bluuebunny/crossref_metadata_2025 huggingface dataset:
Susceptibility of ten species of mosquito larvae to the parasitic nematode Romanomermis iyengari and its development
Authors: Paily K. P. , Balaraman K.
Published: March 2003

Ten species of mosquitoes (Diptera: Culicidae) from five genera were exposed to preparasites of the tropical mermithid nematode species Romanomermis iyengari (Welch) (Nematoda: Mermithidae), a strain isolated in 1978 from Pondicherry. By exposing mosquito larvae during the second instar, nematode infection was invariably lethal, the rate being highest in Culex sitiens Wiedemann (95%) followed by Cx. quinquefasciatus Say (90%), Aedes aegypti (L.) (79%), Anopheles subpictus Grassi (64%), Ae. albopictus (Skuse) and Armigeres subalbatus Coquillett (62%), Cx. tritaeniorhynchus Giles (57%), Mansonia annulifera (Theobald) (46%), An. stephensi Liston (40%) and An. culicifacies Giles (36%). When fourth‐instar larvae were exposed, the infection was highest in Ar. subalbatus (66%), followed by An. stephensi (52%), Cx. quinquefasciatus (47%), Ae. aegypti and An. subpictus (42%), Ae. albopictus (30%), An. culicifacies (29%), Cx. sitiens (24%), Cx. tritaeniorhynchus (19%) and Ma. annulifera (8%), with 2–45% of infected culicines surviving to adulthood. The parasitic phase of the nematode lasted 5–7 days in all the host species, yielding 1.1–3.2 parasites per II instar and 1.1–2.5 parasites per IV instar. The overall output of parasites per 100 mosquito larvae (infected + uninfected) was highest for Ae. aegypti when mosquitoes were exposed during II instar (2.53 parasites/larva) and for Ar. subalbatus when mosquitoes were exposed during IV instar (1.65/larva), and lowest for Ma. annulifera exposed during IV instar (0.09/larva). For routine laboratory culture of R. iyengari it is convenient to employ Cx. quinquefasciatus as the host yielding 90–190 parasites/100 larva.
Seasonal changes in prevalence and intensity of Hypoderma actaeon in Cervus elaphus from central Spain
Authors: Fuente‐López C. De La , Santín‐Durán M. , Alunda J. M.
Published: March 2003

Hypodermosis in red deer, Cervus elaphus Linnaeus (Artilodactyla: Cervidae), caused by the warble fly, Hypoderma actaeon Latreille (Diptera: Oestridae), was studied at Quintos de Mora (Toledo, Spain) over a one‐year period between October 1994 and September 1995. One hundred and twenty‐five red deer were examined for the presence of warble fly larvae. The prevalence of warbles was 44.8% and the intensity of infection was 38.29 (SD ± 61.32) warbles/deer infected. Clear seasonal variations were observed in prevalence and intensity, with the highest values in the autumn and winter. Statistically significant differences were observed in prevalence and intensity among age groups. In contrast, no differences were found in prevalence and intensity between males and females.
Factors influencing the abundance of Japanese encephalitis vectors in ricefields in India – II. Biotic
Authors: Sunish I. P. , Reuben R.
Published: March 2003

Abstract. The relationship of insect predators and phytoplankton with the abundance of Culex tritaeniorhynchus Giles, Cx. vishnui Theobald and Cx. pseudovishnui Colless mosquito larvae and pupae (Diptera: Culicidae) in ricefields was investigated during three rice growing seasons. Notonectids were the most abundant insect predators, whereas diatoms dominated among phytoplankton. Multiple regression analysis showed that the occurrence of notonectids (both nymphs and adults) was negatively associated with larval abundance. Phytoplankton, especially diatoms and blue green algae (BGA), were found to favour abundance of culicine immatures during Navarai and Kuruvai crops, respectively. Larval gut analysis showed that the intake of algae by late instars was high, with 93%, 58% and 24% of diatoms, BGA and green algae, respectively. Filamentous algae may not necessarily be of nutritive value, but they are observed to form mats, which provide protection to the mosquito immatures from the predators.
Consumption of flea faeces and eggs by larvae of the cat flea,Ctenocephalides felis
Authors: Hsu M. H. , Hsu Y. C. , Wu W. J.
Published: March 2003

AbstractThe effects of the consumption of flea faeces and non‐viable eggs on larval development in the cat fleaCtenocephalides felis(Bouché) (Siphonaptera: Pulicidae) were investigated. Only 13.3% of larvae developed into adults when fed a diet of male or female flea faeces alone; however, 90% of larvae developed into adults when fed on flea faeces supplemented with non‐viable flea eggs. When fed with non‐viable eggs alone, larvae did not develop into adults. Nevertheless, non‐viable eggs may provide critical supplemental nutrients, lacking in flea faeces and required for larval development. None of the larvae fed on flea faeces or non‐viable eggs alone formed a cocoon. A diet of flea faeces alone significantly extended the second as well as third larval stadia compared to larvae fed on diets containing non‐viable eggs. It is suggested that the cannibalism of fertile eggs may limit population growth in the cat flea.
The impact of an individual tutorial session on MEDLINE use among obstetrics and gynaecology residents in an academic training programme: a randomized trial
Authors: Erickson S , Warner E R
Published: March 2003

Over the past decade, on‐line databases have become increasingly popular among health care professionals. As a group, these `end‐users' report utilizing databases to keep abreast of medical progress, to conduct research and to address specific patient care issues. Throughout the literature, medical professionals (`content experts') have proved to be less effective searchers than librarians (`search experts'). The potential implications of this discrepancy are worrysome. For any given clinical scenario, for example, published reports may reach contradictory conclusions. A poorly skilled searcher may not retrieve enough articles to appreciate this fact. Optimizing searching skills is therefore a worthwhile goal. As a first step, many medical schools introduce students to on‐line databases, most notably MEDLINE. Residency is an ideal time to continue this training. A recognized obstacle to providing residents with formal MEDLINE instruction is time constraint. We therefore conducted this study to ascertain the impact an individual 1‐hour tutorial session would have on MEDLINE utilization among obstetrics and gynecology residents training at an academic medical centre. Outcome measures included MEDLINE search frequency, duration, recall, precision and searcher satisfaction. Search recall measures the searcher's ability to retrieve articles deemed relevant to the question at hand. Search precision gauges the searchers' ability to eliminate irrelevant articles. Although the sessions were well received, we were unable to demonstrate an improvement in the outcome measures analysed. Further research is therefore indicated so that cost‐effective educational strategies can be recommended for wide‐scale use.
Assessment in general practice: the predictive value of written‐knowledge tests and a multiple‐station examination for actual medical performance in daily practice
Authors: Ram Paul , Vleuten Cees van der , Rethans Jan‐Joost , Schouten Berna , Hobma Sjoerd , Grol Richard
Published: March 2003

This study compares the predictive values of written‐knowledge tests and a standardized multiple‐station examination for the actual medical performance of general practitioners (GPs) in order to select effective assessment methods to be used in quality‐improvement activities.

A comprehensive assessment was performed in four phases. First, 100 GPs from the southern part of the Netherlands were assessed by a general medical knowledge test and by a knowledge test on technical skills. Second, in order to check for time‐order effects, participants were randomly divided into two groups of 50 each, comparable on scores of both knowledge tests and on professional characteristics. Finally, both groups went through a multiple station examination using standardized patients and a practice video assessment of real surgery, but in opposite orders. Consultations were videotaped and assessed by well‐trained peer observers. The drop‐out rate was 10%.

In both groups the predictive value of medical knowledge tests, ranging from 0·43 to 0·56 (Pearson correlation disattenuated), proved to be comparable with the predictive value of the multiple‐station examination for actual performance (0·33–0·59). The overall explained variance of scores of the practice video assessment, measured by multiple regression analysis with performance scores as dependent variables and scores on the knowledge tests and the multiple‐station examination as independent variables was moderate (19%). A time‐order effect showed in only one direction: from practice video assessment to the multiple‐station examination. The GP's professional characteristics did not contribute to the explanation of variation in performance. Medical knowledge tests can predict actual clinical performance to the same extent as a multiple‐station examination. Compared with a station examination, a knowledge test may be a good alternative method for assessment the procedures of a large number of practising GPs.
A prospective analysis of stress and academic performance in the first two years of medical school
Authors: Stewart  , Lam  , Betson  , Wong  , Wong
Published: March 2003

Aim

This study provides prospective, longitudinal data on the relationship between stress‐related measures and academic performance during the first two years of medical school.

Methods

First year medical students (n = 121) were surveyed prior to beginning classes (wave 1), and again 8 months later (wave 2). Personality variables predisposing to distress (optimism and trait anxiety), stress response (depression and state anxiety), and stress management strategies were assessed at wave 1 and wave 2. Pre‐medical academic scores, and grades at the end of five assessment periods over the course of the first 2 years of medical school were also obtained.

Results and conclusions

As expected, pre‐medical‐school academic performance strongly predicted performance in medical school. Academic performance before and during medical school was negatively related to reported stress levels. On bivariate correlations, there were numerous significant relationships between stress reported at waves 1 and 2, and medical school academic performance assessed after these measures. In addition there were modest negative correlations between self‐reported coping strategies of `humour' and `wishful thinking', and consequent academic performance. However, the predictive value of stress and its management on prospective academic performance was much decreased once pre‐medical‐school performance was statistically controlled.
The WISDOM project: training primary care professionals in informatics in a collaborative 'virtual classroom'
Authors: Fox  , Dolman  , Lane  , O‐Rourke  , Roberts
Published: March 2003

Objectives

The WISDOM project applies Internet technologies to create a virtual classroom in health informatics for primary care professionals. Participants use a facilitated E‐mail discussion list supported by a web site which provides on‐line resources and an archive of teaching materials.

Design

The project took an adult‐learning model in which participants identify their learning needs, emphasized using informatics skills in practice, and focused on skills likely to enhance evidence‐based practice. The paper describes the project and an evaluation of the first programme which ran in 1997 with 28 participants. Pre‐ and post‐intervention questionnaires were used to assess perceived skills in informatics and evidence‐based practice.

Setting

University of Sheffield.

Subjects

Primary care professionals.

Results

Participants reported statistically significant increases in eight informatics skills. There were no significant changes in evidence‐based practice skills. The web‐site, seminar programme and discussion list were highly rated as useful in delivering informatics training.

Conclusions

The WISDOM approach is effective for the delivery of informatics training to primary care professionals, and may be used more widely for other subjects and professional groups. There is a need for further research into facilitating virtual classrooms.
Accreditation of postgraduate medical education in the United States and Canada: a comparison of two systems
Authors: Cassie Josephine M , Armbruster Judith S , Bowmer M Ian , Leach David C
Published: March 2003

The systems for accrediting residency programmes in the United States and Canada, although they have developed independently in the two countries, have similar objectives and accreditation requirements. Both have become increasingly focused over the past several decades on the importance of educational programmes structured to provide graded professional responsibility with appropriate guidance and supervision to residents according to their level of training, ability and experience. The Canadian model used by the Royal College of Physicians and Surgeons of Canada is a centrist one, with accreditation decisions on all programmes in all specialties being vested in a single, multidisciplinary accreditation committee. The American model developed by the Accreditation Council for Graduate Medical Education is a distributive one, with accreditation decisions being vested in each specialty Residency Review Committee. In both models, accreditation is based on a system of periodic on‐site visits during which both faculty and residents are interviewed by a surveyor to provide the accrediting body with a first‐hand evaluation of the extent to which each accredited programme meets the standards of accreditation. While they are similar in purpose, there are significant differences in the operation of the two systems.
Genetic evidence for different migration routes of freshwater fish into Norway revealed by analysis of current perch (Perca fluviatilis) populations in Scandinavia
Authors: REFSETH U. H. , NESBØ C. L. , STACY J. E. , VØLLESTAD L. A. , FJELD E. , JAKOBSEN And K. S.
Published: March 2003

To elucidate the colonization of freshwater fish into Norway following the last deglaciation of Europe 10 000 years ago, we have performed a survey using mitochondrial DNA variation (20 populations) and multilocus DNA fingerprinting (14 populations) of the widely distributed perch (Perca fluviatilis) from the Scandinavian peninsula and the Baltic Sea. Sequence analysis of a 378 bp segment of the perch mitochondrial control region (D‐loop) revealed 12 different haplotypes. A nested clade analysis was performed with the aim of separating population structure and population history. This analysis revealed strong geographical structuring of the Scandinavian perch populations. In addition, the level of genetic diversity was shown to differ considerably among the various populations as measured by the bandsharing values (S‐values) obtained from multilocus DNA fingerprinting, with intrapopulation S‐values ranging from 0.19 in Sweden to 0.84 in the central part of Norway. Analysis of the intrapopulation S‐values, with S‐value as a function of lake surface area and region, showed that these differences were significant. The mitochondrial and DNA fingerprinting data both suggest that the perch colonized Norway via two routes: one from the south following the retreating glacier, and the other through Swedish river systems from the Baltic Sea area. Perch utilizing the southern route colonized the area surrounding Oslofjord and the lakes which shortly after deglaciation were close to the sea. Fish migrating from the Baltic Sea seem to have reached no further than the east side of Oslofjord, where they presumably mixed with perch which had entered via the southern route. It seems likely that the migration events leading to the current distribution of perch also apply to other species of freshwater fish showing a similar distribution pattern.
Detection of haplotypic variation and natural hybridization in halepensis‐complex pine species using chloroplast simple sequence repeat (SSR) markers
Authors: BUCCI G. , ANZIDEI M. , MADAGHIELE A. , VENDRAMIN G. G.
Published: March 2003

In this investigation, nine chloroplast, paternally inherited simple‐sequence repeat (cpSSR) markers were used to describe genetic variation of three closely related species belonging to the halepensis complex (Pinus halepensis Ait., P. brutia Mill. and P. eldarica Medwed.). Both the infinite allele model (IAM) and stepwise‐mutation model (SMM) have been applied to the analysis of the genetic structure of natural populations and the geographical distribution of haplotypic variation. SMM‐based estimators performed better than IAM‐based estimators for large values of within‐population diversity and divergence between population pairs. Overall, large haplotypic variation and high genetic divergence were detected for both P. halepensis and P. brutia. The genetic structures of the three species are discussed with consideration to the evolutionary and ecological characteristics of these species. Three highly informative markers showing size variants distinguishing P. halepensis from the other two species were used to provide more information on the occurrence of natural hybridization in a Turkish sympatric population of P. halepensis and P. brutia. Strong evidence of introgression of ‘halepensis’ chloroplast haplotypes into P. brutia seeds (but not vice versa) was detected. According to previous evidence from controlled crossings, matings between the above species seem to be successful only when P. halepensis is the pollen donor and P. brutia is the female parent (but not reciprocally). The existence of unidirectional gene flow in sympatric populations confirms previous evidence about partial reproductive barriers between P. halepensis and P. brutia. Implications of the above evidence for the evolutionary history of these species are discussed.
No evidence for extra‐pair paternity in the western gull
Authors: GILBERT L. , BURKE T. , KRUPA A.
Published: March 2003

The genetic mating system of western gulls Larus occidentalis breeding on Southeast Farallon Island, California, was determined using multilocus DNA fingerprints of 33 chicks from 22 broods. No extra‐pair paternity (EPP) was found, despite extra‐pair copulations (EPCs) occurring. This suggests that paternity guards are effective, and that females gain few genetic benefits from EPCs. The EPP in western gulls concurs with that of other seabirds, reinforcing the idea that seabirds generally have a monogamous genetic mating system.
The use of random amplified polymorphic DNA (RAPD) for hybrid detection in Scirpus from the river Schelde (Belgium)
Authors: DE GREEF B. , TRIEST L.
Published: March 2003

Along the unique freshwater tidal zone of the river Schelde (Belgium), plants of Scirpus species occur primarily in small and fragmented populations. The majority of these are native Scirpus lacustris, S. pungens, S. triqueter, S. tabernaemontani and intermediate morphological forms. The distribution area of S. triqueter is even restricted to this tidal habitat. However, several cultivated S. tabernaemontani strains have recently been introduced. The latter species is often used to stabilize riverbanks. To determine the existing genetic diversity among these species, stems from plants from 44 different locations were subjected to random amplified polymorphic DNA (RAPD) analysis, using 22 decanucleotide primers. Data analysis of the amplified DNA fragments enabled us to unambiguously differentiate among these Scirpus taxa. Hybridization between S. triqueter and S. tabernaemontani was documented, and the studied hybrids were always genetically more similar to S. triqueter than to S. tabernaemontani. Among the introduced clones, at least two different origins could be distinguished. Several of the introduced S. tabernaemontani clones were clearly different from individuals of the same species that were native to this region. As there were different hybrid genotypes owing to different hybrid events or to introgression, this complex should be safeguarded from genetic pollution. New S. tabernaemontani genotypes with markers not previously observed in that hybrid complex of the unique tidal freshwater habitat should be avoided in replantation projects.
The use of amplified fragment length polymorphism (AFLP) in the isolation of sex‐specific markers
Authors: Griffiths RICHARD , Orr KATE
Published: March 2003

Sex identification is a problem in research and conservation. It can often be solved using a DNA test but this is only an option if a sex‐specific marker is available. Such markers can be identified using the amplified fragment length polymorphism (AFLP) technique. This is usually a taxonomic method, as it produces a DNA fingerprint of 50–100 PCR bands. However, if male and female AFLP products are compared, sex‐specific markers are confined to the heterogametic sex and can rapidly be identified. Once a marker is found, AFLP can be used to sex organisms directly or the marker can be sequenced and a standard PCR test designed.
Genetic diversity and pedigree for Sophora toromiro (Leguminosae): a tree extinct in the wild
Authors: Maunder  , Culham  , Bordeu  , Allainguillaume  , Wilkinson
Published: March 2003

Sophora toromiro was endemic to the Pacific island of Rapa Nui (Easter Island) and is extinct in the wild. The species has survived in private and botanic gardens. The species is the subject of an international study to support its conservation ex situ and eventual re‐introduction. As a contribution to this study the genetic diversity of the surviving stocks and herbarium samples has been assessed by means of random amplified polymorphic DNA (RAPD) and inter‐simple sequence repeat (inter‐SSR) analysis. The analysis indicated low levels of genetic diversity suggesting a very small number of founders. In addition, misidentified trees were identified allowing their removal from the conservation project.
Detection of multiple paternity in the Kemp's ridley sea turtle with limited sampling
Authors: Kichler  , Holder  , Davis  , Márquez‐M  , Owens
Published: March 2003

An important question in sea turtle biology is the number of males that contribute to the fertilization of a clutch of eggs. Previous studies on other sea turtle species have indicated little to no multiple paternity. We conclude here that female Kemp's ridleys, Lepidochelys kempi, are polyandrous. DNA from 26 mother and offspring groups was analysed at three microsatellite loci to identify paternal alleles. Three paternal alleles were observed among 14 of the clutches; four paternal alleles were observed among the offspring of an additional female. A maximum likelihood analysis not only rejects the model of single paternity, but also rejects the model of equal paternal contribution to the clutch. By explicitly addressing the high mutation rate of microsatellite markers, our analysis rejected mutation as the sole cause of multiple paternal alleles.
Specific detection of Phialophora gregata and Plectosporium tabacinum in infected soybean plants using polymerase chain reaction
Authors: Chen Weidong , Gray Lynn E. , Kurle James E. , Grau Craig R.
Published: March 2003

The fungal deuteromycetes Phialophora gregata and Plectosporium tabacinum are associated with soybean plants. P. gregata causes brown stem rot (BSR) of soybean, whereas P. tabacinum is a frequent cohabitant of soybean stems. The role of P. tabacinum in soybean growth and in the development of BSR is not known. Traditional methods of isolating and differentiating these two fungi require up to 3 weeks to complete. In order to effectively study the interactions among P. gregata, P. tabacinum, and the soybean plant, we developed specific primers for P. tabacinum based on its rDNA internal transcribed spacer sequences. In combination with specific primers developed previously for P. gregata, the specific primer pairs were used successfully in polymerase chain reactions to detect the targeted fungi in both artificially inoculated and naturally infected soybean plants. Using this technique, we examined 130 soybean plants collected from natural field environments for the presence or absence of P. gregata and P. tabacinum. Statistical analyses of the results showed that the frequency of co‐occurrence of P. gregata and P. tabacinum in soybean plants was significantly less than expected if the two fungi would occur independently, suggesting that one of the fungi may be inhibitory to the other fungus.
Natural selection promotes divergence of transferrin among salmonid species
Authors: Ford Michael J. , Thornton Perry J. , Park Linda K.
Published: March 2003

Transferrin is an iron‐binding protein that plays an important role in iron metabolism and resistance to bacterial infection in a variety of organisms. A comparison of transferrin coding sequences from four salmonid species shows that the rate of evolution at nonsynonymous sites is significantly higher than the rate at synonymous sites, suggesting that positive natural selection for new alleles has played an important role in the evolution of transferrin in some salmon species. We hypothesize that the selective agent driving rapid divergence is interactions between host transferrin and the iron‐scavenging proteins of pathogenic bacteria.
Biogeography and population genetics of the Lake Malawi cichlid Melanochromis auratus: habitat transience, philopatry and speciation
Authors: Markert Jeffrey A. , Arnegard Matthew E. , Danley Patrick D. , Kocher Thomas D.
Published: March 2003

Migration rates among nine populations of the endemic Lake Malawi cichlid Melanochromis auratus were estimated along a 42‐km stretch of habitat in the southern end of the lake. Allele frequencies were surveyed at four simple sequence repeat (SSR) loci. The data suggest migration rates among populations are quite low. Exact tests indicate that statistically detectable allele frequency differences exist between many adjacent populations in the study. The FST value among all populations was estimated to be 0.151 (P < 0.0002). A biogeographic survey suggests that the highest levels of genetic differentiation exist between populations separated by stretches of deep water. Migration is more common between populations separated by shallower water or with shoreline dispersal routes. Reduced allelic diversity was observed at more recently created habitat patches, suggesting that either bottlenecks are associated with the colonization of new habitat patches or that these shallower sites were all founded by genetically depauperate ancestral populations. The extreme philopatry of M. auratus, coupled with the patchy distribution and transient nature of its preferred habitat, provides opportunities for both selection and genetic drift to produce genetic differentiation among populations. Both processes may be important to the evolution of taxonomic diversity in the East African cichlid species flocks.
Male reproductive success in a promiscuous mammal: behavioural estimates compared with genetic paternity
Authors: Coltman D. W. , Bancroft D. R. , Robertson A. , Smith J. A. , Clutton‐brock T. H. , Pemberton J. M.
Published: March 2003

Molecular techniques have enabled behavioural ecologists to reassess mating systems from a genetic perspective. Studies of paternity frequently reveal that mating behaviour does not always reflect parentage, and may bring to light alternative mating tactics. Here we present a comparison of behavioural and genetic measures of male reproductive success in a mammalian mating system in which both sexes are highly promiscuous. Rather than having a stable harem social structure, Soay rams (Ovis aries) on the island of Hirta, St Kilda, UK usually consort with individual oestrous ewes sequentially. Not all matings occur between consort pairs, however, and ewes have been seen to mate with up to 10 different rams on the same day. Using locus‐specific polymorphism at five protein and 10 microsatellite DNA loci, we determined paternity for 236 lambs born into three cohorts, and compared paternity with estimates of mating success derived from more than one census of rutting behaviour. The correlation between the number of ewes with which each ram was witnessed in consort and the number of paternities assigned was positive and statistically significant, and rams that were observed in consort with a ewe were 18 times more likely to have sired her offspring than other candidate rams. However, most lambs (73%) were not sired by a ram seen in consort with the oestrous mother. Many juveniles, yearlings and some adult rams were rarely seen in consort with ewes, yet were assigned a significant number of paternities. These results suggest that mating tactics differ between age groups, and that alternative mating strategies among adults that do not involve forming consorts with many females also confer mating success. For these reasons, census‐based observations of consort associations between individuals cannot be used to accurately estimate individual male reproductive success in this population.
Mitochondrial restriction fragment length polymorphism (RFLP) and sequence variation among closely related avian species and the genetic characterization of hybridDendroicawarblers
Authors: Lovette Irby J. , Bermingham Eldredge , Rohwer Sievert , Wood Chris
Published: March 2003

To address several interconnected goals, we used mitochondrial DNA (mtDNA) sequences to explore evolutionary relationships among four potentially hybridizing taxa in a North American avian superspecies (Dendroica occidentalis,D. townsendi,D. virens, andD. nigrescens). We first compared the results of a previous restriction fragment length polymorphism (RFLP)‐based study with 1453 nucleotides from the mitochondrial cytochrome oxidase subunit I (COI), ATP‐synthase 6 (ATPase 6), and ATP‐synthase 8 (ATPase 8) genes. Separate phylogenetic analyses of the RFLP and sequence data provided identical and well‐supported hierarchical species‐level reconstructions that groupedoccidentalisandtownsendias sister taxa. We then explored several general features of mitochondrial evolution via a comparison of the RFLP and sequence data sets. Qualitative rate differences that seemed evident in highly autocorrelated comparisons of RFLP vs. sequence pairwise distances were not supported when autocorrelation was removed. We also noted a high variance in corresponding RFLP and sequence distances after the removal of autocorrelation effects. This variance suggests that caution should be used when combining RFLP and sequence‐based data in studies that require the large‐scale synthesis of divergence estimates drawn from sources employing different molecular techniques. Finally, we used our parallel RFLP and sequence data to design and validate a rapid and inexpensive polymerase chain reaction‐RFLP (PCR‐RFLP) protocol for determining species‐specific mitochondrial haplotypes. This PCR‐RFLP technique will be applied in ongoing studies of theoccidentalis/townsendihybrid zone, where the historic and geographical complexity of the interbreeding populations necessitates the genotyping of thousands of individual warblers.
Random amplified polymorphic DNA (RAPD) markers detect a single phenotype inLysimachia minoricensisJ.J. Rodr. (Primulaceae), a wild extinct plant
Authors: Calero Cristina , Ibáñez Olga , Mayol Maria , Rosselló Josep A.
Published: March 2003

Lysimachia minoricensisis a Mediterranean (Balearic Islands) endemic that is extinct in the wild but extant in botanical gardens. Previously, no variation at 22 isozyme loci was revealed in more than 150 analysed plants. Random amplified polymorphic DNA (RAPD) analysis was used to examine genetic variation among five individuals from each of eight botanical garden accessions (40 plants). No polymorphisms were detected at 201 amplified bands. This is the first report of RAPD monomorphism in a nonapomictic vascular plant. The lack of detectable genetic variation suggests that an extremely reduced gene pool was recovered in the field before its extinction. Although the screening of other genomic markers is feasible, it is suggested that the knowledge of biological and autoecological features should be prioritized before new re‐introductions are attempted.
Chloroplast DNA variation and reticulate evolution in sexual and apomictic sections of dandelions
Authors: Wittzell Håkan
Published: March 2003

Sequencing 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

Amplified 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

Kinkajou 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

Genetic 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

Allelic 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

Avian 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

Pollen 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

Genetic 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

Throughout 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

Many 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.