Fine-scale spatial genetic structure, mating, and gene dispersal patterns in Parkia biglobosa populations with different levels of habitat fragmentation.

PREMISE: A good understanding of genetic variation and gene dispersal in tree populations is crucial for their sustainable management, particularly in a context of rapid environmental changes. West African Sudanian savannahs are being fragmented and degraded, partly due to expansion of crop cultivation and monocultures that reduce tree density and may impact pollinators. The population dynamics of important indigenous trees could also be affected. We investigated the influence of habitat fragmentation on patterns of genetic diversity and gene dispersal of a key Sudanian agroforestry tree species, Parkia biglobosa. METHODS: Using 10 highly polymorphic nuclear microsatellites, we genotyped 2475 samples from reproductive trees, seedlings, and embryos in four tree populations presenting different levels of habitat fragmentation. RESULTS: Parkia biglobosa presented similar high genetic diversity across the four populations studied. Genetic diversity and inbreeding were similar between adults and embryo cohorts. In all four populations, the selfing rate was less than 1%. The effective number of pollen donors per tree was high (NEP ~ 18-22), as was the pollen immigration rate (from 34 to 74%). Pollen dispersal was characterized by a fat-tailed distribution with mean estimates exceeding 200 m. In three populations, stem diameter had a pronounced effect on male reproductive success. Here, the highest male reproductive success was observed in trees with a diameter at breast height between 60 and 75 cm. CONCLUSIONS: At the scale analyzed, fragmentation does not seem to pose limitations to gene flow in any of the sites investigated, regardless of the landscape configuration associated with the different tree stands. The study provides useful insights on the reproductive biology of an important tree species in the West African savannahs.

Population genomics of the widespread African savannah trees Afzelia africana and Afzelia quanzensis reveals no significant past fragmentation of their distribution ranges.

PREMISE: Few studies have addressed the evolutionary history of tree species from African savannahs. Afzelia contains economically important timber species, including two species widely distributed in African savannahs: A. africana in the Sudanian region and A. quanzensis in the Zambezian region. We aimed to infer whether these species underwent range fragmentation and/or demographic changes, possibly reflecting how savannahs responded to Quaternary climate changes. METHODS: We characterized the genetic diversity and structure of these species across their distribution ranges using nuclear microsatellites (SSRs) and genotyping-by-sequencing (GBS) markers. Six SSR loci were genotyped in 241 A. africana and 113 A. quanzensis individuals, while 2800 high-quality single nucleotide polymorphisms (SNPs) were identified in 30 A. africana individuals. RESULTS: Both species appeared to be mainly outcrossing. The kinship between individuals decayed with the logarithm of the distance at similar rates across species and markers, leading to relatively small Sp statistics (0.0056 for SSR and 0.0054 for SNP in A. africana, 0.0075 for SSR in A. quanzensis). The patterns were consistent with isolation by distance expectations in the absence of large-scale geographic gradients. Bayesian clustering of SSR genotypes did not detect genetic clusters within species. In contrast, SNP data resolved intraspecific genetic clusters in A. africana, illustrating the higher resolving power of GBS. However, these clusters revealed low levels of differentiation and no clear geographical entities, so that they were interpreted as resulting from the isolation by distance pattern rather than from past population fragmentation. CONCLUSIONS: These results suggest that populations have remained connected throughout the large, continuous savannah landscapes. The absence of clear phylogeographic discontinuities, also found in a few other African savannah trees, indicates that their distribution ranges have not been significantly fragmented during the climatic oscillations of the Pleistocene, in contrast to patterns commonly found in African rainforest trees.

Microsatellite markers development for Indonesian nutmeg (Myristica fragrans Houtt.) and transferability to other Myristicaceae spp.

Myristica fragrans (Myristicaceae) is a tropical evergreen tree that yields the two famous spices: nutmeg and mace. Despite its socio-economic importance, the spatial distribution of its genetic diversity is barely documented. In this aim, 48 nuclear microsatellite markers were isolated of which 14 were polymorphic in M. fragrans. Number of alleles per locus ranged from 2 to 6. The level of observed heterozygosity ranged from 0.038 to 0.929 across loci. Transferability of these microsatellites in other Myristica species (M. fatua, M. argentea, and M. crassipes) and Myristicaceae species (Horsfieldia palauensis) was tested and successful. These new microsatellites will be useful for future investigation on genetic diversity and population structure of M. fragrans and phylogenetically-related species.

Seed and pollen dispersal distances in two African legume timber trees and their reproductive potential under selective logging.

The natural regeneration of tree species depends on seed and pollen dispersal. To assess whether limited dispersal could be critical for the sustainability of selective logging practices, we performed parentage analyses in two Central African legume canopy species displaying contrasted floral and fruit traits: Distemonanthus benthamianus and Erythrophleum suaveolens. We also developed new tools linking forward dispersal kernels with backward migration rates to better characterize long-distance dispersal. Much longer pollen dispersal in D. benthamianus (mean distance dp  = 700 m, mp  = 52% immigration rate in 6 km2 plot, s = 7% selfing rate) than in E. suaveolens (dp  = 294 m, mp  = 22% in 2 km2 plot, s = 20%) might reflect different insect pollinators. At a local scale, secondary seed dispersal by vertebrates led to larger seed dispersal distances in the barochorous E. suaveolens (ds  = 175 m) than in the wind-dispersed D. benthamianus (ds  = 71 m). Yet, seed dispersal appeared much more fat-tailed in the latter species (15%-25% seeds dispersing >500 m), putatively due to storm winds (papery pods). The reproductive success was correlated to trunk diameter in E. suaveolens and crown dominance in D. benthamianus. Contrary to D. benthamianus, E. suaveolens underwent significant assortative mating, increasing further the already high inbreeding of its juveniles due to selfing, which seems offset by strong inbreeding depression. To achieve sustainable exploitation, seed and pollen dispersal distances did not appear limiting, but the natural regeneration of E. suaveolens might become insufficient if all trees above the minimum legal cutting diameter were exploited. This highlights the importance of assessing the diameter structure of reproductive trees for logged species.

Extensive seed and pollen dispersal and assortative mating in the rain forest tree Entandrophragma cylindricum (Meliaceae) inferred from indirect and direct analyses.

Pollen and seed dispersal are key processes affecting the demographic and evolutionary dynamics of plant species and are also important considerations for the sustainable management of timber trees. Through direct and indirect genetic analyses, we studied the mating system and the extent of pollen and seed dispersal in an economically important timber species, Entandrophragma cylindricum (Meliaceae). We genotyped adult trees, seeds and saplings from a 400-ha study plot in a natural forest from East Cameroon using eight nuclear microsatellite markers. The species is mainly outcrossed (t = 0.92), but seeds from the same fruit are often pollinated by the same father (correlated paternity, rp  = 0.77). An average of 4.76 effective pollen donors (Nep ) per seed tree contributes to the pollination. Seed dispersal was as extensive as pollen dispersal, with a mean dispersal distance in the study plot approaching 600 m, and immigration rates from outside the plot to the central part of the plot reaching 40% for both pollen and seeds. Extensive pollen- and seed-mediated gene flow is further supported by the weak, fine-scale spatial genetic structure (Sp statistic = 0.0058), corresponding to historical gene dispersal distances (σg ) reaching approximately 1,500 m. Using an original approach, we showed that the relatedness between mating individuals (Fij  = 0.06) was higher than expected by chance, given the extent of pollen dispersal distances (expected Fij  = 0.02 according to simulations). This remarkable pattern of assortative mating could be a phenomenon of potentially consequential evolutionary and management significance that deserves to be studied in other plant populations.

Evolution in African tropical trees displaying ploidy-habitat association: The genus Afzelia (Leguminosae).

Polyploidy has rarely been documented in rain forest trees but it has recently been found in African species of the genus Afzelia (Leguminosae), which is composed of four tetraploid rain forest species and two diploid dry forest species. The genus Afzelia thus provides an opportunity to examine how and when polyploidy and habitat shift occurred in Africa, and whether they are associated. In this study, we combined three plastid markers (psbA, trnL, ndhF), two nuclear markers (ribosomal ITS and the single-copy PEPC E7 gene), plastomes (obtained by High Throughput Sequencing) and morphological traits, with an extensive taxonomic and geographic sampling to explore the evolutionary history of Afzelia. Both nuclear DNA and morphological vegetative characters separated diploid from tetraploid lineages. Although the two African diploid species were well differentiated genetically and morphologically, the relationships among the tetraploid species were not resolved. In contrast to the nuclear markers, plastid markers revealed that one of the diploid species forms a well-supported clade with the tetraploids, suggesting historical hybridisation, possibly in relation with genome duplication (polyploidization) and habitat shift from dry to rain forests. Molecular dating based on fossil-anchored gene phylogenies indicates that extant Afzelia started diverging c. 14.5 or 20Ma while extant tetraploid species started diverging c. 7.0 or 9.4Ma according to plastid and nuclear DNA, respectively. Additional studies of tropical polyploid plants are needed to assess whether the ploidy-habitat association observed in African Afzelia would reflect a role of polyploidization in niche divergence in the tropics.

Large-scale pattern of genetic differentiation within African rainforest trees: insights on the roles of ecological gradients and past climate changes on the evolution of Erythrophleum spp (Fabaceae).

BACKGROUND: The evolutionary events that have shaped biodiversity patterns in the African rainforests are still poorly documented. Past forest fragmentation and ecological gradients have been advocated as important drivers of genetic differentiation but their respective roles remain unclear. Using nuclear microsatellites (nSSRs) and chloroplast non-coding sequences (pDNA), we characterised the spatial genetic structure of Erythrophleum (Fabaceae) forest trees in West and Central Africa (Guinea Region, GR). This widespread genus displays a wide ecological amplitude and taxonomists recognize two forest tree species, E. ivorense and E. suaveolens, which are difficult to distinguish in the field and often confused. RESULTS: Bayesian-clustering applied on nSSRs of a blind sample of 648 specimens identified three major gene pools showing no or very limited introgression. They present parapatric distributions correlated to rainfall gradients and forest types. One gene pool is restricted to coastal evergreen forests and corresponds to E. ivorense; a second one is found in gallery forests from the dry forest zone of West Africa and North-West Cameroon and corresponds to West-African E. suaveolens; the third gene pool occurs in semi-evergreen forests and corresponds to Central African E. suaveolens. These gene pools have mostly unique pDNA haplotypes but they do not form reciprocally monophyletic clades. Nevertheless, pDNA molecular dating indicates that the divergence between E. ivorense and Central African E. suaveolens predates the Pleistocene. Further Bayesian-clustering applied within each major gene pool identified diffuse genetic discontinuities (minor gene pools displaying substantial introgression) at a latitude between 0 and 2°N in Central Africa for both species, and at a longitude between 5° and 8°E for E. ivorense. Moreover, we detected evidence of past population declines which are consistent with historical habitat fragmentation induced by Pleistocene climate changes. CONCLUSIONS: Overall, deep genetic differentiation (major gene pools) follows ecological gradients that may be at the origin of speciation, while diffuse differentiation (minor gene pools) are tentatively interpreted as the signature of past forest fragmentation induced by past climate changes.

Complete chloroplast genome of two nutmeg species, Myristica argentea Warb. 1891 and Myristica fatua Houtt. 1774 (Myristicaceae).

Myristica argentea Warb. 1891 and M. fatua Houtt. 1774 are two South-East Asian food tree species. They are harvested from the wild or cultivated for local uses as a condiment (nutmeg and mace), medicine, and source of wood. In this study, we reconstructed the complete chloroplast (cp) genomes of these two species from whole genome sequencing data using the Illumina NovaSeq platform. The genome sizes of M. argentea and M. fatua were respectively 155,871 base pairs (bp) and 155,898 bp, including 126 genes and an overall GC content of 39.20% in both species. Our study provides useful resources for future evolutionary research and diversity analysis of Myristica species.

Dataset from de novo transcriptome assembly of Myristica fatua leaves using MinION nanopore sequencer.

Myristica fatua is a tropical fruit tree species originating from Indonesia. Very few genomic resources are available for the species. We developed a full-length transcriptome assembly using long-read sequencing (MinION Nanopore technology) and produced 4.3 million reads (3.5 G of bases). The assembled full-length transcript was constructed using the RATTLE program and assembled 21,098 transcripts. The transcript ranged from 201 - 14,174 bp, and N50 was 2,017 bp. The transcripts were annotated with the UNIPROT database using BlastX. The functional annotation was performed using Blast2go software. The 8,445 microsatellite motif-containing contigs were identified. The raw reads are deposited in the ENA (European Nucleotide Archive) with ENA experiment accession number ERX6798613.

Testing species delimitation in sympatric species complexes: the case of an African tropical tree, Carapa spp. (Meliaceae).

Plant species delimitation within tropical ecosystems is often difficult because of the lack of diagnostic morphological characters that are clearly visible. The development of an integrated approach, which utilizes several different types of markers (both morphological and molecular), would be extremely useful in this context. Here we have addressed species delimitation of sympatric tropical tree species that belong to Carapa spp. (Meliaceae) in Central Africa. We adopted a population genetics approach, sampling numerous individuals from three locations where sympatric Carapa species are known to exist. Comparisons between morphological markers (the presence or absence of characters, leaf-shape traits) and molecular markers (chloroplast sequences, ribosomal internal transcribed spacer region (ITS) sequences, and nuclear microsatellites) demonstrated the following: (i) a strong correlation between morphological and nuclear markers; (ii) despite substantial polymorphism, the inability of chloroplast DNA to discriminate between species, suggesting that cytoplasmic markers represent ineffective DNA barcodes; (iii) lineage sorting effects when using ITS sequences; and (iv) a complex evolutionary history within the genus Carapa, which includes frequent inter-specific gene flow. Our results support the use of a population genetics approach, based on ultra-polymorphic markers, to address species delimitation within complex taxonomic groups.

Characterization of new microsatellite loci isolated from Santiria trimera (Burseraceae).

PREMISE OF THE STUDY: To study the genetic structure among three morphotypes of an African rainforest tree species, Santiria trimera, nuclear microsatellite markers were isolated and characterized. METHODS AND RESULTS: Seven polymorphic loci were isolated using a pyrosequencing-based protocol and successfully amplified on three different morphotypes of S. trimera. For six of the seven loci, there is at least one private allele for one of the three morphotypes. The mean effective number of alleles is about four for each of the three morphotypes. CONCLUSIONS: These microsatellite markers are promising to explore the genetic delimitation among sympatric morphotypes found in Gabonese forests and to study the spatial genetic structure within each gene pool.

Domestication Syndrome in Dacryodes edulis (Burseraceae): Comparison of Morphological and Biochemical Traits between Wild and Cultivated Populations.

For millennia, people have harvested fruits from the wild for their alimentation. Gradually, they have started selecting wild individuals presenting traits of interest, protecting and cultivating them. This was the starting point of their domestication. The passage from a wild to a cultivated status is accompanied by a modification of a number of morphological and genetic traits, commonly known as the domestication syndrome. We studied the domestication syndrome in Dacryodes edulis (G.Don) H.J.Lam (known as 'African plum' or 'safoutier/prunier'), a socio-economically important indigenous fruit tree species in West and Central Africa. We compared wild and cultivated individuals for their sex distribution; flower, fruit and seed morphometric characteristics; seed germination temporal dynamic and fruit lipid composition. We found a higher percentage of male and male-hermaphrodite sexual types in wild populations than in cultivated ones; a lower fruit and seed mass in wild individuals; and similar mean time of germination, oil content and fatty acid composition between wild and cultivated individuals. Our results are interpreted in light of the presence of a domestication syndrome in D. edulis.

Isolation of SSR markers for two African tropical tree species, Erythrophleum suaveolens and E. ivorense (Caesalpinioideae).

PREMISE OF THE STUDY: To characterize the level of genetic diversity and gene fl ow, as well as to identify unambiguously two African tropical tree species, Erythrophleum ivorense and E. suaveolens , we have developed a set of nuclear SSR (Simple Sequence Repeats) markers. METHODS AND RESULTS: Nine SSRs that display polymorphism in both species were identified. The nine newly developed SSR markers can be amplified in only two multiplexed reactions. Levels of polymorphism were assessed in two populations per species, yielding two to fifteen alleles per locus in E. ivorense and three to sixteen alleles per locus in E. suaveolens . CONCLUSIONS: The SSR markers developed here are promising to study the spatial distribution of genetic diversity and the genetic delimitation of two Erythrophleum species from central Africa.

Utility of the Mitochondrial Genome in Plant Taxonomic Studies.

Size, structure, and sequence content lability of plant mitochondrial genome (mtDNA) across species has sharply limited its use in taxonomic studies. Historically, mtDNA variation has been first investigated with RFLPs, while the development of universal primers then allowed studying sequence polymorphisms within short genomic regions (<3 kb). The recent advent of NGS technologies now offers new opportunities by greatly facilitating the assembly of longer mtDNA regions, and even full mitogenomes. Phylogenetic works aiming at comparing signals from different genomic compartments (i.e., nucleus, chloroplast, and mitochondria) have been developed on a few plant lineages, and have been shown especially relevant in groups with contrasted inheritance of organelle genomes. This chapter first reviews the main characteristics of mtDNA and the application offered in taxonomic studies. It then presents tips for best sequencing protocol based on NGS data to be routinely used in mtDNA-based phylogenetic studies.

Shifting perceptions, preferences and practices in the African fruit trade: the case of African plum (Dacryodes edulis) in different cultural and urbanization contexts in Cameroon.

BACKGROUND: Understanding the perceptions, preferences and management practices associated with intraspecific variability of emblematic African tree crops is critical for their sustainable management. In this paper, we examine how the agrobiodiversity of a fruit tree species native to Central Africa, the African plum tree (Dacryodes edulis), is perceived and managed by Cameroonian cultivators. METHODS: Semi-structured interviews and tree surveys were conducted over four months with 441 African plum tree owners from three different ethnic groups (Bamileke, Bassa, Beti) in urban, peri-urban and rural areas. Questions focused on trees owners' perceptions-including the local nomenclature-preferences and management practices related to African plum trees and their intraspecific agrobiodiversity. RESULTS: Across the three ethnic groups in the study area, more than 300 different local varietal names were recorded. These were mainly based on morphological and organoleptic traits, with two-thirds of the names referring to fruit size, skin color and fruit taste. The same traits were used by tree owners to describe their fruit preferences, but their relative importance in shaping fruit preferences varied among groups. The preferences of urban dwellers from different ethnic groups when purchasing African plum fruit focused on the fruit's taste characteristics, while those of rural dwellers differed among ethnic groups. In rural areas, where African plums are sold and consumed by their growers, the preferences of Bassa consumers reflect quantity (fruit size) over quality (fruit taste or skin color) considerations. These preferences are reflected in the choice of seeds used for planting. Bassa owners sought seeds from trees with large fruits (with 34.8% of Bassa owners giving top priority to this trait as a selection criterion) to a significantly greater extent than Bamileke and Beti owners who prioritized taste and skin color instead. Among tree growers who selectively retained African plum trees in their fields, 44% considered tree productivity as a primary selection criterion. CONCLUSIONS: Findings linking perceptions of and preferences for fruit traits to intraspecific tree diversity, with attention to inter-ethnic and rural-urban differences, will help design locally specific measures to conserve the agrobiodiversity of African plum in the context of its ongoing domestication.

Trees and their seed networks: The social dynamics of urban fruit trees and implications for genetic diversity.

Trees are a traditional component of urban spaces where they provide ecosystem services critical to urban wellbeing. In the Tropics, urban trees' seed origins have rarely been characterized. Yet, understanding the social dynamics linked to tree planting is critical given their influence on the distribution of associated genetic diversity. This study examines elements of these dynamics (seed exchange networks) in an emblematic indigenous fruit tree species from Central Africa, the African plum tree (Dacryodes edulis, Burseraceae), within the urban context of Yaoundé. We further evaluate the consequences of these social dynamics on the distribution of the genetic diversity of the species in the city. Urban trees were planted predominantly using seeds sourced from outside the city, resulting in a level of genetic diversity as high in Yaoundé as in a whole region of production of the species. Debating the different drivers that foster the genetic diversity in planted urban trees, the study argues that cities and urban dwellers can unconsciously act as effective guardians of indigenous tree genetic diversity.

Plant traits correlated with generation time directly affect inbreeding depression and mating system and indirectly genetic structure.

BACKGROUND: Understanding the mechanisms that control species genetic structure has always been a major objective in evolutionary studies. The association between genetic structure and species attributes has received special attention. As species attributes are highly taxonomically constrained, phylogenetically controlled methods are necessary to infer causal relationships. In plants, a previous study controlling for phylogenetic signal has demonstrated that Wright's FST, a measure of genetic differentiation among populations, is best predicted by the mating system (outcrossing, mixed-mating or selfing) and that plant traits such as perenniality and growth form have only an indirect influence on FST via their association with the mating system. The objective of this study is to further outline the determinants of plant genetic structure by distinguishing the effects of mating system on gene flow and on genetic drift. The association of biparental inbreeding and inbreeding depression with population genetic structure, mating system and plant traits are also investigated. RESULTS: Based on data from 263 plant species for which estimates of FST, inbreeding (FIS) and outcrossing rate (tm) are available, we confirm that mating system is the main influencing factor of FST. Moreover, using an alternative measure of FST unaffected by the impact of inbreeding on effective population size, we show that the influence of tm on FST is due to its impact on gene flow (reduced pollen flow under selfing) and on genetic drift (higher drift under selfing due to inbreeding). Plant traits, in particular perenniality, influence FST mostly via their effect on the mating system but also via their association with the magnitude of selection against inbred individuals: the mean inbreeding depression increases from short-lived herbaceous to long-lived herbaceous and then to woody species. The influence of perenniality on mating system does not seem to be related to differences in stature, as proposed earlier, but rather to differences in generation time. CONCLUSION: Plant traits correlated with generation time affect both inbreeding depression and mating system. These in turn modify genetic drift and gene flow and ultimately genetic structure.

Comparative analysis of two sister Erythrophleum species (Leguminosae) reveal contrasting transcriptome-wide responses to early drought stress.

With the ongoing climate change, African rainforests are expected to experience severe drought events in the future. In Africa, the tropical genus Erythrophleum (Fabaceae) includes two forest sister timber tree species displaying contrasting geographical distributions. Erythrophleum ivorense is adapted to wet evergreen Guineo-Congolian forests, whereas E. suaveolens occurs in a wider range of climates, being found in moist dense forests but also in gallery forests under a relatively drier climate. This geographical distribution pattern suggests that the two species might cope differently to drought at the genomic level. Yet, the genetic basis of tolerance response to drought stress in both species is still uncharacterized. To bridge this gap, we performed an RNA-seq approach on seedlings from each species to monitor their transcriptional responses at different levels of drought stress (0, 2 and 6 weeks after stopping watering seedlings). Monitoring of wilting symptoms revealed that E. suaveolens displayed an earlier phenotypic response to drought stress than E. ivorense. At the transcriptomic level, results revealed 2020 (1204 down-regulated/816 up-regulated) and 1495 differentially expressed genes (DEGs) in response to drought stress from a total of 67,432 and 66,605 contigs assembled in E. ivorense and E. suaveolens, respectively. After identifying 30,374 orthologs between species, we found that only 7 of them were DEGs shared between species, while 587 and 458 were differentially expressed only in E. ivorense or E. suaveolens, respectively. GO and KEGG enrichment analysis revealed that the two species differ in terms of significantly regulated pathways as well as the number and expression profile of DEGs (Up/Down) associated with each pathway in the two stress stages. Our results suggested that the two studied species react differently to drought. E. suaveolens seems displaying a prompt response to drought at its early stage strengthened by the down-regulation of many DEGs encoding for signaling and metabolism-related pathways. A considerable up-regulation of these pathways was also found in E. ivorense at the late stage of drought, suggesting this species may be a late responder. Overall, our data may serve as basis for further understanding the genetic control of drought tolerance in tropical trees and favor the selection of crucial genes for genetically enhancing drought resistance.

Can population genetic structure be predicted from life-history traits?

Population genetic structure is a key parameter in evolutionary biology. Earlier comparative studies have shown that genetic structure depends on species ecological attributes and life-history traits, but species phylogenetic relatedness had not been accounted for. Here we reevaluate the relationships between genetic structure and species traits in seed plants. Each species is characterized by a set of life-history and ecological features as well as by its geographic range size, its heterozygote deficit, and its genetic structure at nuclear and organelle markers to distinguish between pollen- and seed-mediated gene flow. We use both a conventional regression approach and a method that controls for phylogenetic relationships. Once phylogenetic conservatism and covariation among traits are taken into account, genetic structure is shown to be related with only a few synthetic traits, such as mating system for nuclear markers and seed dispersal mode or geographic range size for organelle markers. Along with other studies on invasiveness or rarity, our work illustrates the fact that predicting the fate of species across a broad taxonomic assemblage on the basis of simple traits is rarely possible, a testimony of the highly contingent nature of evolution.

Characterization of microsatellite markers in two exploited African trees, Entandrophragma candollei and E. utile (Meliaceae).

PREMISE OF THE STUDY: Multiplexes of nuclear microsatellite primers were developed to investigate population genetic structure and diversity in two exploited African rainforest trees: Entandrophragma candollei and E. utile (Meliaceae). METHODS AND RESULTS: Microsatellite isolation was performed simultaneously on two nonenriched genomic libraries after next-generation sequencing. We developed 16 and 22 polymorphic markers for E. candollei and E. utile in three and four multiplexes, respectively. The number of alleles ranged from two to 17 for E. candollei and from three to 19 for E. utile. Mean expected and observed heterozygosity ranged between 0.75 ± 0.13 and 0.55 ± 0.23 for E. candollei and between 0.73 ± 0.10 and 0.49 ± 0.2 for E. utile. CONCLUSIONS: These sets of nuclear microsatellite markers constitute useful tools for exploring gene flow patterns in these two Entandrophragma species.