A range wide geographic pattern of genetic diversity and population structure of Castanea mollissima populations inferred from nuclear and chloroplast microsatellites

Understanding geographical pattern of genetic diversity and population structure is of great importance for formulating conservation and utilization strategies. In this study, we investigated the genetic diversity and population structure of 28 natural populations of Castanea mollissima in China using eight nuclear and six chloroplast microsatellite makers (nSSRs and cpSSRs). Populations from central China harbored the highest genetic diversity at both nSSR and cpSSR markers (nSSR: H _E?=?0.705; cpSSR: H?=?0.461). The standardized measure of genetic differentiation estimated as G′ _ST was 0.447 for nSSR and 0.803 for cpSSR, respectively. The G′_ST-based pollen to seed flow ratio is 3.043, indicating that pollen flow is not extensive among C. mollissima populations. No obvious population genetic structure by geographical locations was found by STRUCTURE analysis based on nSSR data, and similarly, no signal of phylogeographic structure was detected for cpSSR analysis. Five boundaries defining zones of maximum genetic differences within the network of the C. mollissima populations were found, and the locations of those barriers were consistent with those of four mountains, i.e., Daloushan Mountain, Dabashan Mountain, Wushan Mountain, and Qingliangfeng Mountain, indicating that those mountains might act as genetic barriers obstructing the genetic exchange among natural C. mollissima populations. These results provide valuable baseline data for conservation and utilization of this species.     

Population differentiation and gene flow within a metapopulation of a threatened tree, Magnolia stellata (Magnoliaceae)

We examined genetic differentiation among eight local populations of a metapopulation of Magnolia stellata using 10 nuclear and three chloroplast microsatellite (nSSR and cpSSR) markers and evaluated the influence of historical gene flow on population differentiation. The coefficient of genetic differentiation among populations for nSSR (F(ST) = 0.053) was less than half that for cpSSR (0.137). An isolation-by-distance pattern was detected for nSSRs, but not cpSSRs. These results suggest that pollen flow, as well as seed dispersal, has significantly reduced genetic differentiation among populations. We also examined patterns of contemporary pollen flow by paternity analysis of seeds from nine seed parents in one of the populations using the nSSR markers and found it to be greatly restricted by the distance between parents. Although most pollen flow occurred within the population, pollen flow from outside the population accounted for 2.5% of the total. When historical and contemporary pollen flows among populations were compared, the levels of pollen flow seem to have declined recently. We conclude that to conserve M. stellata, it is important to preserve the whole population by maintaining its metapopulation structure and the gene flow among its populations.     

Population Structure of and Conservation Strategies for Wild Pyrus ussuriensis Maxim. in China

Pyrus ussriensis Maxim. is native to the northern part of China, but whose habitats are currently being destroyed by environmental changes and human deforestation. An investigation of population structure and genetic diversity of wild Ussurian pear is a priority in order to acquire fundamental knowledge for conservation. A total of 153 individuals of wild Ussurian pear from the main habitats, Heilongjiang, Jilin, and Inner Mongolia in China, possessed low genetic diversity as a result of habitat fragmentation. The genetic diversity of the populations in Inner Mongolia and north east of Heilongjiang was especially low and there was the possibility of inbreeding. Wild Ussurian pears were divided into 5 groups based on the Bayesian clustering method using 20 nuclear SSRs (nSSRs) and 5 groups by haplotype distributions using 16 chloroplast SSRs (cpSSRs), and the populations in Inner Mongolia and north east of Heilongjiang represented unique genotypes. AMOVA indicated there was a 20.05% variation in nSSRs and a 44.40% variation in cpSSRs among populations. These values are relatively high when compared to those of other tree species. Haplotype E, positioned in the center of the cpSSR analysis network and showed the largest number of connections with other haplotypes, represented the most important haplotype. Inner Mongolia and the north east of Heilongjiang are two areas that need urgent conservation because of their genetic vulnerability and peculiarity. We determined 4 conservation units based on the clustering by nSSRs and cpSSRs, and geographic factor. This information is helpful in deciding the conservation strategies for wild Ussurian pear in China.     

Novel Chloroplast Microsatellite (cpSSR) Markers for Genetic Diversity Assessment of Cultivated and Wild Hevea Rubber

Understanding the genetic diversity and population structure of Hevea is of great importance for managing its conservation and for utilization of rubber genetic resources. In this study, we investigated the genetic diversity and population structure of eight populations of Hevea rubber genotypes from Malaysia (MY), India (IN), Sri Lanka (LK), Indonesia (ID), France (FR), Thailand (TH), Brazil (BR), and China (CN), in addition to individual primary clones, using 10 nuclear and 11 polymorphic novel chloroplast microsatellite markers (nSSRs and cpSSRs, respectively). The BR population exhibited the greatest genetic diversity (H _e ) for both nSSR (0.841) and haploid genetic diversity (cpSSR; 0.207) markers. Bayesian analysis was applied to infer genetic structure based on nSSR data using STRUCTURE software, and a neighbor-joining tree was used to construct an unrooted phylogram based on Nei’s genetic distance that clustered these Hevea genotypes into three groups. Six polymorphic cpSSR markers produced 13 alleles and eight chlorotypes. Seven chlorotypes, A, B, C, D, E, F, and H were detected among Brazilian populations from Acre (AC), Rondônia (RO), and Mato Grosso (MT) locations. The G and H chlorotypes were found in Asiatic genotypes or Wickham clones and only one genotype, 15 AC-F-7 38-62 from AC location. These results provide valuable data for in situ or ex situ conservation and utilization of germplasm collections for breeding programs.

     

Effect of a red oak species gradient on genetic structure and diversity of Quercus castanea (Fagaceae) in Mexico

Incipient reproductive barriers are a common characteristic of oak species. Disruption of these barriers promotes changes in diversity and genetic structure of the species involved. Quercus castanea is a red oak with wide geographic distribution in Mexico, which presents atypically high morphological variability when it occurs in sympatry with other red oak species, suggesting that hybridization may explain the observed variation. We tested if the genetic structure and diversity levels of Q. castanea are related to the number of red oak species growing in sympatry. In total, 14 microsatellite (SSRs) primers (six nSSRs and eight cpSSRs) were used in 120 Q. castanea individuals (20/site) belonging to six populations, where the number of red oak species associated varied from zero to five. Results showed a positive and significant relationship between the genetic diversity of Q. castanea and the number of red oak species growing in sympatry, regardless of the marker type or the parameter of genetic diversity analyzed. Also, we found a higher genetic differentiation of Q. castanea populations using cpSSRs in comparison with nSSRs. Our results suggest that temperate forests with high red oaks species richness co-dominated by Q. castanea promote the increase in this species genetic diversity. From a conservation perspective, high genetic diversity levels of foundation species such as Q. castanea may have positive cascade effects extending to other species in the community.     

Genetic diversity and differentiation of <Emphasis Type="Italic">Fagus orientalis</Emphasis> Lipsky in Hyrcanian forests revealed by nuclear and chloroplast microsatellite markers

Oriental beech (Fagus orientalis Lipsky) is a widespread monoecious and wind-pollinated tree species. It is one of the major components of the Hyrcanian forests of Iran and it is of both ecological and economical importance. Twelve beech stands were surveyed at 9 chloroplast (cp) and 6 nuclear (n) polymorphic microsatellite loci (simple sequence repeats, SSR) to provide information on distribution of genetic diversity within and among populations and on gene conservation and silvicultural management of this species. High levels of genetic differentiation were detected for the chloroplast genome (F _ST = 0.80 and R _ST = 0.95), in sharp contrast to the nuclear genome (F _ST = 0.06, R _ST = 0.05). The analysis of molecular variance (AMOVA) showed that 48% of the total cpSSR variation was attributable to differences among regions and 30% to differences among populations within regions, suggesting multiple origins of beech populations in Hyrcanian forests. Nuclear SSRs confirmed the presence of significant differentiation among populations and among geographic regions, even if, as expected, this was less pronounced than that found with cpSSRs (based on AMOVA, differences among regions and among populations within regions each contribute 5% to total nSSR variance). A highly significant correlation between genetic (nSSRs) and geographic distances (R ² = 0.522) was estimated, thus showing an isolation by distance effect. The application of spatial analysis of molecular variance (SAMOVA) using both marker data allowed identification of genetically homogeneous groups of populations. Possible applications of these results for the certification of provenances and/or seed lots and for designing conservation programs are presented and discussed.     

Effects of plant hybridization on the structure and composition of a highly rich community of cynipid gall wasps: the case of the oak hybrid complex <Emphasis Type="Italic">Quercus magnoliifolia</Emphasis> x <Emphasis Type="Italic">Quercus resinosa</Emphasis> in Mexico

The richness and composition of herbivore communities can be influenced by the genetic variation of host plants. Hybrid plant populations are ideal to test these effects because they usually harbor high genetic variation and display a mosaic of phenotypic characters. The goal of this study was to examine the effect of hybridization between two Mexican white oaks, Q. magnoliifolia and Q. resinosa, on the composition and diversity of the associated cynipid gall wasp community. We used eight nuclear microsatellite markers to genotype 150 oak individuals sampled at three different altitudes at the Tequila volcano and conducted monthly samplings of galls in each individual over the course of 2 years. A Bayesian assignment analysis indicated genetic admixture between the two oak species at the study site and allowed classifying individuals as Q. magnoliifolia, Q. resinosa or hybrids. Gall morphospecies richness was significantly higher in the hybrids, intermediate in Q. magnoliifolia and lower in Q. resinosa. Overall, 48 different gall morphospecies were found, with 21 of them being shared among the three groups of plants, 13 between two groups of plants, and 14 were unique to one group of plants, with eight of these being found in hybrids. Several of the shared galls showed differences in abundance among plant groups. Therefore, genetic structure in this oak complex significantly influences the diversity and composition of the associated gall wasp community, and hybrid individuals are probably acting as potential sinks and bridges for the colonization of plant hosts by these highly specialized insect species.     

Diversity and genetic structure in populations of Pseudotsuga menziesii (Pinaceae) at chloroplast microsatellite loci.

Genetic variation was compared between uniparentally-inherited (chloroplast simple sequence repeats, cpSSRs) vs. biparentally-inherited (isozyme and random amplified polymorphic DNA, RAPD) genetic markers in Douglas-fir (Pseudotsuga mensiezii) from British Columbia. Three-hundred twenty-three individuals from 11 populations were assayed. In Douglas-fir, the cpSSR primer sites were well-conserved relative to Pinus thunbergii (11 of 17 loci clearly amplified), but only 3 loci were appreciably polymorphic. At these cpSSR loci, we found an unexpectedly low level of polymorphism within populations, and no genetic differentiation among populations. By contrast, the nuclear markers showed variation typical of conifers, with significant among-population differentiation. This difference is likely the outcome of both historical factors and high pollen dispersal.     

Morphological and molecular diversity among populations of Quercus brantii Lindl. in western forest of Iran

Abstract

This study represents a preliminary step toward understanding the genetic structure of Persian oak in Iran. The genetic variability of Quercus brantii in Western forest of Iran was evaluated by amplified fragment length polymorphism (AFLP), chloroplast microsatellite and leaf morphology. Fifty-five trees from eight regions were sampled from across the range of Chaharmahal va Bakhtiari province of Iran. Twenty morphological traits were analyzed through clustering and ordination method. At morphological level, the applied statistics suggest that macromorphological traits significantly differentiate between populations. The overall sample shows a proportion of AFLP polymorphic markers of 92.1%, denoting a high level of variability. Based on AFLP data, differences among populations within geographic regions account for 11.6% of the total variation and only 0.57% is attributed to variation among regions. Based on chloroplast microsatellite (cpSSR), 34% of total variation was found among populations, suggesting a high within-population haplotype diversity. The dendrogram obtained from cpSSR showed a general pattern quite different from the pattern obtained from morphological analysis and AFLP markers.     

Geographic patterns of genetic variation in native pecans

A structured collection of 80 seedling pecan trees [Carya illinoinensis (Wangenh.) K. Koch], representing 19 putatively native pecan populations across the species range, was evaluated at three plastid and 14 nuclear microsatellite (simple sequence repeat, SSR) loci. Data were analyzed using a priori population designations and also within a Bayesian framework, in which individuals were assigned to clusters regardless of population of origin. Population genetic analyses using a priori populations, clusters based on chloroplast microsatellite data (cpSSR), and clusters based on nuclear microsatellite data (nSSR) yielded consistent results. For all groupings, cpSSR variation exhibited more geographic structure than the nSSR data. Furthermore, cpSSR microsatellite diversity decreased with increasing latitude, but this pattern was not observed with the nuclear data. Contrasting patterns in plastid and nuclear genetic diversity demonstrate unique aspects of postglacial recolonization reflected in the movement of seeds versus pollen. These data suggest that plastid SSRs are useful tools for identifying population structure in pecan and hold promise for ongoing efforts to identify and conserve representative germplasm in ex situ collections.     

Consequences of multiple mating‐system shifts for population and range‐wide genetic structure in a coastal dune plant

Evolutionary transitions from outcrossing to selfing can strongly affect the genetic diversity and structure of species at multiple spatial scales. We investigated the genetic consequences of mating‐system shifts in the North American, Pacific coast dune endemic plant Camissoniopsis cheiranthifolia (Onagraceae) by assaying variation at 13 nuclear (n) and six chloroplast (cp) microsatellite (SSR) loci for 38 populations across the species range. As predicted from the expected reduction in effective population size (N_e) caused by selfing, small‐flowered, predominantly selfing (SF) populations had much lower nSSR diversity (but not cpSSR) than large‐flowered, predominantly outcrossing (LF) populations. The reduction in nSSR diversity was greater than expected from the effects of selfing on N_e alone, but could not be accounted for by indirect effects of selfing on population density. Although selfing should reduce gene flow, SF populations were not more genetically differentiated than LF populations. We detected five clusters of nSSR genotypes and three groups of cpSSR haplotypes across the species range consisting of parapatric groups of populations that usually (but not always) differed in mating system, suggesting that selfing may often initiate ecogeographic isolation. However, lineage‐wide genetic variation was not lower for selfing clusters, failing to support the hypothesis that selection for reproductive assurance spurred the evolution of selfing in this species. Within three populations where LF and SF plants coexist, we detected genetic differentiation among diverged floral phenotypes suggesting that reproductive isolation (probably postzygotic) may help maintain the striking mating‐system differentiation observed across the range of this species.     

Genetic structure of Quercus rubra L. and Quercus ellipsoidalis E. J. Hill populations at gene-based EST-SSR and nuclear SSR markers

Sympatric hybridizing oak species provide a model system for studying local adaptation. Disjunct populations of Quercus rubra L. and Quercus ellipsoidalis E. J. Hill at the northern edge of their distribution may harbor important reservoirs of adaptive genetic variation. Genic (expressed sequence tag- simple sequence repeat?=?EST-SSR) and non-genic nuclear microsatellite (nuclear SSR?=?nSSR) markers were used to estimate neutral and potentially adaptive genetic variation in these two supposedly interfertile oak species showing different adaptations to drought. Eleven populations of putative Q. rubra and Q. ellipsoidalis located in the Western Upper Peninsula of Michigan were characterized using seven EST-SSRs and eight nSSRs. Bayesian cluster analysis revealed two distinct groups corresponding to each species with evidence of low levels of potential introgression. A comparison of the genetic structure of adult trees and seedlings revealed no evidence for selection against hybrids. Overall, similar levels of genetic variation and differentiation between populations and species were found at both EST-SSRs and nSSRs indicating that most EST-SSRs chosen reflect neutral variation. Two loci, 3A05 (nSSR) and GOT021 (EST-SSR, putative histidine kinase 4-like), were identified as putative outlier loci between species showing largely reduced variation in Q. ellipsoidalis. Future analyses of an increased number of EST-SSRs located in functional genes will allow the identification of genes involved in the reproductive isolation between both species.     

Development and use of chloroplast microsatellites in Phaseolus spp. and other legumes

Chloroplast microsatellites (cpSSRs) provide a powerful tool to study the genetic variation and evolution of plants. We have investigated the usefulness of 39 primer pairs tagging cpSSR loci on a set of eight different genera of Leguminosae (Papilionoideae subfamily) and five species belonging to the genus Phaseolus . Thirty-six 'universal' primer pairs were retrieved from the literature, one was re-designed and a further two were designed de novo . The cpSSR loci analysed were highly polymorphic across the individuals examined. Twenty-seven primer pairs were polymorphic in the overall sample, 18 within Phaseolus , and 16 in both P. vulgaris and P. coccineus . Analysis of the plastome sequences of four Leguminosae species (obtained from GenBank) showed that in the loci targeted by universal primer pairs: (i) the originally tagged cpSSRs can be lost; (ii) other cpSSRs can be present; and (iii) polymorphism arises not only from differences in the numbers of cpSSR repeats, but often from other insertion/deletion events. Multilocus linkage disequilibrium analysis suggests that homoplasy is not a major problem in our dataset, and principal component analysis indicates intelligible relationships among the species considered. Our study demonstrates that this set of chloroplast markers provides a useful tool to study the diversity and the evolution of several legumes, and particularly P. vulgaris and P. coccineus .     

Chloroplast simple sequence repeats (cpSSRs): technical resources and recommendations for expanding cpSSR discovery and applications to a wide array of plant species

Chloroplast microsatellites, or simple sequence repeats (cpSSRs), are typically mononucleotide tandem repeats. When located in the noncoding regions of the chloroplast genome (cpDNA), they commonly show intraspecific variation in repeat number. Despite the growing number of studies applying cpSSRs, studies of economically important plants and their relatives remain over‐represented. Thus, the potential of cpSSRs to offer unique insights into ecological and evolutionary processes in wild plant species has yet to be fully realized. This review provides an overview of the technical resources available to aid cpSSR discovery including a list of cpSSR primer sets available and cpDNA sequencing resources. Our updated analysis of 99 whole chloroplast genomes downloaded from GenBank confirms that potentially variable cpSSRs are abundant in the noncoding cpDNA of plants. Overall variation in the frequency of cpSSRs was extreme, ranging from one to 700 per genome (median = 93), while in 81 vascular plants, between 35 and 160 cpSSRs were detected per genome (median = 86). We offer five recommendations to aid wider development and application of cpSSRs: (i) When genus‐specific cpSSR primers are available, cross‐species amplification can often be fruitful. (ii) While potentially useful, universal cpSSR primers at best provide access to only a small number of variable markers. (iii) De novo sequencing of noncoding cpDNA is the most effective and efficient way to develop cpSSR markers in wild species. (iv) DNA sequencing of cpSSR alleles is essential, given the complex nature of the genetic variation associated with hypervariable cpDNA regions. (v) The reliability of cpSSR length based genetic assays need to be validated in all studies.     

Genetic diversity and differentiation of the endangered Japanese endemic tree Magnolia stellata using nuclear and chloroplast microsatellite markers

Genetic diversity and differentiation were analyzed in 11 populations of Magnolia stellata (Sieb. and Zucc.) Maxim. (Magnoliaceae) in the Tokai district, Japan. Variation at four nuclear microsatellite (nSSR) loci was examined, three chloroplast microsatellite (cpSSR) markers were developed and 13 haplotypes identified. The 11 populations were divided into three groups (A, B and C). Each population within the group was separated less than 40 km. Group B harbored the highest gene diversity (H) and allelic richness (Ar) for nSSR (H=0.74 and Ar=8.02). Group C had the highest diversity of chloroplast haplotypes (H=0.79 and Ar=6.8): 2.5 times more haplotypes than the other groups. Each population contributed differently to the total diversity, with respect to nSSR and cpSSR. AMOVA revealed that 58% of haplotypic and 15% of nSSR variation was partitioned among populations within groups. A Mantel test revealed significant correlations between population pairwise geographic ln(distance) and F_ST/(1−F_ST) for both nSSR (r=0.479; P=0.001) and cpSSR (r=0.230; P=0.040). Dendrograms of populations for nSSR, based on Nei’s genetic distance, were constructed using UPGMA and the neighbor-joining method. These results suggest that populations in group C have diverged from the other populations, while those in group B are similar to each other. For group B, fragmentation between populations should be avoided in order to maintain gene flow. For group C, the uniqueness of each population should be given the highest priority when planning genetic conservation measures for the species.     

Development and characterization of chloroplast microsatellite markers for <Emphasis Type="BoldItalic">Pinus massoniana</Emphasis> and their application in <Emphasis Type="BoldItalic">Pinus</Emphasis> (Pinaceae) species

Pinus massoniana is one of the important afforestation and pioneer tree species, which is widely distribute in southern China. Chloroplast simple sequence repeat markers (cpSSRs) have been widely used in studies of tree genetics, phylogenetic and breeding. We sequenced the whole chloroplast genome sequences of P. massoniana using PCR and Sanger sequencing. A total of 71 cpSSRs were identified, among which mononucleotide repeats were predominant (70.42%). Seventeen primer pairs were developed and amplification tests were conducted with 15 P. massoniana individuals. Also, cross-species amplification tests were conducted among 15 individuals per Pinus species, including P. elliottii, P. bungeana, P. armandii, P. caribaea, P. tabulaeformis, P. taiwanensis and P. yunnanensis which revealed polymorphic information content ranging from 0.2 to 0.8 and average of haploid diversity (h) ranging from 0.29 to 0.63. In addition, the polymorphic cpSSRs were useful in distinguishing the sampled pine species, and could be powerful tool in phylogenetic studies.     

Genetic diversity and population structure in natural populations of Moroccan Atlas cedar (Cedrus atlantica; Pinaceae) determined with cpSSR markers

Atlas cedar (Cedrus atlantica) is an ecologically and economically important forest tree species of northern Africa and is considered one of the endangered conifer species in the region. Chloroplast microsatellites (cpSSR) were used to study genetic variation within and among populations and geographical structure in natural populations of C. atlantica throughout its entire distribution range in Morocco. A total of 25 chloroplast haplotypes and 66 cpSSR alleles were found among 162 individuals. The cpSSRs indicate that C. atlantica appears to maintain a high level of genetic diversity (mean H(e) = 0.95), as observed in most coniferous species. Values of mean pairwise distance within a population (D(2)(SH)) were related to the size and location of the populations. AMOVA analysis showed that most of the variation in C. atlantica occurs within populations and confirmed the general tendency of gymnosperms to display lower values of population differentiation than angiosperms. The distance-based clustering method (PCoA and neighbor-joining analysis) and the geographical structure revealed a poor structure among the six populations of Cedrus atlantica. Also, a Mantel test indicated a weak correlation between geographic and genetic distances (P = 0.106, r = 0.363). These results are also interpreted in the context of postglacial history of the region plus human impacts.     

Comparison of genetic diversity estimates within and among populations of maritime pine using chloroplast simple-sequence repeat and amplified fragment length polymorphism data

We compared the genetic variation of Pinus pinaster populations using amplified fragment length polymorphism (AFLP) and chloroplast simple-sequence repeat (cpSSR) loci. Populations' levels of diversity within groups were found to be similar with AFLPs, but not with cpSSRs. The high interlocus variance associated with the AFLP loci could account for the lack of differences in the former. Although AFLPs revealed much lower genetic diversity than cpSSRs, the levels of among-population differentiation found with the two types of marker were similar, provided that loci showing fewer than four null-homozygotes, in any population, were pruned from the AFLP data. Moreover, the French and Portuguese populations were clearly differentiated from each other, with both markers. The Mantel test showed that the genetic distance matrix calculated using the AFLP data was correlated with the matrix derived from the cpSSRs. Because of the concordance found between markers we conclude that gene flow was indeed the predominant force shaping nuclear and chloroplastic genetic variation of the populations within regions, at the geographical scale studied.     

Assessment of the domestication state of ackee (Blighia sapida K.D. Koenig) in Benin based on AFLP and microsatellite markers

Ackee (Blighia sapida) is a native multipurpose species important for the livelihoods of the rural populations in Benin. Trees are found in natural forests or are managed by farmers in different traditional agroforestry systems. Genetic variation at amplified fragment length polymorphism (AFLP) markers, four nuclear microsatellites (nSSRs) and one chloroplast microsatellite (cpSSR) were investigated in 279 individuals from six wild and eight cultivated populations from Benin. The AFLP data revealed moderate levels of diversity of ackee in Benin (mean diversity values are proportion of polymorphic loci = 52.8% and Nei??s gene diversity = 0.157, for 375 AFLP fragments). The mean diversity values based on nSSR-markers are expected heterozygosity = 0.286, allelic richness = 2.77. Genetic variation of wild and cultivated populations did not differ markedly. AMOVA revealed that only 7.3 and 5.2% of the variation was partitioned among populations for nSSR- and AFLP-markers, respectively. A Mantel test based on these both marker-types revealed significant correlations between population pairwise geographic distance and genetic differentiation. Differentiation among cultivated populations was higher than among wild populations. The only polymorphic chloroplast microsatellite marker (ccmp7) showed three haplotypes. Cultivated populations from northeastern Benin were fixed on one haplotype which was not observed elsewhere indicating a different origin of these populations possibly from neighboring Nigeria. Farmer-led domestication had an impact on the spatial distribution of genetic variation but did not result in significant losses of diversity within populations. Measures to conserve genetic resources of ackee in each of the three main bioclimatic zones in Benin are proposed.