bluuebunny/crossref_metadata_2025_split huggingface dataset:
A microsatellite‐based estimation of clonal diversity and population subdivision in Zostera marina, a marine flowering plant
Authors: Reusch T. B. H. , Stam W. T. , Olsen J. L. 
Published: March 2003

AbstractWe examined the genetic population structure in eelgrass (Zostera marina L.), the dominant seagrass species of the northern hemisphere, over spatial scales from 12 km to 10 000 km using the polymorphism of DNA microsatellites. Twelve populations were genotyped for six loci representing a total of 67 alleles. Populations sampled included the North Sea (four), the Baltic Sea (three), the western Atlantic (two), the eastern Atlantic (one), the Mediterranean Sea (one) and the eastern Pacific (one). Microsatellites revealed substantial genetic variation in a plant group with low allozyme diversity. Average expected heterozygosities per population (monoclonal populations excluded) ranged from 0.32 to 0.61 (mean = 0.48) and allele numbers varied between 3.3 and 6.7 (mean = 4.7). Using the expected frequency of multilocus genotypes within populations, we distinguished ramets from genetic individuals (i.e. equivalent to clones). Differences in clonal diversity among populations varied widely and ranged from maximal diversity (i.e. all ramets with different genotype) to near or total monoclonality (two populations). All multiple sampled ramets were excluded from further analysis of genetic differentiation within and between populations. All but one population were in Hardy–Weinberg equilibrium, indicating that Zostera marina is predominantly outcrossing. From a regression of the pairwise population differentiation with distance, we obtained an effective population size Ne of 2440–5000. The overall genetic differentiation among eelgrass populations, assessed as ρ (a standardized estimate of Slatkin’s RST) was 0.384 (95% CI 0.34–0.44, P < 0.001). Genetic differentiation was weak among three North Sea populations situated 12–42 km distant from one another, suggesting that tidal currents result in an efficient exchange of propagules. In the Baltic and in Nova Scotia, a small but statistically significant fraction of the genetic variance was distributed between populations (ρ = 0.029−0.053) at scales of 15–35 km. Pairwise genetic differentiation between European populations were correlated with distance between populations up to a distance of 4500 km (linear differentiation‐by‐distance model, R2 = 0.67). In contrast, both Nova Scotian populations were genetically much closer to North Sea and Baltic populations than expected from their geographical distance (pairwise ρ = 0.03−0.08, P < 0.01). A biogeographical cluster of Canadian with Baltic/North Sea populations was also supported using a neighbour‐joining tree based on Cavalli–Sforza’s chord distance. Relatedness between populations may be very different from predictions based on geographical vicinity.
Molecular systematics, biogeography and population structure of Neotropical freshwater needlefishes of the genus Potamorrhaphis
Authors: Lovejoy N. R. , De Araújo M. L. G. 
Published: March 2003

AbstractPhylogenetic relationships of populations and species within Potamorrhaphis, a genus of freshwater South American needlefishes, were assessed using mitochondrial cytochrome b sequences. Samples were obtained from eight widely distributed localities in the Amazon and Orinoco rivers, and represented all three currently recognized species of Potamorrhaphis. The phylogeny of haplotypes corresponded imperfectly to current morphological species identities: haplotypes from P. guianensis, the most widespread species, did not make up a monophyletic clade. Geography played a strong role in structuring genetic variation: no haplotypes were shared between any localities, indicating restricted gene flow. Possible causes of this pattern include limited dispersal and the effects of current and past geographical barriers. The haplotype phylogeny also showed a complex relationship between fishes from different river basins. Based on the geographical distribution of clades, we hypothesize a connection between the middle Orinoco and Amazon via rivers of the Guianas. More ancient divergence events may have resulted from Miocene alterations of river drainage patterns. We also present limited data for two other Neotropical freshwater needlefish genera: Belonion and Pseudotylosurus. Pseudotylosurus showed evidence of substantial gene flow between distant localities, indicating ecological differences from Potamorrhaphis.
Sex ratio and fledging success of supplementary‐fed Tengmalm’s owl broods
Authors: Hörnfeldt B. , Hipkiss T. , Fridolfsson A.‐K. , Eklund U. , Ellegren H. 
Published: March 2003

AbstractA nest box population of Tengmalm’s owls (Aegolius funereus) in northern Sweden was studied to investigate the effects of extra food on the sex ratio between hatching and fledging in this sexually size‐dimorphic species. The brood size and brood sex ratio of supplementary‐fed and control broods were compared. Newly hatched nestlings were blood sampled and sexed by polymerase chain reaction (PCR) amplification of the sex‐linked CHD1Z and CHD1W genes. The brood sex ratio at hatching was strongly male biased (65%); this was also the case in broods where all eggs hatched (72%). There was no relationship between hatch order and sex ratio, and hatching sex ratio did not vary significantly with laying date. Brood size decreased between hatching and fledging, but did not differ between fed and control broods at either stage. Brood sex ratio did not differ between hatching and fledging, and fledging sex ratio did not differ between fed and control broods. It was concluded that, at least during the year in which the study was carried out, feeding had no effect on brood reduction, and that male and female nestlings did not show any differential mortality. The mechanisms behind the male‐biased sex ratio at hatching, and any possible adaptive reasons for it, are not known.
Sex, parthenogenesis and genetic structure of rotifers: microsatellite analysis of contemporary and resting egg bank populations
Authors: Gómez A. , Carvalho G. R. 
Published: March 2003

AbstractCyclically parthenogenetic rotifers are a valuable model for investigating the relationship between reproductive mode and population structure, although advances in this field have been hindered by low allozyme variability in these organisms. A high genotypic diversity is predicted after population establishment, which would be eroded by clonal selection during the parthenogenetic phase. The resting egg bank, produced sexually, is presumed to store high levels of genetic diversity, with subsequent effects on planktonic population structure. Here, we provide the first application of microsatellite markers to a rotifer planktonic population and its associated resting egg bank. Seven polymorphic microsatellite loci were screened in populations of the rotifer Brachionus plicatilis in a temporary pond to analyse: (i) the genetic structure of the resting egg bank; (ii) the changes in the genetic structure of rotifer populations during the parthenogenetic phase; and (iii) the population structure after its initiation from resting eggs. Microsatellites proved to be a useful tool for clone identification, revealing a surprisingly high clonal diversity in rotifer populations. The last sample in the parthenogenetic phase showed evidence of clonal selection, as indicated by a low observed clonal diversity and the appearance of linkage disequilibria. The resting egg bank, analysed comprehensively for the first time in any zooplankter, is in Hardy–Weinberg and linkage equilibrium, and contains a high genotypic diversity. Unexpectedly, the resting egg bank differed from the planktonic population in its allelic composition, suggesting that resting egg hatching is biased.
Origin and evolution of invasive naturalized material ofRhododendron ponticumL. in the British Isles
Authors: Milne Richard I. , Abbott Richard J. 
Published: March 2003

AbstractInformation concerning the area of origin, genetic diversity and possible acquisition of germplasm through hybridization is fundamental to understanding the evolution, ecology and possible control measures for an introduced invasive plant species.Rhododendron ponticumis extensively naturalized in the British Isles, but it is not known whether native material in Turkey, Spain or Portugal gave rise to the naturalized material, or to what extent introgression has affected this material. Chloroplast (cp) and nuclear ribosomal DNA (rDNA) restriction fragment length polymorphisms (RFLPs) were sought which could distinguish between native material ofR. ponticum, and between 15 otherRhododendronspecies includingR. ponticum's closest relatives. Thereafter, a total of 260 naturalized accessions ofR. ponticumfrom throughout the British Isles was examined with respect to informative polymorphisms. It was found that 89% of these accessions possessed a cpDNA haplotype that occurred in native material ofR. ponticumderived almost entirely from Spain, while 10% of accessions had a haplotype unique to Portuguese material. These results therefore indicated an Iberian origin for British material. rDNA or cpDNA evidence of introgression fromR. catawbiensewas found in 27 British accessions ofR. ponticum, and such accessions were significantly more abundant in Britain's coldest region, eastern Scotland, than elsewhere. This could indicate that introgression fromR. catawbienseconfers improved cold tolerance. Introgression fromR. maximumand an unidentified species was also detected.
Delineation of genetic zones in the European Norway spruce natural range: preliminary evidence
Authors: Bucci Gabriele , Vendramin Giovanni Giuseppe 
Published: March 2003

AbstractWe applied geostatistics to previously reported chloroplast simple sequence repeats (cpSSR) haplotype frequency data from 95 European Norway spruce populations to provide preliminary evidence about the following issues: (i) delineation of genetically homogeneous regions (‘genetic zones’); (ii) prediction of their haplotype frequencies and definition of related criteria to be applied for provenance identification and certification of seedlots; (iii) identification of putative allochthonous stands; and (iv) construction of a continental‐scale ‘availability map’ of the intraspecific biodiversity for Norway spruce. Direct evidence of large‐scale geographical structure over the European natural range was obtained, detecting both geographical clines and stationary patterns. The increase of the mean genetic divergence by geographical distance (up to approximately 1800 km apart) provided a strong hint that geographical distance is a major factor of differentiation in Norway spruce. Haplotype frequency surfaces were obtained by applying ordinary kriging to sampling frequency data. Cluster analysis carried out on haplotype frequency surfaces revealed a fair discrimination among 16 genetic zones, with an accuracy of 0.916. Dendrogram analysis carried out on the predicted mean haplotype frequency confirmed a fairly good separability of the genetic zones detected. Reclassification of populations by discriminant analysis confirmed the robustness of the genetic subdivision obtained. Combining the information from discriminant analysis and cross‐validation of sampling points, three populations likely to be of nonlocal origin were identified. The application of geostatistical analysis to genetic marker data is discussed in relation to breeding activities and to the formulation of appropriate conservation strategies.
Genetic evidence for host specificity in the hemi‐parasitic Viscum album L. (Viscaceae)
Authors: Zuber D. , Widmer A. 
Published: March 2003

AbstractNuclear ribosomal DNA (nrDNA) ITS sequences and partial sequences of three non‐coding chloroplast DNA (cpDNA) introns and spacers were used to assess genetic variation within and among three presumed host races of the hemi‐parasite Viscum album L. Currently, identification of host races occurs via the host trees, and morphological differences are minute at best. cpDNA and nrDNA ITS sequences revealed little sequence variation, but the variation found consistently supported the distinction of three host races. cpDNA and ITS sequences were not incongruent, as assessed by the incongruence length difference test. A combined analysis supported the sister group relationship between mistletoes from deciduous trees and fir.
Population subdivision in Europe’s great bustard inferred from mitochondrial and nuclear DNA sequence variation
Authors: Pitra C. , Lieckfeldt D. , Alonso J. C. 
Published: March 2003

AbstractA continent‐wide survey of sequence variation in mitochondrial (mt) and nuclear (n) DNA of the endangered great bustard (Otis tarda) was conducted to assess the extent of phylogeographic structure in a morphologically monotypic bird. DNA sequence variation in a combined 809 bp segment of the mtDNA genome from 66 individuals from the last six breeding regions showed relatively low levels of intraspecific sequence diversity (π = 0.32%) but significant differences in the regional distribution of 11 haplotypes (ΦST = 0.49). Despite their exceptional potential for dispersal, a complete and long‐term historical separation between the populations from the Iberian Peninsula (Spain) and mainland Europe (Hungary, Slovakia, Germany, and Russia) was demonstrated. Divergence between populations based on a 3‐bp insertion–deletion polymorphism within the intron region of the nuclear CHD‐Z gene was geographically concordant with the primary subdivision identified within the mtDNA sequences. Inferred aspects of phylogeography were used to formulate conservation recommendations for this endangered species.
Absence of a genetic bottleneck in a wild rabbit (Oryctolagus cuniculus) population exposed to a severe viral epizootic
Authors: Queney G. , Ferrand N. , Marchandeau S. , Azevedo M. , Mougel F. , Branco M. , Monnerot M. 
Published: March 2003

AbstractInfectious diseases and their demographic consequences are thought to influence the genetic diversity of populations. In Europe, during the last 50 years, the European rabbit (Oryctolagus cuniculus) has suffered two important viral epizootics: myxomatosis and rabbit viral haemorraghic disease (RVHD). Although mortality rates were very high, the impact of these diseases on genetic diversity has never been assessed directly. The subject of this paper is a wild rabbit population in France, which has been studied since the beginning of the 1980s. The first outbreak of RVHD occurred in 1995 and provoked a demographic crash. The population, sampled for the first time in 1982 and 1994, was sampled again at the end of 1996 to examine the impact of the epizootic on genetic diversity. In spite of the observed high mortality rate (≈ 90%), analysis of 14 polymorphic loci (allozymes and microsatellites) showed no loss in genetic diversity after the epizootic. Determination of temporal changes in allele frequencies indicated that the population evolved under genetic drift. The temporal method of Waples demonstrated a significant decrease in the effective population size (Ne) correlated with the demographic crash due to the epizootic. However, the population had only been studied for two generations after the epizootic and the remnant population size probably stayed high enough (≈ 50 individuals) to keep its genetic diversity at the precrash level. These results suggest that, contrary to what is usually thought and in spite of the subsequent high mortality rates, past epizootics (especially myxomatosis) may have had little effect on the genetic diversity of wild rabbit populations in Europe.
Glacial vicariance and historical biogeography of rock ptarmigan (Lagopus mutus) in the Bering region
Authors: Holder K. , Montgomerie R. , Friesen V. L. 
Published: March 2003

AbstractIn this paper, we address alternative hypotheses for the evolution of subspecies of rock ptarmigan (Lagopus mutus) endemic to the Aleutian Archipelago. To do this we examined patterns of genetic differentiation among populations of rock ptarmigan in the Aleutian Islands and parts of both Alaska and Siberia. Variation in mitochondrial control region sequences of 105 rock ptarmigan from 10 subspecies within the Bering region revealed three major phylogenetic lineages, two of which are endemic to the Aleutian Islands. Accordingly, haplotype and nucleotide diversities of rock ptarmigan within the archipelago are much higher than within mainland Alaska or Siberia. For Aleutian rock ptarmigan, analyses of molecular variance indicated significant genetic structuring and low estimates of gene flow among populations, despite small interisland distances within the archipelago. However, isolation by distance did not describe the pattern of gene flow or differentiation at this scale. Our estimates of divergence times of lineages suggest that Aleutian rock ptarmigan became isolated prior to the most recent Pleistocene glaciation event (late Wisconsin Stade) and that current patterns of genetic variation reflect the postglacial redistribution of divergent lineages and subsequent limited gene flow. In addition, genetic divergence among lineages was concordant with the distribution of plumage types among subspecies. The patterns of genetic variation described here for rock ptarmigan provide evidence for the role of glacial vicariance in contributing to genetic diversity within this and other Bering region species.
Genetic differentiation of Euterpe edulis Mart. populations estimated by AFLP analysis
Authors: Cardoso S. R. S. , Eloy N. B. , Provan J. , Cardoso M. A. , Ferreira P. C. G. 
Published: March 2003

AbstractHeart‐of‐palm (Euterpe edulis Mart.) is a wild palm with a wide distribution throughout the Atlantic Rainforest. Populations of E. edulis represent important renewable natural resources but are currently under threat from predatory exploitation. Furthermore, because the species is indigenous to the Atlantic Rainforest, which is located in the most economically developed and populated region of Brazil, social and economic pressures have devastated heart‐of‐palm forests. In order to estimate the partitioning of genetic variation of endangered E. edulis populations, 429 AFLP markers were used to analyse 150 plants representing 11 populations of the species distribution range. Analysis of the genetic structure of populations carried out using analysis of molecular variance (amova) revealed moderate genetic variation within populations (57.4%). Genetic differentiation between populations (FST = 0.426) was positively correlated with geographical distance. These results could be explained by the historical fragmentation of the Atlantic coastal region, together with the life cycle and mating system. The data obtained in this work should have important implications for conservation and future breeding programmes of E. edulis.
Evolution of balanced genetic polymorphism
Authors: Richman Adam 
Published: March 2003

AbstractExtreme genetic polymorphism maintained by balancing selection (so called because many alleles are maintained in a balance by a mechanism of rare allele advantage) is intimately associated with the important task of self/non‐self‐discrimination. Widely disparate self‐recognition systems of plants, animals and fungi share several general features, including the maintenance of large numbers of alleles at relatively even frequency, and persistence of this variation over very long time periods. Because the evolutionary dynamics of balanced polymorphism are very different from those of neutral genetic variation, data on balanced polymorphism have been used as a novel source for inference of the history of populations. This review highlights the unique evolutionary properties of balanced genetic polymorphism, and the use of theoretical understanding in analysis and application of empirical data for inference of population history. However, a second goal of this review is to point out where current theory is incomplete. Recent observations suggest that entirely novel selective forces may act in concert with balancing selection, and these novel forces may be extremely potent in shaping genetic variation at self‐recognition loci.
Limited differentiation in microsatellite DNA variation among northern populations of the yellow warbler: evidence for male‐biased gene flow?
Authors: Gibbs H. Lisle , Dawson Robert J. G. , Hobson Keith A. 
Published: March 2003

AbstractComparisons of the patterns of differentiation among genetic markers with different modes of inheritance can provide insights into patterns of sex‐biased dispersal and gene flow. Here, we compare the patterns of differentiation in six microsatellite loci among eight northern breeding populations of the yellow warbler (Dendroica petechia) with results obtained with mitochondrial DNA. Significant but low levels of differentiation (overall FST = 0.014; overall RST = 0.015) were present across all populations. The level of differentiation is substantially less than that observed in the same samples based on mitochondrial DNA control region variation. The presence of low population imbalance index values and significant isolation‐by‐distance relationships for both FST and RST suggests that these populations are at evolutionary equilibrium and that the high degree of similarity between populations may be due to high levels of male‐biased gene flow. This suggests that there may be significant but previously unappreciated differences in the long‐distance and/or episodic dispersal behaviour of males and females in these birds.
Anarchy in the UK: Detailed genetic analysis of worker reproduction in a naturally occurring British anarchistic honeybee,Apis mellifera, colony using DNA microsatellites
Authors: Châline N. , Ratnieks F. L. W. , Burke T. 
Published: March 2003

AbstractAnarchistic behaviour is a very rare phenotype of honeybee colonies. In an anarchistic colony, many workers’ sons are reared in the presence of the queen. Anarchy has previously been described in only two Australian colonies. Here we report on a first detailed genetic analysis of a British anarchistic colony. Male pupae were present in great abundance above the queen excluder, which was clearly indicative of extensive worker reproduction and is the hallmark of anarchy. Seventeen microsatellite loci were used to analyse these male pupae, allowing us to address whether all the males were indeed workers’ sons, and how many worker patrilines and individual workers produced them. In the sample, 95 of 96 of the males were definitely workers’ sons. Given that ≈ 1% of workers’ sons were genetically indistinguishable from queen's sons, this suggests that workers do not move any queen‐laid eggs between the part of the colony where the queen is present to the area above the queen excluder which the queen cannot enter. The colony had 16 patrilines, with an effective number of patrilines of 9.85. The 75 males that could be assigned with certainty to a patriline came from 7 patrilines, with an effective number of 4.21. They were the offspring of at least 19 workers. This is in contrast to the two previously studied Australian naturally occurring anarchist colonies, in which most of the workers’ sons were offspring of one patriline. The high number of patrilines producing males leads to a low mean relatedness between laying workers and males of the colony. We discuss the importance of studying such colonies in the understanding of worker policing and its evolution.