bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chloroplast DNA variation and reticulate evolution in sexual and apomictic sections of dandelions
Authors: Wittzell Håkan 
Published: March 2003

AbstractSequencing of the trnL–trnF intergenic spacer in chloroplast DNA (cpDNA) from 237 sexual and apomictic species of dandelions (genus Taraxacum) from Europe, Asia and arctic North America revealed 46 haplotypes, which differed mainly by a variable number of polymorphic tRNA pseudogenes next to the trnF gene. The haplotypes could be divided into 20 cpDNA lineages, but independent duplications and deletions of the pseudogene copies made it difficult to further reconstruct the phylogeny. Intraspecific cpDNA variation was found in the primitive sexual T. serotinum. However, in contrast to a recent study, no cpDNA variation was detected within 12 apomictic species representing a variety of haplotypes. The cpDNA haplotype may therefore help to define these critical apomicts. On the other hand, the genetic variation may easily be overestimated, if the clones are not correctly identified, because some morphologically similar microspecies carried very different haplotypes. In all, 36 sections of the genus were sampled. Four primitive, mainly sexual, sections only displayed a group of ancient haplotypes, whereas morphologically more advanced sections often exhibited many different haplotypes from up to seven cpDNA lineages. In the latter cases, the lineages were rarely unique to a certain section. For example, the two most widespread haplotypes, belonging to different lineages, were found together in nine sections. This suggests that significant gene flow has occurred among the advanced sections, although sexual reproduction is not currently known in several of them. The result is consistent with the reticulate distribution of morphological characters among the sections.
An analysis of genetic variation in natural populations ofSticherus flabellatus[R. Br. (St John)] using amplified fragment length polymorphism (AFLP) markers
Authors: Keiper F. J. , McConchie R. 
Published: March 2003

AbstractAmplified fragment length polymorphisms (AFLPs) were used to characterize the genetic diversity within and among natural populations ofSticherus flabellatus. Eight populations within the Sydney region of New South Wales, Australia were surveyed using 11 primer combinations. A total of 1108 reproducible bands were detected of which 469 (42%) were polymorphic.FSTestimates averaged over all polymorphic loci indicated that significant genomic differentiation occurs among populations (average = 0.783). Genetic diversity within populations was assessed according to average heterozygosity (H) and percentage polymorphic loci (P) per population. Within‐population diversity ranged fromH = 0.12 andP = 33.69 toH = 0.04 andP = 15.99. Analysis of genetic similarity among populations suggested that the eight populations studied fall into two groups of four populations, based on population size and the condition of the habitat. Phenetic analysis (amova) indicated that genetic variation is greater among populations (74.34%) than within populations (25.66%). These findings suggest that the breeding system ofS. flabellatusis predominantly inbreeding, with genetic diversity maintained by occasional outcrossing in larger populations. The results presented in this study could provide evidence to support the proposal to protect natural stands ofS. flabellatus, which has implications for the Australian horticulture industry.
Microsatellite analysis of kinkajou social organization
Authors: Kays R. W. , Gittleman J. L. , Wayne R. K. 
Published: March 2003

AbstractKinkajou social groups generally consist of one adult female, two males, one subadult and one juvenile. Based on analysis of variation in 11 microsatellite loci, we assess the degree of kinship within and between four social groups totaling 25 kinkajous. We use exclusion and likelihood analyses to assign parents for seven of the eight offspring sampled, five with ≥ 95% certainty, and two with ≥ 80% certainty. Five of six identified sires of group offspring came from the same social group as the mother and pup. Adult males and females within a group were unrelated and subadults and juveniles were offspring of the group adults, suggesting a family structure. All five identified paternities within a social group were by the dominant male of the group. However, this copulation asymmetry does not necessarily reflect cooperation due to kinship ties between the two adult males within a group as one of two adult male pairs sampled was unrelated. Neighbouring male kinkajous were more closely related to each other than neighbouring female kinkajous, suggesting that females disperse more often or farther than males.
Discrepancies in population differentiation at microsatellites, mitochondrial DNA and plumage colour in the pied flycatcher — inferring evolutionary processes
Authors: Haavie J. , Sætre G.‐P. , Moum T. 
Published: March 2003

AbstractGenetic differentiation between three populations of the pied flycatcher Ficedula hypoleuca (Norway, Czech Republic and Spain, respectively) was investigated at microsatellite loci and mitochondrial DNA (mtDNA) sequences and compared with the pattern of differentiation of male plumage colour. The Czech population lives sympatrically with the closely related collared flycatcher (F. albicollis) whereas the other two are allopatric. Allopatric populations are on average more conspicuously coloured than sympatric ones, a pattern that has been explained by sexual selection for conspicuous colour in allopatry and a character displacement on breeding plumage colour in sympatry that reduces the rate of hybridization with the collared flycatcher. The Czech population was genetically indistinguishable from the Norwegian population at microsatellite loci and mtDNA sequences. Recent isolation and/or gene flow may explain the lack of genetic differentiation. Accordingly, different selection on plumage colour in the two populations is either sufficiently strong so that gene flow has little impact on the pattern of colour variation, or differentiation of plumage colour occurred so recently that the (presumably) neutral, fast evolving markers employed here are unable to reflect the differentiation. Genetically, the Spanish population was significantly differentiated from the other populations, but the divergence was much more pronounced at mtDNA compared to microsatellites. This may reflect increased rate of differentiation by genetic drift at the mitochondrial, compared with the nuclear genome, caused by the smaller effective population size of the former genome. In accordance with this interpretation, a genetic pattern consistent with effects of small population size in the Spanish population (genetic drift and inbreeding) were also apparent at the microsatellites, namely reduced allelic diversity and heterozygous deficiency.
Genetic variation of European beech (Fagus sylvatica L.) along an altitudinal transect at mount Vogelsberg in Hesse, Germany
Authors: Sander Thomas , König Susanne , Rothe Gunter M. , Janßen Alwin , Weisgerber Hans 
Published: March 2003

AbstractAllelic and genotypic variation at 13 different enzyme loci of autochthonous European beech (Fagus sylvatica L.) was investigated in six 110–160‐year‐old stands growing at elevations between 150 and 660 m above sea level on the western slope of mount Vogelsberg in central Germany. The highest elevated population showed the highest number of effective alleles (Ne), the highest total heterozygosity (He) and the highest population differentiation δT . Also, the genotype SKD‐A2A3 of shikimate dehydrogenase was significantly more frequent at the two highest elevated stands (P = 11%) than at the three lowest elevated stands (P = 1%). Further differences in genotype frequencies between 11 of 15 stand pairs were elevation independent.
Bottlenecks and multiple introductions: population genetics of the vector of avian malaria in Hawaii
Authors: Fonseca Dina M. , Lapointe Dennis A. , Fleischer Robert C. 
Published: March 2003

AbstractAvian malaria has had a profound impact on the demographics and behaviour of Hawaiian forest birds since its vector, Culex quinquefasciatus the southern house mosquito, was first introduced to Hawaii around 1830. In order to understand the dynamics of the disease in Hawaii and gain insights into the evolution of vector‐mediated parasite–host interactions in general we studied the population genetics of Cx. quinquefasciatus in the Hawaiian Islands. We used both microsatellite and mitochondrial loci. Not surprisingly we found that mosquitoes in Midway, a small island in the Western group, are quite distinct from the populations in the main Hawaiian Islands. However, we also found that in general mosquito populations are relatively isolated even among the main islands, in particular between Hawaii (the Big Island) and the remaining Hawaiian Islands. We found evidence of bottlenecks among populations within the Big Island and an excess of alleles in Maui, the site of the original introduction. The mitochondrial diversity was typically low but higher than expected. The current distribution of mitochondrial haplotypes combined with the microsatellite information lead us to conclude that there have been several introductions and to speculate on some processes that may be responsible for the current population genetics of vectors of avian malaria in Hawaii.
Estimation of gene flow in the tropical‐rainforest tree Neobalanocarpus heimii (Dipterocarpaceae), inferred from paternity analysis
Authors: Konuma Akihiro , Tsumura Yoshihiko , Lee Chai Ting , Lee Soon Leong , Okuda Toshinori 
Published: March 2003

AbstractPollen flow and population genetic structure among 30 potentially flowering individuals of Neobalanocarpus heimii, a tropical emergent tree, were investigated in a lowland tropical rainforest of Malaysia using microsatellite polymorphism. The 248 offspring in the vicinity of five reproductive trees of the 30 potentially flowering trees were used in paternity analysis for pollen‐flow study. Four primer pairs, developed in different species of dipterocarps, were adopted to detect microsatellite polymorphism. Based upon microsatellite polymorphism, pollen flow and seed migration were detected. Pollen‐flow events of more than 400 m were observed directly, based on paternity analysis in the study plot. The estimated average mating distance of the five reproductive trees was 524 m. This result suggests that reproduction of this species is mediated by a long‐distance pollinator. The haplotypes of some offspring were not compatible with the nearest reproductive tree. Thus, the results suggest that some seeds are dispersed by a seed dispersal vector. Investigation of genetic structure showed significant and negative correlation of genetic relatedness and spatial distances between the 30 potentially flowering trees, but this correlation was weak. We suggest that long‐distance gene flow and seed migration are responsible for the poorly developed genetic structure of this species.
Population subdivision and genetic diversity in two narrow endemics ofAntirrhinumL.
Authors: Mateu‐Andrés I. , Segarra‐Moragues J. G. 
Published: March 2003

AbstractGenetic diversity and its partition within and among populations and families of two species ofAntirrhinumL.,A. charidemiLange andA. valentinumF.Q., have been studied. Both species are narrow‐range endemics, self‐incompatible, ecologically specialized and form small isolated populations. Despite these similarities, the species differ markedly in the distribution of genetic diversity. InA. valentinum, 61.64% of the total variation was distributed among populations, whereas inA. charidemiit was only 8.55%.A. charidemishowed little population divergence (GST = 0.0542) relative toA. valentinum(GST = 0.4805). In neither species was within‐population genetic diversity correlated with population size, nor were there significant correlations between genetic and geographical distances. These results are discussed in relation to differences in flowering time and habitat continuity. They suggest that caution should be taken when making generalizations about levels of genetic variation and patterns of plant reproduction, life history and geographical distribution.
Genetic structure of the annual weedSenecio vulgarisin relation to habitat type and population size
Authors: Müller‐Schärer H. , Fischer M. 
Published: March 2003

AbstractThroughout the world, the highly selfing annual common groundsel,Senecio vulgaris(Asteraceae) is a common weed. Recently, it has also colonized ecological compensation areas in agro‐ecosystems. We investigated the genetic structure ofS. vulgarisusing random amplified polymorphic DNA (RAPD) profiles of 80 plants from nine populations representing three habitat types in two regions in Switzerland. RAPD variation among regions (19.8%), among populations within regions (19.2%) and within populations (61.1%) was highly significant (amova;P < 0.001). Gene flow estimated from the observed differentiation among populations (ΦST = 0.382) was low (assuming Wright’s island model,Nem = 0.404). Genetic distances between pairs of populations were significantly correlated with geographical distances (Mantel test;r = 0.37,P < 0.03). Molecular variance obtained withamovawas lowest in the small populations in compensation areas (1.13), intermediate in vineyard populations (2.49), all located in northern Switzerland and highest in the larger vegetable field populations from western Switzerland (3.41;P < 0.05). Overall, there was a positive correlation of molecular variance and population size (P < 0.05), as expected under genetic drift. However, molecular variance was negatively correlated with population size among populations in ecological compensation areas, suggesting that selection was also important. We also applied triazine herbicide to leaves of three offspring of each of the 80 plants. Plants from populations of compensation areas showed higher mean levels and reduced variation in the resistance to triazine herbicide than plants from vineyards and vegetable fields. This suggests that compensation areas were colonized from adjacent corn fields, in which there has been selection for herbicide resistance. We discuss the implications of our results for the biological control ofS. vulgaris.
Independent origins and horizontal transfer of bacterial symbionts of aphids
Authors: Sandström Jonas P. , Russell Jacob A. , White Joshua P. , Moran Nancy A. 
Published: March 2003

AbstractMany insect groups have obligate associations with primary endosymbionts: mutualistic bacteria that are maternally transmitted and derived from an ancient infection. Often, the same insects are hosts to ‘secondary’ bacterial symbionts which are maternally transmitted but relatively labile within host lineages. To explore the dynamics of secondary symbiont associations in aphids, we characterized bacteria infecting 15 species of macrosiphine aphids using DNA sequencing, diagnostic polymerase chain reaction (PCR), diagnostic restriction digests, phylogenetic analyses, and electron microscopy to examine aphids from nature and from laboratory colonies. Three types of bacteria besidesBuchnerawere found repeatedly; all three fall within the Enterobacteriaceae. The R‐type has a 16S rDNA less than 0.1% different from that of the secondary symbiont previously reported fromAcyrthosiphon pisumand is related toSerratiaspecies. The T‐type includes a symbiont previously reported from a whitefly; the U‐type comprises a new cluster near the T‐type. The T‐type was found in every one of 40Uroleucon ambrosiaeclones collected throughout the United States. In contrast,A. pisumindividuals were infected by any combination of the three symbiont types. Secondary symbionts were maternally transmitted for 11 months within laboratory‐rearedA. pisumclones and were present in sexually produced eggs. PCR screens for a bacteriophage, APSE‐1, indicated its presence in bothA. pisumandU. ambrosiaecontaining secondary symbionts. Electron microscopy of R‐type and T‐type bacteria inA. pisumand inU. ambrosiaerevealed rod‐shaped organisms that attain extremely high densities within a few bacteriocytes.
Population structure and biogeography of migratory freshwater fishes (Prochilodus: Characiformes) in major South American rivers
Authors: Sivasundar Arjun , Bermingham Eldredge , Ortí Guillermo 
Published: March 2003

AbstractMitochondrial DNA (mtDNA) sequences were used to infer the phylogenetic relationships ofProchilodusspecies in the Paraná, Amazonas, Orinoco, and Magdalena basins. Sequences of ATPase subunits 6 and 8 (total 840 bp) were obtained for 21Prochilodusspecimens from the four river systems. UsingSemaprochilodusas an outgroup, phylogenetic analyses showed that: (i) each river basin contains a monophyletic group of mtDNA lineages; and (ii) the branching order places Magdalena in a basal position with subsequent branching of Orinoco, Amazon and Paraná. The mitochondrial control region was sequenced for 26P. lineatus(from the Paraná basin) and six otherProchilodusspecimens from the Magdalena, Orinoco and Amazon. All 26 control region haplotypes were unique with sequence divergence ranging from 0.3 to 3.6%. The control region phylogeny is well resolved but phylogenetic structure is not associated with geography. For example, mtDNA haplotypes from the upper Paraná (Mogui Guassú) and the upper Bermejo, separated by at least 2600 km, have close genealogical ties. Phylogeographic analyses, including nested clade analysis, suggest high levels of gene flow within this basin.
How many species of cichlid fishes are there in African lakes?
Authors: Turner George F. , Seehausen Ole , Knight Mairi E. , Allender Charlotte J. , Robinson Rosanna L. 
Published: March 2003

AbstractThe endemic cichlid fishes of Lakes Malawi, Tanganyika and Victoria are textbook examples of explosive speciation and adaptive radiation, and their study promises to yield important insights into these processes. Accurate estimates of species richness of lineages in these lakes, and elsewhere, will be a necessary prerequisite for a thorough comparative analysis of the intrinsic and extrinsic factors influencing rates of diversification. This review presents recent findings on the discoveries of new species and species flocks and critically appraises the relevant evidence on species richness from recent studies of polymorphism and assortative mating, generally using behavioural and molecular methods. Within the haplochromines, the most species‐rich lineage, there are few reported cases of postzygotic isolation, and these are generally among allopatric taxa that are likely to have diverged a relatively long time in the past. However, many taxa, including many which occur sympatrically and do not interbreed in nature, produce viable, fertile hybrids. Prezygotic barriers are more important, and persist in laboratory conditions in which environmental factors have been controlled, indicating the primary importance of direct mate preferences. Studies to date indicate that estimates of alpha (within‐site) diversity appear to be robust. Although within‐species colour polymorphisms are common, these have been taken into account in previous estimates of species richness. However, overall estimates of species richness in Lakes Malawi and Victoria are heavily dependent on the assignation of species status to allopatric populations differing in male colour. Appropriate methods for testing the specific status of allopatric cichlid taxa are reviewed and preliminary results presented.
Plague dynamics and population genetics of the desert locust: can turnover during recession maintain population genetic structure?
Authors: Ibrahim Kamal M. 
Published: March 2003

AbstractThe desert locust (Schistocerca gregaria) undergoes crowding‐induced phase transformation from solitary form to gregarious form. The transformations involves changes in behaviour, colour, development, morphometry, fecundity and endocrine physiology. Recession populations of the desert locust exist primarily in the solitary phase as small populations in patchy environments and are prone to extinction because of climatic events. Significant genetic differentiation among recession populations along the Red Sea coast of Eritrea was previously reported. It was hypothesized that despite the mixing effect of recurrent swarms, metapopulation dynamics could have produced genetic divergence among these highly scattered recession populations. A Monte Carlo simulation of the population dynamics of the desert locust in a metapopulation setting, with a realistic range of parameter values clearly demonstrated that this is possible. Population growth was represented by a discrete‐time logistic equation. The duration of recessions and swarms was sampled from normal distributions whose means and standard deviations were varied based on reported estimates. An average recession duration of 10 ± 3 generations and swarm periods half as long but almost twice as variable produced a partitioning of the total genetic variance most similar to that in the empirical study. In conventional metapopulation analysis, whether turnover leads to increased or reduced divergence is dependent on the number of colonists relative to the number of recurrent migrants, and on whether the colonists arise from a single patch or many patches. In the case of locusts, the stochastic boom and bust cycle is the overriding factor. Divergence between patches during recession due to founder effect and recurrent drift is balanced by the high rate of mixing during plagues.
Genetic diversity of Iberian populations of Bemisia tabaci (Hemiptera: Aleyrodidae) based on random amplified polymorphic DNA–polymerase chain reaction
Authors: Moya A. , Guirao P. , Cifuentes D. , Beitia F. , Cenis J. L. 
Published: March 2003

AbstractThe genetic structure of six Iberian populations of the whitefly Bemisia tabaci, two of them biotype Q, one biotype B, and the other three a mixture of both, has been studied using random amplified polymorphic DNA–polymerase chain reaction (RAPD–PCR). A total of 336 individuals was completely discriminated by means of 234 scored bands. Separate analyses of molecular variance of haploid males and diploid females using the pairwise number of differences between haplotypes showed that biotypes contribute significantly more to the observed variability than populations within biotypes. On average, gene flow between two biotypes of the same population is lower than between populations of identical biotypes. On the basis of these results and the nondetection under natural conditions of a single hybrid, we consider that both biotypes are genetically isolated under the ecological conditions prevailing in the south Iberian Peninsula. All populations of biotype Q presented similar values of intrapopulational diversity, which were higher than the values shown by populations of biotype B.