Greater Genetic Differentiation Research Articles

Nuclear genetic variation across the range of ponderosa pine (Pinus ponderosa): Phylogeographic, taxonomic and conservation implications

Ponderosa pine (Pinus ponderosa) is among the most broadly distributed conifer species of western North America, where it possesses considerable ecological, esthetic, and commercial value. It exhibits complicated patterns of morphological and genetic variation, suggesting that it may be in the process of differentiating into distinct regional lineages. A robust analysis of genetic variation across the ponderosa pine complex is necessary to ensure the effectiveness of management and conservation efforts given the species’ large distribution, the existence of many isolated disjunct populations, and the potential susceptibility of some populations to climate change and other threats. We used highly polymorphic nuclear microsatellite markers and isozyme markers from 3113 trees in 104 populations to assess genetic variation and structure across the geographic range of ponderosa pine. The results reveal pervasive inbreeding and patterns of genetic diversity consistent with the hypothesis that ponderosa existed in small, as-yet-undetected Pleistocene glacial refugia north of southern Arizona and New Mexico. The substructuring of genetic variation within the species complex was consistent with its division into two varieties, with genetic clusters within varieties generally associated with latitudinal zones. The analyses indicate widespread gene flow and/or recent common ancestry among genetic clusters within varieties, but not between varieties. Isolated disjunct populations had lower genetic variation by some measures and greater genetic differentiation than main-range populations. These results should be useful for decision-making and conservation planning related to this widespread and important species.

Genetic structure analysis of Spirometra erinaceieuropaei isolates from central and southern China.

BackgroundSparganosis caused by invasion of the plerocercoid larvae (spargana) of Spirometra erinaceieuropaei have increased in recent years in China. However, the population genetic structure regarding this parasite is still unclear. In this study, we used the sequences of two mitochondrial genes cytochrome b (cytb) and cytochrome c oxidase subunit I (cox1) to analyze genetic variation and phylogeographic structure of the S. erinaceieuropaei populations.Methodology/Principal FindingsA total of 88 S. erinaceieuropaei isolates were collected from naturally infected frogs in 14 geographical locations of China. The complete cytb and cox1 genes of each sample was amplified and sequenced. Total 61 haplotypes were found in these 88 concatenated sequences. Each sampled population and the total population have high haplotype diversity (Hd), accompanied by very low nucleotide diversity (Pi). Phylogenetic analyses of haplotypes revealed two distinct clades (HeN+HuN+GZ-AS clade and GX+HN+GZ-GY clade) corresponding two sub-networks yielded by the median-joining network. Pairwise F ST values supported great genetic differentiation between S. erinaceieuropaei populations. Both negative Fu’s F S value of neutrality tests and unimodal curve of mismatch distribution analyses supported demographic population expansion in the HeN+HuN+GZ-AS clade. The BEAST analysis showed that the divergence time between the two clades took place in the early Pleistocene (1.16 Myr), and by Bayesian skyline plot (BSP) an expansion occurred after about 0.3 Myr ago.Conclusions S. erinaceieuropaei from central and southern China has significant phylogeographic structure, and climatic oscillations during glacial periods in the Quaternary may affect the demography and diversification of this species.

Genetic purity and patterns of relationships among tropical highland adapted quality protein and normal maize inbred lines using microsatellite markers

Conversion of normal maize (Zea mays L.) into quality protein maize (QPM) significantly improves its nutritional value for humans and animals. Highland adapted normal maize inbred lines were backcrossed with selected QPM donor lines to incorporate the opaque-2 gene. The objectives of this study were to verify the genetic purity, determine the effect of conversion of normal maize lines to QPM and understand patterns of relationships among 36 white maize inbred lines (30 QPM and 6 non-QPM) using 25 simple sequence repeat (SSR) markers. The proportion of observed heterozygosity within an inbred line varied from 4 to 16.7 % and the average was 7.9 %. Twenty of the 36 inbred lines (55.6 %) showed higher than the expected 6.25 % mean residual heterozygosity for inbred lines developed after four generations of selfing. The genetic distances between pair-wise comparisons of the 36 inbred lines ranged from 0.077 to 0.780 and the average was 0.52. Nearly 98 % of the pair-wise comparisons had a distance between 0.30 and 0.78, which indicates large genetic differences among most lines. The model-based population structure, principal coordinate and neighbor-joining cluster analyses revealed the presence of two to three groups, which is generally consistent with pedigree information and partly with heterotic grouping. Analysis of molecular variance indicated that difference among heterotic groups explained 8.6 to 15.4 % of the total SSR variance, indicating the presence of moderate to great genetic differentiation among heterotic groups.

Comparative assessment of SSR, ISSR and AFLP markers for characterization of selected genotypes of Himalayan Chir pine (Pinus roxburghii Sarg.) based on resin yield

AbstractA set of 19 SSR (Simple Sequence Repeats), 9 ISSR (Inter-Simple Sequence Repeats) and 5 AFLP (Amplified Fragment Length Polymorphism) primer combinations were used to evaluate the variability among 53 genotypes of Pinus roxburghii selected based on resin yield from the natural zone of occurrence of this species in Uttarakhand, India. The selected trees of pine varied in resin yield from 0.25 to 8 kg/year/tree. Based on the comparative assessment of SSR, ISSR and AFLP markers, SSR markers were found most polymorphic with an average PIC value of 0.327 and 2.42 alleles per marker, while ISSR markers showed the highest effective multiplex ratio (15.536) and marker index (4.958). AFLP markers showed the maximum resolving power (8.099) which was comparable to the resolving power (8.059) of ISSR markers. UPGMA-based dendrogram using SSR markers revealed more distinct grouping of genotypes on the basis of resin yield as compared to ISSR and AFLP markers. AMOVA by collection site revealed no significant variation among the populations. Whereas, AMOVA by resin yield using SSR, ISSR and AFLP markers revealed FSTvalues to be 0.1096, 0.0483 and 0.2422 indicating moderate, low and great genetic differentiation among the groups. This clearly indicated that the variation at the molecular level was attributed to the resin yield and not the site of collection.

Statistical analysis and genetic diversity of three dog breeds using simple sequence repeats

There are more than 400 pure dog breeds developed through intentional artificial selection and purebred breeding. Purebred animals have higher risk of inbreeding depression and hereditary diseases. We investigated the genetic diversity and structure of three dog breeds in South Korea by using 12 microsatellite loci for one Korean native dog breed, Sapsaree, and two foreign breeds, German shepherd and Belgian Malinois. The mean allele number of nine loci across all dog breeds was 4.833, and the number of alleles per locus ranged from 2 to 8. The mean of expected and observed heterozygosity were 0.415 and 0.577, respectively. Sapsaree, Korean native dog, had higher level of genetic diversity than the foreign German shepherd and Belgian Malinois. The highest mean value of polymorphism information content was found in Sapsaree (0.480), followed by Belgian Malinois (0.373) and German shepherd (0.355). Pairwise genetic differentiation was estimated using fixation index F ST. Sapsaree and German shepherd (F ST = 0.2536) and Sapsaree and Belgian Malinois (F ST = 0.2522) had very great genetic differentiation, while moderate level of genetic differentiation was observed between German shepherd and Belgian Malinois (F ST = 0.1003). These genetic information and structure of the three dog breeds will be effective in conservation and preservation of the genetic diversity of the three dog breeds.

Distinct genetic structure in populations of Chrysoperla externa (Hagen) (Neuroptera, Chrysopidae) shown by genetic markers ISSR and COI gene

Distinct genetic structure in populations of Chrysoperla externa (Hagen) (Neuroptera, Chrysopidae) shown by genetic markers ISSR and COI gene. Green lacewings are generalist predators, and the species Chrysoperla externa presents a great potential for use in biological control of agricultural pests due to its high predation and reproduction capacities, as well as its easy mass rearing in the laboratory. The adaptive success of a species is related to genetic variability, so that population genetic studies are extremely important in order to maximize success of the biological control. Thus, the present study used nuclear (Inter Simple Sequence Repeat - ISSR) and mitochondrial (Cytochrome Oxidase I - COI) molecular markers to estimate the genetic variability of 12 populations in the Sao Paulo State, Brazil, as well as the genetic relationships between populations. High levels of genetic diversity were observed for both markers, and the highest values of genetic diversity appear associated with municipalities that have the greatest areas of native vegetation. There was high haplotype sharing, and there was no correlation between the markers and the geographic distribution of the populations. The AMOVA indicated absence of genetic structure for the COI gene, suggesting that the sampled areas formed a single population unit. However, the great genetic differentiation among populations showed by ISSR demonstrates that these have been under differentiation after their expansion or may also reflect distinct dispersal behavior between males and females.

Genetic differentiation of invasive Aedes albopictus by RAPD-PCR: implications for effective vector control

Aedes albopictus is an invasive mosquito species of great concern to public health as it is responsible for the biological transmission of several pathogens causing dengue, chikungunya, yellow fever, etc. In 2009, this mosquito was detected for the first time in Agra City. This study represents the first genetic analysis of A. albopictus from India. Random amplified polymorphic DNA (RAPD) was used to study the genetic structure of A. albopictus in four populations from different larval habitats. Seven RAPD primers produced 141 loci. The results displayed rich genetic variation among larval populations which is evident from high value of genetic differentiation (G ST), i.e. 0.280, indicating a very great genetic differentiation. Effective migration rates were observed to be 1.28, depicting a limited gene flow. According to analysis of molecular variance (AMOVA), the genetic distance between populations was significant (P < 0.05), showing a very high intrapopulation variation (96%) with only 4% variation among populations. Average genetic distances between populations were also calculated using PopGene software. Nei's average genetic distance between these populations was 0.112 (0.05-0.18). The cluster analysis technique of unweighted pair-group mean analysis (UPGMA) method of arithmetic averages was used to develop the phylogenetic tree which clearly shows two clusters of different larval habitats. The findings highlight high genetic differentiation indicating a slight migration rate confirming the recent introduction of this species in Agra region.

A preliminary study for identification of candidate AFLP markers under artificial selection for shell color in pearl oyster Pinctada fucata

Pearl oyster Pinctada fucata is widely cultured to produce seawater pearl in South China, and the quality of pearl is significantly affected by its shell color. Thus the Pearl Oyster Selective Breeding Program (POSBP) was carried out for the shell color and growth traits. The black (B), gold (G), red (R) and white (W) shell strains with fast growth trait were achieved after five successive generation selection. In this study, AFLP technique was used to scan genome of four strains with different shell colors to identify the candidate markers under artificial selection. Eight AFLP primer combinations were screened and yielded 688 loci, 676 (98.26%) of which were polymorphic. In black, gold, red and white strains, the percentage of polymorphic loci was 90.41%, 87.79%, 93.60% and 93.31%, respectively, Nei's gene diversity was 0.3225, 0.2829, 0.3221 and 0.3292, Shannon's information index was 0.4801, 0.4271, 0.4825 and 0.4923, and the value of FST was 0.1805. These results suggested that the four different shell color strains had high genetic diversity and great genetic differentiation among strains, which had been subjected to the continuous selective pressures during the artificial selective breeding. Furthermore, six outlier loci were considered as the candidate markers under artificial selection for shell color. This study provides a molecular evidence for the inheritance of shell color of P. fucata.

Genetic diversity in Egyptian and Saudi goat breeds using microsatellite markers

Objective: The genetic polymorphism within and among three indigenous goat breeds found in Egypt (Barki and Zaraibi) and in Saudi Arabia (Ardi) was detected by twelve microsatellites.Methodology and results: A total of 95 blood samples were collected from the Egyptian and Saudi goat breeds. Genomic DNA was extracted from whole blood of each sample and microsatellites techniques were used for analysis of DNA. The results showed that, the total number of detected alleles varied from 2 (MMP9) to 16 (DRB2). The mean numbers of alleles per locus are 4.8, 4.3 and 6.2 in Barki, Ardi and Zaraibi, respectively. The mean of expected heterozygosity of the breeds ranged from 0.696 to 0.725. After corrections for multiple significance tests, deviations from Hardy-Weinberg equilibrium were statistically significant over all populations and loci, reflecting the deficiencies of heterozygotes (global FIS=0.053). Based on pairwise FST and Nm between different breeds, there was a great genetic differentiation between Ardi goat and the other two Egyptian breeds, UPGMA dendrogram based on Nei’s genetic distance grouped the investigated goat breeds genotypes into two clusters. The first cluster includes Egyptian breeds (Barki and Zaraibi) where as the second cluster includes Saudi breed (Ardi) which appeared to be most distant from the other breeds.Conclusions and application of findings. In conclusion, these results can be useful for the development of a rational breeding strategy for genetic improvement of goats in Egypt and Saudi Arabia. The studied Mediterranean breeds sampled from African and Asian populations seem to have differentiated from each other with only little genetic exchange between the geographically isolated populations.Key words: Microsatellites, Goats, Genetic diversity, Genotype.

Genetic population structure of the blister beetle, Gnathium minimum: core and peripheral populations.

Populations on the periphery of a species' range tend to contain lower genetic variation and increased genetic differentiation compared to populations at the core of a species range, although some exceptions to this generalization occur. The blister beetle Gnathium minimum (Say) exhibits a wide-ranging distribution in the western United States but has peripheral or disjunct populations in Mexico, Florida, and Wisconsin. We used amplified fragment length polymorphism (AFLP) to compare the genetic variation and magnitude of genetic differentiation of the Wisconsin peripheral population to western core populations (Colorado, Kansas, New Mexico, and Texas). The proportion of polymorphic loci was 53.6 and 54.3, and expected heterozygosity 0.1864 and 0.1933 for the Kansas/Colorado (n = 87) and New Mexico/Texas (n = 35) regions, respectively. Specimens from Wisconsin (n = 121) had a lower proportion of polymorphic loci (38.4) and expected heterozygosity (0.1475). Genetic cluster estimation with GENELAND and F ST values showed greater genetic differentiation among the sampling locations within Wisconsin compared to core regions. Significant isolation-by-distance (IBD) was also observed in Wisconsin but not within the core regions. Lower genetic variation and increased isolation may reduce the Wisconsin population's ability to respond to change, thereby increasing their susceptibility to extinction.

Deep phylogeographic break among Octopus variabilis populations in China: Evidence from mitochondrial and nuclear DNA analyses

The genetic structure of marine populations is greatly influenced by the dispersal ability of the organisms, and it is intuitive that a limited dispersal capability would result in greater genetic differentiation. Octopus variabilis is a typical cephalopod species that shows limited dispersal potential, and previous genetic surveys by a mitochondrial DNA analyses revealed high levels of genetic differentiation among its populations, suggesting the existence of cryptic or subspecies. To test this hypothesis, amplified fragment length polymorphisms (AFLPs) and the cytochrome oxidase II (COII) gene sequence were used to re-evaluate the spatial genetic structure of five populations of O. variabilis along the coast of China. Four distinct groups were identified within these five populations: the Dalian + Qingdao, Zhoushan, Wenzhou, and Dongshan groups. A deep genetic break among the Dongshan, Wenzhou, and other two groups were specifically recognized by both genetic markers. A considerable number of distinct alleles for AFLP and a deep divergence of 13.9–19.4% in the COII gene sequences were found among them, suggesting the occurrence of potential cryptic or subspecies of O. variabilis. A genetic structure of isolation by distance was identified in O. variabilis by a Mantel test, with the geographic distance explaining 62% of the variation in genetic differentiation. This result suggests that gene flow is geographically restricted for this species and that limited dispersal may be the main reason for the genetic differentiation among O. variabilis populations. The present results indicate that special care should be taken in future fishery exploitation and conservation efforts for this species and that conservation management should include populations representing all lineages.

Combined analyses of kinship and FST suggest potential drivers of chaotic genetic patchiness in high gene-flow populations.

We combine kinship estimates with traditional F-statistics to explain contemporary drivers of population genetic differentiation despite high gene flow. We investigate range-wide population genetic structure of the California spiny (or red rock) lobster (Panulirus interruptus) and find slight, but significant global population differentiation in mtDNA (ΦST = 0.006, P = 0.001; Dest_Chao = 0.025) and seven nuclear microsatellites (FST = 0.004, P < 0.001; Dest_Chao = 0.03), despite the species’ 240- to 330-day pelagic larval duration. Significant population structure does not correlate with distance between sampling locations, and pairwise FST between adjacent sites often exceeds that among geographically distant locations. This result would typically be interpreted as unexplainable, chaotic genetic patchiness. However, kinship levels differ significantly among sites (pseudo-F16,988 = 1.39, P = 0.001), and ten of 17 sample sites have significantly greater numbers of kin than expected by chance (P < 0.05). Moreover, a higher proportion of kin within sites strongly correlates with greater genetic differentiation among sites (Dest_Chao, R2 = 0.66, P < 0.005). Sites with elevated mean kinship were geographically proximate to regions of high upwelling intensity (R2 = 0.41, P = 0.0009). These results indicate that P. interruptus does not maintain a single homogenous population, despite extreme dispersal potential. Instead, these lobsters appear to either have substantial localized recruitment or maintain planktonic larval cohesiveness whereby siblings more likely settle together than disperse across sites. More broadly, our results contribute to a growing number of studies showing that low FST and high family structure across populations can coexist, illuminating the foundations of cryptic genetic patterns and the nature of marine dispersal.

Genetic diversity and structure of wintersweet (Chimonanthus praecox) revealed by EST-SSR markers

As an ancient and endemic plant in China, Chimonanthus praecox has been widely distributed in southern China in the past. The population number of C. praecox has declined significantly because of habitat fragmentation and human influence. Thirty-one EST-SSR markers were developed from the species’ EST sequences and eight polymorphic EST-SSR markers were chosen to analyze the genetic diversity and structure of ten natural populations. The results indicated that the genetic diversity levels were low among populations and genetic variations of populations were mainly emerged among groups. F-statistics revealed great genetic differentiation among populations (FST=0.270), albeit the moderate gene flow existed (Nm=0.676). Complex genetic differentiation and genetic structure of C. praecox were determined with UPGMA cluster tree and Bayesian clustering analysis. Five barriers were implied in the species’ geographical distributions using the Landscape Shape Interpolation and Monmonier's Maximum Difference Algorithm analysis. According to the genetic results and habitat-dependent characteristics of the species, in situ conservation strategy was suggested to all populations.

Aproximación a la filogenia de Spodoptera (Lepidoptera: Noctuidae) con el uso de un fragmento del gen de la citocromo oxidasa I (COI)

The genus Spodoptera includes 30 species of moths considered important pests worldwide, with a great representation in the Western Hemisphere. In general, Noctuidae species have morphological similarities that have caused some difficulties for assertive species identification by conventional methods. The purpose of this work was to generate an approach to the genus phylogeny from several species of the genus Spodoptera and the species Bombyx mori as an out group, with the use of molecular tools. For this, a total of 102 S. frugiperda larvae were obtained at random in corn, cotton, rice, grass and sorghum, during late 2006 and early 2009, from Colombia. We took ADN samples from the larval posterior part and we analyzed a fragment of 451 base pairs of the mitochondrial gene cytochrome oxydase I (COI), to produce a maximum likelihood (ML) tree by using 62 sequences (29 Colombian haplotypes were used). Our results showed a great genetic differentiation (K2 distances) amongst S. frugiperda haplotypes from Colombia and the United States, condition supported by the estimators obtained for haplotype diversity and polymorphism. The obtained ML tree clustered most of the species with bootstrapping values from 73-99% in the interior branches; with low values also observed in some of the branches. In addition, this tree clustered two species of the Eastern hemisphere (S littoralis and S. litura) and eight species of the Western hemisphere (S. androgea, S. dolichos, S. eridania, S. exigua, S. frugiperda, S. latifascia, S. ornithogalli and S. pulchella). In Colombia, S. frugiperda, S. ornithogalli and S. albula represent a group of species referred as "the Spodoptera complex" of cotton crops, and our work demonstrated that sequencing a fragment of the COI gene, allows researchers to differentiate the first two species, and thus it can be used as an alternative method to taxonomic keys based on morphology. Finally, the ML tree did not cluster S. frugiperda with S. ornithogalli, suggesting that both species do not share the same recent ancestral even though they coexist in cotton. We suggest sequencing other genes (mitochondrial and nuclear) to increase our understanding of this genus evolution.

TESTING THE LINK BETWEEN POPULATION GENETIC DIFFERENTIATION AND CLADE DIVERSIFICATION IN COSTA RICAN ORCHIDS

Species population genetics could be an important factor explaining variation in clade species richness. Here, we use newly generated amplified fragment length polymorphism (AFLP) data to test whether five pairs of sister clades of Costa Rican orchids that differ greatly in species richness also differ in average neutral genetic differentiation within species, expecting that if the strength of processes promoting differentiation within species is phylogenetically heritable, then clades with greater genetic differentiation should diversify more. Contrary to expectation, neutral genetic differentiation does not correlate directly with total diversification in the clades studied. Neutral genetic differentiation varies greatly among species and shows no heritability within clades. Half of the variation in neutral genetic differentiation among populations can be explained by ecological variables, and species-level traits explain the most variation. Unexpectedly, we find no isolation by distance in any species, but genetic differentiation is greater between populations occupying different niches. This pattern corresponds with those observed for microscopic eukaryotes and could reflect effective widespread dispersal of tiny and numerous orchid seeds. Although not providing a definitive answer to whether population genetics processes affect clade diversification, this work highlights the potential for addressing new macroevolutionary questions using a comparative population genetic approach.

Great genetic differentiation among populations of Meconopsis integrifolia and its implication for plant speciation in the Qinghai-Tibetan Plateau.

The complex tectonic events and climatic oscillations in the Qinghai-Tibetan Plateau (QTP), the largest and highest plateau in the world, are thought to have had great effects on the evolutionary history of the native plants. Of great interest is to investigate plant population genetic divergence in the QTP and its correlation with the geologic and climatic changes. We conducted a range-wide phylogeographical analysis of M. integrifolia based on the chloroplast DNA (cpDNA) trnL-trnF and trnfM-trnS regions, and defined 26 haplotypes that were phylogenetically divided into six clades dated to the late Tertiary. The six clades correspond, respectively, to highly differentiated population groups that do not overlap in geographic distribution, implying that the mountain ranges acting as corridors or barriers greatly affected the evolutionary history of the QTP plants. The older clade of M. integrifolia only occurs in the southwest of the species' range, whereas the distributions of younger clades extend northeastward in the eastern QTP, suggesting that climatic divergence resulting from the uplift of the QTP triggered the initial divergence of M. integrifolia native to the plateau. Also, the nrDNA ITS region was used to clarify the unexpected phylogenetic relationships of cpDNA haplotypes between M. integrifolia and M. betonicifolia. The topological incongruence between the two phylogenies suggests an ancestral hybridization between the two species. Our study indicates that geographic isolation and hybridization are two important mechanisms responsible for the population differentiation and speciation of Meconopsis, a species-rich genus with complex polyploids.

Current and Historical Drivers of Landscape Genetic Structure Differ in Core and Peripheral Salamander Populations

With predicted decreases in genetic diversity and greater genetic differentiation at range peripheries relative to their cores, it can be difficult to distinguish between the roles of current disturbance versus historic processes in shaping contemporary genetic patterns. To address this problem, we test for differences in historic demography and landscape genetic structure of coastal giant salamanders (Dicamptodon tenebrosus) in two core regions (Washington State, United States) versus the species' northern peripheral region (British Columbia, Canada) where the species is listed as threatened. Coalescent-based demographic simulations were consistent with a pattern of post-glacial range expansion, with both ancestral and current estimates of effective population size being much larger within the core region relative to the periphery. However, contrary to predictions of recent human-induced population decline in the less genetically diverse peripheral region, there was no genetic signature of population size change. Effects of current demographic processes on genetic structure were evident using a resistance-based landscape genetics approach. Among core populations, genetic structure was best explained by length of the growing season and isolation by resistance (i.e. a ‘flat’ landscape), but at the periphery, topography (slope and elevation) had the greatest influence on genetic structure. Although reduced genetic variation at the range periphery of D. tenebrosus appears to be largely the result of biogeographical history rather than recent impacts, our analyses suggest that inherent landscape features act to alter dispersal pathways uniquely in different parts of the species' geographic range, with implications for habitat management.

Genetic and geographical structure in grapevines from northwestern Spain

AbstractThe grapevine germplasm bank from Estación de Viticultura e Enoloxía de Galicia contains 110 accessions collected from more than 100‐year‐old grapevines from northwestern Spain. We identified 60 different genotypes (among which ‘Pinot Noir’ and ‘Shyrah’ were included as references) with 32 polymorphic microsatellites (SSRs), 21 of which were unlinked SSRs and without null alleles, which were used to detect genetic structure. We found four reconstructed populations that were highly differentiated by analysis of molecular variance (18.3%): (i) western Galician group (‘Caíño Bravo’); (ii) eastern Galician group (‘Merenzao’); (iii) Castilian group (‘Garnacha’) and (iv) southern Spanish group (‘Moscatel’). The greatest genetic differentiation was found between the western Galician/eastern Galician groups and the southern Spanish/Castilian groups, with Fst &gt; 0.13. Western and eastern Galician groups contained most of the ancient Galician cultivars (86%) and included ancestors from central Europe, such as ‘Pinot Noir’ and ‘Shyrah’ in the western Galician group and the introgressant ‘Merenzao’ (French ‘Trousseau’) in the eastern Galician group; the Castilian and southern Spain groups included traditional cultivars from central and southern Spanish and suggest a further introduction of those cultivars in northwestern plantations. Genetic structure corresponded with East‐to‐West geographical differentiation in the northern Iberian Peninsula, following the old path to Santiago de Compostela from France, with the southern Spanish and Castilian groups in the East (Castilian plateau and southern Spain), the eastern Galician group and the western Galician group in the West. Five new relationships were discovered: ‘Caíño Bravo’/‘Caíño Longo2’, ‘Albarín Tinto’/‘Torrontés1’, ‘Treixadura’/‘Treixadura Francesa’, ‘Moscatel’/‘Moscatel de Bago Miúdo’ and ‘Moscatel’/‘Moscatel de Hamburgo’, indicating that hybridisation and further selection by growers have been the origin of most of the genetic diversity found in northwestern Spain.

Ontogeny of flower parts on naturally growing Iris pumila clones: Implications for population differentiation and phenotypic plasticity studies

Previous studies revealed significant phenotypic plasticity, genetic variability and population differentiation of flower morphometric traits on dwarf bearded iris Iris pumila. Also, study of I. pumila flowering phenology revealed significant impact of habitat type as well as population differentiation for flowering time. Since the flowering time can influence other flower traits, we performed this analysis of flower morphometric traits in three time points during the flower bud ontogenic development in two habitat types (open vs. shaded). Analysis revealed that for most of the traits greater trait values were recorded for open habitat but only on latter time points. For most of the analyzed traits direction of differences in bud stage was the opposite to the direction of differences in mature flower stage detected in previous studies. However, length of the stem, a trait that showed the greatest variability between habitats and populations and therefore greatest genetic differentiation and phenotypic plasticity, was significantly greater in the samples from the late flowering shaded habitat in all time samples, indicating that in case of this trait different mechanisms were involved. Those findings have implications for design of the future studies on I. pumila.

Contrasted patterns of selection on MHC-linked microsatellites in natural populations of the Malagasy plague reservoir.

Plague (Yersinia pestis infection) is a highly virulent rodent disease that persists in many natural ecosystems. The black rat (Rattus rattus) is the main host involved in the plague focus of the central highlands of Madagascar. Black rat populations from this area are highly resistant to plague, whereas those from areas in which the disease is absent (low altitude zones of Madagascar) are susceptible. Various lines of evidence suggest a role for the Major Histocompatibility Complex (MHC) in plague resistance. We therefore used the MHC region as a candidate for detecting signatures of plague-mediated selection in Malagasy black rats, by comparing population genetic structures for five MHC-linked microsatellites and neutral markers in two sampling designs. We first compared four pairs of populations, each pair including one population from the plague focus and one from the disease-free zone. Plague-mediated selection was expected to result in greater genetic differentiation between the two zones than expected under neutrality and this was observed for one MHC-class I-linked locus (D20Img2). For this marker as well as for four other MHC-linked loci, a geographic pattern of genetic structure was found at local scale within the plague focus. This pattern would be expected if plague selection pressures were spatially variable. Finally, another MHC-class I-linked locus (D20Rat21) showed evidences of balancing selection, but it seems more likely that this selection would be related to unknown pathogens more widely distributed in Madagascar than plague.