Genetic Structure of Oryza rufipogon Griff. Natural Populations in Malaysia: Implications for Conservation and Genetic Introgression of Cultivated Rice

Thirty polymorphic Oryza sativa microsatellite loci (SSRs) were used to study population genetic structure of O. rufipogon Griff. natural populations in Malaysia. A total of 445 alleles were detected with an average of 14.8 alleles per locus in 176 individuals of O. rufipogon sampled from the states of Penang, Kedah, Kelantan and Terengganu where the natural populations are still found. The Kelantan population in the northeast of Peninsular Malaysia had the highest level of genetic diversity as measured by the mean number of alleles per locus, A_a?=?7.67, average number of effective alleles, A_e?=?5.50, percentage of polymorphic loci, P?=?100%, observed heterozygosity, H_o?=?0.631 and expected heterozygosity, H_e?=?0.798. In contrast, the Terengganu population in the east showed the lowest level of genetic diversity measured by the same criteria (A_a?=?4.23, A_e?=?2.10, P?=?100%, H_o?=?0.549 and H_e?=?0.449). Model–based clustering analysis using the STRUCTURE 2.2 program placed all the individuals into 12 clusters that corresponded to the geographic sampling locations. Neighbour-joining tree was constructed based on Nei’s genetic distance to further assess the genetic structure of the O. rufipogon individuals, showed good agreement (93.8%) with the model-based cluster analysis. However, the neighbour-joining tree identified sub-populations that STRUCTURE could not identify. The classification of individuals from the same populations under the same cluster supported the population differentiation. These two analyses seemed to indicate expansion of populations from the northeast of Peninsular Malaysia (Tumpat, Pasir Mas and Kota Bahru, Kelantan) not only to the immediate south of the region i.e. Terengganu but also into the northwest (i.e. Penang and Kedah) with the former being more recent. Oryza rufipogon accession IRGC105491 and O. sativa ssp. indica cultivar MR219, which were included in this study for comparisons with the local wild rice accessions, indicated that introgression of cultivated rice could change genetic composition and affect the population genetic structure of wild rice. This possibility should be carefully considered in plans to conserve this wild rice.     

Allozyme Diversity and Geographic Variation among Populations of the Locally Endangered Taxon Carex magellanica subsp. irrigua (Cyperaceae)

Carex magellanica subsp. irrigua is a wet habitat taxon that is extinct or declining in the Baltic States and Central Europe, but still quite common in northern areas, in Fennoscandia and Alaska. We investigated the extent of genetic variation within and among populations and geographic regions of this subspecies. Isozyme electrophoresis in polyacrylamide gels was applied to characterize genetic diversity with allozymes as genetic markers. Of the nine putative isozyme loci assessed, five (56%) were found to be polymorphic. The genetic diversity in small and fragmented Estonian populations was lower (H _e?=?0.034) than in larger Fennoscandian and Alaskan populations (average H _e?=?0.082). All standard genetic parameters (A _e, H _o, H _e, P, F _is, t) showed the lowest values in Estonian populations. The heterozygosity level in Fennoscandian populations was low (H _o?=?0.01), whereas no heterozygotes were found in Estonian and Alaskan populations. High F _is values indicate that C. magellanica subsp. irrigua is predominantly inbreeding. The main reason for its decline in Estonia is the destruction of suitable habitats. More attention to the protection of Estonian habitats is needed to maintain genetic diversity and stop further decline of this taxon.     

Genetic Diversity and Population Structure in Chinese Indigenous Poplar (Populus simonii) Populations Using Microsatellite Markers

Populus simonii Carr. is an important ecological and commercial breeding species in northern China; however, human interference during the last few centuries has led to the reduction and fragmentation of natural populations. To evaluate genetic diversity and differentiation within and among existing populations, we used 20 microsatellite markers to examine the genetic variation and structure of 16 natural populations. Our results indicated that the level of genetic diversity differed among populations, with average number of alleles per locus (AR) and expected heterozygosity (H _e) ranging from 3.7 to 6.11 and 0.589 to 0.731, respectively. A marginal population from Qilian in the Qinghai–Tibetan Plateau showed the highest values (AR?=?6.11, H _e?=?0.731), and the Zhangjiakou and Yishui populations showed the lowest values (AR?=?4.08, H _e?=?0.589 and AR?=?3.7, H _e?=?0.604). The inbreeding coefficient (F _IS) values for all populations were positive, which indicated an excess of homozygotes. The microsatellites allowed the identification of a significant subpopulation structure (K?=?3), consistent with an isolation by distance model for P. simonii populations. Additionally, molecular variance analysis revealed that 14.2 % of the variation resided among populations, and 85.8 % could be attributed to variation within populations. These data provide valuable information for natural resource conservation and for optimization of breeding programs in the immediate future.     

Isozyme analysis of genetic variability and population structure of Lactuca L. germplasm

Isozymes were used to investigate the genetic variability, population structure, and relationships of Lactuca germplasm. The isozyme systems revealed 16 putative loci of a total of 31 alleles. Out of these 16 loci, 11 were polymorphic. The average values of expected heterozygosity (H_e), observed heterozygosity (H_o), mean number of alleles per locus (A) and effective number of alleles per locus (A_e) were 0.2227, 0.266, 1.3005 and 1.369, respectively. The average fixation indices were lower than zero for most of the accessions studied, indicating an excess of heterozygotes. Genetic differentiation among accessions (F_ST) exhibited that 51.3% of the isozyme variation was recorded among accessions, and 48.7% of the genetic variation resided within accessions. The average values of total heterozygosity (H_T) and intra-accessional genetic diversity (H_S) were 0.352 and 0.171, respectively. Moreover, the inter-accessional genetic diversity (D_ST) ranged from 0 to 0.424 with an average of 0.18. Cluster analysis revealed that L. sativa cultivars were distributed throughout different Lactuca species. Thereby, isozymes results confirms the hypothesis of the polyphyletic origin of L. sativa. This high level of genetic variation proved that isozymes are efficient for polymorphism analysis of Lactuca germplasm.     

Genetic diversity of populations of a rare species of Dictamnus gymnostylis Stev. in Bashkir Cis-Urals

We examined genetic diversity in populations of Dictamnus gymnostylis Stev., a rare species growing in the Bashkir Cis-Urals, based on the analysis of 8 gene-enzyme systems and detected a fairly high level of intraspecific genetic diversity and population differentiation. We determined the average number of alleles per locus (A) as 1.57; the portion of polymorphic loci (P ₉₅) as 0.508; the observed heterozygosity (H _o) as 0.139; and the expected heterozygosity (H _e) as 0.169. Of the total genetic diversity, 88.3% stems from variability within populations, and 11.7% is due to variation among populations. The average value for the Nei’s genetic distance (D) constituted 0.028.     

Patterns of Genetic Diversity in Platanthera bifolia (Orchidaceae) with Respect to Life History Traits and Recent Range Expansion

For evolutionary and ecological analyses, genetic diversity at different scales needs to be studied in terms of biological properties, habitat, population size and population history. We surveyed Platanthera bifolia populations from six regions in northeastern Poland to determine the impact of the mating system and population history on genetic diversity. Based on variation at allozyme markers, genetic variation was relatively moderate (P?=?22.3%, A?=?1.48, H _O?=?0.083, F _IS?=??0.015) and similar to other Platanthera species. These parameters varied between populations (P?=?13.3%–26.6%, A?=?1.26–1.66, H _O?=?0.055–0.111, F _IS?=??0.262–0.147). The genetic diversity patterns were shaped by different proportions of facilitated selfing and/or outcrossing, resulting in positive and negative F _IS values, respectively. No relationship between inbreeding coefficient and population size, however, and no impact of apomixis on the level of genetic diversity of P. bifolia were found. The relatively low level of genetic differentiation among the investigated regions (F _CT?=?0.002, P?>?0.05) and among populations (F _ST?=?0.048, P?<?0.001), and the lack of a significant relationship between genetic and geographical distance, are discussed in the context of possible scenaria of postglacial expansion.     

Fine-scale genetic structure of the threatened rosewood Dalbergia nigra from the Atlantic Forest: comparing saplings versus adults and small fragment versus continuous forest

Assessing the population genetic structure of threatened species is important for developing successful conservation strategies. In this study, we evaluated the fine-scale spatial genetic structure (SGS) of Dalbergia nigra from a regenerating secondary forest fragment and compared it with previous data from a primary forest of a large reserve. A total of 107 adult and 111 saplings were mapped and genotyped for seven microsatellite loci. The genetic diversity was high and similar in adults (H _e?=?0.682) and saplings (H _e?=?0.680). The spatial extent of SGS was higher in adults than in saplings. Overlapping generations in the potentially reproductive individuals is the likely explanation for the higher SGS in adults (Sp?=?0.016) in relation to the saplings (Sp?=?0.010). The SGS in the adults from the secondary forest fragment was similar to that found in the primary forest. Considering the SGS found in adults, from both the secondary and primary forests, seeds for ex situ conservation should be collected from trees at least 80 m apart to reduce the genetic similarity between samples. These results highlight the importance of preserving small forest fragments to allow successful regeneration and maintenance of the genetic diversity in D. nigra.     

Patterns of differentiation among endangered pondberry populations

Pondberry, Lindera melissifolia, is an endangered and partially clonally reproducing shrub species found in isolated populations that inhabit seasonally wet depressions in forested areas of the lower Mississippi River alluvial valley and southeastern regions of the United States. With eleven microsatellite loci, we quantified population genetic differentiation and diversity among 450 genets in 10 locations distributed across pondberry’s range. We used estimates of F _st and Jost’s D _est to measure genetic differences between populations and between geographic regions. The largest pairwise regional difference was found between eastern and western regional population groups (F _st = 0.23, D _est = 0.67), with the northern-most population groups in each region exhibiting larger divergence from each other than the southern-most population groups. Genetic diversity was lowest in the Sand Pond Conservation Area (A _e = 1.9, H _e = 0.36), which was the northern-most pondberry population, and highest in the Francis Marion National Forest (A _e = 4.1, H _e = 0.69), although we identified only 17 genets in that admixed population. Following adjustments for estimated null allele frequencies, we identified heterozygote excess in four eastern populations and found no evidence for inbreeding in any population. The observed patterns of differentiation indicate a phylogeography that exhibits an Appalachian Mountain discontinuity coupled with northward migrations along the Southern Atlantic Coastal Plain and into the Mississippi Alluvial Plain. The genetic consequences of this proposed phylogeographical structure may affect selection of germplasm sources for population reestablishment programs across pondberry’s range.     

Genetic diversity and structure of an endemic and critically endangered stream river salamander (Caudata: Ambystoma leorae) in Mexico

Small or isolated populations are highly susceptible to stochastic events. They are prone and vulnerable to random demographic or environmental fluctuations that could lead to extinction due to the loss of alleles through genetic drift and increased inbreeding. We studied Ambystoma leorae an endemic and critically threatened species. We analyzed the genetic diversity and structure, effective population size, presence of bottlenecks and inbreeding coefficient of 96 individuals based on nine microsatellite loci. We found high levels of genetic diversity expressed as heterozygosity (H_o = 0.804, H_e = 0.613, H_e* = 0.626 and H_Nei = 0.622). The population presents few alleles (4–9 per locus) and genotypes (3–14 per locus) compared with other mole salamanders species. We identified three genetically differentiated subpopulations with a significant level of genetic structure (F_ST = 0.021, R_ST = 0.044 y D_est = 0.010, 95 % CI). We also detected a reduction signal in population size and evidence of a genetic bottleneck (M = 0.367). The effective population size is small (Ne = 45.2), but similar to another mole salamanders with restricted distributions or with recently fragmented habitat. The inbreeding coefficient levels detected are low (F_IS = ?0.619–0.102) as is gene flow. Despite, high levels of genetic diversity A. leorae is critically endangered because it is a small isolated population.     

Is the genetic diversity of small scattered forest tree populations at the southern limits of their range more prone to stochastic events? A wild cherry case study by microsatellite-based markers

Wild cherry (Prunus avium L.) is a widespread, partially asexual, noble hardwood European species characterized by a scattered distribution, small population sizes, and human exploitation for its valuable wood. These characteristics, especially at the southern limits of the species natural distribution where additional varying stresses may occur, render P. avium populations prone to potential stochastic, genetic, and demographic events. In this study, we used dominant inter simple sequence repeat (ISSR) and codominant simple sequence repeat (SSR) markers to infer the genetic structure of P. avium. Five populations from northern Greece were evaluated based on 46 ISSR and 11 SSR loci. Populations presented a relatively high level of genetic variation, with a mean genetic diversity of H _e?=?0.166 and H _e?=?0.740 regarding ISSR and SSR analysis, respectively. We observed moderate population differentiation for ISSR (G _ST?=?0.113) and SSR (F _ST?=?0.097) markers. AMOVA also detected significant differentiation among populations for ISSRs (?? _ST?=?0.338) and SRRs (?? _ST?=?0.162). According to linkage disequilibrium analysis, estimates of effective population size were generally sufficient for maintaining extant genetic variability and evolutionary potential. A possible bottleneck was detected for only one population. In general, it appears that despite the particular characteristics of the P. avium populations studied, genetic stochasticity events were not apparent. The studied populations, located at the rear edge of the species European distribution, reveal a wealth of genetic variation that is very valuable for the genetic conservation of local adaptive gene complexes, especially under contemporary climatic change scenarios.     

Population genetic structure of the noxious weed Amaranthus retroflexus in Central Europe

Genetic variation was assessed in a range of populations of Amaranthus retroflexus using isoenzyme analysis. Population genetic diversity was measured by evaluating patterns of variation at six putatively neutral isoenzyme loci (comprising 24 putative alleles) within and among 20 populations of A. retroflexus collected in different habitats: ruderal habitats, cereal fields and hop gardens. Amaranthus retroflexus is a noxious weed of North American origin that infests various crops. Overall, A. retroflexus displayed moderate levels of genetic diversity in comparison with other herbaceous plants. The percentage of polymorphic loci was 50.0%, with mean values of 2.01, 0.142 and 0.227 for the average number of alleles per polymorphic locus (A), observed heterozygosity (H_o) and expected heterozygosity (H_e), respectively. A discrepancy between observed and expected heterozygosity and significant differences from H-W expectation indicate that there is an excess of homozygotes in many populations. As a result, there is strong evidence of inbreeding within populations (F_IS = 0.382) and significant population differentiation (F_ST = 0.270). Even though the species is partly autogamous, inbreeding does not lead to strong inbreeding depression resulting from self-pollination, as inbreeding has no effect on the success of the species in today's countryside. Moreover, allele frequencies detected in agricultural habitats (i.e., cereal fields and hop gardens) differed from those detected in populations collected from ruderal habitats, which is probably caused by systematic application of herbicides in agricultural ecosystems.     

Genetic diversity of nine faba bean (Vicia faba L.) populations revealed by isozyme markers

Seven isozyme systems (Sod, 6-Pgd, Me, Est, Skdh, Fdh and Gdh) representing nine loci were used to study the genetic diversity of nine faba bean populations. Seven loci revealed polymorphic bands and showed the same quaternary structure as that found in several species. They revealed a high number of phenotypes. Indeed, from 3 to 9 phenotypes per locus were investigated in this study. The percentage of polymorphic loci (P = 59.3 %) was higher than that mentioned in the autogamous species (P = 20.3 %) and less than the optimum (P=96 %) indicated for allogamous plants. Total genetic diversity (H _T) and within population genetic diversity (H _S) were estimated with the isozyme markers. The contribution of among population genetic diversity (D _ST) to total genetic diversity was 22%. Enzyme markers pointed out an average inbreeding level for whole population (F _IT) and within population (F _IS). Within population genetic diversity represents 78% of total diversity. Intra-population genetic diversity (H _S = 0.206) was ranged with the respect of allogamous species and was clearly higher than that of among population genetic diversity (D _ST = 0.057) indicating an out-crossing predominance in the studied populations. The expected heterozygosity was higher than that observed heterozygosity at the allogamous species was confirmed in this study. Although, the mean estimated gene flow was less than 1(Nm=0.814), the dendrogram based on Nei’s genetic distance of the 9 populations using UPGMA method showed some genetic drift between populations.     

Genetic diversity and structure of the endangered species Megaleranthis saniculifolia in Korea as revealed by allozyme and ISSR markers

The genetic diversity and structure of 12 populations of Megaleranthis saniculifolia, a rare endemic Korean plant, were analyzed using 14 allozyme loci coding 10 enzymes and 78 ISSR loci using seven primers. The genetic diversity of M. saniculifolia at the species level was similar to that observed in out-crossing and long-lived perennials, while at the population level, it was significantly low. The high F _IS value of many populations as well as homozygote excess occurred relatively evenly in many populations in relation to the Hardy-Weinberg expectation, suggesting that inbreeding was occurring within the M. saniculifolia populations. The degree of genetic differentiation based on the two markers was high, and there was no correlation between geographic and genetic distance. Bayesian cluster analysis did not reveal any remarkable geographic trends. Positive correlations were observed between genetic diversity (H _e and h) and population size. Therefore, low genetic diversity within the population and high population differentiation of M. saniculifolia were closely related to the influence of genetic drift, particularly in highly isolated populations. In addition, the fixation of the main alleles at several loci in the opposite direction provided good evidence for genetic drift. The genetic diversity of M. saniculifolia could be compromised if the distribution area or the size of the population were further reduced. In particular, the isolated populations that are fragmented within an area could be at high risk of extinction due to accelerated inbreeding or genetic drift. Considering this, a close monitoring of the population size and of the changes in the genetic structure must be performed. Some practical measures for genetic conservation are also proposed.     

The genetic signature of ecologically different grassland Lepidopterans

The level of genetic diversity found for species is strongly influenced by properties of the species’ ecology, abundance and behaviour (as dispersal). To address this coherence, we selected twenty-two grassland butterfly and burnet moth species, which were previously analysed by allozyme electrophoresis (using 15–25 loci per species) over a study area in western Germany with adjoining areas of Luxembourg and north-eastern France. For this study area, we calculated the species’ specific climatic niche breadths and derived various ecological parameters from literature and own field observations. The obtained parameters of genetic diversity (heterozygosity, number of alleles and percentage of polymorphic loci), genetic differentiation (D _est as well as F _ST and F _IS values as proxis for genetic differentiation among populations and inbreeding within populations), as well as ecological and climatic niche dimensions did not show significant differences among the different Lepidoptera families; therefore taxonomic assignment apparently has a negligible influence on the genetic structure of taxa. Genetic diversity and differentiation showed a significant correlation with the ecological and climatic niche-breadth of species in many cases: generalistic species with rather unspecific ecological characteristics and climatic niche had higher genetic diversities and tend to have lower differentiation and inbreeding, whereas specialist taxa (i.e. with narrow ecological and climatic niches) have lower genetic diversities and higher differentiation and inbreeding. The results might reflect contrasting population structures of specialist species with lower abundances compared with the more common generalists. The more restricted and isolated occurrence of specialists might consequence a reduction in genetic diversity and an increase in genetic differentiation among local populations. In contrast, generalists with unspecific habitat requirements occur in higher abundances and in consequence show a more homogenous genetic structure with higher diversities.     

Genetic diversity and population structure of the Asian green mussel Perna viridis in South China Sea based on microsatellite markers

The green mussel, Perna viridis is ecologically and economically important in the coastal region of the South China Sea. Determining its population genetic structure at this fine geographic scale will help sustainable management of natural stocks. In this study, we examined the genetic diversity and population genetic structure of P. viridis from four locations in the South China Sea (n = 45–48) using nine microsatellite loci. The results showed moderate levels of genetic diversity in all four samples (mean A = 13.222–14.000, mean A_e = 7.092–7.571, mean A_r = 12.894–13.746, mean H_o = 0.596–0.656, mean H_e = 0.690–0.733) and a large effective population size estimate for the pooled sample (total N_e estimates = infinity, 95% CI = 1869.0-infinity). We did not detect any sign of recent bottleneck events in P. viridis populations in the South China Sea. The conventional and a model-based analysis reveal low, non-significant genetic divergence among the four samples (F_ST = − 0.001–0.005, P > 0.05/6). The results obtained from this study can provide valuable genetic information for the conservation and fishery management of P. viridis by retaining the high N_e estimates.     

Microsatellites reveal substantial among-population genetic differentiation and strong inbreeding in the relict fern Dryopteris aemula

Background and Aims

A previous study detected no allozyme diversity in Iberian populations of the buckler-fern Dryopteris aemula. The use of a more sensitive marker, such as microsatellites, was thus needed to reveal the genetic diversity, breeding system and spatial genetic structure of this species in natural populations.

Methods

Eight microsatellite loci for D. aemula were developed and their cross-amplification with other ferns was tested. Five polymorphic loci were used to characterize the amount and distribution of genetic diversity of D. aemula in three populations from the Iberian Peninsula and one population from the Azores.

Key Results

Most microsatellite markers developed were transferable to taxa close to D. aemula. Overall genetic variation was low (H_T = 0·447), but was higher in the Azorean population than in the Iberian populations of this species. Among-population genetic differentiation was high (F_ST = 0·520). All loci strongly departed from Hardy–Weinberg equilibrium. In the population where genetic structure was studied, no spatial autocorrelation was found in any distance class.

Conclusions

The higher genetic diversity observed in the Azorean population studied suggested a possible refugium in this region from which mainland Europe has been recolonized after the Pleistocene glaciations. High among-population genetic differentiation indicated restricted gene flow (i.e. lack of spore exchange) across the highly fragmented area occupied by D. aemula. The deviations from Hardy–Weinberg equilibrium reflected strong inbreeding in D. aemula, a trait rarely observed in homosporous ferns. The absence of spatial genetic structure indicated effective spore dispersal over short distances. Additionally, the cross-amplification of some D. aemula microsatellites makes them suitable for use in other Dryopteris taxa.     

Low levels of genetic variation within populations of the four rare orchids Gymnadenia cucullata, Gymnadenia camtschatica, Amitostigma gracile, and Pogonia minor in South Korea: indication of genetic drift and implications for conservation

Many terrestrial orchids are relatively rare, and their populations are small and spatially isolated. Population genetics theory predicts that populations of such species, affected historically by random genetic drift, would maintain low levels of genetic diversity and exhibit a high degree of among-population divergence. To test this prediction, I used enzyme electrophoresis. Genetic diversity within populations of the four rare, terrestrial orchids Gymnadenia cucullata (four populations) and its congener G. camtschatica (four populations), Amitostigma gracile (four populations in one region and three in another region), and Pogonia minor (three populations each in two regions) was investigated in South Korea at the landscape level. As predicted, populations of the four species harbor low levels of genetic diversity within populations: the mean percentage of polymorphic loci, %P, the mean number of alleles per locus, A, and the average expected heterozygosity, H _e, were 12.5%, 1.13, and 0.036 for G. cucullata, respectively; 18.2%, 1.18, and 0.067 for G. camtschatica; 3.0%, 1.04, and 0.009 for A. gracile; and 2.7%, 1.06, and 0.014 for P. minor. Except for G. camtschatica (F _ST = 0.000), a significantly high degree of genetic divergence between conspecific populations was detected in the other three species: F _ST = 0.081 for G. cucullata; 0.348 and 0.811 in two regions for A. gracile; and 0.469 and 0.758 in two regions for P. minor. In addition, individuals within populations are highly structured in the four species (overall F _IS = 0.276 for G. cucullata; 0.308 for G. camtschatica; 0.758 for A. gracile; and 0.469 for P. minor), suggesting that selfing, biparental inbreeding, and/or consanguineous mating have occurred in populations of the four species. With the exception of G. camtschatica, an allele at a locus is fixed in a population, whereas alternative alleles with low or high frequencies are detected in another population across the landscape. My results suggest that evolutionary histories of G. cucullata, A. gracile, and P. minor are different from G. camtschatica. Historical genetic drift would be an important force shaping the genetic structure of the Korean populations of G. cucullata, A. gracile, and P. minor. For G. camtschatica on Ulleung Island, relatively higher levels of genetic variation within populations compared to its congener G. cucullata (H _e = 0.067 vs. 0.036) and little evidence of population genetic structure among populations (F _ST = 0.000) suggest that individuals were, presumably, once continuously distributed on Ulleung Island, and populations have recently been isolated by habitat fragmentation through natural succession (e.g,. probably the encroachment of woody vegetation on grasslands) or human-mediated disturbances (e.g., collections). Thus, conservation strategies for the four species should be differently developed in order to preserve genetic diversity in South Korea.     

Conservation implications of genetic structure in the narrowest endemic quillwort from the Eastern Amazon

The quillwort Isoëtes cangae is a critically endangered species occurring in a single lake in Serra dos Carajás, Eastern Amazon. Low genetic diversity and small effective population sizes (N _e) are expected for narrow endemic species (NES). Conservation biology studies centered in a single species show some limitations, but they are still useful considering the limited time and resources available for protection of species at risk of extinction. Here, we evaluated the genetic diversity, population structure, N _e, and minimum viable population (MVP) of I. cangae to provide information for effective conservation programs. Our analyses were based on 55 individuals collected from the Amendoim Lake and 35,638 neutral SNPs. Our results indicated a single panmictic population, moderate levels of genetic diversity, and N _e in the order of thousands, contrasting the expected for NES. Negative F_IS values were also found, suggesting that I. cangae is not under risk of inbreeding depression. Our findings imply that I. cangae contains enough genetic diversity to ensure evolutionary potential and that all individuals should be treated as one demographic unit. These results provide essential information to optimize ex situ conservation efforts and genetic diversity monitoring, which are currently applied to guide I. cangae conservation plans.     

A mountain range is a strong genetic barrier between populations of <Emphasis Type="Italic">Afzelia quanzensis</Emphasis> (pod mahogany) with low genetic diversity

Understanding patterns of genetic diversity of plants is important in guiding conservation programs. The aim of our study was to characterize genetic diversity in Afzelia quanzensis, an economically important African tree species. We genotyped 192 individuals at 10 nuclear microsatellite loci. Samples were collected from nine sites in Zimbabwe, five in the north and four in the south, separated by a mountain range, the Kalahari-Zimbabwe axis. Overall, genetic diversity was relatively low across all sites (expected heterozygosity (H _E)?=?0.452, mean number of alleles (A)?=?4.367, allelic richness (A _R)?=?2.917, effective number of alleles (A _E)?=?2.208, and private allelic richness (PA_R)?=?0.197). Genetic diversity estimates, H _E, A, A _R, and PA_R, were not significantly different between northern and southern sites. Allelic richness was significantly higher in southern sites. Significant population differentiation was observed among all sites (F _ST ?=?0.0936, G′ _ST ?=?0.1982, G _ST ?=?0.1001, D _JOST?=?0.0598). STRUCTURE analysis and principal components analysis identified two gene pools, one predominantly made up of southern individuals, and the other of northern individuals. A Monmonier’s function detected a genetic barrier that coincided with the Kalahari-Zimbabwe axis. The relatively low level of genetic diversity in A. quanzensis may reduce adaptability and limit future evolutionary responses. All sites should be monitored for deleterious effects of low genetic diversity, and genetic resource management should take into consideration the existence of the distinct gene pools to capture the entire extant genetic variation.     

Genetic structure in peripheral Western European populations of the endangered species Cochlearia pyrenaica (Brassicaceae)

Cochlearia pyrenaica is one of the most endangered plant species in Europe, listed in many European and regional conservation policy documents (e.g. Spain, France, Belgium, Switzerland). To study its genetic structure, define its conservation units and propose a management strategy for this species, amplified fragment length polymorphism markers were used to analyse the genetic diversity within and between five representative populations of the species distribution in Western Europe (Cantabrian Range, North of Spain; Pyrenees, France; Wallonia, Belgium). Low levels of genetic diversity were revealed by the population percentage of polymorphic bands (PPB?=?36.56%), average within-population diversity (H _S?=?0.0990) and genetic diversity within populations (H _pop?=?0.1541), although high levels were reported at species level (PPB?=?81.16%; total genetic diversity for the species, H _T?=?0.0990; and genetic diversity within whole species, H _sp?=?0.2515). The coefficient of genetic differentiation among populations (G _ST) was 0.3869. The analysis of Shannon diversity index in population and for the total data set partitioned (38.72%) and AMOVA (53%) detected a high level of interpopulation diversity, in broad agreement with the result of genetic differentiation analysis. NeighborNet network and principal coordinate analyses clustered the populations in three major groups congruent with geographical regions. Bayesian clustering also confirmed these three distinct genetic clusters. The level of gene flow (Nm) was estimated as 0.3961 individuals per generation among populations, with the genetic identity (I) and genetic distance (D) among populations ranging from 0.8679 to 0.9651 and from 0.0355 to 0.1417, respectively. Therefore, the low levels of genetic variation and high divergence of regional gene pools indicate that there is a need to protect each disjunct region of Western Europe.