Variability of essential oils of Satureja montana L. and Satureja kitaibelii wierzb. ex Heuff. from the central part of the balkan peninsula

The results of the essential oil composition confirm that there are differences between populations within the same subspecies (Satureja montana ssp. montana, between the subspecies (Satureja montana ssp. montana and Satureja montana ssp. pisidica) and the species (Satureja montana and S. kitabelii). The essential oil composition of S. montana ssp. montana is more related to the Satureja montana ssp. pisidica than S. kitaibelii which separates as a whole species.     

Comparison of British populations of potato cyst nematodes with populations from continental Europe and South America using RAPDs.

Genetic variation between populations of Globodera pallida, primarily from Britain but including populations from continental Europe and South America and two Globodera rostochiensis populations, was examined using random amplified polymorphic DNA (RAPD). Fourteen primers were used and 250 amplification products observed. A comparison was made of the similarities between the species and, within G. pallida, between populations from Britain, The Netherlands, Germany, and Switzerland, of the pathotypes Pa2 and Pa3. In addition, one Pa1 population and two others from South America were included. On the basis of the RAPD analysis, all the Pa2-Pa3 populations, except one from Scotland (Luffness), constituted a single group with no clear distinction based on pathotype designation. The Luffness population is known to be distinct in its virulence. The data indicated that the main Pa2-Pa3 group could be subdivided based on geographic origin, but this is not well supported by bootstrap analysis. The Pa1 population and the two populations from South America all formed distinct groups.     

Conservation genetics and taxonomic status of the rare Kentucky lady's slipper: Cypripedium kentuckiense (Orchidaceae)

Cypripedium kentuckiense is a recently described rare orchid found in Arkansas (predominantly) and in eight other states. Much debate has focused on whether this taxon should be recognized as a distinct species or considered to be an extreme manifestation of the variability present in the widespread taxon Cypripedium parviflorum var. pubescens. In this study, 12 isozyme loci were analyzed for 14 populations of C. parviflorum var. pubescens and eight populations of C. kentuckiense. These data were used to examine the genetic similarity of these taxa, assess whether isozyme data support the continued recognition of C. kentuckiense as a distinct species, and assess whether a newly discovered disjunct Virginia population of C. kentuckiense is genetically isolated from other C. kentuckiense populations. The isozyme data revealed that the two taxa are very closely related with a high interspecific genetic identity. However, C. kentuckiense populations contain a subset of the variation present in C. parviflorum var. pubescens, and they have expected levels of heterozygosity that are one-quarter that of C. parviflorum var. pubescens populations. Cypripedium kentuckiense also possesses one widespread unique allele and a unique multilocus genotype. These data suggest that C. kentuckiense should be recognized as a distinct species, possibly of recent origin from C. parviflorum. Lastly, the isozyme data support the hypothesis that gene flow between the Virginia population and other populations of C. kentuckiense has been restricted.     

Species delimitation and evolution of metal bioaccumulation in the lichenized Acarospora smaragdula (Ascomycota, Fungi) complex

The crustose lichenized fungi in the Acarosporaceae are splendid examples of organisms managing to survive in extremely harsh environments, such as highly mineralized rocks and low-pH habitats. Some representatives of the Acarospora smaragdula complex are known to accumulate substantial amounts of potentially toxic metals including iron and copper, resulting in populations with highly divergent coloration and morphology. These populations have often been treated as distinct species by lichen taxonomists. Parsimony and parsimony jackknifing analyses of β-tubulin, nuclear ITS rDNA, and mtSSU rDNA sequence data sets was used to investigate the evolution of iron and copper accumulation and the production of the secondary compound norstictic acid in populations within the A. smaragdula species complex in Sweden, with additional samples mainly from Norway and the UK. Phylogenetic species recognition (concordance of single-gene phylogenies) was used to investigate species delimitations. Seven species are recognized in the complex. Atypically green, copper-accumulating samples, often given species rank, do not form a distinct group but are nested within A. smaragdula s. str., indicating that this ability is widespread in this species. Rust-coloured, iron-accumulating samples form two well supported separate groups, indicating that two morphologically distinct, obligate, iron-accumulating species are present, but facultatively iron-accumulating populations occur in at least one additional species. Norstictic acid, sometimes claimed to characterize the whole A. smaragdula complex, is only present in A. smaragdula s. str. The evolutionary significance of metal accumulation in Acarospora is discussed, as is the significance of our results for the application of phylogenetic species recognition/gene tree concordance-based species recognition, and DNA barcoding.
© The Willi Hennig Society 2009.     

Mating system and population structure of Acacia aroma and A. macracantha (Fabaceae)

Acacia aroma and A. macracantha are closely related species that inhabit northern and central Argentina. The reproductive barriers between them seem to be weak. They exhibit low genetic differentiation, high levels of interspecific gene flow, and extensive areas of sympatry. Isoenzymatic approaches were used to evaluate the population structure and mating system parameters in natural Argentine populations of A. aroma and A. macracantha and to provide new tools for the analysis of relationships between these two species. All studied populations had high levels of genetic variability and no significant departures from Hardy-Weinberg expectations, but the two species did not differ from each other. Most variability occured within populations. Mating system analysis showed high levels of outcrossing, no biparental inbreeding, and a high probability that individuals within progeny arrays are full rather than half sibs. In all A. aroma and A. macracantha populations, polymorphic loci had the same allelic variants, and no geographic or genetic isolation between species was found. The results favor the hypothesis that these two entities represent a single polymorphic species rather than two distinct species.     

Genetic variation within and between Iliamna corei and I. remota (Malvaceae): implications for species delimitation

Iliamna corei and I. remota are classified as endangered species; however, their designation as separate species has been questioned. In order to address this problem, intersimple sequence repeat (ISSR) data were generated to examine patterns of genetic differentiation within and between these two taxa. ISSRs were used to screen individuals for genetic diversity of I. corei from the single known natural population and two garden populations, and individuals of I. remota from the six natural populations and four garden populations. Using ten primers, 140 informative markers were generated. Ninety-four percent of loci detected revealed polymorphisms. Cluster analysis (neighbour-joining, NJ) revealed that the two species are genetically distinct and that the Illinois populations of I. remota were genetically distinct from the Virginia populations of I. remota . Ordination by Principal Coordinate Analysis (PCoA) supported the findings of the NJ, with a separation of I. corei and I. remota . Analysis of Molecular Variance (AMOVA) revealed that the majority of variation detected was within populations, which is consistent with other self-incompatible plants. The results indicate a correlation between the geographical distributions of the species and gene flow.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 345–354.     

Riparian populations of minnesota reed canarygrass (Phalaris arundinacea) are most likely native,based on SNPs (DArTseqLD)

The native vs. exotic status of reed canarygrass (RCG), a major invasive species of Minnesota wetlands, is unknown. The aim of this study was to investigate this native vs. exotic status to enhance its management. Genetic comparison of wild RCG populations from six Minnesota and six Czech Republic rivers was performed. A total of 2521 polymorphic SNP markers (single nucleotide polymorphisms) were used to evaluate 478 RCG samples across all collections. In the PCoA, all (n = 256) tested extant wild, riparian RCG genotypes from six Minnesota Rivers and six Czech Republic Rivers were genetically distinct, although some SNPs were common in both populations since they are the same species. DAPC analysis also resulted in the formation of two primary clusters separating the Minnesota Rivers and Czech Republic Rivers riparian samples, with little overlap; STRUCTURE analysis also supported this clustering with k = 4 groups as it separated the Czech Republic Rivers populations into three groups, along with Minnesota Rivers. The uniformity of PCoA, DAPC, STRUCTURE, and Evanno results indicates the distinct separation of Minnesota Rivers and Czech Republic Rivers populations. Portions of the genome (specific SNPs) are preserved or in common across continents, as indicated by STRUCTURE similarities. Nonetheless, overall significant SNP differences between the continents indicate that the Minnesota riparian populations are distinct enough from the European (Czech) collections to be delineated as native N. American RCG. PCoA of all the Minnesota RCG collections clustered Minnesota Rivers, Herbarium, Extant Herbarium, Research Field and Native Field collections together. STRUCTURE analysis (k = 2; Evanno) divided these Minnesota collections from the Commercial Field and Cultivars collections. There are two genetically distinct groups of RCG in Minnesota and since the Minnesota Rivers, the Research Field, the Native Field and pre-1930 herbaria collections clustered together, they are most likely native N. American types. Analysis of molecular variance (AMOVA) indicated that the genetic variation was more significant within, rather than among, the RCG populations. Native, historic herbaria types cluster together with all wild RCG river populations in Minnesota, all of which were distinct from those in Central Europe, suggesting native RCG type persistence in N. America. Also, cultivated forage types of RCG are distinct from wild RCG Minnesota river populations. The SNP genetic data shows that riparian Minnesota RCG populations are native. These data will facilitate future management strategies to control RCG as a native, but invasive, species.

     

Hybridization in contact zone between temperate European pine species

Hybridization studies are important to advance our understanding of the interspecific gene flow and its evolutionary consequences in closely related species. Hybridization and admixture patterns were assessed in a contact zone and reference populations of European pine species using sequence data from 26 nuclear genes and a species-diagnostic cpDNA marker. Reference populations formed three distinct genetic clusters comprising Pinus sylvestris, Pinus mugo/Pinus uliginosa, and Pinus uncinata. Evidence of population structure was found only in P. uliginosa. Based on phenotypic characteristics and molecular data, we identified five groups of individuals in the contact zone in Poland, comprising forms of the parental species and intermediates that were most probably the result of interspecific crosses. A combination of nuclear gene sequence data and a diagnostic organelle marker were used to show that hybridization is frequent in the contact zone and results in hybrid trees with distinct phenotypic identity. The influence of selection in maintaining hybrid phenotypes in environments unsuited to parental species was inferred from nucleotide polymorphism data. A lack of admixture in reference populations suggests that hybridization has not occurred during post-glacial migration and so the contact zone represents a distinct, active example of ongoing evolution. Pine populations in this zone will be a valuable system for studying the genetic basis of hybrid advantage in environmental conditions untypical of pure parental species.     

Genetic differences among mainland and insular forms of the Citril Finch Serinus citrinella

The Citril Finch Serinus citrinella breeds in several mountains of central and southern Europe and on Corsica, Sardinia and Tuscany islands. Several studies have emphasized differences in phenotype and vocalization, and some authors consider mainland and insular forms to be two distinct species. A genetic approach based on the sequences of a mitochondrial DNA fragment was used to estimate genetic distance separating several populations. Individuals from the Alps and the Pyrenees belong to one group and the individuals from Corsica to the second. These results, discussed together with data on ecology, biometrics and vocalization, suggest keeping only one polytypic species which includes two distinct forms.     

珍稀濒危蕨类植物东方水韭的遗传多样性

采用ISSR分子标记对珍稀濒危蕨类植物东方水韭和中华水韭4个自然居群共72个样品进行了DNA多态性分析。从65个随机引物中筛选出11个有效引物,共产生98条DNA片段,其中68条为多态性条带,多态位点百分率(PPL)为66.33%。东方水韭两个居群的多态位点百分比率(PPL)较低(8.16%和7.14%)。中华水韭两个居群的PPL也较低(9.18%和23.47%)。中华水韭物种水平上的PPL(51.02%)高于东方水韭(9.18%)。AMO-VA分析结果表明,东方水韭遗传变异中主要存在于居群内(94.74%),而中华水韭绝大部分的遗传变异却存在于居群间(86.71%)。东方水韭和中华水韭个体间UPGMA聚类结果表明:同一物种的个体完全能聚在一起,中华水韭的两个居群也能明显分开,而东方水韭两居群的个体并不能完全聚在一起。探讨了可能造成上述居群遗传结构模式的主要因素,同时提出今后工作中需重点解决的问题。     

Use of amplified fragment length polymorphism markers to assess genetic diversity of Lolium species from Portugal

We evaluated the use of amplified fragment length polymorphism (AFLP) markers to distinguish genotypes, populations and species of Lolium. Accessions of two species Lolium perenne and Lolium multiflorum and their hybrid Lolium x hybridum, collected by the Institute of Grass and Environmental Research in 1995 from locations across Portugal, were used. The genetic variation within and between populations from the extremes of latitude and altitude was determined and assessed. Three primer pair combinations generated 765 polymorphic bands. Principal coordinate analysis of similarities between 127 plants showed high dimensionality in the data. Axes 1-3 were associated primarily with species differences, axes 4-14 with population differences within species and axis 15 onwards with within population differences. UPGMA analysis confirmed the groupings. The three populations of L. perenne formed a discrete cluster widely separated from all other populations. There were two distinct groups of L. x hybridum, of which one was similar to and overlapped with L. multiflorum and the second formed a distinct cluster. Analyses of individual bands showed that every inter- and intraspecific contrast involved a different sets of bands, again confirming the high dimensionality of the data. No single band was strictly diagnostic of any population or species. Nevertheless, the UPGMA analysis showed little or no overlap between populations. Thus, despite the high ratio of within-to-between population genetic variance, the full AFLP banding pattern of each genotype is a relatively reliable fingerprint diagnostic of its parent population. The high dimensionality implies that many different factors contribute to the differences observed. This adds to the potential value of the methodology, since it implies that there is a reasonably high likelihood of finding bands relevant to a given environmental gradient or other factor influencing the distribution of genetic diversity.     

Assessment of genetic diversity in the critically endangered Australian corroboree frogs, Pseudophryne corroboree and Pseudophryne pengilleyi, identifies four evolutionarily significant units for conservation

The iconic and brightly coloured Australian northern corroboree frog, Pseudophryne pengilleyi , and the southern corroboree frog, Pseudophryne corroboree are critically endangered and may be extinct in the wild within 3 years. We have assembled samples that cover the current range of both species and applied hypervariable microsatellite markers and mitochondrial DNA sequences to assess the levels and patterns of genetic variation. The four loci used in the study were highly variable, the total number of alleles observed ranged from 13 to 30 and the average number of alleles per locus was 19. Expected heterozygosity of the four microsatellite loci across all populations was high and varied between 0.830 and 0.935. Bayesian clustering analyses in structure strongly supported four genetically distinct populations, which correspond exactly to the four main allopatric geographical regions in which the frogs are currently found. Individual analyses performed on the separate regions showed that breeding sites within these four regions could not be separated into distinct populations. Twelve mtND2 haplotypes were identified from 66 individuals from throughout the four geographical regions. A statistical parsimony network of mtDNA haplotypes shows two distinct groups, which correspond to the two species of corroboree frog, but with most of the haplotype diversity distributed in P. pengilleyi . These results demonstrate an unexpectedly high level of genetic diversity in both species. Our data have important implications for how the genetic diversity is managed in the future. The four evolutionarily significant units must be protected and maintained in captive breeding programmes for as long as it is possible to do.     

Genetic variation in zinc-tolerant populations of Glyceria fluitans

Amplified fragment length polymorphism (AFLP) was used to conduct a study of the genetic diversity of zinc-tolerant populations of Glyceria fluitans from 10 sites from across Europe. Six different primer combinations were used on five to nine plants from each of the 10 sites to generate a total of 796 bands, of which 670 were polymorphic. These data were then used to calculate a dendrogram by agglomerative clustering using the unweighed pair group method with average linkage (UPGMA). The dendrogram contained two distinct clusters, with little overlap between populations. Genetic diversity between populations of G. fluitans did not always correlate with geographical distances, for example, plants from the Navan population from Ireland were more genetically similar to populations from Poland than other populations from Ireland. In other instances, geographical origin was significant, for example, all Polish populations were genetically similar to each other. Populations from two English sites only 160 km apart, showed such a high degree of genetic diversity that they were placed in different clusters in the dendrogram. They were more closely related to Irish and Polish populations than to each other. Plants from different zinc-contaminated sites were found not to cluster together. The conclusion was that the cluster groupings were not related to exposure to zinc at the sites of origin, and that the drive to generate distinct metal-tolerant populations may not occur in this species due to the existence of a constitutive tolerance to metals.     

Global phylogeography of a cryptic copepod species complex and reproductive isolation between genetically proximate "populations"

The copepod Eurytemora affinis has a broad geographic range within the Northern Hemisphere, inhabiting coastal regions of North America, Asia, and Europe. A phylogenetic approach was used to determine levels of genetic differentiation among populations of this species, and interpopulation crosses were performed to determine reproductive compatibility. DNA sequences from two mitochondrial genes, large subunit (16S) rRNA (450 bp) and cytochrome oxidase I (COI, 652 bp), were obtained from 38 populations spanning most of the species range and from two congeneric species, E. americana and E. herdmani. Phylogenetic analysis revealed a polytomy of highly divergent clades with maximum sequence divergences of 10% in 16S rRNA and 19% in COI. A power test (difference of a proportion) revealed that amount of sequence data collected was sufficient for resolving speciation events occurring at intervals greater than 300,000 years, but insufficient for determining whether speciation events were approximately simultaneous. Geographic and genetic distances were not correlated (Mantel's test; r = 0.023, P = 0.25), suggesting that populations had not differentiated through gradual isolation by distance. At finer spatial scales, there was almost no sharing of mtDNA haplotypes among proximate populations, indicating little genetic exchange even between nearby sites. Interpopulation crosses demonstrated reproductive incompatibility among genetically distinct populations, including those that were sympatric. Most notably, two geographically distant (4000 km) but genetically proximate (0.96% 16S, 0.15% COI) populations exhibited asymmetric reproductive isolation at the F2 generation. Large genetic divergences and reproductive isolation indicate that the morphologically conservative E. affinis constitutes a sibling species complex. Reproductive isolation between genetically proximate populations underscores the importance of using multiple measures to examine patterns of speciation.     

Lack of reproductive isolation between the Western and Eastern phylogroups of the tench

The Eurasian range of the tench distribution is subdivided into deeply divergent Western and Eastern phylogroups evidenced by nuclear and mitochondrial DNA sequence markers. A broad zone of overlap exists in central and western Europe, suggesting post-glacial contact with limited hybridisation. We conducted a population genetic test of this indication that the two phylogroups may represent distinct species. We analysed variation at introns of nuclear genes, microsatellites, allozymes and mitochondrial DNA in populations from two postglacial lakes within the contact zone in Germany. The test is based on the expectation that in the presence of strong barriers to reproduction, a hybrid population will show genome-wide associations among alleles and genotypes from each phylogroup even after hundreds of generations of interbreeding. In contrast to this expectation, no consistent significant deviations from linkage and Hardy–Weinberg equilibria were found. Samples from both lakes did show significant disequilibria but they were limited to individual loci and were not concordant between populations, and were not robust to the method used. The single consistent association can be attributed to physical linkage between two microsatellite loci. Thus, results of our study support the hypothesis of free interbreeding between the two phylogroups of tench. Therefore, although the phylogroups may be considered as separate phylogenetic species, the present data suggest that they are a single species under the biological species concept.     

A multivariate morphometric investigation of Atherina boyeri Risso, 1810 and A. presbyter Cuvier, 1829 (Teleostei: Atherinidae): morphometric evidence in support of the two species

Two recently developed morphometric methodologies, multiple group principal components analysis (MGPCA) and the box truss method of body form transformation are used to re-address whether Atherina boyeri Risso, 1810 and A. presbyter Cuvier, 1829 are morphometrically distinct. The results revealed that morphometric differences are present between A. boyeri and A. presbyter , consistent with expectations of the existence of two species.
Females of the two species were clearly discriminated into two separate groups because the within-group covariances of several characters within populations of each species were different between species i.e., the covariances were heteroscedastic. The occurrence of heteroscedasticity within the data, although statistically invalidating the results of canonical variates anslysis, indicated there to be a large amount of morphological variation between females of the two species. Males were differentiated as a result of differences in body 'shape', particularly the relationship between head 'shape' and body 'shape'.
Several probable reasons are given for the failure of a previous study to differentiate the two species. The data rejects the synonymy of the two species in support of the continued use of the taxa A. boyeri Risso, 1810 and A. presbyter Cuvier, 1829.     

Mitochondrial DNA Variation and Phylogeography of the Ferruginous Pygmy-Owl (Glaucidium brasilianum)

Sequences from the mitochondrial cytochrome b gene were used to examine patterns of variation within and among populations of the ferruginous pygmy-owl (Glaucidium brasilianum) from both North America (including populations from Mexico) and South America. As currently conceived, G. brasilianum is paraphyletic, with North American and South American clades representing two distinct groups that should be recognized as the distinct species G. ridgwayi and G. brasilianum, respectively. Within the G. ridgwayi clade, populations from Arizona, Sonora, and Sinaloa are genetically distinct and share no mitochondrial haplotypes with populations occurring in Texas and other regions of Mexico. According to nested clade analysis this separation may be the consequence of past fragmentation that predates the origin of the Sonora desert. In addition, gene flow between the Arizona/Sonora/Sinaloa populations and the Texas/other Mexico populations is practically nonexistent, with estimates being approximately one individual every 10 generations. Collectively, these data suggest that the Arizona/Sonora/Sinaloa clade should be recognized as either a distinct subspecies or phylospecies from the group containing populations in Texas and the remainder of Mexico. These data should be used as guidelines for pygmy-owl recovery and conservation, as they meet the recommendations of task 3 of the pygmy-owl recovery plan that lists genetic data as essential information for pygmy-owl management.     

Genetic divergence and ecological specialisation of seed weevils (Exapion spp.) on gorses (Ulex spp.)

Abstract.  1. Reproductive isolation of sympatric populations may result from divergent selection of populations in different environments, and lead to ecological specialisation. In Brittany (France), the gorse Ulex europaeus (Fabaceae, Genisteae), may be encountered in sympatry with one of the two other gorse species present: U. gallii and U. minor . A recent study based on morphological identification of seed predators of gorse has shown that two weevil species (Curculionoidea, Apionidae) infest gorse pods at different seasons and have different host ranges: Exapion ulicis infests U. europaeus in spring, whereas E. lemovicinum infests U. gallii and U. minor in autumn. Weevil populations may thus have diverged in sympatry.
2. As morphological identification of weevils is often difficult and some of the characters used may exhibit individual or environmental variation, mitochondrial and nuclear sequences of weevils collected within pods of the three gorse species in 10 populations of Brittany were used to reconstruct their phylogeny.
3. The results reveal that species differentiation based on morphological characters is confirmed by the two molecular data sets, showing that E. ulicis and E. lemovicinum are distinct species, and suggesting the absence of host races. Finally, E. ulicis was able to use U. gallii and U. minor pods in spring in some years in some populations, which appeared to depend on the availability of pods present during its reproductive period.
4. Divergence between E. ulicis and E. lemovicinum may have resulted from temporal isolation of reproductive periods of weevil populations followed by specialisation of insects to host phenology.     

Species distinction in Irish populations of Quercus petraea and Q. robur: morphological versus molecular analyses

BACKGROUND AND AIMS: Populations of oak (Quercus petraea and Q. robur) were investigated using morphological and molecular (AFLP) analyses to assess species distinction. The study aimed to describe species distinction in Irish oak populations and to situate this in a European context. METHODS: Populations were sampled from across the range of the island of Ireland. Leaf morphological characters were analysed through clustering and ordination methods. Putative neutral molecular markers (AFLPs) were used to analyse the molecular variation. Cluster and ordination analyses were also performed on the AFLP markers in addition to calculations of genetic diversity and F-statisitcs. KEY RESULTS: A notable divergence was uncovered between the morphological and molecular analyses. The morphological analysis clearly differentiated individuals into their respective species, whereas the molecular analysis did not. Twenty species-specific AFLP markers were observed from 123 plants in 24 populations but none of these was species-diagnostic. Principal Coordinate Analysis of the AFLP data revealed a clustering, across the first two axes, of individuals according to population rather than according to species. High F(ST) values calculated from AFLP markers also indicated population differentiation (F(ST) = 0.271). Species differentiation accounted for only 13 % of the variation in diversity compared with population differentiation, which accounted for 27 %. CONCLUSIONS: The results show that neutral molecular variation is partitioned more strongly between populations than between species. Although this could indicate that the populations of Q. petraea and Q. robur studied may not be distinct species at a molecular level, it is proposed that the difficulty in distinguishing the species in Irish oak populations using AFLP markers is due to population differentiation masking species differences. This could result from non-random mating in small, fragmented woodland populations. Hybridization and introgression between the species could also have a significant role.