bluuebunny/crossref_metadata_2025 huggingface dataset:
Selection of Anopheles dirus for refractoriness and susceptibility to Plasmodium yoelii nigeriensis
Authors: Somboon P. , Prapanthadara L. , Suwonkerd W.
Published: March 2003

Two lines of the Oriental malaria vector mosquito Anopheles dirus species A (Diptera: Culicidae), one fully refractory and one fully susceptible to Plasmodium yoelii nigeriensis (an African rodent malaria parasite), were established after 17 generations of mass selection, followed by single female selection for one or two generations. Prior to selection, the stock colony of An. dirus was 17% refractory. Both lines of An. dirus produced abundant ookinetes that started to invade the midgut within 24 h post‐infection, as seen in histological sections. In most of the refractory mosquitoes, oocysts stopped development < 12 h post‐invasion, indicating a rapid defence mechanism. Dead P. y. nigeriensis parasites were apparently localized as small melanized spots (2–5 μm) seen in wet preparations of mosquito midguts dissected 5–7 days post infective bloodmeal. In some refractory An. dirus females, apart from the spots, a small number of totally encapsulated oocysts (c. 10 μm) were also present. These larger melanized parasites predominated in a few females: they appeared 2–3 days post‐infection as a secondary delayed defence mechanism. The progeny of reciprocal matings between susceptible and refractory lines had ∼50% susceptibility. Backcrosses of F1 hybrids with susceptible or refractory lines increased or decreased the susceptibility of backcross progeny accordingly. Overall, these results suggest polygenic control of susceptibility to P. y. nigeriensis infection. The refractory line of An. dirus showed normal susceptibility to natural infections of the human malarias P. falciparum and P. vivax from local patients.
The use of direct sequencing of dengue virus cDNA from individual field‐collected Aedes aegypti for surveillance and epidemiological studies
Authors: Romero‐Vivas C. M. E. , Sutherland C. J. , Falconar A. K. I.
Published: March 2003

The relative efficiencies of four methods to extract viral RNA from individual dengue‐2 virus (D‐2V)‐infected mosquitoes, Aedes aegypti (L.) (Diptera: Culicidae), were compared. The most efficient of these methods was then used to extract viral RNA for the preparation of cDNA from the abdomens of six engorged D‐2V‐infected mosquitoes and sera from three dengue fever (DF) patients collected in an isolated rural town in Colombia. Comparisons of viral envelope (E) gene sequences from each of these strongly suggested that the D‐2V population which circulated in this study area was a homogeneous genotype which was unrelated to any of the D‐2 viruses isolated from elsewhere in the world. When coupled with our rapid method to identify viruses in individual mosquitoes (
Romero‐Vivas et al. (1998)
Medical and Veterinary Entomology, 12, 101–105), the methodology we describe should be useful for epidemiological and surveillance studies of dengue viruses and other arboviruses.
Phosphoglucomutase and trehalase isoenzymes of Venezuelan Simulium vectors of Onchocerca volvulus
Authors: Davies J. B. , Basáñez M. G. , Frontado H. , Villamizar N. , Raybould J. N. , Petralanda I.
Published: March 2003

Phosphoglucomutase (PGM) and trehalase (Tre) isoenzymes of five species of Simulium blackflies (Diptera: Simuliidae), vectors of onchocerciasis in Venezuela, were investigated by means of a portable electrophoresis field kit. Tre differed between S. incrustatum and S. oyapockense s.l. Electrophoretic variation of Tre in other members of the S. amazonicum and S. incrustatum groups merit further investigation. PGM appears to be more useful for separating populations within species complexes. Multiple populations and/or seasonal changes in population structure of S. guianense s.l., S. exiguum s.l. and S. metallicum s.l. were inferred from elecrophoretic variation of PGM.
DNA in situ hybridization on polytene chromosomes of Simulium sanctipauli at loci relevant to insecticide resistance
Authors: Boakye D. A. , Cornel A. J. , Meredith S. E. , Brakefield P. M. , Collins F. H.
Published: March 2003

A DNA technique for in situ hybridization developed by
Kumar & Collins (1994) for use on polytene chromosomes of adult Anopheles mosquitoes (Diptera: Culicidae) was modified for use with Simulium larval salivary gland chromosomes (Diptera: Simuliidae). Cloned fragments of several Simulium genes (coding for aspartate amino transferase, cytochrome P450 and DNA polymerase) were successfully mapped physically by assigning specific band locations in Simulim sanctipauli V. & D. This represents the first attempt at locating genes beyond the resolution of linkage to inversions in any blackfly species.
Genetic differentiation of Anopheles claviger s.s. in France and neighbouring countries
Authors: Schaffner F. , Raymond M. , Pasteur N.
Published: March 2003

An investigation of polymorphism of 11 autosomal and one sex‐linked allozyme loci was made on 18 samples of Anopheles claviger Meigen (Diptera: Culicidae) from localities across France and neighbouring sites in Germany and Switzerland, plus one sample of Anopheles petragnani Del Vecchio from the French Pyrénées. Genetic differentiation between these two sibling species was confirmed (Nei genetic distance 0.33–0.44) and two genetically distinct groups of populations were identified within An. claviger. These two forms of An. claviger showed contiguous geographical distributions, Group I found across western and Central France, Group II in eastern France and nearby parts of Germany and Switzerland. The two groups were in contact in a region near the Rhone Valley where two intermediate samples were found. The taxonomic significance of this finding is discussed in the context of the recent climatic history of Europe and in relation to the vector potential of each member of the An. claviger complex.
Anopheles funestus resistant to pyrethroid insecticides in South Africa
Authors: Hargreaves K. , Koekemoer L. L. , Brooke B. D. , Hunt R. H. , Mthembu J. , Coetzee M.
Published: March 2003

Northern Kwazulu/Natal (KZN) Province of South Africa borders on southern Mozambique, between Swaziland and the Indian Ocean. To control malaria vectors in KZN, houses were sprayed annually with residual DDT 2 g/m2 until 1996 when the treatment changed to deltamethrin 20–25 mg/m2. At Ndumu (27°02′ S, 32°19′ E) the recorded malaria incidence increased more than six‐fold between 1995 and 1999. Entomological surveys during late 1999 found mosquitoes of the Anopheles funestus group (Diptera: Culicidae) resting in sprayed houses in some sectors of Ndumu area. This very endophilic vector of malaria had been eliminated from South Africa by DDT spraying in the 1950s, leaving the less endophilic An. arabiensis Patton as the only vector of known importance in KZN. Deltamethrin‐sprayed houses at Ndumu were checked for insecticide efficacy by bioassay using susceptible An. arabiensis (laboratory‐reared) that demonstrated 100% mortality. Members of the An. funestus group from Ndumu houses (29 males, 116 females) were identified by the rDNA PCR method and four species were found: 74 An. funestus Giles sensu stricto, 34 An. parensis Gillies, seven An. rivulorum Leeson and one An. leesoni Evans. Among An. funestus s.s. females, 5.4% (4/74) were positive for Plasmodium falciparum by ELISA and PCR tests. To test for pyrethroid resistance, mosquito adults were exposed to permethrin discriminating dosage and mortality scored 24 h post‐exposure: survival rates of wild‐caught healthy males were 5/10 An. funestus, 1/9 An. rivulorum and 0/2 An. parensis; survival rates of laboratory‐reared adult progeny from 19 An. funestus females averaged 14% (after 1 h exposure to 1% permethrin 25 : 75 cis : trans on papers in WHO test kits) and 27% (after 30 min in a bottle with 25 μg permethrin 40 : 60 cis : trans). Anopheles funestus families showing > 20% survival in these two resistance test procedures numbered 5/19 and 12/19, respectively. Progeny from 15 of the families were tested on 4% DDT impregnated papers and gave 100% mortality. Finding these proportions of pyrethroid‐resistant An. funestus, associated with a malaria upsurge at Ndumu, has serious implications for malaria vector control operations in southern Africa.
A comparison of the feeding behaviour of tsetse and stable flies
Authors: Schofield S. , Torr S. J.
Published: March 2003

Abstract In Zimbabwe, observations were made of the behaviour of individual stable flies (Stomoxys spp.) (Diptera: Muscidae) and tsetse (Glossina spp.) (Diptera: Glossinidae) feeding on cattle during the wet (Stomoxys and tsetse) and dry (tsetse only) seasons. For Stomoxys landing on adult cattle, only 27% took a full meal (mean feeding time = 147 s). Most Stomoxys left the host before completing their meal, largely due to disturbance by the host's defensive behaviour (24%, mean time = 59 s) or other flies (44%, 71 s). The probability of a Stomoxys leaving the host progressively increased with time. Simultaneous observations of tsetse showed that, compared to Stomoxys, their feeding success was lower (15%), feeding was interrupted earlier (33 s) and the time taken to complete a meal was shorter (109 s). Further studies of tsetse across different seasons and hosts showed that feeding success varied according to host age (adult = 7%; calf = 3%) and was negatively correlated with the frequency of host defensive behaviour and the relative abundance of non‐biting Diptera. Disturbances were more often caused by host behaviour (69%) than other flies (31%) and the probability of tsetse leaving decreased with time on the host. Overall, these results suggest that tsetse and Stomoxys have different feeding strategies. In particular, tsetse appear to be more responsive to host defensive behaviour, which reduces their feeding success relative to Stomoxys. These behavioural differences are consistent with the respective life‐history characteristics of Stomoxys and tsetse.
Imprecise terms in UK medical multiple‐choice questions: what examiners think they mean
Authors: Holsgrove Gareth , Elzubeir Margaret
Published: March 2003

Many multiple‐choice questions (MCQs) used in medical education in the UK contain undefined, imprecise terms. They are particularly common in true/false items and can be found in classroom tests, published examples of MCQs and, more importantly, in high‐stakes examinations which determine a candidate's graduation or membership of a professional body. This study investigated imprecise terms used in some MB BS finals examinations and the Part 1 Membership Examination of the Royal College of Physicians. It revealed that imprecise terms occur commonly, yet there is a wide range of opinion among the examiners themselves about their meanings. The numbers and variety of imprecise terms which were found in high‐stakes MCQ examinations are described in this paper and details are given concerning the lack of consensus about their meanings as reported by the responsible examiners. A second type of construction error – disproportionately large numbers of `true' branches – was also recorded. Exemplary practices do exist in MCQ quality assurance, but in the UK they are very much the exception rather than the rule. The findings of this investigation strongly indicate a need for change.
The use of multidisciplinary consensus groups in the planning phase of an integrated problem‐based curriculum
Authors: Lloyd‐Jones G , Ellershaw J , Wilkinson S , Bligh J G
Published: March 2003

In response to the General Medical Council's initiative to reform UK medical undergraduate education only a minority of medical schools have developed entirely novel curricula. Although the experiences gained by these schools in curriculum design and planning have not been recorded in the literature they are likely to be of interest to other medical schools still contemplating course revision. The medical school at the University of Liverpool recently launched an integrated problem‐based course differing radically from its predecessor. The General Medical Council considered integration of contributing disciplines one of the most important aims of reform, yet courses that integrate independent component disciplines may be perceived by staff as threatening due to the loss of structure and disciplinary autonomy. Strategies for early course development must take account of these concerns as well as dealing with the identification of course content. A multidisciplinary consensus group process, designed to combat some of these problems, was employed to identify the learning objectives and core content for the new course. The purpose of this paper is to describe, first, the processes employed to identify the core palliative care component for a new PBL curriculum and secondly, how these objectives were integrated horizontally and vertically throughout all course elements.
Contribution of medical student research to the MedlineTM‐indexed publications of a German medical faculty
Authors: Cursiefen Claus , Altunbas Ayhan
Published: March 2003

Medical students in Germany have to write a research thesis to acquire the title of medical doctor. This study evaluates the contribution of student research to the Medline™‐indexed publications of a German medical faculty. A 1993–1995 Medline™‐publication list, on which medical students among authors should be marked, was sent to medical faculty staff of the University of Würzburg, Germany (n = 238). Faculty members responded (106, 45%), 66 were working at a clinic, 26 at a clinic‐associated institute and 14 at a basic science institute. Between 1993 and 1995, 1128 Medline™‐indexed papers were published by these faculty members, who on average supervised 4·5 medical students (n = 477). Medical students were among the authors of 316 (28%) and were the first authors of 88 papers (7·8%). For 66% of medical students their research resulted in a Medline™‐indexed publication. Medical student research activity can significantly influence the published output of a medical faculty.
Evaluation of a programme of workshops for promoting the teaching of critical appraisal skills
Authors: Ibbotson  , Grimshaw  , Grant
Published: March 2003

The aim of this study was to assess the effectiveness of four training workshops at the inception of a programme to cascade critical appraisal skills training throughout Scotland. Data were collected from all participants and organizers at four commissioned critical appraisal skills training workshops in Scotland. The collection of data involved three components: a survey of workshop participants before and after each workshop to determine knowledge of the principles of clinical effectiveness; semi‐structured interviews with organizers before, during and after the programme of commissioned workshops to assess views on the workshops; and a postal survey to determine involvement in critical appraisal activities following the initial workshops. The main outcome measures were `change in knowledge' and subsequent involvement in teaching. An average of 41 people attended each workshop. Participants improved their scores on understanding of clinical effectiveness. Not all of the improvement can be ascribed to the workshops, however, because control item scores also improved, albeit to a lesser extent. The workshops were perceived as an acceptable way of acquiring critical appraisal skills, but doubts were expressed about whether participants would be able to roll out the programme on their own. Of the 32 (42%) attendees who were involved in CASP‐style workshops after the initial workshops, 26 (34%) providing aspects of teaching, and a further six (8%) were participants. The evaluation of the CASP workshop technique suggests that it does improve knowledge of clinical effectiveness, but concerns remain about the viability and reliability of this approach as it rolls out training within Scotland.
Cultural sensitivity training among foreign medical graduates
Authors: Majumdar Basanti , Keystone  , Cuttress Lori A
Published: March 2003

Objectives

 To examine the effectiveness of culture sensitivity training for foreign‐trained medical graduates licensed to practice in Ontario, Canada.

Design

 A study of pretest–post‐test design was conducted to determine the effect of cultural sensitivity training on newly immigrated physicians licensed in Canada. Twenty‐four physicians, those who had passed the medical licensing exam in 1996 and had not yet started their residency program, were given 15 hours of cultural sensitivity training and were considered the experimental group. This group was compared with a control group of 24 physicians who had passed the licensing exam and were in the process of completing residency.

Setting

 University of Toronto.

Subjects

 Foreign‐trained medical graduates.

Results

 Both groups completed the Cross‐Cultural Adaptability Inventory both before and after the training of the experimental group. Statistical significance in three subscales of the Open‐Mindedness/Flexibility, Emotional Resilience and Perceptual Acuity dimensions were demonstrated in the experimental group as compared with the control group.

Conclusions

 In order for Canada to mould professional and effective physicians great care must be taken in the design and process of cultural sensitivity programmes to enhance both knowledge and skills. Follow‐up should be undertaken to compare their effectiveness with the control group.
Medication discussion groups in the Netherlands: five years of experience
Authors: Kocken Geert A L
Published: March 2003

Introduction

Nation‐wide implementation of medication discussion (MD) groups in the Netherlands was designed as a bottom‐up approach and has been in progress for five years. This invites a review of what has been achieved in these structured discussions between general practitioners and pharmacists.

Context

Early in 1997 the Dutch Foundation for Effective Use of Medication (DGV) initiated a fact‐finding exercise among general practitioners and pharmacists representing MD groups all over the country.

Objective

Description of the setting up and the operation of medical discussion groups. Comparison of the quality of the consultations between the start of the project (1992) and 1997.

Methods

Two surveys of medical discussion groups in 1992 and 1997, respectively.

Results

The quality of the consultations was found to have improved in comparison with an evaluation shortly after the start of the project.

Conclusion

The overwhelming majority of those interviewed were satisfied with the MD process, which they consider a useful effort. But there is also a wish for increased commitment to guidelines agreed in MD group consultations.
Nested clade analyses of phylogeographic data: testing hypotheses about gene flow and population history
Authors: TEMPLETON
Published: March 2003

Since the 1920s, population geneticists have had measures that describe how genetic variation is distributed spatially within a species’ geographical range. Modern genetic survey techniques frequently yield information on the evolutionary relationships among the alleles or haplotypes as well as information on allele frequencies and their spatial distributions. This evolutionary information is often expressed in the form of an estimated haplotype or allele tree. Traditional statistics of population structure, such as F statistics, do not make use of evolutionary genealogical information, so it is necessary to develop new statistical estimators and tests that explicitly incorporate information from the haplotype tree. One such technique is to use the haplotype tree to define a nested series of branches (clades), thereby allowing an evolutionary nested analysis of the spatial distribution of genetic variation. Such a nested analysis can be performed regarding the geographical sampling locations either as categorical or continuous variables (i.e. some measure of spatial distance). It is shown that such nested phylogeographical analyses have more power to detect geographical associations than traditional, nonhistorical analyses and, as a consequence, allow a broader range of gene‐flow parameters to be estimated in a precise fashion. More importantly, such nested analyses can discriminate between phylogeographical associations due to recurrent but restricted gene flow vs. historical events operating at the population level (e.g. past fragmentation, colonization, or range expansion events). Restricted gene flow and historical events can be intertwined, and the cladistic analyses can reconstruct their temporal juxtapositions, thereby yielding great insight into both the evolutionary history and population structure of the species. Examples are given that illustrate these properties, concentrating on the detection of range expansion events.
Speciation and phylogeography of Hawaiian terrestrial arthropods
Authors: RODERICK G. K. , GILLESPIE R. G.
Published: March 2003

The Hawaiian archipelago is arguably the world’s finest natural laboratory for the study of evolution and patterns of speciation. Arthropods comprise over 75% of the endemic biota of the Hawaiian Islands and a large proportion belongs to species radiations. We classify patterns of speciation within Hawaiian arthropod lineages into three categories: (i) single representatives of a lineage throughout the islands; (ii) species radiations with either (a) single endemic species on different volcanoes or islands, or (b) multiple species on each volcano or island; and (iii) single widespread species within a radiation of species that exhibits local endemism. A common pattern of phylogeography is that of repeated colonization of new island groups, such that lineages progress down the island chain, with the most ancestral groups (populations or species) on the oldest islands. While great dispersal ability and its subsequent loss are features of many of these taxa, there are a number of mechanisms that underlie diversification. These mechanisms may be genetic, including repeated founder events, hybridization, and sexual selection, or ecological, including shifts in habitat and/or host affiliation. The majority of studies reviewed suggest that natural selection is a primary force of change during the initial diversification of taxa.
Dispersal patterns of Lonicera periclymenum determined by genetic analysis
Authors: GRASHOF‐BOKDAM C. J. , JANSEN J. , SMULDERS M. J. M.
Published: March 2003

Colonization of Lonicera periclymenum L. (honeysuckle) was studied by RAPD analysis of young ramets in two woodlots planted 20 years ago, and in all ramets in older woodlots within a range of 1 km. Mature ramets that climbed in a particular tree always belonged to one individual. Twenty‐five percent of the mature individuals had reproduced vegetatively to other trees or patches nearby, which indicates that the larger part of reproduction is sexual. Some young plants that were growing at close distances from each other were genetically highly similar and shared high similarities to the same mature plants. They may be the product of one dispersal event. Detection of parents of young individuals by exclusion was not successful, because of the dominant nature of the bands. Average distances from young plants to genetically most similar mature plants were variable, due to the small number of colonization events. However, four ways of analysis of genetic similarity among all individuals indicated that exchange of genetic material by seed and pollen occurs to a large extent over small distances and within woodlots: (i) using the Mantel test, pairs of individuals with highest similarity were found significantly more often in the same woodlot than in different woodlots; (ii) genetic similarities between individuals decreased significantly with geographical distance, but only for distances up to 300 m; (iii) individuals of woodlots in the Western part of the study area were hardly related to individuals in the Eastern part of the study area, a distance of 2–3 km; (iv) ΦST in the study area was 0.186, indicating a limited gene flow between woodlots. These results are consistent with the dispersal distance as estimated from the average distance between colonized woodlots and the nearest occupied old woodlot in earlier research.
Evolution on a volcanic conveyor belt: using phylogeographic reconstructions and K–Ar‐based ages of the Hawaiian Islands to estimate molecular evolutionary rates
Authors: FLEISCHER ROBERT C. , MCINTOSH CARL E. , TARR CHERYL L.
Published: March 2003

The Hawaiian Islands form as the Pacific Plate moves over a ‘hot spot’ in the earth’s mantle where magma extrudes through the crust to build huge shield volcanos. The islands subside and erode as the plate carries them to the north‐west, eventually to become coral atolls and seamounts. Thus islands are ordered linearly by age, with the oldest islands in the north‐west (e.g. Kauai at 5.1 Ma) and the youngest in the south‐east (e.g. Hawaii at 0.43 Ma). K–Ar estimates of the date of an island’s formation provide a maximum age for the taxa inhabiting the island. These ages can be used to calibrate rates of molecular change under the following assumptions: (i) K–Ar dates are accurate; (ii) tree topologies show that derivation of taxa parallels the timing of island formation; (iii) populations do not colonize long after island emergence; (iv) the coalescent point for sister taxa does not greatly predate the formation of the colonized younger island; (v) saturation effects and (vi) among‐lineage rate variation are minimal or correctable; and (vii) unbiased standard errors of distances and regressions can be estimated from multiple pairwise comparisons. We use the approach to obtain overall corrected rate calibrations for: (i) part of the mitochondrial cytochrome b gene in Hawaiian drepanidines (0.016 sequence divergence/Myr); (ii) the Yp1 gene in Hawaiian Drosophila (0.019/Myr Kambysellis et al. 1995); and (iii) parts of the mitochondrial 12S and 16S rRNA and tRNAval in Laupala crickets (0.024–0.102/Myr, Shaw 1996). We discuss the reliability of the estimates given the assumptions (i–vii) above and contrast the results with previous calibrations of Adh in Hawaiian Drosophila and chloroplast DNA in lobeliods.
Empirical evaluation of preservation methods for faecal DNA
Authors: FRANTZEN M. A. J. , SILK J. B. , FERGUSON J. W. H. , WAYNE R. K. , KOHN M. H.
Published: March 2003

We evaluate the relative effectiveness of four methods for preserving faecal samples for DNA analysis. PCR assays of fresh faecal samples collected from free‐ranging baboons showed that amplification success was dependent on preservation method, PCR‐product size, and whether nuclear or mitochondrial DNA was assayed. Storage in a DMSO/EDTA/Tris/salt solution (DETs) was most effective for preserving nuclear DNA, but storage in 70% ethanol, freezing at –20°C and drying performed approximately equally well for mitochondrial DNA and short (<200 bp) nuclear DNA fragments. Because faecal DNA is diluted and degraded, repeated extractions from faeces may be necessary and short nuclear markers should be employed for genotyping. A review of molecular scatology studies further suggests that three to six faeces per individual should be collected.
Molecular resolution of marine turtle stock composition in fishery bycatch: a case study in the Mediterranean
Authors: LAURENT L. , CASALE P. , BRADAI M. N. , GODLEY B. J. , BRODERICK G. GEROSA§ and A. C. , SCHROTH W. , SCHIERWATER B. , LEVY A. M. , FREGGI D. , ABD EL‐MAWLA E. M. , HADOUD D. A. , GOMATI H. E. , DOMINGO M. , HADJICHRISTOPHOROU M. , KORNARAKY L. , DEMIRAYAK F. , GAUTIER CH.
Published: March 2003

Based on an extensive sampling regime from both nesting populations and bycatch, frequency analyses of mitochondrial (mt) DNA control region haplotypes in the Mediterranean were used to assess the genetic structure and stock composition of the loggerhead sea turtle, Caretta caretta, in different marine fisheries. The analyses show the following. (i) In drifting longline fisheries working in Mediterranean pelagic habitats 53–55% of turtles caught originated from the Mediterranean stock; (ii) In bottom‐trawl fisheries all turtle bycatch is derived from this regional stock; (iii) This regional stock contribution to fishery bycatch suggests that the population size of the Mediterranean loggerhead nesting population is significantly larger than previously thought. This is consistent with a recent holistic estimate based on the discovery of a large rookery in Libya. (iv) Present impact of fishery‐related mortality on the Mediterranean nesting population is probably incompatible with its long‐term conservation. Sea turtle conservation regulations are urgently needed for the Mediterranean fisheries. (v) The significant divergence of mtDNA haplotype frequencies of the Turkish loggerhead colonies define this nesting population as a particularly important management unit. Large immature and adult stages from this management unit seem to be harvested predominantly by Egyptian fisheries. (vi) Combined with other data, our findings suggest that all the nesting populations in the Mediterranean should be considered as management units sharing immature pelagic habitats throughout the Mediterranean (and possibly the eastern Atlantic), with distinct and more localized benthic feeding habitats in the eastern basin used by large immatures and adults. (vii) Between the strict oceanic pelagic and the benthic stages, immature turtles appear to live through an intermediate neritic stage, in which they switch between pelagic and benthic foods.
Short allele dominance as a source of heterozygote deficiency at microsatellite loci: experimental evidence at the dinucleotide locus Gv1CT inGracilaria gracilis(Rhodophyta)
Authors: WATTIER R. , ENGEL C. R. , SAUMITOU‐LAPRADE P. , VALERO M.
Published: March 2003

In this study, we compared the genotypes obtained at a microsatellite locus using two methods of amplification and detection of variation in a set of individuals belonging to the red alga haplo‐diploid species,Gracilaria gracilis. The methods varied in their capacity to detect longer alleles in heterozygotes, resulting in an apparent heterozygote deficiency. We attributed this bias in favour of short alleles to competition leading to the preferential amplification of shorter alleles (short allele dominance). To test this hypothesis, we created artificial heterozygotes (mixtures of two haploid DNA samples) and showed that long alleles already less intense than short alleles, ‘suffer’ more from being in association.
The use of molecular markers to study patterns of genotypic diversity in some invasive alien Fallopia spp. (Polygonaceae)
Authors: HOLLINGSWORTH M. L. , HOLLINGSWORTH P. M. , JENKINS G. I. , BAILEY J. P. , FERRIS C.
Published: March 2003

Random amplified polymorphic DNA (RAPDs) and inter‐simple sequence repeats (inter‐SSRs) have been used to study clonal growth and hybridization in some non‐native, gynodioecious, invasive weeds from the genus Fallopia (Polygonaceae). At the study site (the River Kelvin, Glasgow, UK) a single genotype of Japanese knotweed (Fallopia japonica) was detected, consistent with all the individuals sampled being ramets of a single clone. Two genotypes of giant knotweed (F. sachalinensis) were detected, with one genotype accounting for all but one of the samples, again indicative of widespread clonal growth. Five genotypes of the hybrid between Japanese and giant knotweed (F.×bohemica) were recovered. F.×bohemica is the only male‐fertile taxon present at the site and it seems probable that at least some of this genetic variation is attributable to hybrid fertility. A single plant identified using morphological methods as a backcross between F. japonica and F.×bohemica was analysed, and the molecular data were consistent with this theory. A comparison of RAPDs and inter‐SSRs showed that the two techniques gave data that are broadly congruent, and both techniques showed a similar sensitivity in the number of genotypes detected.
Patterns of gene flow and population genetic structure in the canyon treefrog, Hyla arenicolor (Cope)
Authors: Barber PAUL H.
Published: March 2003

Patterns of gene flow and genetic structuring were examined in the canyon treefrog, Hyla arenicolor (Cope). Hierarchical analysis of genetic variation was performed on mitochondrial cytochrome b haplotypes from 323 individuals, representing 32 populations from previously described phylogeographic regions. Results from AMOVA revealed that 60.4–78.9% of the recovered genetic variation was the result of differences in the apportionment of genetic variation between subdivisions of the primary phylogeographic regions. In contrast, populations only contained between 13.9 and 30.1% of the observed haplotypic variation. Gene flow estimates based on calculations of ΦST revealed moderate levels of gene flow within phylogeographic regions, but there was no evidence of gene flow between these regions, suggesting that geographical boundaries were probably important in the formation of phylogeographic structure in H. arenicolor. Phylogeographic regions exhibited very different patterns of gene flow. One region showed evidence of recent colonization. Another region exhibited very limited gene flow. Moderate to high estimates of gene flow were obtained for populations from two distinct phylogeographic regions characterized by mesic and xeric environments. Isolation by distance was observed in both regions suggesting that these regions are in genetic equilibrium. Because gene flow is extremely unlikely between the populations in the xeric region, this result is interpreted as historical gene flow. These results indicate that isolation‐by‐distance effects may still be observed even when population genetic structure and gene flow are the result of historical association.
Extreme ecological and phenotypic differences in the tropical tree chicozapote (Manilkara zapota (L.) P. Royen) are not matched by genetic divergence: a random amplified polymorphic DNA (RAPD) analysis
Authors: Heaton H. J. , Whitkus R. , Gómez‐Pompa A.
Published: March 2003

The chicozapote (Manilkara zapota) is a tropical fruit tree that occurs in two morphologically distinct populations in the Yucatan peninsula of Mexico. Forest populations consist of tall, straight trees, while swamp populations have a short, shrub‐like growth form. Swamp populations also have smaller leaves, fruit and seeds. We performed a random amplified polymorphic DNA (RAPD) analysis on four different populations of chicozapote to test if there was a genetic component to this variation. The populations differed in respect to habitat type (swamp vs. forest) and geographical location (east vs. west). We surveyed 80 random primers, nine of which revealed interpopulation band differences (28 band differences in total). Unweighted pair group method analysis (UPGMA) and neighbour‐joining dendrograms showed no separation of individuals between the different populations. Analysis of the RAPD data showed no significant differences between swamp and forest populations (P > 0.1). The lack of genetic differentiation suggests a failure to find a correlation between the RAPD loci and adaptive traits. The observed morphological differences between the swamp and forest populations of chicozapote may either be that gene flow has prevented a build‐up of neutral marker differences or a plastic response to differences in habitat.
Genetic relationship of 32 cell lines of the Euplotes octocarinatus species complex revealed by random amplified polymorphic DNA (RAPD) fingerprinting
Authors: Möllenbeck M.
Published: March 2003

Random amplified polymorphic DNA (RAPD) fingerprinting was used in this study to determine the genetic relationship of different cell lines of the hypotrichous ciliate Euplotes octocarinatus. Stocks isolated from different habitats in the USA, and from a group of genetically recombined laboratory strains, were characterized. Band‐sharing indices (D) for all possible pairwise comparisons revealed a remarkable genetic diversity between the different cell lines. Investigation of the genetic structure in natural populations found diversity — although to a different extent — in all populations investigated. No clonal structure could be observed, as proposed for several protozoa and recently shown for E. daidaleos. These findings suggest frequent conjugation in the populations of E. octocarinatus. No correlation between the genetic relationship of cell lines from different habitats and the distance between the corresponding sampling locations was found. Once separated geographically, the exchange of genetic material between populations appears to be nearly impossible. Therefore, these groups tend to separate into sibling species. The data generally support the occurrence of different syngens in the E. octocarinatus species complex. This finding is in accordance with our observation that the morphological ‘species’ of E. octocarinatus consists of several syngens or sibling species, similar to findings for the Paramecium aurelia‐, Tetrahymena pyriformis‐ and E. vannus‐species complexes.
PCR amplification of the mating‐type idiomorphs in Cryphonectria parasitica
Authors: Marra R. E. , Milgroom M. G.
Published: March 2003

In the laboratory, the ascomycete fungus Cryphonectria parasitica is rarely self‐fertile, and has a self‐incompatibility system that resolves into two intersterility groups, controlled by a single locus. In natural populations, however, self‐fertilization occurs frequently. In this report, we show that the C. parasitica self‐incompatibility locus (MAT) comprises two idiomorphs (alleles that are highly divergent in sequence), conforming to the paradigm of self‐incompatibility as described for other ascomycetes. Starting with a fragment putatively from the MAT‐2 idiomorph, we used a PCR‐based cloning approach to identify 3.5‐ and 2‐kb sequences unique to MAT‐1 and MAT‐2 isolates, respectively. These sequences were then used to design idiomorph‐specific PCR primer pairs, allowing us to efficiently identify the mating types of isolates, a crucial component of our research on the environmental and genetic factors underlying this mixed mating system.
A retrospective assessment of the accuracy of the paternity inference program cervus
Authors: Slate Jon , Marshall Tristan , Pemberton Josephine
Published: March 2003

cervus is a Windows‐based software package written to infer paternity in natural populations. It offers advantages over exclusionary‐based methods of paternity inference in that multiple nonexcluded males can be statistically distinguished, laboratory typing error is considered and statistical confidence is determined for assigned paternities through simulation. In this study we use a panel of 84 microsatellite markers to retrospectively determine the accuracy of statistical confidence when
cervus was used to infer paternity in a population of red deer (Cervus elaphus). The actual confidence of
cervus‐assigned paternities was not significantly different from that predicted by simulation.
Are recession populations of the desert locust (Schistocerca gregaria) remnants of past swarms?
Authors: Ibrahim Kamal M. , Sourrouille Patricia , Hewitt Godfrey M.
Published: March 2003

The desert locust (Schistocerca gregaria) undergoes crowding‐induced phase transformation from solitary to gregarious, which involves changes in behaviour, colour, development, morphometry, fecundity and endocrine physiology. During recession, solitary locusts persist in the central, drier part of the species’ range in small pocket populations that are prone to extinction. During the intermittent upsurges and the subsequent plagues, gregarious swarms attain huge population size and invade a vast area causing major damage to agriculture. A highly variable nuclear DNA marker, a noncoding 3′ end fragment of an antennapedia‐class homeobox gene, was screened in locust samples from Eritrea. Despite the homogenizing potential of plague swarms, the last of which was in 1986–89 and originated in this region, the population genetic structure of solitary phase locusts along the Red Sea coast of Eritrea revealed significant divergence. The pattern of divergence indicated that the invasion of the western and northern plains in the summer of 1995 may not, as reported then, have originated in eastern Chad or western Sudan. A number of interrelated hypotheses have been presented to explain the observed genetic heterogeneity between the sampled populations. We conclude, with caution due to the limited sample sizes, that: (i) geographical isolation between breeding sites during plagues and recession; (ii) the marked differences in the flight behaviour of plague swarms and recession populations; (iii) possible failure of gregarious locusts to solitarize and re‐establish in recession areas; and (iv) the effect of repeated extinction and recolonization in the meta‐population contribute to the maintenance of the genetic structure of recession populations. Potentially productive future research has been identified.
Genetic analysis of the mating system of the common brushtail possum (Trichosurus vulpecula) in New Zealand farmland
Authors: Taylor A. C. , Cowan P. E. , Fricke B. L. , Cooper D. W.
Published: March 2003

We examined male reproductive success in a common brushtail possum population in New Zealand farmland. Paternity was assigned to 66 of 91 pouch young (maternity known), using a likelihood approach applied to genotypes at six microsatellite loci having an overall average exclusion probability of around 99%. The distribution of number of offspring per male was L‐shaped with a standardized variance of 1.52. At least 46% of the 76 sampled reproductively mature males, bred, siring between one and four offspring each. Although breeding males were on average older and larger than nonbreeding males, the small differences did not result in a significant overall difference between the two groups in a multivariate permutation test analagous to a t‐test. Paternity analysis of 22 sibling pairs (resulting from experimental removal of pouch young early in the breeding season, inducing a second oestrous) suggested that sequential mating of females with the same male was uncommon (≈ 16–27%). Whilst there was a tendency for female possums to mate with nearby males, consistent with previous observations of territorial mating behaviour in Australian populations, some interhabitat matings were also inferred. The study population displayed only a low degree of polygyny, which may in part reflect population and habitat characteristics of the study site. A comprehensive understanding of the mating system of Trichosurus vulpecula awaits genetic paternity analysis in additional populations from both Australia and New Zealand, using quantitative approaches undertaken in this study.
Hybrid origins of honeybees from Italy (Apis mellifera ligustica) and Sicily (A. m. sicula)
Authors: Franck P. , Garnery L. , Celebrano G. , Solignac M. , Cornuet J.‐M.
Published: March 2003

The genetic variability of honeybee populations Apis mellifera ligustica, in continental Italy, and of A. m. sicula, in Sicily, was investigated using nuclear (microsatellite) and mitochondrial markers. Six populations (236 individual bees) and 17 populations (664 colonies) were, respectively, analysed using eight microsatellite loci and DraI restriction fragment length polymorphism (RFLP) of the cytochrome oxidase I (COI)–cytochrome oxidase II (COII) region. Microsatellite loci globally confirmed the southeastern European heritage of both subspecies (evolutionary branch C). However, A. m. ligustica mitochondrial DNA (mtDNA) appeared to be a composite of the two European (M and C) lineages over most of the Italian peninsula, and only mitotypes from the African (A) lineage were found in A. m. sicula samples. This demonstrates a hybrid origin for both subspecies. For A. m. ligustica, the most widely exported subspecies, this hybrid origin has long been obscured by the fact that in the main area of queen production (from which most of the previous ligustica bee samples originated) the M mitochondrial lineage is absent, whereas it is present almost everywhere else in Italy. This presents a new view of the evolutionary history of European honeybees. For instance, the Iberian peninsula was considered as the unique refuge for the M branch during the quaternary ice periods. Our results show that the Apennine peninsula played a similar role. The differential distribution of nuclear and mitochondrial markers observed in Italy seems to be a general feature of introgressed honeybee populations. Presumably, it stems from the social nature of the species in which both genome compartments are differentially affected by the two (individual and colonial) reproduction levels.
Rapid identification of cyst (Heterodera spp., Globodera spp.) and root‐knot (Meloidogyne spp.) nematodes on the basis of ITS2 sequence variation detected by PCR‐single‐strand conformational polymorphism (PCR‐SSCP) in cultures and field samples
Authors: Clapp J. P. , Stoel C. D. van der , Putten W. H. van der
Published: March 2003

Cyst and root‐knot nematodes show high levels of gross morphological similarity. This presents difficulties for the study of their ecology in natural ecosystems. In this study, cyst and root‐knot nematode species, as well as some ectoparasitic nematode species, were identified using the second internal transcribed spacer (ITS2) sequence variation detected by polymerase chain reaction‐single‐strand conformational polymorphism (PCR‐SSCP). The ITS2 region was sufficiently variable within the taxa investigated to allow species to be separated on the basis of minor sequence variation. The PCR primers used in this study were effective for 12 species with three genera within the Heteroderinae (Globodera pallida, G. rostochiensis, Heterodera arenaria/avenae, H. ciceri, H. daverti, H. hordecalis, H. mani, H. schachtii, H. trifolii, Meloidogyne ardenensis, M. duytsi and M. maritima). However, pathotypes of Globodera pallida and G. rostochiensis could not be distinguished. The method was tested at two coastal dune locations in The Netherlands (one in the lime‐poor dunes of the north and one in calcareous dunes of the south) to determine the population structure of cyst nematodes. At each site, cyst nematodes were associated with three plant species: two plant species on the foredune (Elymus farctus and Ammophila arenaria) and one plant species occurring further inland (Calamagrostis epigejos). Two species of cyst nematodes, H. arenaria and H. hordecalis, were found. H. arenaria associated with vigorous A. arenaria and H. hordecalis in association with degenerating A. arenaria and C. epigejos. The field survey demonstrated that in coastal dunes abiotic factors may be the important affecting the distribution of cyst nematodes.
Estimating the probability of identity among genotypes in natural populations: cautions and guidelines
Authors: Waits Lisette P. , Luikart Gordon , Taberlet Pierre
Published: March 2003

Individual identification using DNA fingerprinting methods is emerging as a critical tool in conservation genetics and molecular ecology. Statistical methods that estimate the probability of sampling identical genotypes using theoretical equations generally assume random associations between alleles within and among loci. These calculations are probably inaccurate for many animal and plant populations due to population substructure. We evaluated the accuracy of a probability of identity (P(ID)) estimation by comparing the observed and expected P(ID), using large nuclear DNA microsatellite data sets from three endangered species: the grey wolf (Canis lupus), the brown bear (Ursus arctos), and the Australian northern hairy‐nosed wombat (Lasiorinyus krefftii). The theoretical estimates of P(ID) were consistently lower than the observed P(ID), and can differ by as much as three orders of magnitude. To help researchers and managers avoid potential problems associated with this bias, we introduce an equation for P(ID) between sibs. This equation provides an estimator that can be used as a conservative upper bound for the probability of observing identical multilocus genotypes between two individuals sampled from a population. We suggest computing the actual observed P(ID) when possible and give general guidelines for the number of codominant and dominant marker loci required to achieve a reasonably low P(ID) (e.g. 0.01–0.0001).