bluuebunny/crossref_metadata_2025 huggingface dataset:
The 2000 epidemic of Rift Valley fever in Saudi Arabia: mosquito vector studies
Authors: JUPP P. G. , KEMP A. , GROBBELAAR A. , LEMAN P. , BURT F. J. , ALAHMED A. M. , MUJALLI D. AL , KHAMEES M. AL , SWANEPOEL R.
Published: March 2003

Abstract. In mid‐September 2000, Rift Valley fever (RVF) virus was diagnosed as the cause of infection in humans and livestock in Jizan Region, Saudi Arabia. This is the first time that this arbovirus has been found outside Africa and Madagascar. Collections of mosquitoes (Diptera: Culicidae) were therefore undertaken (from 25 September to 10 October) at eight sites during the epidemic to obtain mosquitoes for attempted RVF virus isolation. Among 23 699 mosquito females tested, isolations of RVF virus were made from six of 15 428 Culex (Culex) tritaeniorhynchus Giles and from seven of 8091 Aedes vexans arabiensis Patton. Minimum mosquito infection rates per 1000 at sites with infected mosquitoes were 0.3–13.8 Cx. tritaeniorhynchus and 1.94–9.03 Ae. v. arabiensis. Viral activity moved northwards as collecting was in progress and collectors ‘caught up’ with the virus at the two most northerly sites on the last two trapping evenings. Other species occurred in small numbers and were identified but not tested. Both Cx. tritaeniorhynchus and Ae. v. arabiensis were susceptible to RVF virus and transmitted between hamsters, and an additional quantitative test with Cx. tritaeniorhynchus showed that 71–73% of mosquitoes became infected after ingesting 6.9–7.9 log10 FFU/mL of virus; transmission rates were 10% (post‐infection day 14) and 26% (post‐infection day 20). It was concluded that both species were vectors on grounds of abundance, distribution, preference for humans and sheep, the virus isolations and vector competence tests.
Verifying the curriculum of a family medicine clerkship
Authors: Snell Laura M , Battles James B , Bedford Joe A , Washington Evelyn T
Published: March 2003

The learning experience during a medical school clinical rotation is largely shaped by students' patient encounters. This paper reports on how a log system for recording these encounters can be used for course planning and evaluation.

Over the past 5 years, 960 third‐year students completed log forms based on their clinical encounters during a required 4‐week family medicine clerkship at UT Southwestern. These forms were then optically scanned and the information entered into a computerized database.

Log form data revealed that the most common medical problems encountered by students in their ambulatory settings were similar to those reported in the general family practice literature. There was a great deal of consistency in the types of encounters from year to year. The data also showed some differences among clerkship sites in terms of patient demographics and the most frequently reported diagnoses.

Information generated from student log forms has been used by the clerkship faculty to determine required readings, prioritize didactic topics and other teaching, adjust curriculum content, prepare support materials and develop examinations. Given the utility of the information obtained and the ease of use of optical mark encounter sheets, we recommend this system for other clerkships.
The development and evaluation of a personal learning log for Senior House Officers
Authors: Kelly Diane R , Murray
Published: March 2003

Object

To develop and evaluate the effect of having a personal learning log on Senior House Officers knowledge and confidence.

Methods

A multiple choice paper and a confidence checklist for two hospital specialties were developed to assess knowledge and confidence. These were administered to a control group and to an intervention group who had the learning log. Both groups completed an evaluation at the end of the post.

Setting

The study took place in Accident & Emergency and Obstetric & Gynaecology posts in Greater Glasgow and Lanarkshire.

Subjects

79 Senior House Officers in Accident & Emergency and 78 Senior House Officers in Obstetrics & Gynaecology.

Results

The mean scores in the MCQ and the mode in the confidence checklist increased significantly in both specialties during the post, but there was no significant difference between the control and intervention groups. Forty two learning logs were returned at the end of the study and analysis of these revealed that there was great scope for learning but few documented the specific learning achieved. Evaluation of the posts revealed that some improvements had taken place in teaching and assessment frequency, however, there was scope for further improvement.

Conclusion

While the problems of hospital training are well documented, an attempt to improve the situation using a learning log did not have a statistically significant impact on SHO knowledge or confidence. A six‐month hospital post appears to present many opportunities for learning but these are not exploited. It is suggested that three things are needed. Firstly, active participation by and personalized feedback from a senior member of staff, with training where needed. Secondly, protected time for tutorials with a planned system of formative assessment, and thirdly, a more positive approach to learning by both SHOs and consultants. Once this occurs, a learning log may have a more significant impact on training.
Counting apples with oranges: a limitation of the discrimination index
Authors: Hobsley
Published: March 2003

Objectives

Three consecutive diets of the Professional and Linguistic Assessment Board's multiple choice question examination in Medicine were analysed in two different ways, taking into account the responses of the candidates to the three separate specialities within medicine.

Design

First, discrimination indices were obtained from calculations involving all 60 questions, each with five completions. Then, the 60 questions were analysed separately in the three constituent disciplines of Surgery (15 questions), Obstetrics and Gynaecology (12 questions) and Medicine (33 questions).

Setting

Professional and Linguistic Assessment Board.

Results

By the first analysis, performed by considering the whole paper to be a single entity, discrimination indices for medicine were greater than for the other two disciplines; one candidate obtained a random score, i.e. one that was no better than could have arisen, with 95% confidence, by chance as predicted by the hypergeometric distribution, and reliability coefficients were high (0·87). In the second analysis, the paper was considered as three separate components and discrimination indices calculated for each discipline separately. Discrimination indices were similar in all three disciplines, there were 26 random scores, and reliability coefficients were reduced – moderately in Medicine, considerably in the other two disciplines.

Conclusions

These findings emphasize the importance of defining the territory of the subject and ensuring that all the items are drawn from that territory, as well as of using a sufficiently large number of items.
The relation between understanding and practice in problem‐based medical education
Authors: Margetson
Published: March 2003

The importance of conceptions of the soundness of medical education are considered briefly. This leads to the question of misconceptions. A pervasive misconception characterized by the separation of understanding from action and practice, illustrated by two examples from the literature on medical education, is discussed. Questions as to the soundness of medical education are usually approached in terms of empirical inquiry; this paper takes a different, complementary, approach. Five medical faculties in Australia, Sweden and the UK. Problem‐based medical course staff and students. The practical effect of the separation between action and practice is illustrated in the question of problem‐solving as conceived in transitional semiproblem‐based curricula in common with traditional curricula, limiting the development of sound professional education. The centrality of the misconception generates a widespread approach to the curriculum, described as the `Convenient peg' model. In contrast, the `Growing web' model enables the design of rigorous problem‐based curricula which acknowledge that action and practice are necessarily related to understanding in a way unrecognized in the `Convenient peg' model. Consequently, rigorous problem‐based curricula embody a thoroughly integrated curriculum enabling improved medical education.
Gender comparisons of medical students' psychosocial profiles
Authors: Hojat Mohammadreza , Glaser Karen , Xu Gang , Veloski J Jon , Christian Edward B
Published: March 2003

Objectives

This study was designed to compare male and female medical students on selected personality attributes that could influence their academic attainment and personal success.

Design

Participants were 1157 medical students (743 men, 414 women) who completed a set of psychosocial questionnaires measuring intensity and chronicity of loneliness, general anxiety, test anxiety, neuroticism, depression, extraversion, self‐esteem, locus of control, perceptions of parents, general health and appraisals of stressful life events. Data were analysed by employing multivariate and univariate analysis of variance and chi‐square analysis.

Setting

Jefferson Medical College.

Subjects

Medical students.

Results

Men scored significantly higher on the intensity of loneliness, and women scored higher on general anxiety, test anxiety and neuroticism scales, but the magnitudes of the effect size estimates were not large. No significant gender difference was observed on measures of chronicity of loneliness, depression, extraversion, self‐esteem, external locus of control, perception of general health and perceptions of the mother and the father. Women who experienced stressful life events, such as death in the family or personal illness, appraised these events more negatively than did their male counterparts.

Conclusions

Implications of the findings for medical education and practice are discussed.
Genetic diversity within and among vegetative compatibility groups of Stereum sanguinolentum determined by arbitrary primed PCR
Authors: STENLID J. , VASILIAUSKAS R.
Published: March 2003

Genetic variation within and among vegetative compatibility groups (VCGs) of Stereum sanguinolentum isolates was investigated with various geographical distances. DNA fingerprints were made using the M13 core sequence as a primer. A total of 113 isolates from 12 plots in Sweden, Finland and Lithuania were studied. Each VCG produced a discrete group of banding patterns. Among 20 isolates from the largest VCG, G1, the incidence of identical banding patterns was 24% within a sample plot, 8% among sample plots within a country, and 0% among countries. In the other 15 VCGs that comprised two and more isolates, corresponding percentages were 42%, 30% and 0%. Average band‐sharing indices (ABSIs) within VCGs decreased with increasing geographical distance: for isolates from VCG G1, ABSI was 91.3% within sample plots, 85.4% among sample plots within a country, and 79.2% among countries. Corresponding figures for the other 15 VCGs were 97.0%, 92.7% and 80.4%, respectively. Among VCGs similarities were significantly lower (P < 0.001) and the trend of decreasing similarity with larger geographical distances was less pronounced: ABSI within sample plots was 73.7%, among sample plots within countries 73.8%, and among countries 71.1%. However, the similarity of populations as compared within and between countries differed significantly (P < 0.001), suggesting geographical differentiation between S. sanguinolentum populations separated by 400 km and the Baltic sea. Calculations of GST clearly indicated geographical population subdivision within the large VCG but not among the total sample. In summary, the results show population structure of inbred lines within VCGs containing closely related strains in local populations and more distant relationships among populations.
Glacial survival does not matter – II: RAPD phylogeography of Nordic Saxifraga cespitosa
Authors: TOLLEFSRUD M. M. , BACHMANN K. , JAKOBSEN K. S. , BROCHMANN C.
Published: March 2003

It has been suggested that many arctic‐alpine plant species have limited dispersal ability and cannot have arrived in Scandinavia and the arctic archipelago of Svalbard by long‐distance dispersal after a total glaciation. It has therefore been proposed that such species must have survived the entire glaciation(s) in ice‐free refugia in southern Norway, northern Norway and Svalbard. We investigated random amplified polymorphic DNA (RAPD) variation among 28 populations from Norway and Svalbard of one of these arctic‐alpine ‘short‐distance dispersers’, the selfing polyploid Saxifraga cespitosa. In an analysis of molecular variance (AMOVA), more variation was found among populations within the three postulated refugia regions (45%) than among these regions (25%). Spatial autocorrelation (Mantel) analyses showed that the genetic distance monotonously increased with increasing geographical distance. In UPGMA and PCO analyses, the populations from Norway and Svalbard formed a south–north cline that continued across the Barents Sea barrier. The results suggest that there has been recent dispersal among the three postulated refugia regions and thus that postglacial dispersal into these refugia regions from other distant areas also must represent a possibility. The observed geographical pattern of the genetic variation may have been established after expansion from different source areas outside the North European ice sheet and/or from different refugia areas ‘within’ the ice sheet, but it is probably not possible to distinguish among these alternatives. The results for S. cespitosa are consistent with a dynamic late‐ and postglacial scenario with extensive plant dispersal, and support the conclusion from our previous study of the outbreeding Saxifraga oppositifolia; the hypothesis of glacial survival in Norway and/or Svalbard is superfluous.
Hierarchical analyses of genetic differentiation in a hybrid zone of Sorex araneus (Insectivora: Soricidae)
Authors: LUGON‐MOULIN N. , BRÜNNER H. , WYTTENBACH A. , HAUSSER J. , GOUDET J.
Published: March 2003

Microsatellites are used to unravel the fine‐scale genetic structure of a hybrid zone between chromosome races Valais and Cordon of the common shrew (Sorex araneus) located in the French Alps. A total of 269 individuals collected between 1992 and 1995 was typed for seven microsatellite loci. A modified version of the classical multiple correspondence analysis is carried out. This analysis clearly shows the dichotomy between the two races. Several approaches are used to study genetic structuring. Gene flow is clearly reduced between these chromosome races and is estimated at one migrant every two generations using R‐statistics and one migrant per generation using F‐statistics. Hierarchical F‐ and R‐statistics are compared and their efficiency to detect inter‐ and intraracial patterns of divergence is discussed. Within‐race genetic structuring is significant, but remains weak. FST displays similar values on both sides of the hybrid zone, although no environmental barriers are found on the Cordon side, whereas the Valais side is divided by several mountain rivers. We introduce the exact G‐test to microsatellite data which proved to be a powerful test to detect genetic differentiation within as well as among races. The genetic background of karyotypic hybrids was compared with the genetic background of pure parental forms using a CRT–MCA. Our results indicate that, without knowledge of the karyotypes, we would not have been able to distinguish these hybrids from karyotypically pure samples.
Fragmentation and genetic differentiation among subpopulations of the endangered Hawaiian mintHaplostachys haplostachya(Lamiaceae)
Authors: Morden C. W. , Loeffler W.
Published: March 2003

Haplostachys haplostachyawas at one time a prevalent species in the mid‐elevation (1650–1800 m) xerophytic shrubland between Mauna Loa and Mauna Kea on Hawaii. Grazing pressure by feral ungulates, destruction of habitat from military activity, and conversion of forest to pastures have fragmented its range to small subpopulations restricted to several cinder cones and portions of the remaining shrubland. Some subpopulations are still extensive, while others are reduced to 20 or fewer individuals. Genetic analyses using random amplified polymorphic DNA (RAPD) markers demonstrate that plants in subpopulations with a large number of individuals maintain levels of genetic variation similar to the entire population, whereas plants in a small subpopulation at Pu‘u Leilani (14 individuals remaining) have reduced levels of variation. Of the 122 loci identified, 54 (44%) were polymorphic. Two large populations showed variation at 45 and 49 loci, but the Pu‘u Leilani plants showed variation at only 37 loci. The mean expected heterozygosity (H) in this subpopulation was also lower (0.137 vs. 0.163 and 0.154) and genetic differentiation (GST) was higher (0.167 vs. 0.018 and 0.052) than in other subpopulations. An examination of variation indicates that although plants of the three subpopulations are genetically similar, there is evidence of genetic restructuring among the subpopulations. The impact of these results towards conservation efforts of this and other endangered species is discussed.
Identification of roots of woody species using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis
Authors: BOBOWSKI B. R. , HOLE D. , WOLF P. G. , BRYANT L.
Published: March 2003

Within the last two decades, substantial progress has been made in understanding seed‐bank dynamics and the contribution of the soil seed bank to a postdisturbance plant community. There has been relatively little progress, however, in understanding perennial bud‐bank dynamics and the contribution of the soil bud bank to secondary succession. This lack of information is due primarily to the inability to reliably identify roots, rhizomes and lignotubers that lie dormant beneath the soil surface. This investigation addressed the issue of identification of below‐ground woody structures. The first objective was to develop a method that used molecular tools to identify woody plant species from subsoil tissue samples. The second objective was to develop a key in which molecular markers served as criteria for the identification and differentiation of selected tree and shrub species common to the mountains of northeast Oregon and southeast Washington. Application of restriction fragment length polymorphism (RFLP) analysis of polymerase chain reaction (PCR)‐amplified rbcL appears to be a reliable method to identify and differentiate 15 plants to the genus level. Two restriction enzymes, DpnII and HhaI, provided restriction site polymorphisms in the PCR product. The fragment number and length were used to develop an identification key. However, plants not analysed in this ‘exploratory key’ might share the same banding patterns, resulting in a false identification of unknowns.
Features of DNA fragments obtained by random amplified polymorphic DNA (RAPD) assays
Authors: RABOUAM CORINNE , COMES ANA MARIA , BRETAGNOLLE VINCENT , HUMBERT JEAN‐FRANÇOIS , PERIQUET GEORGES , BIGOT YVES
Published: March 2003

Random amplified polymorphic DNA (RAPD) fragments were prepared from samples of Calonectris diomedea (Cory's shearwater, Aves) and Haemonchus contortus (Nematoda) DNA by polymerase chain reaction (PCR) using decamers containing two restriction enzyme sites as primers. Six of 19 studied RAPD fragments probably originated from traces of commensal microorganisms. Many rearranged fragments, absent in the original genomic DNA, were synthesized and amplified during the processing of all the DNA samples, indicating that interactions occur within and between strands during the annealing step of PCR. The model of interactions between molecular species during DNA amplification with a single arbitrary oligonucleotide primer was modified to include nested primer annealing and interactions within and between strands. The presence of these artefacts in the final RAPD have a major effect on the interpretation of polymorphism studies.
Direct conjugal transfers of Ti plasmid to soil microflora
Authors: Teyssier‐Cuvelle S. , Mougel C. , Nesme X.
Published: March 2003

The bacterial species in soil that can receive a Ti plasmid by conjugation from Agrobacterium spp. were investigated. In order to have direct access to the potential reservoir of Ti plasmid amongst soil microflora, the conjugal system consisting of a multiply auxotrophic derivative of C58 (ST‐96‐4) and a derivative of pTiC58ΔaccR (pSTiEGK) containing a triple antibiotic‐resistance cassette in traM was used to transfer the Ti plasmid in a complex soil microflora used as the recipient. Numerous transconjugants were obtained by this method but none was identified as Agrobacterium. This could be explained by the low density of Agrobacterium in the tested soil. As indicated by analysis of the ribosomal gene rrs, transconjugants recovered directly from soil were found to be new bacterial species which appeared to be closely related to Sinorhizobium spp.
Random amplified polymorphic DNA variation among remnant big bluestem (Andropogon gerardiiVitman) populations from Arkansas’ Grand Prairie
Authors: Gustafson D. J. , Gibson D. J. , Nickrent D. L.
Published: March 2003

Random amplified polymorphic DNA (RAPD) analysis was used to characterize genetic diversity and genetic distinctiveness ofAndropogon gerardiifrom remnant Arkansas prairies. Six oligonucleotide primers, which generated 37 RAPD bands, were used to analyse 30–32 plants from six Grand Prairie populations, Baker Prairie (Arkansas Ozarks), two Illinois prairies and two cultivars. Genetic diversity of the Arkansas remnants ranged from 82.7 to 99.3%, with 89% of the total genetic variation within and 11% among populations. The partitioning of genetic variation was consistent with that reported for other outcrossing perennial grasses, using the more conservative allozyme markers. Principal component analysis indicated a northern and southern association within Arkansas’ Grand Prairie. Although there was no genetic structuring at the landscape level, the Illinois prairies and cultivars were different from all Arkansas prairies tested. There was significant within‐population structuring in four of the seven Arkansas remnants, with a negative relationship between genetic similarity and geographical distance. The three nonstructured populations were from a linear railroad remnant, suggesting different population‐level dynamics from nonlinear prairies. The results of this study indicated that small isolated remnant big bluestem populations were not genetically depauperate and that genetic relationships among populations could not be predicted solely on geographical proximity.
Genetic structure of fragmented populations of red squirrel (Sciurus vulgaris) in the UK
Authors: Barratt E. M. , Gurnell J. , Malarky G. , Deaville R. , Bruford M. W.
Published: March 2003

The relationships among 207 squirrels from 12 locations in the UK and three in mainland Europe were examined using mitochondrial DNA (mtDNA) control region sequence. Twenty‐six haplotypes were detected, many of which were population specific. Eighty per cent of the populations analysed contained two or more haplotypes. Hierarchical analysis of molecular variance showed the majority of genetic variation to be partitioned among populations. Genetic diversity varied considerably within the UK, and conformed to no obvious geographical trend. The populations in Argyll and Spadeadam Forest showed the highest levels of variation in the UK. However, the greatest genetic diversity was seen in Bavaria, southern Germany where six unique alleles were detected in a sample of 10 individuals. Phylogenetic analysis revealed no evolutionary divergence between UK and mainland European haplotypes. We conclude that, within the UK, the genetic patterns observed are most likely to be explained by the effects of genetic drift which has occurred since the isolation of populations during the past few hundred years, hence we cannot detect any underlying phylogeographic pattern. Therefore, the use of larger, geographically distinct populations within the UK for augmentation of small isolated populations is unlikely to pose problems of genetic incompatibility. Further, the role that demographic factors may have in complicating the application of current genetically based management unit criteria is likely to need further attention.
Community structure of ectomycorrhizal fungi in a Pinus muricata forest: minimal overlap between the mature forest and resistant propagule communities
Authors: Taylor D. L. , Bruns T. D.
Published: March 2003

We have investigated colonization strategies by comparing the abundance and frequency of ectomycorrhizal fungal species on roots in a mature Pinus muricata forest with those present as resistant propagules colonizing potted seedlings grown in the same soil samples. Thirty‐seven fungal species were distinguished by internal transcribed spacer (ITS) restriction fragment length polymorphisms (RFLPs); most were identified to species level by sporocarp RFLP matches or to genus/family level by using sequence databases for the mitochondrial and nuclear large‐subunit rRNA genes. The below‐ground fungal community found in the mature forest contrasted markedly with the resistant propagule community, as only four species were found in both communities. The dominant species in the mature forest were members of the Russulaceae, Thelephorales and Amanitaceae. In contrast, the resistant propagule community was dominated by Rhizopogon species and by species of the Ascomycota. Only one species, Tomentella sublilacina (Thelephorales), was common in both communities. The spatial distribution of mycorrhizae on mature roots and propagules in the soil differed among the dominant species. For example, T. sublilacina mycorrhizae exhibited a unique bias toward the organic horizons, Russula brevipes mycorrhizae were denser and more clumped than those of other species and Cenococcum propagules were localized, whereas R. subcaerulescens propagules were evenly distributed. We suggest that species differences in resource preferences and colonization strategies, such as those documented here, contribute to the maintenance of species richness in the ectomycorrhizal community.
Spatial and temporal aspects of the genetic structure ofJuniperus communispopulations
Authors: Merwe M. Van Der , Winfield M. O. , Arnold G. M. , Parker J. S.
Published: March 2003

Juniperus communisis a dioecious, wind pollinated shrub or small tree that produces ‘berries’ (female cones) containing a small number of seeds that are thought to be dispersed by birds. The expectation, therefore, would be that populations of Juniper are genetically diverse with little structuring between them. In Britain, the species has two main centres of distribution: a highland zone in the north and west, in which populations are still large and sexually reproducing, and a southern zone on chalk downlands in which populations are small and fragmented and individuals suffer from a decline in fertility. Thus, one would expect the large sexually viable populations in the north to exhibit high levels of within‐population genetic variation, while the declining southern populations would be genetically depauperate. The analysis of amplified fragment length polymorphisms (AFLPs) was used to test this hypothesis. Surprisingly, all populations studied showed high levels of genetic variation although there was clear structuring between populations. On the basis of the geographical structuring of the populations it was hypothesized thatJ. communiscolonized Britain via three separate routes.
Mitochondrial DNA variation in the hybridizing fire‐bellied toads,Bombina bombinaandB. variegata
Authors: Szymura J. M. , Uzzell T. , Spolsky C.
Published: March 2003

Using five restriction enzymes, geographical variation of mitochondrial DNA (mtDNA) inBombina bombinaandB. variegatawas studied in samples from 20 locations. Each restriction enzyme produced a species‐specific fragment pattern.B. bombinahaplotypes A and B were closely related to each other. In contrast, haplotypes A and B ofB. variegataformed two distinct lineages. A very distinctive haplotype (C) was found in the Carpathian Mountains, whereas two other haplotypes, D and E (differing by a singleAvaI site), were present in western Europe and the Balkans, respectively. Populations polymorphic for haplotypes D and E occurred in the central Balkans where the haplotypes could replace each other clinally. mtDNA sequence divergence betweenB. bombinaandB. variegatawas estimated as 6.0–8.1% and 4.7–5.2% between type C and types D/E ofB. variegata. The latter divergence is contrary to allozyme and morphological data that place the western and CarpathianB. v. variegatatogether (Nei'sD = 0.07) and separate them from the Balkan subspeciesB. v. scabra(Nei'sD = 0.18). Broad interspecific correlation among morphology, allozymes and mtDNA types in European fire‐bellied toads argues that, despite continuous hybridization (interrupted perhaps during Pleistocene glacial maxima), little or no mtDNA introgression between the species has occurred outside the narrow hybrid zones that separate these parapatric species.
Phylogeography and natural selection in the Tenerife gecko Tarentola delalandii: testing historical and adaptive hypotheses
Authors: Gübitz T. , Thorpe R. S. , Malhotra A.
Published: March 2003

Combining phylogeographic and matrix correspondence approaches in the analysis of geographical variation provides a fruitful approach to inferring the causes of molecular and morphological evolution within species. Here we present a study on the gecko Tarentola delalandii on the island of Tenerife, Canary Islands, which provides an outstanding model of an exceptionally high degree of phylogeographic differentiation in magnitude and pattern on a small spatial scale. We reconstruct the population history of T. delalandii using phylogeographic information, matrix correspondence tests and estimates of divergence times in conjunction with geological data. It appears that populations differentiated on three precursor islands and secondary contact followed the junction of these islands. The cytochrome b sequence appears to be evolving at least at ≈ 1% per million years in this species. Matrix correspondence tests indicate that morphological character systems may reflect ecological selection regimes (colour pattern), history (body dimensions) or both (scalation). The results imply that natural selection can override a historical legacy, but also underline the potential relevance of molecular phylogenetic data for the interpretation of geographical variation in morphology.
Dietary separation of sympatric carnivores identified by molecular analysis of scats
Authors: Farrell Laura E. , Roman Joseph , Sunquist Melvin E.
Published: March 2003

We studied the diets of four sympatric carnivores in the flooding savannas of western Venezuela by analysing predator DNA and prey remains in faeces. DNA was isolated and a portion of the cytochrome bgene of the mitochondrial genome amplified and sequenced from 20 of 34 scats. Species were diagnosed by comparing the resulting sequences to reference sequences generated from the blood of puma (Puma concolor), jaguar (Panthera onca), ocelot (Leopardus pardalus) and crab‐eating fox (Cerdocyon thous). Scat size has previously been used to identify predators, but DNA data show that puma and jaguar scats overlap in size, as do those of puma, ocelot and fox. Prey‐content analysis suggests minimal prey partitioning between pumas and jaguars. In field testing this technique for large carnivores, two potential limitations emerged: locating intact faecal samples and recovering DNA sequences from samples obtained in the wet season. Nonetheless, this study illustrates the tremendous potential of DNA faecal studies. The presence of domestic dog (Canis familiaris) in one puma scat and of wild pig (Sus scrofa), set as bait, in one jaguar sample exemplifies the forensic possibilities of this noninvasive analysis. In addition to defining the dietary habits of similar size sympatric mammals, DNA identifications from faeces allow wildlife managers to detect the presence of endangered taxa and manage prey for their conservation.
Microsatellite analysis of population structure and genetic differentiation within and between populations of the root vole,Microtus oeconomusin the Netherlands
Authors: Van De Zande L. , Van Apeldoorn R. C. , Blijdenstein A. F. , De Jong D. , Van Delden W. , Bijlsma R.
Published: March 2003

Eight microsatellite markers for the root vole (Microtus oeconomus) were developed to assess the amount of genetic variation for nine Dutch root vole populations from four different regions, and to evaluate the degree of differentiation and isolation. All eight microsatellite loci were found to be highly variable with observed heterozygosity values ranging from 0.61 to 0.82. These values are similar to those observed for more distant populations from Norway, Finland and Germany. Therefore, the populations seem not particularly depauperate of genetic variation at the microsatellite level. Genetically, the Dutch populations were found to have diverged considerably. Pairwise comparisons of all populations studied revealedFSTvalues significantly greater than zero for most comparisons. However, the magnitude of these values considerably depends on the compared population pair. The level of differentiation between local populations within Dutch regions is generally significantly lower than the differentiation between Dutch regions. The level of differentiation between Dutch regions, however, is not significantly different from that between populations of larger geographical distance. This implies that the regional Dutch populations are both isolated from each other and from other European populations. The observation that even local populations show low but significant genetic differentiation may be indicative for progressive isolation of these populations.
Differences in population structure of the anther smut fungus Microbotryum violaceum on two closely related host species, Silene latifolia and S. dioica
Authors: Bucheli E. , Gautschi B. , Shykoff J. A.
Published: March 2003

We investigated the genetic population structure of the sexually transmitted plant pathogen, the fungus Microbotryum violaceum, on the two closely related host species Silene latifolia and S. dioica using microsatellite markers. We found strong deviations from Hardy–Weinberg expectations, with significant heterozygote deficiency in almost all populations. Fungal strains from the two host species were differentiated, and these host races differed in amount of variation within populations and differentiation among populations. Anther smut from S. latifolia harboured significantly less microsatellite diversity and were more genetically differentiated from each other than those from S. dioica. Small effective population sizes, rapid population turnover, and less gene flow among populations could lead to this higher population differentiation and lower within population genetic diversity for anther smut populations on S. latifolia than on S. dioica. These results are in concordance with host ecology because S. latifolia grows in more disturbed habitats than S. dioica and may provide a shorter‐lived host environment.
Genetic population structure and introgression inAnopheles dirusmosquitoes in South‐east Asia
Authors: Walton Catherine , Handley Jane M. , Collins Frank H. , Baimai Visut , Harbach Ralph E. , Deesin Vanida , Butlin Roger K.
Published: March 2003

Genetic structure and species relationships were studied in three closely related mosquito species,Anopheles dirusA, C and D in Thailand using 11 microsatellite loci and compared with previous mitochondrial DNA (mtDNA) data on the same populations. All three species were well differentiated from each other at the microsatellite loci. Given the almost complete absence of mtDNA differentiation betweenAn. dirusA and D, this endorses the previous suggestion of mtDNA introgression between these species. The high degree of differentiation between the northern and southern population ofAn. dirusC (RST = 0.401), in agreement with mtDNA data, is suggestive of incipient species. The lack of genetic structure indicated by microsatellites in four populations ofAn. dirusA across northern Thailand also concurs with mtDNA data. However, inAn. dirusD a limited but significant level of structure was detected by microsatellites over ~400 km in northern Thailand, whereas the mtDNA detected no population differentiation over a much larger area (>1200 km). There is prior evidence for population expansion in the mtDNA. If this is due to a selective sweep originating inAn. dirusD, the microsatellite data may indicate greater barriers to gene flow withinAn. dirusD than in species A. Alternatively, there may have been historical introgression of mtDNA and subsequent demographic expansion which occurred first inAn. dirusD so enabling it to accumulate some population differentiation. In the latter case the lack of migration‐drift equilibrium precludes the inference of absolute or relative values of gene flow inAn. dirusA and D.
Bottlenecks, drift and differentiation: the population structure and demographic history of sika deer (Cervus nippon) in the Japanese archipelago
Authors: Goodman Simon J. , Tamate Hidetoshi B. , Wilson Rebecca , Nagata Junko , Tatsuzawa Shirow , Swanson Graeme M. , Pemberton Josephine M. , McCullough Dale R.
Published: March 2003

We assessed genetic differentiation and diversity in 14 populations of sika deer (Cervus nippon) from Japan and four populations of sika deer introduced to the UK, using nine microsatellite loci. We observed extreme levels of differentiation and significant differences in diversity between populations. Our results do not support morphological subspecies designations, but are consistent with previous mitochondrial DNA analyses which suggest the existence of two genetically distinct lineages of sika deer in Japan. The source of sika introduced to the UK was identified as Kyushu. The underlying structure of Japanese populations probably derives from drift in separate glacial refugia and male dispersal limited by distance. This structure has been perturbed by bottlenecks and habitat fragmentation, resulting from human activity from the mid‐nineteenth century. Most current genetic differentiation and differences in diversity among populations probably result from recent drift. Coalescent model analysis suggests sika on each of the main Japanese islands have experienced different recent population histories. Hokkaido, which has large areas of continuous habitat, has maintained high levels of gene flow. In Honshu the population is highly fragmented and is likely to have been evolving by drift alone. In Kyushu there has been a balance between gene flow and drift but all the populations have experienced high levels of drift. Habitat fragment size was not significantly associated with genetic diversity in populations but there was a significant correlation between habitat fragment size and effective population size.
Intraspecific phylogeny and geographical variation of six species of northeastern AsiaticSorexshrews based on the mitochondrial cytochromebsequences
Authors: Ohdachi Satoshi , Dokuchaev Nikolai E. , Hasegawa Masami , Masuda Ryuichi
Published: March 2003

Intraspecific phylogeny and genetic variation were investigated based on nucleotide sequences of the mitochondrial cytochromebgene in six soricine shrew species,Sorex unguiculatus,S. caecutiens,S. shinto,S. gracillimus,S. minutissimusandS. hosonoi, collected primarily from northeastern Asia. Maximum likelihood trees and a phylogenetic network were generated to estimate intraspecific phylogenies.S. minutissimusshowed high congruence between phylogenetic position and geographical origin andS. gracillimusshowed low congruence. In contrast, there was no congruence between phylogeny and geography inS. unguiculatusand theS. caecutiensfrom Sakhalin‐Eurasia. Positive correlation between genetic and geographical distances was found inS. minutissimusandS. gracillimus, but not in the other species (or regional populations). The results of the phylogenetic and genetic analyses suggest thatS. minutissimusandS. gracillimushave occupied their present ranges for a longer time than the other species if we assume a stepping‐stone model of population structure. In addition, there was no contradiction between the present investigations and the hypotheses of multiple immigration byS. gracillimusand a single immigration byS. unguiculatusinto Hokkaido Island. It is proposed that these six northeastern Asian species experienced different historical processes of range expansion and dispersal despite the fact that some of them currently show similar patterns of distribution.
The effects of mode of development on phylogeography and population structure of North Atlantic Crepidula (Gastropoda: Calyptraeidae)
Authors: Collin Rachel
Published: March 2003

The mode of development of marine invertebrates is thought to influence levels of population structure and the location of species range endpoints via differences in dispersal ability. To examine these effects, populations of three sympatric clades of sedentary, marine gastropods in the genus Crepidula were sampled along the Atlantic and Gulf coasts of North America. A haplotype tree was constructed for each clade based on 640 bp sequences of mitochondrial cytochrome oxidase c subunit I. Examination of the tree topology, and amova analysis show that species with direct development (those hatching as benthic juveniles) have higher levels of population structure than do species with planktonic development. Both species in the direct‐developing C. convexa clade have high levels of geographical differentiation, with most populations representing a discrete clade of haplotypes. The planktotrophic species C. fornicata contains two major haplotype clades, both of which include samples from throughout the Atlantic coast. In this species there is no geographical differentiation among haplotypes but amova analysis detects a small but statistically significant level of geographical structure. The population structure within the C. plana species complex appears also to vary with mode of development: C. atrasolea, a direct‐developing species, has higher levels of population structure than does C. depressa, a sympatric planktotrophic species. The coincident occurrence of range endpoints and genetic breaks along the east coast of Florida in both direct‐developing species and species with planktonic development indicates that this biogeographic break is not due to development‐specific mechanisms such as hydrographic effects on larval recruitment.
Population history of Manihot esculenta (Euphorbiaceae) inferred from nuclear DNA sequences
Authors: Olsen Kenneth M.
Published: March 2003

The nature of gene flow in plants — including the propensity for interspecific introgression — makes them interesting candidates for phylogeographical analysis. Plant phylogeography studies have been limited, however, by the availability of suitable intraspecific variation. In this study, DNA sequence variation from a nuclear gene [Glyceraldehyde 3‐phosphate dehydrogenase; (G3pdh)] was used to examine the population history of Manihot esculenta ssp. flabellifolia and a potentially hybridizing species, M. pruinosa. These species occur in the rainforest–savanna ecotone adjoining the Amazon basin, a region believed to have undergone major habitat shifts since the Pleistocene. Geographical distributions of the G3pdh haplotypes indicate genetic isolation‐by‐distance across the range of M. esculenta ssp. flabellifolia. However, there is greater genetic similarity between northeastern and western populations than would be expected given the present species distribution. A nested clade analysis suggests that northeastern and western populations were connected by gene flow until relatively recently, when they became fragmented. This inferred fragmentation event is consistent with post‐Pleistocene habitat shifts proposed for the Amazon basin. At the interspecific level, haplotype sharing with M. pruinosa may reflect either recent interspecific introgression or incomplete lineage sorting between these closely related species.
Sex‐specific genetic structure in Schistosoma mansoni: evolutionary and epidemiological implications
Authors: Prugnolle F. , De Meeûs T. , Durand P. , Sire C. , Théron A.
Published: March 2003

We studied the population genetic structure of 360 and 1247 adult Schistosoma mansoni using seven microsatellite and seven random amplified polymorphic DNA (RAPD) markers, respectively. Parasites were collected from their natural definitive host Rattus rattus in Guadeloupe (West Indies). We found a sex‐specific genetic structure, a pattern never before reported in a parasitic organism. Male genotypes were more randomly distributed among rats than female genotypes. This interpretation was consistent with a lower differentiation between hosts for males relative to females, the higher genetic similarity between females in the same host and the observed local (i.e. within‐individual‐host) differences in allele frequencies between the two sexes. We discuss our results using ecological and immunological perspectives on host–parasite relationships. These results change our view on the epidemiology of schistosomiasis, a serious disease affecting humans in African and American intertropical zones.
Individual female clutch identification through yolk protein electrophoresis in the communally breeding guira cuckoo (Guira guira)
Authors: Cariello Mariana O. , Schwabb Hubert G. , Lee Raymond W. , Macedo Regina H. F.
Published: March 2003

Avian communal breeding systems generate alternative behavioural strategies for females, resulting in differences in reproductive success. Identifying eggs of different females in such systems is problematic, however, due to egg destruction before incubation, difficulty of capturing adults, and/or inaccuracy of egg identification based on egg morphometry. Here, we describe a technique that uses electrophoresis of yolk proteins to determine egg ownership, which we applied to communally breeding guira cuckoos (Guira guira). Validation of the method included identical yolk protein banding patterns in all eggs of the same female, but different patterns in eggs of different females in budgerigars (Melopsittacus undulatus), and identical patterns in yolk follicles of the same females in guira cuckoos. We applied the protocol to 195 guira cuckoo eggs from 34 joint nests in 2 years. All multiple guira cuckoo eggs laid on the same day in single nests had distinct banding patterns of yolk proteins, practically eliminating the possibility of more than one female being represented by the same pattern. Some identical banding patterns were repeated in different days within a nesting bout, indicating that some females laid several eggs in shared nests. Identical patterns occasionally occurred in renestings of groups, indicating that some females lay eggs in consecutive nestings. Yolk protein electrophoresis is a useful tool to identify egg maternity in other circumstances, such as polygynous mating systems with joint nests and intraspecific parasitism. Additionally, it is an alternative method for species where electrophoresis of egg white proteins does not show sufficient polymorphism.