bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nuclear ribosomal DNA (nrDNA) concerted evolution in natural and artificial hybrids of Armeria (Plumbaginaceae)
Authors: Fuertes Aguilar J. , Rosselló J. A. , Nieto Feliner G. 
Published: March 2003

AbstractNuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) sequences from artificial hybrids and backcrosses between Armeria villosa ssp. longiaristata and A. colorata were studied to assess the possible effects of concerted evolution in natural hybrids. F1 artificial hybrids show the expected pattern of additive polymorphisms for five of the six variable sites as estimated from direct sequences. However, homogenization of polymorphism is already observed in the F2, and is biased towards A. colorata except for one site. In backcrosses, an expected tendency towards homogenization of polymorphic sites in the direction of the recurrent parent is observed for five sites, although this does not necessarily imply concerted evolution. Conversely, the sixth site appears to elude such a mechanism and thus provides additional support for the occurrence of biased concerted evolution. Our findings are relevant to interpreting phylogeographic patterns involving gene flow and are also consistent with the hypothesis of a hybrid origin of A. villosa ssp. carratracensis.
Suppression of randomly primed polymerase chain reaction products (random amplified polymorphic DNA) in heterozygous diploids
Authors: Reineke A. , Karlovsky P. , Zebitz C. P. W. 
Published: March 2003

AbstractIn a study of genetic polymorphism in the gypsy moth Lymantria dispar we observed the aberrant inheritance of a random amplified polymorphic DNA (RAPD) fragment designated H11‐589. This fragment was present in amplification products of F1 progeny of different crosses although it was not amplified from either parental DNA. DNA‐mixing experiments revealed that the presence of DNA containing a template for another product (H11‐746), amplified with the same primer, suppressed the synthesis of H11‐589. The templates for both RAPD products were highly repetitive and scattered throughout the L. dispar genome. Southern hybridization and sequence analysis of H11‐746 and H11‐589 revealed an extensive sequence homology and an internal repetitive motif of 17 nucleotides present in both products. Interactions between templates for H11‐746 and H11‐589 are expected to occur during the polymerase chain reaction (PCR), offering an explanation for the suppression of the amplification of H11‐589. The role of the internal repetitive motif and of the copy number of both templates in the suppression effect are discussed. Our results corroborate doubts regarding the suitability of the RAPD technique for quantitative genetic analysis, in particular where mixed populations are concerned.
Colonization history and introduction dynamics ofCapsella bursa‐pastoris(Brassicaceae) in North America: isozymes and quantitative traits
Authors: Neuffer B. , Hurka H. 
Published: March 2003

AbstractMultilocus isozyme genotypic composition for aspartate aminotransferase (AAT), leucine aminopeptidase (LAP) and glutamate dehydrogenase (GDH) was studied forCapsellain the source continent, Europe (9000 plants from 593 populations), and in the colonized continent, North America (2700 plants from 88 populations). North America was depauperate in the number of genotypes (by ≈ 50%), but in terms of frequencies, a few genotypes were common and shared by both continents. Although some, very rare, genotypes were, however, unique for North America, our data provided no evidence to indicate that the introduced gene pools were reconstructed on a multilocus genetic basis after introduction. Instead, they argued for a considerable number of independent introduction events. Geographical distribution patterns of multilocus genotypes in Europe and North America were pronounced and enabled us to trace the colonization history of CalifornianCapsellaback to Spanish ancestral populations and those of temperate North America back to temperate European gene pools. A random‐block field experiment with 14 Californian populations from different climatic regions revealed that variation patterns of quantitative traits reflect ecotypic variation, and the ecological amplitude ofCapsellain North America is similar to that in Europe, which can be traced back to the introduction of preadapted genotypes. It appears that certain multilocus isozyme genotypes are associated with certain ecotypes. The variable European gene pool ofCapsellawas essentially introduced into North America without major genetic changes.
DNA fingerprinting data and the analysis of population genetic structure by comparing band‐sharing patterns
Authors: Bertorelle G. , Bucchini L. , Pilastro A. , Matessi C. 
Published: March 2003

AbstractGenetic isolation among populations can be effectively investigated by multilocus DNA fingerprinting. If populations have diverged, it is expected that the mean proportion of bands shared by individuals from the same population, Bw, exceeds the corresponding mean, Bb, calculated from pairs of individuals from distinct populations. A problem arises in deciding whether any difference between Bw and Bb is statistically significant. In fact, any two band‐sharing data (bij), contributing to Bw or Bb, are not independent if they share a common individual (like bij and bjl). This prevents a correct application of parametric tests, such as the Student’s t‐test. Recently, a modification of this test has been proposed that should avoid the independence problem. Using a large number of samples of fingerprints, simulated from an appropriate ‘genetic’ model, under a wide range of conditions, we compared the performances of the Student’s t‐test, the modified t‐test and five new permutation tests, where individuals, rather than bij values, are permuted. We found that: (i) the Student’s t‐test can be very permissive, rejecting too often the null hypothesis when true, but is correct or conservative in certain cases; (ii) the modified t‐test is extremely conservative when the null hypothesis is true and very inefficient otherwise; (iii) all five permutation tests are strictly correct, provided that individuals are ordered randomly on gels; and (iv) in this case, the permutation tests are equally efficient, and are not inferior to the Student’s t‐test when the latter is approximately correct and provides a fair benchmark.
An examination of hybridization between the cattail speciesTypha latifoliaandTypha angustifoliausing random amplified polymorphic DNA and chloroplast DNA markers
Authors: Kuehn M. Marcinko , Minor J. E. , White B. N. 
Published: March 2003

AbstractTypha glaucarepresents a significant portion of the biomass of the wetlands surrounding the Great Lakes, USA. It is generally accepted to be a form of hybrid betweenT. latifoliaandT. angustifolia, which itself appears to be an exotic introduction from Europe. Based on morphological and isozyme data, conflicting theories have been proposed for the hybrid nature ofT. glauca: it has been described as a hybrid swarm, a distinct hybrid species and an F1hybrid. Therefore, we developed random amplified polymorphic DNA (RAPD) and chloroplast DNA markers, specific to the parental species, to assess hybrids. Ten RAPD primers gave 17 fragments specific toT. angustifoliaand 13 fragments specific toT. latifolia. All of the interspecific hybrids contained each of the species‐specific markers, indicating an F1hybrid status. Furthermore, all hybrids tested contained theT. angustifoliachloroplast haplotype, which is consistent with differential interspecific crossing success found previously. Additional confirmation of an F1hybrid status was gained by examining seedlings fromT. glauca. These progeny were expected to be advanced‐generation hybrids, as opposed to the F1hybrid parent. Analysis of the seedlings revealed segregating marker patterns consistent with patterns observed in experimental advanced‐generation hybrids, although these advanced hybrids do not appear to be a significant part of mature stands. Our data do not provide support for extensive gene flow betweenT. latifoliaandT. angustifolia. However, our results suggest that hybridization between the native and introducedTyphaspecies has impacted the native population through the spread of the F1hybrid,T. glauca.
Wild relatives and crop cultivars: detecting natural introgression and farmer selection of new genetic combinations in agroecosystems
Authors: Jarvis Devra I. , Hodgkin Toby 
Published: March 2003

AbstractWhether new combinations of genes that result from hybridization and introgression between wild and cultivated taxa are maintained, with the resultant development of populations with new characteristics, depends on natural selection, and in the case of crops, on human selection. While many cases of deliberate introgression of desirable traits into crop cultivars as part of breeding programmes are known, the extent and significance of natural or farmer‐assisted introgression is uncertain. A range of techniques have been used to document natural hybridization and introgression of agricultural crops and their wild relatives in many crops including maize, wheat, barley, oats, pearl millet, foxtail millet, quinoa, hops, hemp, potato, cocona, casava, common bean, cowpea, pigeon pea, carrots, squash, tomato, radish, letuce, chilli, beets, sunflower, cabbage, and rasberries. However, the majority of these studies are based on morphological characters, and few have investigated the frequency with which such new types are produced and retained in natural and agroecosystems for farmer selection. Even more limited is information on the role of farmers in recognizing and selecting new genetic variation from the natural introgression of crops with their wild relatives, and the impact, once selected, of these new genetic combinations on the crop diversity. Molecular evaluation of natural introgression linked to investigations of farmer recognition and use of introgressed types provide ways of evaluating whether farmer selection for introgressed types is a significant process in increasing the genetic diversity of crop plants.
High genetic diversity in a population of the ectomycorrhizal basidiomycete Laccaria amethystina in a 150‐year‐old beech forest
Authors: Gherbi H. , Delaruelle C. , Selosse M.‐A. , Martin F. 
Published: March 2003

AbstractThe genetic structure of a population of the ectomycorrhizal basidiomycete Laccaria amethystina (Bolt. ex Hooker) Murr. was assessed in a closed 150‐year‐old beech (Fagus sylvatica L.) forest in the Vosges Mountains in northeastern France. During the autumn of 1994 and 1997, sporophores were collected from three 100‐m2 sampling plots located along a 120‐m transect crossing the beech stand. The genetic variation of 676 sporophores was initially estimated using heteroduplex analysis of the ribosomal DNA intergenic spacer (IGS1). Ten unique IGS1 heteroduplex/homoduplex patterns were identified, although three types represented most of the sporophores analysed. Each group of IGS1 type was then analysed using random amplified microsatellite analysis (RAMS). RAMS resolved 388 different genotypes amongst the 634 sporophores analysed from the three plots during the autumn of 1994 and 1997. Density as high as 130 genets per 100 m2 was observed during the autumn of 1994. The largest clone covered ≈ 1 m2, but most genets covered a few cm2 and produced only one to three sporophores. Only eight genotypes identified in 1994 were found in 1997. Although L. amethystina has the capacity for vegetative persistence, the present study indicates that its populations maintain a genetic structure more consistent with a high frequency of sexual reproduction. This suggests that beech trees could be recolonized by new genotypes each year. Alternatively, this spatial distribution may also arise from erratic fruiting of underground persistent genets. These features (i.e. numerous genets of small size), typical of ruderal species, contrast with studies carried out on other ectomycorrhizal basidiomycetes occurring in mature closed forests.
Patterns of genetic variation in native grape phylloxera on two sympatric host species
Authors: Downie D. A. 
Published: March 2003

AbstractRandom amplified polymorphic DNA (RAPD) markers were used to examine population genetic structure in populations of native grape phylloxera. This research asked: (i) do RAPD markers distinguish two groups corresponding to the two host plant species; and (ii) do RAPD markers distinguish groups according to spatial location, independent of host plant association? Forty‐nine phylloxera clones were collected from five pairs of adjacent individuals of two sympatric grape species in five sites along a 145 km transect in Missouri, USA. A high level of polymorphism was observed, with some evidence for structuring between host plant species and no evidence for spatial structuring. An analysis of molecular variance (amova) found that 6.52% of the variance in RAPD banding patterns was attributable to host species and 7.96% of the variance was attributable to spatial location. A cluster analysis did not result in two groups corresponding to the two hosts, or to five groups corresponding to the geographical sites sampled. A Mantel test showed a low correlation between genetic similarity and spatial location. Two of the 93 RAPD markers were nonrandomly associated between the hosts. It is suggested that there may be a small host‐mediated effect on genetic variation but stochastic dispersal and a highly heterogeneous environment may be the primary influences on the observed polymorphism.
The linkage disequilibrium between chloroplast DNA and mitochondrial DNA haplotypes in Beta vulgaris ssp. maritima (L.): the usefulness of both genomes for population genetic studies
Authors: Desplanque B. , Viard F. , Bernard J. , Forcioli D. , Saumitou‐Laprade P. , Cuguen J. , Van Dijk H. 
Published: March 2003

AbstractThe structure and evolution of the plant mitochondrial genome may allow recurrent appearance of the same mitochondrial variants in different populations. Whether the same mitochondrial variant is distributed by migration or appears recurrently by mutation (creating homoplasy) in different populations is an important question with regard to the use of these markers for population genetic analyses. The genetic association observed between chloroplasts and mitochondria (i.e. two maternally inherited cytoplasmic genomes) may indicate whether or not homoplasy occurs in the mitochondrial genome. Four‐hundred and fourteen individuals sampled in wild populations of beets from France and Spain were screened for their mitochondrial and chloroplast polymorphisms. Mitochondrial DNA (mtDNA) polymorphism was investigated with restriction fragment length polymorphism (RFLP) and chloroplast DNA (cpDNA) polymorphism was investigated with polymerase chain reaction PCR–RFLP, using universal primers for the amplification. Twenty and 13 variants for mtDNA and cpDNA were observed, respectively. Most exhibited a widespread geographical distribution. As a very strong linkage disequilibrium was estimated between mtDNA and cpDNA haplotypes, a high rate of recurrent mutation was excluded for the mitochondrial genome of beets. Identical mitochondrial variants found in populations of different regions probably occurred as a result of migration. We concluded from this study that mtDNA is a tool as valuable as cpDNA when a maternal marker is needed for population genetics analyses in beet on a large regional scale.
Phylogeography of the pitviper clade Agkistrodon: historical ecology, species status, and conservation of cantils
Authors: Parkinson Christopher L. , Zamudio Kelly R. , Greene Harry W. 
Published: March 2003

AbstractWe used mitochondrial DNA sequences from three gene regions and two tRNAs (ND4, tRNA‐HIS‐SER, 12S, and 16S rDNA) to investigate the historical ecology of the New World pitviper clade Agkistrodon, with emphasis on the disjunct subspecies of the cantil, A. bilineatus. We found strong evidence that the copperhead (A. contortrix) is basal to its congeners, and that the cottonmouth (A. piscivorus) is basal to cantils. Phylogeography and natural history of the living terminal taxa imply that Agkistrodon primitively occupied relatively temperate habitats, with subsequent evolution of tropicality in ancestral A. bilineatus. Our best supported phylogeny rejects three gulf arc scenarios for the biogeography of A. bilineatus. We find significant statistical support for an initial divergence between populations on the east and west coasts of México and subsequent occupancy of the Yucatán Peninsula, by way of subhumid corridors in northern Central America. Based on phylogenetic relationships, morphological and molecular divergence, and allopatry we elevate A. b. taylori of northeastern México to species status. Taylor’s cantil is likely threatened by habitat destruction and small geographical range, and we offer recommendations for its conservation and management.
Allochronic speciation, secondary contact, and reproductive character displacement in periodical cicadas (Hemiptera:Magicicadaspp.): genetic, morphological, and behavioural evidence
Authors: Cooley John R. , Simon Chris , Marshall David C. , Slon Karen , Ehrhardt Christopher 
Published: March 2003

AbstractPeriodical cicadas have proven useful in testing a variety of ecological and evolutionary hypotheses because of their unusual life history, extraordinary abundance, and wide geographical range. Periodical cicadas provide the best examples of synchronous periodicity and predator satiation in the animal kingdom, and are excellent illustrations of habitat partitioning (by the three morphologically distinct species groups), incipient species (the year classes or broods), and cryptic species (a newly discovered 13‐year species,Magicicada neotredecim). They are particularly useful for exploring questions regarding speciation via temporal isolation, or allochronic speciation. Recently, data were presented that provided strong support for an instance of allochronic speciation by life‐cycle switching. This speciation event resulted in the formation of a new 13‐year species from a 17‐year species and led to secondary contact between two formerly separated lineages, one represented by the new 13‐year cicadas (and their 17‐year ancestors), and the other represented by the pre‐existing 13‐year cicadas. Allozyme frequency data, mitochondrial DNA (mtDNA), and abdominal colour were shown to be correlated genetic markers supporting the life‐cycle switching/allochronic speciation hypothesis. In addition, a striking pattern of reproductive character displacement in male call pitch and female pitch preference between the two 13‐year species was discovered. In this paper we report a strong association between calling song pitch and mtDNA haplotype for 101 individuals from a single locality within theM. tredecim/M. neotredecimcontact zone and a strong association between abdomen colour and mtDNA haplotype. We conclude by reviewing proposed mechanisms for allochronic speciation and reproductive character displacement.
Colony kin structure and male production inDolichovespulawasps
Authors: Foster Kevin R. , Ratnieks Francis L. W. , Gyllenstrand Niclas , Thorén Peter A. 
Published: March 2003

AbstractIn annual hymenopteran societies headed by a single outbred queen, paternity (determined by queen mating frequency and sperm use) is the sole variable affecting colony kin structure and is therefore a key predictor of colony reproductive characteristics. Here we investigate paternity and male production in five species ofDolichovespulawasps. Twenty workers from each of 10 colonies of each of five species, 1000 workers in total, were analysed at three DNA microsatellite loci to estimate paternity. To examine the relationship between kin structure and reproductive behaviour, worker ovary activation was assessed by dissection and the maternal origin of adult males was assessed by DNA microsatellites. Effective paternity was low in all species (D.media1.08,D. maculata1.0,D. sylvestris1.15,D. norwegica1.08 andD. saxonica1.35), leading to the prediction of queen–worker conflict over male production. In support of this, workers with full‐size eggs in their ovaries (four out of five species) and adult males that were workers’ sons (all five species) were found in queenright colonies. However, workers were only responsible for a minority of male production (D.media7.4%,D. maculata20.9%,D. sylvestris9.8%,D. norwegica2.6% andD. saxonica34.6%) suggesting that the queen maintains considerable reproductive power over the workers. Kin structure and reproductive conflict inDolichovespulacontrast with their sister groupVespula.Dolichovespulais characterized by low paternity, worker reproduction, and queen–worker conflict andVespulaby high paternity, effective worker policing and absence of worker reproduction. The trend revealed by this comparison is as predicted by kin selection theory suggesting that colony kin structure has been pivotal in the evolution of the yellowjacket wasps.
Sex‐biased dispersal and a density‐independent mating system in the Australian brushtail possum, as revealed by minisatellite DNA profiling
Authors: Ji W. , Sarre S. D. , Aitken N. , Hankin R. K. S. , Clout M. N. 
Published: March 2003

AbstractNatal dispersal can have important effects on mammal population structure and dynamics following a local population crash. Such dispersal is of practical importance when applied to the control of pest species because dispersal may significantly, and undesirably, reduce the population recovery time following a control operation. The relative dispersal rate of the sexes is also critical because that too will affect the rate of population increase. Here, we describe a field experiment in which we reduce the density of two populations of the Australian brushtail possum, and use genetic similarity, as estimated by minisatellite DNA profiles, to investigate dispersal in the original (undisturbed) and recovering populations. Our results show that the genetic similarity within the undisturbed populations was lower between males than between females. Conversely, the genetic similarities between males and females in the two recovering populations were not significantly different, while relatedness among males was significantly higher in the recovering populations when compared with those in the pre‐removal populations. These data indicate two important characteristics of dispersal in possums: (i) that dispersal in established populations is sex biased towards males; and (ii) that within the first 3 years following population control, ‘the vacuum effect’, whereby individuals from areas adjacent to a control area expand their home range and invade the depopulated area, is the most important factor in the re‐colonization process for possums. We found no evidence that the mating system, which is polygynous, varied when the density was markedly reduced. These results indicate that drastic reductions in population density by conventional control will not affect the rate of spread of biological control agents that rely on sexual transmission for dissemination.