift of the main barrier to gene flow from the Lake Victoria basin to the ERV, highlighting the dynamic environmental and evolutionary history of the region.
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Bioactive constituents in Prunus africana: geographical variation throughout Africa and associations with environmental and genetic parameters.
Phytochemistry, 2012Co-Authors: C. A. C. Kadu, Silvio Schueler, Geoffrey M. Muluvi, Oscar Eyog-matig, Alice Muchugi, Vivienne L. Williams, Lolona Ramamonjisoa, Heino Konrad, Alexandra Parich, Consolatha KapingaAbstract:Abstract Prunus africana – an evergreen tree found in Afromontane forests – is used in traditional medicine to cure benign prostate hyperplasia. Different bioactive constituents derived from bark extracts from 20 tree populations sampled throughout the species’ natural range in Africa were studied by means of GC–MSD. The average concentration [mg/kg w/w] in increasing order was: lauric acid (18), myristic acid (22), n-docosanol (25), ferulic acid (49), β-sitostenone (198), β-sitosterol (490), and ursolic acid (743). The concentrations of many bark constituents were significantly correlated and concentration of n-docosanol was highly significantly correlated with all other analytes. Estimates of variance components revealed the highest variation among populations for ursolic acid (66%) and the lowest for β-sitosterol (20%). In general, environmental parameters recorded (temperature, precipitation, altitude) for the samples sites were not correlated with the concentration of most constituents; however, concentration of ferulic acid was significantly correlated with annual precipitation. Because the concentration of compounds in bark extracts may be affected by tree size, the diameter of sampled plants at 1.3 m tree height (as proxy of age) was recorded. The only relationship with tree diameter was a negative correlation with ursolic acid. Under the assumption that genetically less variable populations have less variable concentrations of bark compounds, correlations between variation parameters of the concentration and the respective genetic composition based on chloroplast and nuclear DNA markers were assessed. Only variation of β-sitosterol concentration was significantly correlated with haplotypic diversity. The fixation index (FIS) was positively correlated with the variation in concentration of ferulic acid. Principal Components Analysis (PCA) indicated a weak geographic pattern. Mantel tests, however, revealed associations between the geographic patterns of bioactive constituents and the phylogenetic relationship among the populations sampled. This suggests an independent evolution of bark metabolism within different phylogeographical lineages, and the molecular phylogeographic pattern is partly reflected in the variation in concentration of bark constituents. The results have important implications for the design of strategies for the sustainable use and conservation of this important African tree species.
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Phylogeography of the Afromontane Prunus africana reveals a former migration corridor between East and West African highlands.
Molecular ecology, 2010Co-Authors: C. A. C. Kadu, Silvio Schueler, Geoffrey M. Muluvi, Oscar Eyog-matig, Alice Muchugi, Vivienne L. Williams, Lolona Ramamonjisoa, Consolatha Kapinga, Heino Konrad, Bernard FoahomAbstract:Scattered populations of the same tree species in montane forests through Africa have led to speculations on the origins of distributions. Here, we inferred the colonization history of the Afromontane tree Prunus africana using seven chloroplast DNA loci to study 582 individuals from 32 populations sampled in a range-wide survey from across Africa, revealing 22 haplotypes. The predominant haplotype, HT1a, occurred in 13 populations of eastern and southern Africa, while a second common haplotype, HT1m, occurred in populations of western Uganda and western Africa. The high differentiation observed between populations in East Africa was unexpected, with stands in western Uganda belonging with the western African lineage. High genetic differentiation among populations revealed using ordered alleles (NST = 0.840) compared with unordered alleles (GST = 0.735), indicated a clear phylogeographic pattern. Bayesian coalescence modelling suggested that ‘east’ and ‘west’ African types likely split early during southward migration of the species, while further more recent splitting events occurred among populations in the East of the continent. The high genetic similarity found between western Uganda and west African populations indicates that a former Afromontane migration corridor may have existed through Equatorial Africa.
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Genetic variation in the threatened medicinal tree Prunus africana in Cameroon and Kenya: implications For current management and evolutionary history
South African Journal of Botany, 2006Co-Authors: Alice Muchugi, Geoffrey M. Muluvi, C. A. C. Kadu, Ard G. Lengkeek, E.n.m. Njagi, Ian K. DawsonAbstract:Abstract Listed as vulnerable under Appendix II of CITES, populations of the commercially valuable African highland medicinal tree Prunus africana are threatened by over-exploitation in a number of countries. Here, random amplified polymorphic DNA (RAPD) analysis was used to assess patterns of genetic variation in the species in Cameroon and Kenya, two countries where exploitation has been particularly high and where information on genetic structure is a crucial input for developing the national management plans that are a requirement of CITES listing. Analysis of molecular variance (AMOVA), which employed 39 RAPD markers, indicated that a significantly greater proportion of total country variation partitioned among eight stands in Kenya than among nine stands in Cameroon (values of 55% and 24%, respectively), with important implications for conservation strategies. Kenyan stands appear to represent a particularly diverse resource for conservation, evaluation and domestication, although possible human movement of germplasm during cultivation raises integrity concerns. Data also shed light on the evolutionary history of P. africana stands. A genetic disjunction between western and central Kenyan populations was observed, with individuals from western Kenya more similar to geographically distant stands from Cameroon (> 2000 km) than to central Kenya (
