Amplified Fragment Length Polymorphism Markers Research Articles

Genetic Diversity and Relationships among Sugarcane (Saccharum sp.) from Thailand Revealed by RAPD and AFLP Markers

Objective: The objective of the present research was to evaluate the genetic diversity and relationships of sugarcane ( Saccharum sp.) that collected from the sugarcane germplasm collection, Thailand. Methods: Genetic diversity of sugarcane was detected by DNA sequencing, Random Amplified Polymorphic DNA (RAPD) and Amplified Fragment Length Polymorphism (AFLP) markers. Findings: The trnL- trnF region of the chloroplast genome was amplified for 26 cultivars with C and F primers that the fragment was approximately 950 base pairs (bp). The taxonomic status and relationships of these sequences are not resolved. RAPD marker was used to study genetic variation and relationships among 56 sugarcane varieties and their hybrids. Ninety-six RAPD primers were screened and nine primers of them produced reproducible and recordable bands were used in analysis. The eighty-eight polymorphic bands (96.70%) were detected and genetic similarity was 0.657. The best five AFLP primer combinations were selected and generated 187 polymorphic bands (80.26%). Comparing the results from the RAPD and AFLP markers in 19 sugarcane cultivars, the genetic similarity ranging from 0.582 to 0.927, with the average of 0.756 for AFLP and ranging from 0.449 to 0.865, with the average of 0.657 for RAPD that demonstrating a low level of genetic diversity. For dendrogram analysis, AFLP marker showed itself to be more efficient at discriminating sugarcane cultivars. However, the genetic relationship of the samples slightly correlated with sucrose content. Application: RAPD and AFLP markers can be used to help plant breeder to select cultivars for future sugarcane improvement programs.

Desarrollo de marcadores moleculares para la identificación de especies de Eucalyptus

Uno de los principales problemas que enfrentan los programas de mejoramiento genético en eucaliptos es la dificultad para identificar las especies e híbridos. El objetivo de este estudio fue encontrar marcadores moleculares asociados a cinco especies de Eucalyptus (E. saligna, E. tereticornis, E. urophylla, E. grandis and E. brassiana), mediante marcadores AFLP (Amplified Fragment Length Polymorphism) y BSA (Bulk Segregant Analysis), para su uso en programas de mejoramiento genético en Brasil. En 33 combinaciones de cebadores, se obtuvo un total de 868 fragmentos polimórficos, que representan un 91,65% del polimorfismo. Las mejores combinaciones que muestran potenciales marcadores para la identificación de especies, fueron encontradas en los cebadores M+GGT/E+ACC, que estuvo un 70% de los individuos asociados a la especie E. urophylla. Sin embargo, la combinación de cebadores compuesta de M+GGA/E+ACC identificó el 60% de individuos en la especie E. saligna; la combinación de los cebadores M+GTC/E +AAC, confirmó dos marcas, una en 60% y la otra en 50% para la identificación de individuos de la especie E. grandis. El tratamiento compuesto por los cebadores M+GGC/E+AAA, confirmó un 30% de los individuos perteneciente a la especie E. brassiana, siendo igual para la combinación de cebadores M+GGC/E+ACC, identificando el 30% de los individuos de la especie E. tereticornis. El análisis AFLP en asocio a BSA proporcionan una herramienta rápida para la identificación de cultivares en Eucalyptus, a la vez de que puede ser usados en los programas de mejoramiento genético forestal.

Rates of gene flow in a freshwater snail and the evolution of phenotypic plasticity

The evolution of phenotypic plasticity requires a number of conditions. Selection of plasticity is favoured when the organism experience environmental change, costs are low and cues are reliable about the environmental heterogeneity. However, organisms living in stable environments, not showing constitutive traits but a large amount of plasticity, are predicted to demonstrate high rates of gene flow in order for selection to favour the evolution of phenotypic plasticity, which accordingly should provide weak genetic structures across populations. We used the pulmonate freshwater gastropod Radix balthica, a species with known and considerable shell shape variation due to predator-induced plasticity, and used amplified fragment length polymorphism markers to test if the rate of gene flow can explain the evolution of phenotypic plasticity. Since R. balthica inhabit water bodies with different but consistent predator regimes, we envisaged a large dispersal rate. However, we found a contradictory result with clear population structures, even among adjacent ponds in southern Sweden. We discuss this apparent paradox in contrast to the evolution of ecotype formation, colonization mechanisms that have the potential to reduce gene flow and, in the context of costs of plasticity, we consider new perspectives about relaxed and variable selection that may drive the evolution of phenotypic plasticity. (Less)

Association analysis of biotic and abiotic stresses resistance in chickpea (Cicer spp.) using AFLP markers

ABSTRACTChickpea suffers from different biotic and abiotic stresses, which has led to considerable decreases in seed yield. Since the economic value of a cultivar is determined by its phenotypic characteristics, good knowledge of the genetic structure and identification of genomic loci associated with desired traits will facilitate crop breeding. Amplified fragment length polymorphism (AFLP) markers associated with different agro-morphological characteristics, cold and drought tolerance as well as Ascochyta blight resistance were identified in chickpea by using 44 genotypes comprising cultigens, landraces, internationally developed improved lines and wild relatives, evaluated in a randomized complete block design with three replications at the Urmia rainfed research station. Using six AFLP primer combinations, 64 clear and reproducible markers were developed. The polymorphism information content values calculated for each primer pair ranged from 0.155 (EcoR1-ACC/Mse1-CAG) to 0.270 (EcoR1-ACC/ Mse1-CTG) with an average of 0.237. Analysis of molecular variance (AMOVA) revealed that 90% of the total variance was due to differences within populations and 10% due to differences among populations. Using a general linear model and applying multiple testing corrections, 24 AFLP markers associated with genes controlling the studied traits were identified. Some identified markers were associated with more than one trait. The identified markers could be of interest in marker-assisted selection in chickpea breeding programmes.

Identification of male-specific AFLP and SCAR markers in the dioecious plant Humulus scandens

In this study, 17 male-specific amplified fragment length polymorphism (AFLP) markers were identified between male and female Humulus scandens plants. BLAST analysis revealed that 7 of the 17 sex-linked sequences were highly similar to retrotransposons. Two stable male-specific sequence-characterized amplified regions (SCAR) markers were developed. These AFLP and SCAR markers are novel molecular probes that can be used efficiently to identify the genetic gender of H. scandens and may provide a basis for further investigations on the evolution of sex chromosomes.

Rare Pyrenophora teres Hybridization Events Revealed by Development of Sequence-Specific PCR Markers.

Pyrenophora teres f. teres and P. teres f. maculata cause net form and spot form, respectively, of net blotch on barley (Hordeum vulgare). The two forms reproduce sexually, producing hybrids with genetic and pathogenic variability. Phenotypic identification of hybrids is challenging because lesions induced by hybrids on host plants resemble lesions induced by either P. teres f. teres or P. teres f. maculata. In this study, 12 sequence-specific polymerase chain reaction markers were developed based on expressed regions spread across the genome. The primers were validated using 210 P. teres isolates, 2 putative field hybrids (WAC10721 and SNB172), 50 laboratory-produced hybrids, and 7 isolates collected from barley grass (H. leporinum). The sequence-specific markers confirmed isolate WAC10721 as a hybrid. Only four P. teres f. teres markers amplified on DNA of barley grass isolates. Amplified fragment length polymorphism markers suggested that P. teres barley grass isolates are genetically different from P. teres barley isolates and that the second putative hybrid (SNB172) is a barley grass isolate. We developed a suite of markers which clearly distinguish the two forms of P. teres and enable unambiguous identification of hybrids.

Asymmetric hybridization and introgression between sibling species of the pufferfish Takifugu that have undergone explosive speciation

Pufferfishes belonging to the genus Takifugu are a prominent example of recent adaptive radiations of marine fishes. Using amplified fragment length polymorphism (AFLP) and mitochondrial DNA (mtDNA) markers, the genetic characteristics of natural hybrids between two sibling species, Takifugu snyderi and Takifugu stictonotus, were investigated to gain insights into the role of hybridization in rapid diversification. Numerous early generations of hybrids (131 F1 hybrids and 18 first-generation backcrosses) were screened by Bayesian assignment procedures from samples collected at three sites off the Pacific coast of eastern Honshu, Japan (Ibaraki: 36°21′N, 140°37′E; Fukushima: 37°03′N, 141°03′E; Iwate: 40°02′N, 141°59′E), during 2012–2014. Analysis of mtDNA indicated that hybridization is highly directional, as the majority of the F1 hybrids (75.6%) were offspring between T. stictonotus females and T. snyderi males. Among the 18 backcrosses, 17 were toward T. snyderi and one was toward T. stictonotus. Two of 118 individuals classified as genetically pure T. snyderi based on AFLP markers were affected by mtDNA introgression from T. stictonotus. These results suggest that interspecific gene flow has been highly asymmetrical toward T. snyderi, which may partly explain the marked difference in intraspecific genetic diversity between the two species. The proportion of F1 hybrids in the Ibaraki and Fukushima areas is exceptionally high compared with that of other marine fishes, indicating the need for continuous monitoring of hybridization and its impact on integrity of each parental species under the changing marine environment.

Using AFLP genome scanning to explore serpentine adaptation and nickel hyperaccumulation in Alyssum serpyllifolium

Alyssum section Odontarrhena is the largest single clade of Ni-hyperaccumulator plants, most of which are endemic to ultramafic (serpentine) soils. Alyssum serpyllifolium is a facultative hyperaccumulator able to grow both on limestone-derived and ultramafic soils. Analysis of different populations of this species with contrasting phenotypes could allow the identification of genes involved in Ni-hyperaccumulation and serpentine tolerance. A glasshouse pot experiment on compost-amended ultramafic soil was carried out with three ultramafic (U) and two non-ultramafic (NU) populations of A. serpyllifolium. The leaf ionome was determined by elemental analysis and used as a proxy for serpentine adaptation. A Ni-hyperaccumulating phenotype was estimated from leaf Ni concentrations. Cultured plants were genotyped using Amplified Fragment Length Polymorphism (AFLP) markers. Outlier analysis and regressions of leaf ionome over band distribution were applied to detect markers potentially involved in Ni-hyperaccumulation and serpentine tolerance. As well as U populations, some plants from NU populations were found to be able to hyperaccumulate Ni in leaves to concentrations exceeding 0.1% (w/w). U populations had a higher Ca/Mg leaf ratio than NU populations, mainly due to Mg exclusion. 374 AFLP markers were amplified and a potential adaptive value was identified in 34 of those markers. Phenotype regression analyses were found to be more powerful than outlier analyses and indicated that regulation of foliar concentrations of Ni, Ca, Mg and P are the main factors involved in serpentine adaptation. More research is needed in order to resolve the ancestral or recently -evolved nature of Ni-hyperaccumulation.

Genetic diversity of giant reed (Arundo donax) in Australia

The perennial grass, Arundo donax, has shown potential as a promising biomass crop. However, it has become invasive in a number of areas and declared a noxious weed in some jurisdictions, making proposals to grow A. donax for commercial use in Australia controversial. Evidence of asexual reproduction and the presence of a single genetic clone in Australia was investigated, as such characteristics would indicate a limited risk of escape and invasion. Using amplified fragment length polymorphism markers, the genetic diversity of 218 A. donax samples from across Australia was examined. The samples were found to separate into two distinct genetic groups, or clades. There was only a small amount of genetic diversity within a clade (0.9 and 1.5%). However, there was a larger difference between the clades of 19.8%, suggesting the presence of two distinct A. donax genotypes in Australia. The low level of genetic variation in Australian A. donax that was found in this study indicates that spread is essentially by vegetative means and suggests that if grown in areas where it is separated from natural water dispersal events, A. donax poses a low risk of becoming invasive.

AFLP assessment of genetic variability and relationships in an Asian wild germplasm collection of Dactylis glomerata L.

Orchardgrass (Dactylis glomerata L.), an excellent perennial and cool season forage species distributed in most temperate regions, has been cultivated widely in Western China. Amplified fragment length polymorphism markers were employed to determine the genetic variability and population structure among 41 indigenous orchardgrass accessions from Central Asia and Western China. On the basis of 531 polymorphic fragments resulted from eight primer combinations, polymorphic information content (PIC), marker index (MI) and resolving power (RP) averaged 0.252, 16.34 and 25.27 per primer combination, respectively, demonstrating the high efficiency and reliability of the markers used. We found relatively low differentiation (Fst=0.135) for three geographical groups, where Central Asia (CA) and Southwest China (SWC) group exhibited higher intra-population diversity (He=0.20 and 0.21) than that of the Xinjiang (XJ) group (He=0.14). We also did not detect a clear pattern of isolation by distance with a low value of r=0.301 in the Mantel test. STRUCTURE, FLOCK, UPGMA clustering and PCoA analyses showed that CA group is more related to the SWC Group rather than to the XJ Group. In addition, this study strongly suggests that geographical and ecological environmental factors together could better explain the genetic differentiation between different geographical regions than geographic isolation alone, especially for Xinjiang accessions. The present study also could support that Southwest China might be the internal diversity center of D. glomerata in China. The knowledge about the genetic variability of the Asian accessions examined contributes to rapid characterization, defining gene pools of wild accessions, and selecting appropriate germplasms for plant improvement.

Genetic structure of phenotypic variants and somaclones of the genus Cereus (Cactaceae) as revealed by AFLP markers

ABSTRACTThe amplified fragment length polymorphism (AFLP) technique was used to investigate the genetic relationship among somaclonal variants and cultivated varieties of Cereus at the molecular level. Samples of tortuosus and monstruosus varieties, as well as cacti with typical erect shoots, monstruosus somaclones, and somaclones with erect shoots were analyzed using six AFLP primer pairs. The highest value for genetic diversity was detected among the monstruosus somaclones. High identity values were detected among erect, monstruosus, and tortuosus varieties as well as among erect and monstruosus somaclones. The AFLP markers revealed divergences in the in vitro cultures and in the natural environment (in vivo), and also illustrated the potential of the monstruosus and tortuosus varieties as well as the Cereus somaclones for generating new varieties of ornamental value.

Effects of Selection for Seedling Vigor on the Genetic Variation in Leymus cinereus

Basin wildrye (Leymus cinereus [Scribn. & Merr. Á. Löve]) is a perennial grass native to western regions of North America. Despite its importance for rangelands, stand establishment of basin wildrye is difficult due to its poor seedling vigor. We undertook to increase the seedling vigor of the basin wildrye cultivar “Trailhead” by using selection for emergence from deep seeding depth. We carried out two cycles of selection in two select populations and included two random populations, in which no direct selection occurred. We characterized the indirection effect of the selection on biomass, seed production, and stand percentage in these populations under field conditions. We used amplified fragment length polymorphic (AFLP) markers to identify regions of the genome associated with the selection by identifying allele frequency changes between the base population and the select and random populations. The second cycle select population and the first cycle random population possessed the highest total emergence from deep seeding (60% and 59%, respectively) compared with the base population (26%). The field evaluations showed no differences in genetic variation among the base, select, and random populations for biomass, seed production, and stand percentage. On the basis of the analysis of the AFLP markers, diversity increased slightly among the random populations and decreased slightly among the select populations. In the select populations, band frequencies increased for aggcac403, actcag185, and aggcac208. The band frequencies of aggctg212 and actctc66 decreased in both random and selected cycles. The results indicate that targeted selection for trait improvement in this native grass can be successfully completed with minimal effect on population genetic diversity.

Estimation of Outcrossing Rates in Biodiesel Species Pongamia pinnata Based on AFLP and Microsatellite Markers

Outcrossing rates in biodiesel species Pongamia pinnata were estimated using amplified fragment length polymorphism (AFLP) and microsatellite markers. Five AFLP primer combinations and eight pairs of microsatellite primers were used for fingerprinting of 55 open pollinated progenies derived from five mother trees. The multilocus out-crossing rate was quite high with AFLP (0.917; SD = 0.103) and comparatively low with microsatellite markers (0.748; SD = 0.127). The multilocus out-crossing rate was higher than single locus out-crossing rate in case of both marker systems (tm − ts = 0.203; SD = 0.090) which implies that biparental inbreeding occurred at significant levels. The estimated F was higher than the expected which also indicated towards high inbreeding in the progeny population analyzed. This is the first study on estimation of outcrossing rates using any kind of molecular marker systems in Pongamia. We expect an increasing use of such high throughput PCR-based technologies in mating-system studies in various other tree species.

Genotyping of Individually Isolated gametes from Gossypium hirsutum Chromosome Substitution Lines

As an important crop for US agricultural security and sustainable agriculture, cotton genetic improvement requires development of innovative analytical tools. Genetic analyses based on individual gametes provide several advantages including minimum sample requirement, genetic identification of male parent and overcoming the complexity of polyploidy due to haploid nature of microspores. This research used tetraploid cotton (G. hirsutum x G. barbadense) chromosome substitution (CS) lines with G. barbadense chromosomes 17 and 25 in G. hirsutum background. The individually isolated pollen grains were germinated to release their DNAs and genomic DNA was increased by modified primer extension pre-amplification (PEP) using MasterAmp™ Extra-Long PCR Kit (EPICENTRE®, Madison, WI). Also from select cotton lines, microspores just released from tetrad developmental stage were individually isolated and gamete DNA was extracted as well as amplified through multiple displacement amplification (MDA) using REPLI-g Single Cell Kit (QIAGEN, Valencia, CA). The parental samples along with PEP and MDA amplified individual gamete DNAs were then analyzed using simple sequence repeat (SSR) as well as IRD800 and IRD-700 labeled (Li-Cor, Lincoln, NE) amplified fragment length polymorphism (AFLP) methods. Nineteen SSR and 28 AFLP primer pairs were used to analyze TM-1, 3-79, CS-B17 and CS-B25 cotton lines. The amplification of parental SSR and AFLP markers from both mature pollen as well as early free microspore samples provided unique tools for comparative genetic studies using agarose and polyacrylamide gel electrophoresis, respectively.

Differential butterfly performance on host plant variants from populations under intense vs. low mammalian herbivory

AbstractEvolutionary interactions between a pair of species can be modified by the presence of another species that interacts with either or both species. However, only a few studies have demonstrated such complex interactions. Here, we report a case where a population of the red admiral butterfly (Vanessa indica) is assumed to change fitness traits in response to an evolutionary change in its major host plant, the Japanese stinging nettle (Urtica thunbergiana), caused by intense browsing pressure from sika deer (Cervus nippon). Nara Park (NP) in Japan has been home to several hundred protected sika deer for approximately 1200 yr, and their intense browsing pressure is assumed to have selected for heavily haired nettles that are more resistant to deer browsing compared to normal lightly haired nettles occurring in areas with low densities of sika deer. We found that the water and nitrogen contents of leaves are lower and the specific leaf mass is higher in heavily haired nettles at NP compared to the lightly haired nettles at the Takatori Castle Site (TCS) 30 km south of NP. Feeding experiments showed that V. indica larvae from NP reared on heavily haired nettles reach a greater adult body mass and relative abdomen mass than those from TCS, suggesting the possibility that the NP V. indica population has adapted to the heavily haired, nutritionally poorer variant. Analysis of the nucleotide sequence of the mitochondrial cytochrome c oxidase subunit I gene of V. indica from NP and nearby locations including TCS found one haplotype exclusive to NP, suggesting that movement of this butterfly is somewhat restricted. However, analysis using amplified fragment length polymorphism markers showed no genetic differentiation between the seven V. indica populations including the NP and TCS populations. These results suggest that adaptation of the NP population to the heavily haired nettle occurred in a relatively short period. Our study demonstrates a rare example of an indirect evolutionary impact of one herbivore (sika deer) on another herbivore (red admiral butterfly) through an evolutionary change in their shared food plant (Japanese nettle).

Patterns of Genetic Divergence amongMyotis californicus,M. ciliolabrum, andM. leibiiBased on Amplified Fragment Length Polymorphism

The California myotis (Myotis californicus) and the western small-footed myotis (Myotis ciliolabrum) are largely sympatric in western North America, and are especially similar morphologically such that only subtle features of their skull distinguish the two species. Previous analysis of mitochondrial DNA (mtDNA) sequence data resulted in paraphyly of these two species. Our objective was to examine genetic differences in nuclear loci between M. californicus and M. ciliolabrum, investigate their relationship with M. leibii, and to address the conflicting morphological and mtDNA data sets. We analyzed 198 amplified fragment length polymorphism (AFLP) fragments from 17 M. californicus, 16 M. ciliolabrum, and 10 M. leibii using principal coordinate (PCoA), neighbor-joining, Bayesian, and parsimony analyses. Our analyses recovered well-supported separation of M. californicus and M. ciliolabrum based on nuclear markers, suggesting the failure of the mitochondrial markers to recover monophyletic lineages was due to a lack of lineage sorting. Unexpectedly, M. ciliolabrum was paraphyletic with respect to M. leibii individuals from the eastern United States. In conclusion, our analysis of nuclear AFLP markers recovered distinct genetic lineages or clusters that corresponded to the recognized species defined by morphology, M. californicus, M. ciliolabrum, and M. leibii. We propose that these divergences are somewhat incomplete and the divergence between M. ciliolabrum and M. leibii occurred more recently than the speciation events separating the currently sympatric species M. californicus and M. ciliolabrum.

English

Phylogenetic relationship and polymorphism was detected in 10 cowpea lines comprising of leaf, flower and stem mutants, their putative parents and an exotic accession using 10 random amplified polymorphic DNAs (RAPDs) and three primer combinations of amplified fragment length polymorphism (AFLP) markers. These mutants were earlier obtained through the probable activities of transposable elements. The RAPD and AFLP markers revealed a genetic diversity of 47 and 31%, respectively, within the cowpea lines used.  Genetic distance ranged from 0.05 to 0.30 based on AFLP markers, while it ranged between 0.13 and 0.44 for RAPD markers. Cluster analysis indicated that there are differences in RAPD markers between the various mutants and it grouped an exotic genotype separately. OPC-14 primer had the highest discriminatory capacity (11 polymorphic fragments). The AFLP analysis was able to group two of the flower mutants, leaf mutants and wild types separately. A combined analysis of the two markers gave a similar grouping as was obtained from the AFLP analysis. AFLP was more discriminatory in grouping the plant samples and the exotic line was distinguished based on both markers. Useful heterotic prediction can be done based on the genetic distance between the mutants and their parents. This will further broaden the genetic base of cowpea and enhance the use of these mutants which have some evolutionary significance. In addition, unique allele RAPD_OPC15-500bp can be harnessed in genetic identification of reduced petal mutant. This study further corroborates the discriminatory power of AFLP over RAPDs. Key words: Vigna unguiculata, amplified fragment length polymorphism (AFLP), randomly amplified polymorphic DNA (RAPD), mutants, transposable elements.

Assessment of genetic diversity among six populations of Rhododendron triflorum in Tibet using ISSR and AFLP markers

In order to assess genetic variations among Rhodendron trifolium populations sampled from Tibet and determine the correlation among genetic variations, the geographic location of a population, and factors that influence high-level genetic diversity, in total of 107 R. triflorum samples using inter simple sequence repeats (ISSR) and amplified fragment length polymorphisms (AFLP). All genotypes were collected from six different areas. Eleven ISSR primers and five AFLP primer pairs were screened, and 118 and 169 amplification products were produced, of which, 96.61% in ISSR and 95.27% in AFLP were polymorphic. High genetic diversity was observed at the species level: Nei's genetic diversity (H) was 0.3382 and 0.306, and Shannon's information index (I) was 0.5085 and 0.4642 in ISSR and AFLP, respectively. Both the coefficient of gene differentiation (GST 0.3752 in ISSR, 0.31 in AFLP) and AMOVA analysis (75% in ISSR, 71% in AFLP) indicated that most genetic diversity was distributed within populations. Gene flow (Nm) was 0.8326 in ISSR and 1.1127 in AFLP. The analyze of unbiased genetic distances determined by an unweighted pair group method using arithmetic mean (UPGMA) phonograms indicated that there was a certain degree correlation between the genetic distance and the geographic distance, which was confirmed by a principal coordinate analysis. The results maybe indicated that difference of geographical environment and variation of habitat types caused the genetic differentiation of R. triflorum. At last, some conservation strategies for R. triflorum germplasm were put forward according to these results.

Population genetic structure, differentiation, and diversity in Tetrix subulata pygmy grasshoppers: roles of population size and immigration.

Genetic diversity within and among populations and species is influenced by complex demographic and evolutionary processes. Despite extensive research, there is no consensus regarding how landscape structure, spatial distribution, gene flow, and population dynamics impact genetic composition of natural populations. Here, we used amplified fragment length polymorphisms (AFLPs) to investigate effects of population size, geographic isolation, immigration, and gene flow on genetic structure, divergence, and diversity in populations of Tetrix subulata pygmy grasshoppers (Orthoptera: Tetrigidae) from 20 sampling locations in southern Sweden. Analyses of 1564 AFLP markers revealed low to moderate levels of genetic diversity (PPL = 59.5–90.1; Hj = 0.23–0.32) within and significant divergence among sampling localities. This suggests that evolution of functional traits in response to divergent selection is possible and that gene flow is restricted. Genetic diversity increased with population size and with increasing proportion of long‐winged phenotypes (a proxy of recent immigration) across populations on the island of Öland, but not on the mainland. Our data further suggested that the open water separating Öland from the mainland acts as a dispersal barrier that restricts migration and leads to genetic divergence among regions. Isolation by distance was evident for short interpopulation distances on the mainland, but gradually disappeared as populations separated by longer distances were included. Results illustrate that integrating ecological and molecular data is key to identifying drivers of population genetic structure in natural populations. Our findings also underscore the importance of landscape structure and spatial sampling scheme for conclusions regarding the role of gene flow and isolation by distance.

Genetic diversity and structure of Brazilian ginger germplasm (Zingiber officinale) revealed by AFLP markers.

Ginger is a vegetable with medicinal and culinary properties widely cultivated in the Southern and Southeastern Brazil. The knowledge of ginger species' genetic variability is essential to direct correctly future studies of conservation and genetic improvement, but in Brazil, little is known about this species' genetic variability. In this study, we analyzed the genetic diversity and structure of 55 Brazilian accessions and 6 Colombian accessions of ginger, using AFLP (Amplified Fragment Length Polymorphism) molecular markers. The molecular characterization was based on 13 primers combinations, which generated an average of 113.5 polymorphic loci. The genetic diversity estimates of Nei (Hj), Shannon-Weiner index (I) and an effective number of alleles (n e ) were greater in the Colombian accessions in relation to the Brazilian accessions. The analysis of molecular variance showed that most of the genetic variation occurred between the two countries while in the Brazilian populations there is no genetic structure and probably each region harbors 100% of genetic variation found in the samples. The bayesian model-based clustering and the dendrogram using the dissimilarity's coefficient of Jaccard were congruent with each other and showed that the Brazilian accessions are highly similar between themselves, regardless of the geographic region of origin. We suggested that the exploration of the interspecific variability and the introduction of new varieties of Z.officinale are viable alternatives for generating diversity in breeding programs in Brazil. The introduction of new genetic materials will certainly contribute to a higher genetic basis of such crop.