bluuebunny/crossref_metadata_2025 huggingface dataset:
Peridomestic distribution of Triatoma garciabesi and Triatoma guasayana in north‐west Argentina
Authors: Canale D. M. , Cecere M. C. , Chuit R. , Gürtler R. E.
Published: March 2003

The Reduviid bugs Triatoma garciabesi Carcavallo et al. (Hemiptera: Reduviidae: Triatominae), previously known as T. sordida Ståhl in the semi‐arid chaco region, and T. guasayana Wygodzinsky & Abalos, vectors of Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae), were found to occupy wide but different ranges of ecotopes in the peridomestic environment. At Amamá and nearby rural villages in north‐western Argentina, a combined total of 1233 specimens were collected from 325/2314 (14%) sites surveyed at 6‐monthly intervals from November 1994 to November 1996. Triatoma garciabesi and T. guasayana displayed a significantly different distribution among peridomestic ecotopes. Triatoma garciabesi predominated over T. guasayana in the prevalence of infested sites, the number of colonies and the number of bugs collected. For T. garciabesi, the predominant ecotopes most likely to yield T. garciabesi repeatedly were the rugged bark of Prosopis alba or P. nigra (Fabaceae) trees, where chickens roosted, and chicken coops. For T. guasayana the main ecotopes were goat or sheep corrals, piled materials and orchard fences. Triatoma garciabesi and T. guasayana were collected concurrently from the same site on 9/2314 (0.4%) occasions, and on different dates at the same site on 12 (0.5%) occasions. The observed low frequency of mixed populations (< 1%) was not significantly different from that expected from a hypothesis of independence. Triatoma garciabesi clearly outnumbered T. guasayana in four of the nine mixed populations, none of which persisted as such. Neither T. garciabesi nor T. guasayana colonized human habitations, even in the absence of T. infestans (formerly the predominant domestic vector of T. cruzi in this area), a situation that apparently has not changed in the last 50 years in northern Argentina.
An epizootic of patent iridescent virus disease in multiple species of blackflies in Chiapas, Mexico
Authors: Hernández O. , Maldonado G. , Williams T.
Published: March 2003

Simulium blackfly larvae (Diptera: Simuliidae) were collected from rivers and streams at 500–1500 m a.s.l. in Chiapas State of southern Mexico. Among 45 sites surveyed over an area of 2300 km2 (around 15°15′ N 92°20′ W), some Simulium larvae from three sites were opalescent violet‐blue, interpreted as patent infection with invertebrate iridescent virus (IIV). Dissection confirmed the presence of putative Iridovirus particles, 130 nm diameter, but no IIV isolates were obtained from homogenates injected into Galleria mellonella (L) larvae (Lepidoptera: Pyralidae). All Simulium with patent IIV infection died before metamorphosis, whereas ∼60% of asymptomatic Simulium survived to adulthood in the laboratory.

 During 1997, standard monthly samples from two parallel rivers 42–50 km north‐west of Tapachula comprised the following species proportions (and rates of patent IIV infection): 41.8% (47%) Simulium mexicanum Bellardi complex, 31.3% (31.4%) S. rubicundum Knab, 10.1% (13.1%) S. paynei, 6.5% (2.9%) S. callidum (Dyar & Shannon), 6.3% (5.1%) S. ochraceum Walker complex, 3.1% (0.7%) S. downsi Vargas et al. 0.7% S. samboni Jennings and 0.2% S. metallicum Bellardi complex, showing a strong correlation between blackfly abundance and the prevalence of patent infection. An epizootic of IIV in January and February (infection rates 41–100%) was followed by absence of larvae (March–August) until the end of the rainy season, when numbers collected on nylon strings rose to ≈ 1/cm with patent IIV infection rates of 0–12.5% during September–December. Further investigations are underway to isolate this IIV and assess its potential usefulness for biological control of Simulium pests and vectors of onchocerciasis.
Effect of temperature on the transmission of orbiviruses by the biting midge, Culicoides sonorensis
Authors: Wittmann E. J. , Mellor P. S. , Baylis M.
Published: March 2003

Abstract The influence of temperature on the likelihood of Culicoides sonorensis Wirth & Jones (Diptera: Ceratopogonidae) transmitting African horse sickness virus (AHSV) serotypes 4 and 6, bluetongue virus (BTV) serotypes 10 and 16 and epizootic haemorrhagic disease of deer virus (EHDV) serotype 1 was investigated. Extrinsic incubation periods (EIP), vector competence and vector survival were determined at 15, 20, 25 and 30°C. The effect of humidity on vector survival was also investigated by maintaining adult C. sonorensis at 40, 75 and 85% r.h. at each temperature. Higher temperatures were associated with a shorter EIP for all virus serotypes except AHSV6, to which C. sonorensis was orally refractory, increased vector competence for AHSV4 and EHDV1, but not for BTV10 or BTV16, and a reduction in vector survival. Humidity interacted with temperature in influencing vector survival, such that at low temperatures, lower humidity (40 and 75% r.h.) was detrimental for survival (up to 18% reduction in longevity), whereas at high temperatures, high humidity (85% r.h.) was detrimental (up to 36% reduction in longevity). In general, the transmission potential of C. sonorensis for AHSV4, EHDV1, BTV10 and BTV16 was greater at higher temperatures, because although vector survival was reduced, this was more than compensated for by the accompanying decrease in duration of the EIP.
A laboratory and field evaluation ofMacrocyclops distinctus,Megacyclops viridisandMesocyclops pehpeiensisas control agents of the dengue vectorAedes albopictusin a peridomestic area in Nagasaki, Japan
Authors: DIENG H. , BOOTS M. , TUNO N. , TSUDA Y. , TAKAGI M.
Published: March 2003

AbstractThe use of the cyclopoid copepodsMacrocyclops distinctus(Richard)Megacyclops viridis(Jurine) andMesocyclops pehpeiensisHu (Cyclopoida: Cyclopidae) as biological control agents against the dengue vectorAedes albopictus(Skuse) (Diptera: Culicidae) was evaluated. In the laboratory their predatory ability was highest against the younger instars ofAe. albopictusand none of the three copepods killed the fourth instar. Except forM. viridis, predatory ability was affected by the size of the container: the smaller the container, the higher the predation. A 4‐month field test was conducted to examine the impact of these predators on wildAe. albopictus. Thirty artificial containers were placed in a peridomestic area to allowAe. albopictuscolonization. We showed continuous and similar oviposition responses in treated and control containers. The densities ofAe. albopictusshowed considerable short‐term changes and were much reduced by the copepod species.Macrocyclopsand the mixture of all three provided betterAe. albopictuscontrol than eitherMegacyclopsorMesocyclopsalone. When larval densities peaked in the control containers in August and September, the overall reduction due to the copepods was nearly complete.Mesocyclopsinoculated alone had the highest population survival. However, the growth and survival of all the copepod species was poor when the three genera were mixed. Based on their performance and survival in the trial,MacrocyclopsandMesocyclopsmerit consideration as bio‐control agents ofAe. albopictus.
Effect of adult nutrition on the melanization immune response of the malaria vector Anopheles stephensi
Authors: KOELLA J. C. , SØRENSEN F. L.
Published: March 2003

Abstract Two dietary resources − blood and sugar − were assessed for effects on the melanization immune response of the mosquito Anopheles stephensi Liston (Diptera: Culicidae) towards inoculated Sephadex beads (negatively charged C‐25). This melanization is conferred by genetic factors capable of making the mosquito refractory to malaria parasites. If An. stephensi females had obtained a bloodmeal one day before inoculation with a bead, the efficacy of their immune response increased with the concentration of sugar ingested. At the highest sugar concentration (6%) tested, 38% of the mosquitoes completely melanized their bead, whereas at the lowest sugar concentration (2%), none of the mosquitoes were able to melanize their bead completely. Among mosquitoes not having a bloodmeal, the immuno‐competence was low (c. 9% of the mosquitoes completely melanized their bead) and independent of sugar concentration. The observed interaction between these two resources indicates that both resources are required for the Anopheles female to develop an effective melanization immune response.
Domestic scorpion control with pyrethroid insecticides in Mexico
Authors: Ramsey J. M. , Salgado L. , Cruz‐Celis A. , Lopez R. , Alvear A. L. , Espinosa L.
Published: March 2003

Abstract Scorpion stings cause more morbidity in Mexico than any other country, leading to about 100 deaths annually. In 1999, the State of Morelos reported nine deaths among 30 663 cases of scorpion sting. To replace lindane used for scorpion control, field trials of pyrethroid pesticides were undertaken in Morelos during 1998–2000 at the village of Chalcatzingo (population initially with 2760 inhabitants and 530 houses).

Pre‐intervention surveys detected scorpions (Scorpiones: Buthidae) of two species in the majority of houses: Centruroides limpidus limpidus Karsch outnumbering Vaejovis mexicanus smithi Koch. Scorpion prevalence was assessed, pre‐ and post‐spray, directly by searching (40 min/house) and by householder reports of sightings inside houses. Pre‐intervention perceptions of scorpion abundance were similar for all areas, with sightings in 12–18% of houses, whereas daytime searches detected more infestations in eastern parts of the village (prevalence 17% indoors, 22% outdoors) than in other sectors (9% indoors, 14% outdoors).

Pyrethroids were evaluated as residual treatments in separate sectors of Chalcatzingo, with almost complete coverage indoors and peridomestically, using the following four formulations: bifenthrin 10% wettable powder (WP) applied at 50 mg a.i./m2, cyfluthrin 10% WP (Solfac 10 WP) at 44–55 mg a.i./m2, deltamethrin 2.5% suspension concentrate (Biothrin 25 SC) at 11 mg a.i./m2 and 5% WP (K‐Othrine 50 WP) at 35 mg a.i./m2. Phase 1 compared bifenthrin 10 WP, Solfac 10 WP and Biothrin 25 SC sprayed in December 1998; phase 2 compared Solfac 10 WP and K‐Othrine 50 WP sprayed in June and again in December 2000, with follow‐up surveys of scorpions one month post‐spray and subsequently.

Scorpion prevalence was reduced by 64–77% peridomestically one month post‐spray and by 83, 46 and 15% in houses sprayed with cyfluthrin WP, bifenthrin WP or deltamethrin SC, respectively. Householder reports of sighting scorpions indoors were 33–85% below pre‐intervention levels. Cumulative effects of the three spray‐rounds over 3 years reduced scorpion prevalence by ∼60% in the deltamethrin WP re‐sprayed area and by ∼90% in the cyfluthrin WP re‐sprayed area. Householder sightings also fell by 67 and 28% in the cyfluthrin and deltamethrin re‐sprayed areas, respectively. Operational efficacy of these products against scorpions at the dosages applied was ranked as cyfluthrin WP > bifenthrin WP > deltamethrin SC > WP. Reported cases of scorpion sting intoxication fell by 17% during this study after having risen by ∼40% over four previous years.
A system for maintaining the educational and training standards of junior doctors
Authors: Rolfe  , Gordon  , Atherton  , Pearson  , Kay  , Fardell
Published: March 2003

The development of junior doctors' competence is complex because the hospital environment in which doctors work places many demands on them. The need for quality education and training and personal development may be in direct conflict with the service commitments required from hospitals. This paper describes the methods by which the Postgraduate Medical Council of New South Wales, Australia, addresses the needs of junior doctors in the state in order to improve the quality of their education. Key elements of the Council's function include the provision of hospital clinical supervisors who oversee junior doctor education and training, and central involvement in supplying the junior doctor workforce to all state hospitals who must meet defined accreditation standards. This paper also provides data on evaluation of those methods and some educational outcomes.
The difference between Japan and other countries, in particular the United Kingdom, in views regarding the teaching of geriatrics to undergraduate medical students
Authors: Matsuse Takeshi , Ozawa Toshio , Orimo Hajime , Fukuchi Yoshinosuke , Ouchi Yasuyoshi , Iriki Masamitsu
Published: March 2003

Objectives

To examine differences in views on geriatrics education at the undergraduate level between Japan and other industrialized countries, including the United Kingdom.

Design

We conducted a nationwide survey of professorial staff responsible for undergraduate education in all medical schools in Japan, and an international survey of 37 medical schools and geriatric institutes in other industrialized countries, including 16 medical schools in the United Kingdom.

Results

The results indicate that undergraduate education in geriatrics in Japan emphasizes the theoretical aspects of the aging process and the features of diseases in the elderly, and lacks attention to the practical aspects of care. In contrast, geriatrics education in the United Kingdom and other countries places emphasis on practical aspects of the care of the elderly.

Conclusions

The introduction of practical aspects of management and care of the elderly to the undergraduate education programme in geriatrics in each medical school in Japan is strongly recommended. This is especially important to meet the needs of the rapid demographic shift towards an older population in this country.
Does formal approval of educational courses guarantee quality?
Authors: Nicol  , Patterson
Published: March 2003

Objectives

To assess whether organizers of continuing medical education for general practitioners used principles of adult learning when designing their meetings.

Design

A questionnaire study of organizers of approved educational meetings for general medical practitioners (GPs).

Setting

South East Scotland

Subjects

Organizers of educational meetings.

Results

Organizers often failed to use principles of adult learning in the construction of their meetings. Organizers with prior training in medical education were, however, significantly more likely to adopt these principles.

Conclusions

Given concern about the quality of educational meetings as assessed by their educational impact, formal approval is not an indicator of quality. Postgraduate bodies should use explicit criteria both in the development and approval of continuing educational meetings.
Teaching support in the behavioural sciences for non‐English speaking background medical undergraduates
Authors: Chur‐Hansen
Published: March 2003

Introduction

This paper reports on a teaching strategy designed to support first year undergraduate medical students from non‐English speaking backgrounds in a behavioural science course taught at an Australian university.

Method

The strategy is described, as is the language profile of students from two successive cohorts who participated in the teaching programme. The effectiveness of the intervention in improving students’ academic performance is explored, as gauged by summative assessment and student perceptions.

Conclusions

Findings suggest that students disadvantaged by difficulties with language and/or knowledge of Australian culture were able to perform at least as well as other students on a number of summative criteria. Non‐English speaking background students perceived the behavioural science course to be difficult, and indicated that they found the teaching support offered to them to be useful. The methodological difficulties and limitations involved in the evaluation of a teaching programme such as this are discussed and the conclusions that can be validly drawn are considered.
Can medical students contribute to quality assurance programmes in day surgery?
Authors: Rudkin Glenda E , O’Driscoll Mary C E , Limb Robin
Published: March 2003

Subjects and methods

Health care delivery has undertaken a major shift from inpatient management to ambulatory surgical care with increasing emphasis on quality assurance (QA) processes. Educational opportunities for medical undergraduate programmes are being sought in the day surgery environment. Our study was undertaken to explore ways in which senior medical students can actively contribute to the QA processes as part of an undergraduate day surgery educational programme.

Subjects and methods

Fifty‐nine final year medical students followed allocated patients with common surgical conditions through all phases of the day surgery process. Students kept records about each case in a log book and also presented their cases at weekly Problem Based Learning tutorials. An audit of student log books and review of tutorial records was conducted for the 1996 and 1997 academic years, in order to evaluate student contribution to QA.

Results

Students followed 621 cases, representing a sampling of 14·1% day surgery cases. Categories of problems highlighted by students included inappropriate patient and procedure selection, inadequate pain management, discharge, communication and resource issues. Students made a number of recommendations including the development of multilingual videotapes and patient information sheets for non‐English speaking patients, avoidance of bilateral surgical procedures and improved links with local medical officers. They also developed new guidelines and protocols.

Conclusions

Our study confirms that students are able to identify QA issues and propose solutions. We recommend that students have a formally recognized place in day surgery QA programmes, to close the QA loop and to adequately prepare them for medical practice in the 21st century.
Microsatellite analysis of demographic genetic structure in fragmented populations of the tropical tree Symphonia globulifera
Authors: ALDRICH PRESTON R. , HAMRICK J. L. , CHAVARRIAGA PAUL , KOCHERT GARY
Published: March 2003

We developed genetic markers for three microsatellite loci in the tropical tree Symphonia globulifera and used them to examine the demographic genetic consequences of forest fragmentation. High levels of genetic variation were revealed in samples of adults, saplings, and seedlings. The more‐variable loci exhibited less stability in allelic composition across sites and stages. The number of alleles per hectare (ha) of forest was similar when continuous forest plots were compared to plots from fragmented forest for all three stages. This pattern also held for the number of unique multilocus adult and sapling genotypes, but the number of unique seedling genotypes per ha of fragmented forest greatly exceeded expectations based on continuous forest data, probably due to the concentration of seeds into remnant forest patches by foraging bats. Significant inbreeding and genetic differentiation were most often associated with the fragmented forest and the seedlings. Finally, principal component analysis reaffirmed that a bottleneck, acting in concert with pre‐existing genetic structure in the adults, had led to enhanced and rapid divergence in the seedlings following deforestation, a result that is of central interest for landscape management.
Microsatellites indicate a high frequency of multiple paternity in Apodemus (Rodentia)
Authors: Baker R. J. , Makova K. D. , Chesser R. K.
Published: March 2003

Microsatellites were employed to estimate frequency of multiple paternity litters of two species of mice (genus Apodemus): striped field mouse (A. agrarius), and wood mouse (A. sylvaticus). Ten pregnant females of A. agrarius and six of A. sylvaticus were collected from natural populations in the northern Ukraine and analysed with 11 and nine microsatellite loci, respectively. Multiple paternity was indicated in eight of 10 litters in A. agrarius and in three of six litters in A. sylvaticus. Multiple paternity was documented at several loci (ranging from two to 10). In two cases (A. agrarius), three males were estimated to have fathered the litter.
Clonal diversity in the rareCalamagrostis porterissp.insperata(Poaceae): comparative results for allozymes and random amplified polymorphic DNA (RAPD) and intersimple sequence repeat (ISSR) markers
Authors: ESSELMAN E. J. , JIANQIANG L. , CRAWFORD D. J. , WINDUS J. L. , WOLFE A. D.
Published: March 2003

Four populations of the rare, highly clonal grassCalamagrostis porterissp.insperatawere examined using allozymes and the two polymerase chain reaction (PCR)‐based markers, random amplified polymorphic DNA (RAPD) and intersimple sequence repeat (ISSR) bands. Only one of the 15 allozyme loci was variable and two alleles were detected, both of which were found in two populations, while only one genotype was detected in the other two populations. ISSR and RAPD markers detected more genotypes within populations than did allozymes. ISSR markers detected more diversity than RAPD markers in three of the four populations examined. In one population, no RAPD diversity was found whereas eight different genotypes were found among the 10 plants with ISSR markers. This diversity is present despite rare flowering, no documented occurrence of seed set in natural populations and very low seed set with experimental pollinations, all of which suggest that sexual reproduction rarely occurs. The subspecies is self‐compatible, but seed initiation is lower in selfed ovules; also, there is high embryo abortion regardless of pollen source. Variation detected by RAPD and ISSR primers may reflect higher levels of sexual reproduction in the past, very rare sexual reproduction in extant populations, somatic mutations, or a combination of the three. Although the PCR‐based markers identify several multilocus genotypes within populations, it is not known whether these all represent distinct genets generated by sexual reproduction or result from somatic mutations in the old, perennial and highly clonal plants.
Population genetics of the yellow fever mosquito in Trinidad: comparisons of amplified fragment length polymorphism (AFLP) and restriction fragment length polymorphism (RFLP) markers
Authors: Yan G. , Romero‐Severson J. , Walton M. , Chadee D. D. , Severson D. W.
Published: March 2003

Recent development of DNA markers provides powerful tools for population genetic analyses. Amplified fragment length polymorphism (AFLP) markers result from a polymerase chain reaction (PCR)‐based DNA fingerprinting technique that can detect multiple restriction fragments in a single polyacrylamide gel, and thus are potentially useful for population genetic studies. Because AFLP markers have to be analysed as dominant loci in order to estimate population genetic diversity and genetic structure parameters, one must assume that dominant (amplified) alleles are identical in state, recessive (unamplified) alleles are identical in state, AFLP fragments segregate according to Mendelian expectations and that the genotypes of an AFLP locus are in Hardy–Weinberg equilibrium (HWE). The HWE assumption is untestable for natural populations using dominant markers. Restriction fragment length polymorphism (RFLP) markers segregate as codominant alleles, and can therefore be used to test the HWE assumption that is critical for analysing AFLP data. This study examined whether the dominant AFLP markers could provide accurate estimates of genetic variability for the Aedes aegypti mosquito populations of Trinidad, West Indies, by comparing genetic structure parameters using AFLP and RFLP markers. For AFLP markers, we tested a total of five primer combinations and scored 137 putative loci. For RFLP, we examined a total of eight mapped markers that provide a broad coverage of mosquito genome. The estimated average heterozygosity with AFLP markers was similar among the populations (0.39), and the observed average heterozygosity with RFLP markers varied from 0.44 to 0.58. The average FST (standardized among‐population genetic variance) estimates were 0.033 for AFLP and 0.063 for RFLP markers. The genotypes at several RFLP loci were not in HWE, suggesting that the assumption critical for analysing AFLP data was invalid for some loci of the mosquito populations in Trinidad. Therefore, the results suggest that, compared with dominant molecular markers, codominant DNA markers provide better estimates of population genetic variability, and offer more statistical power for detecting population genetic structure.
Molecular markers linked to breeding system differences in segregating and natural populations of the cereal aphid Rhopalosiphum padi L.
Authors: Simon J.‐C. , Leterme N. , Latorre A.
Published: March 2003

The aphid Rhopalosiphum padi shows coexistence of sexual and asexual populations, providing an opportunity to study the evolution of breeding system variation in the context of theories on the origin and maintenance of sex. However, assessments of the distribution of sexual and asexual lineages of this aphid are complicated by the difficulties in rapidly characterizing their breeding system. To facilitate this task and to gain insight into the genetic relatedness between sexual and asexual genotypes, molecular markers linked to breeding system differences were recently developed. In this study, we have successfully converted a random amplified polymorphic DNA (RAPD) marker associated with life‐cycle variation in R. padi into a codominant sequence‐characterized amplified region (SCAR). Segregating and natural populations of known breeding systems were examined to evaluate the life cycle–SCAR marker association. Complete linkage was found in segregating populations while the association averaged 94% in field populations. Detailed analysis of allelic distribution and sequence divergence of the SCAR locus among sexual and asexual populations provides further evidence for a unique and apparently ancient loss of sexuality in this aphid. It also suggests that occasional gene flow occurs between populations differing in their breeding system, mediated by males produced by ‘asexual’ lineages. This system provides the possibility for the recurrent emergence of new asexual lineages, ensuring the longer persistence of asexuality, and would have important implications for the assessment of costs and benefits of sex in aphids.
Temporal genetic variation of mitochondrial DNA and the female effective population size of red drum (Sciaenops ocellatus) in the northern Gulf of Mexico
Authors: Turner Thomas F. , Richardson Linda R. , Gold John R.
Published: March 2003

We studied genetic drift of mitochondrial DNA (mtDNA) haplotype frequencies in a natural population of red drum (Sciaenops ocellatus) from the northern Gulf of Mexico (Gulf). The amount of genetic drift observed across temporally adjacent year classes (1986–89) was used to estimate variance effective (female) population size (Nef). Nef was estimated to be 14 308 and the ratio of female effective size to adult female census size was approximately 0.004, which is among the lowest value reported for vertebrate animals. Low effective size relative to census size among red drum in the northern Gulf may result from yearly fluctuations in the number of breeding females, high variance in female reproductive success, or both. Despite low genetic effective size relative to census size, the genetic effective population size of red drum in the northern Gulf appears sufficiently large to preclude potentially deleterious effects of inbreeding.
High level of variation at Abies alba chloroplast microsatellite loci in Europe
Authors: Vendramin G. G. , Degen B. , Petit R. J. , Anzidei M. , Madaghiele A. , Ziegenhagen B.
Published: March 2003

Based on two polymorphic chloroplast microsatellites that had been previously identified and sequence characterized in the genus Abies, genetic variation was studied in a total of 714 individuals from 17 European silver fir (Abies alba Mill.) populations distributed all over the natural range. We found eight and 18 different length variants at each locus, respectively, which combined into 90 different haplotypes. Genetic distances between most populations were high and significant. There is also evidence for spatial organization of the distribution of haplotypes, as shown by permutation tests, which demonstrate that genetic distances increase with spatial distances. A large heterogeneity in levels of diversity across populations was observed. Furthermore, there is good congruence in the levels of allelic richness of the two loci across populations. The present organization of levels of allelic richness across the range of the species is likely to have been shaped by the distribution of refugia during the last glaciation and the subsequent recolonization processes.
A mitochondrial marker for red algal intraspecific relationships
Authors: Zuccarello G. C. , Burger G. , West J. A. , King R. J.
Published: March 2003

Intraspecific studies of red algae have relied on nuclear or plastid markers rather than mitochondrial data to address questions of systematics, biogeography or population genetics. In this study, primers were developed that spanned the noncoding intergenic region between the mitochondrial cytochrome oxidase subunit 2 and cytochrome oxidase subunit 3 genes. These primers were demonstrated to be successful on a variety of red algae in different orders: Gracilariales, Bonnemaisoniales and Ceramiales (families: Delesseriaceae, Ceramiaceae and Rhodomelaceae). Amplification products were between 450 and 320 bp in length, with variation in length shown among geographically distant isolates within a species. The region was variable within a single species, as shown for Bostrychia moritziana and B. radicans, and within populations of Caloglossa leprieurii. In the latter species, four mitochondrial haplotypes were observed in isolates from a single locality in Woolooware Bay, New South Wales, Australia. Analysis of hybrids between different mitochondrial haplotypes of B. moritziana revealed that the mitochondria are maternally inherited in this species. This is the first report of a mitochondrial marker that is variable within red algal populations and may lead to a better understanding of the population ecology of these important marine organisms.
Genetic structure of the world’s polar bear populations
Authors: Paetkau D. , Amstrup S. C. , Born E. W. , Calvert W. , Derocher A. E. , Garner G. W. , Messier F. , Stirling I. , Taylor M. K. , Wiig Ø. , Strobeck C.
Published: March 2003

We studied genetic structure in polar bear (Ursus maritimus) populations by typing a sample of 473 individuals spanning the species distribution at 16 highly variable microsatellite loci. No genetic discontinuities were found that would be consistent with evolutionarily significant periods of isolation between groups. Direct comparison of movement data and genetic data from the Canadian Arctic revealed a highly significant correlation. Genetic data generally supported existing population (management unit) designations, although there were two cases where genetic data failed to differentiate between pairs of populations previously resolved by movement data. A sharp contrast was found between the minimal genetic structure observed among populations surrounding the polar basin and the presence of several marked genetic discontinuities in the Canadian Arctic. The discontinuities in the Canadian Arctic caused the appearance of four genetic clusters of polar bear populations. These clusters vary in total estimated population size from 100 to over 10 000, and the smallest may merit a relatively conservative management strategy in consideration of its apparent isolation. We suggest that the observed pattern of genetic discontinuities has developed in response to differences in the seasonal distribution and pattern of sea ice habitat and the effects of these differences on the distribution and abundance of seals.
Amplified fragment length polymorphism (AFLP) markers reveal that population structure of triploid dandelions (Taraxacum officinale) exhibits both clonality and recombination
Authors: Van Der Hulst R. G. M. , Mes T. H. M. , Den Nijs J. C. M. , Bachmann K.
Published: March 2003

Highly variable amplified fragment length polymorphism (AFLP) fingerprints of triploid apomictic dandelions obtained from three localities in an area where diploids are lacking were analysed to infer the predominant modes of reproduction. The distribution of markers was analysed using character compatibility to infer whether many genotypes agree with a tree‐like structure in the data set. The presence of incompatible character state combinations (matrix incompatibility; MI) was used as a measure of genetic exchange. The detection of overrepresented genotypes, of which some were widespread, confirmed asexual reproduction. Not all genotypes were overrepresented; approximately half of the genotypes in the three localities were found only once. Because, in terms of genotype frequencies, only a part of the genetic variation is described, more important aspects of the molecular data such as relationships between markers or genotypes have been studied. The analysis of character compatibility indicated a disagreement of the data with a clonal structure. Nearly all genotypes contributed to MI and this contribution varied considerably among genotypes in each sampled locality. A gradual decrease of matrix incompatibility upon successive deletion of genotypes showing the highest contribution to MI indicated that marker distribution of virtually all genotypes disagreed with a tree‐like structure in the data. This result suggested that many genotypes were separated by one or more sexual generations. Consistent with this conclusion was the fact that markers that show a low probability of contributing to MI are different in every sampled locality, which is most easily explained as the result of recombination. Apparently, asexual reproduction has resulted in overrepresented, widespread genotypes but sexual recombination has also substantially contributed to genetic variation in the sites studied.
Multiple paternity in side‐neck turtlesPodocnemis expansa: evidence from microsatellite DNA data
Authors: Valenzuela N.
Published: March 2003

Multiple paternity was found in two clutches ofPodocnemis expansausing eight microsatellite loci. When loci were analysed separately a minimum of two males was estimated for nest N23, and three for nest C17. When all loci were combined, three patrilines were detected in N23, and six in C17. The distribution of full‐sib cluster sizes indicated a disproportionate contribution of one male to clutch C17, consistent with possible sperm competition, or the mixing of leftover and newly acquired sperm. High mutation rates were detected at several loci. Multiple paternity has positive implications for this endangered species as it may slow the loss of genetic variability caused by drift. This is the first report of multiple paternity in the suborder Pleurodira.
Microsatellite DNA analysis of genetic effects of harvesting in old‐growth eastern white pine (Pinus strobus) in Ontario, Canada
Authors: Rajora O. P. , Rahman M. H. , Buchert G. P. , Dancik B. P.
Published: March 2003

Microsatellite DNA markers from 13 simple sequence repeat (SSR) loci were used to compare genetic diversity between preharvest pristine and postharvest residual gene pools of two adjacent virgin, old‐growth (≈ 250 years) stands of eastern white pine (Pinus strobus L.) in Ontario. There was concurrence in genetic diversity changes in the postharvest gene pools of the two stands. The total and mean numbers of alleles detected in each stand were reduced by ≈ 26% after tree density reductions of ≈ 75%. Approximately 18 and 21% of the low‐frequency (0.25 > P ≥ 0.01) alleles and 76 and 92% of the rare (P < 0.01) alleles were lost from residual stands A and B, respectively, after harvesting. Multilocus gametic diversity was reduced by 38 and 85% and genotype additivity by ≈ 50% in the residual stands after harvesting. Latent genetic potential of each stand was reduced by ≈ 40%. Although heterozygosity was reduced (1–5%) in the postharvest residual stands, the reductions were not substantial and not comparable to those using other genetic diversity measures. The reductions in genetic diversity measures were slightly higher than those theoretically expected in postbottleneck populations according to drift theory. In the absence of substantial gene migration that could ameliorate the genetic losses, the ability of the postharvest white pine gene pools to adapt to changing environmental and disease conditions may have been compromised. The microsatellite DNA results for genetic effects of harvesting in old‐growth eastern white pine stands were similar to those that we reported earlier from allozyme analysis (
Buchert et al. 1997
). The results indicate that silvicultural practices should ensure that the gene pools of remaining pristine old‐growth stands are reconstituted in the regenerating stands.
Phylogeographical pattern correlates with Pliocene mountain building in the alpine scree weta (Orthoptera, Anostostomatidae)
Authors: Trewick S. A. , Wallis G. P. , Morgan‐Richards M.
Published: March 2003

Most research on the biological effects of Pleistocene glaciation and refugia has been undertaken in the northern hemisphere and focuses on lowland taxa. Using single‐strand conformation polymorphism (SSCP) analysis and sequencing of mitochondrial cytochrome oxidase I, we explored the intraspecific phylogeography of a flightless orthopteran (the alpine scree weta, Deinacrida connectens) that is adapted to the alpine zone of South Island, New Zealand. We found that several mountain ranges and regions had their own reciprocally monophyletic, deeply differentiated lineages. Corrected genetic distance among lineages was 8.4% (Kimura 2‐parameter [K2P]) / 13% (GTR + I + Γ), whereas within‐lineage distances were only 2.8% (K2P) / 3.2% (GTR + I + Γ). We propose a model to explain this phylogeographical structure, which links the radiation of D. connectens to Pliocene mountain building, and maintenance of this structure through the combined effects of mountain‐top isolation during Pleistocene interglacials and ice barriers to dispersal during glacials.
Molecular phylogeography and cryptic speciation in the mosses, Mielichhoferia elongata and M. mielichhoferiana (Bryaceae)
Authors: Shaw A. J.
Published: March 2003

Nucleotide sequence variation in the ITS1–5.8S–ITS2 region of nuclear ribosomal DNA (nrDNA) from 70 populations of Mielichhoferia elongata and M. mielichhoferiana, plus two outgroup species, was analysed using maximum parsimony and maximum likelihood methods. High levels of nucleotide substitution and numerous insertion–deletion events were detected within and between the two species. M. elongata is monophyletic with regard to nrDNA variation, but M. mielichhoferiana is paraphyletic. (M. elongata is nested within it.) A clade within M. mielichhoferiana provides evidence of vicariance, with North American and Scandinavian sister groups of populations. Two major clades are resolved in M. elongata by sequence data that are completely congruent with previous isozyme work. One clade includes populations from both North America and Europe whereas the other is strictly North American. These two clades, resolved by multiple independent loci, clearly represent cryptic species within the morphologically uniform M. elongata. Certain geographical areas, most notably southwestern Colorado in Ouray and San Juan Counties, harbour diverse populations of M. elongata with distinct phylogenetic and phylogeographical histories. Morphologically indistinguishable but phylogenetically distant populations were detected a few metres apart at one site. In contrast, all populations collected over hundreds of kilometres in California belong to a single clade. Arctic North American populations belong to a clade that includes disjunct populations in Alaska, northern Ellesmere Island, and the northeastern USA, but not subarctic Swedish populations, which are more closely related to plants from the Rocky Mountains. Morphological uniformity belies complex infraspecific phylogenetic patterns within M. elongata and M. mielichhoferiana.
Accurate gene diversity estimates from amplified fragment length polymorphism (AFLP) markers
Authors: Krauss Siegfried L.
Published: March 2003

Three procedures for the estimation of null allele frequencies and gene diversity from dominant multilocus data were empirically tested in natural populations of the outcrossing angiosperm Persoonia mollis (Proteaceae). The three procedures were the square root transform of the null homozygote frequency, the Lynch & Milligan procedure, and the Bayesian method. Genotypes for each of 116 polymorphic loci generated by amplified fragment length polymorphism (AFLP) were inferred from segregation patterns in progeny arrays. Therefore, for the plus phenotype (band present), heterozygotes were distinguished from homozygotes. In contrast to previous studies, all three procedures produced very similar mean estimates of heterozygosity, which were in turn accurate estimators of the direct value (HO = 0.28). A second population of P. mollis displayed markedly lower levels of heterozygosity (HO = 0.20) but approximately twice as many polymorphic loci (284). These AFLP results show that biases in estimates of average null allele frequency and heterozygosity are largely eliminated in highly polymorphic dominant marker data sets displaying a J‐shaped beta distribution with a high percentage of loci containing more than three null homozygotes and relatively few loci with no null homozygotes. This distribution may be typical of outcrossing angiosperms.
RAPD variation and population genetic structure inPrunus mahaleb(Rosaceae), an animal‐dispersed tree
Authors: Jordano Pedro , Godoy José A.
Published: March 2003

We examined the patterns of random amplified polymorphic DNA (RAPD) variation among sevenPrunus mahaleb(Rosaceae) populations extending over ≈ 100 km2to examine local differentiation in relation to spatial isolation due to both geographical distance and differences in elevation. No less than 51.4% of the RAPD loci were polymorphic, but very few were fixed and among‐population variation accounted for 16.46% of variation in RAPD patterns. Mean gene diversity was 0.1441, with mean Nei’s genetic diversity for individual populations ranging between 0.089 and 0.149. MeanGSTvalue across loci was 0.1935 (range, 0.0162–0.4685), giving an average estimate forNmof 1.191. These results suggest extensive gene flow among populations, but higherGSTand lowerNmvalues relative to other outcrossing, woody species with endozoochorous dispersal, also suggest a process of isolation by distance. The combined effect of both geographical and elevation distances and nonoverlapping flowering and fruiting phenophases on theGSTmatrix was partially significant, revealing only marginal isolation of theP. mahalebpopulations. The matrix correlation between estimatedNmvalues among populations and the geographical + elevation distance matrices (r = −0.4623,P = 0.07), suggests a marginal trend for more isolated populations to exchange less immigrants. Long‐distance seed dispersal by efficient medium‐sized frugivorous birds and mammals is most likely associated to the high levels of within‐population genetic diversity. However, vicariance factors and demographic bottlenecks (high postdispersal seed and seedling mortality) explain comparatively high levels of local differentiation.
High genetic variation in leopards indicates large and long‐term stable effective population size
Authors: Spong G. , Johansson M. , Björklund M.
Published: March 2003

In this paper we employ recently developed statistical and molecular tools to analyse the population history of the Tanzanian leopard (Panthera pardus), a large solitary felid. Because of their solitary lifestyle little is known of their past or present population dynamics. Eighty‐one individuals were scored at 18 microsatellite loci. Overall, levels of heterozygosity were high (0.77 ± 0.03), with a small heterozygote deficiency (0.06 ± 0.03). Effective population size (Ne) was calculated to be 38 000–48 000. A Ne:N ratio of 0.42 (average from four cat studies) gives a present population size of about 100 000 leopards in Tanzania. Four different bottleneck tests indicated that this population has been large and stable for a minimum of several thousand years. FST values were low and no significant genetic structuring of the population could be detected. This concurs well with the large migration values (Nm) obtained (>3.3 individuals/generation). Our analysis reveals that ecological factors (e.g. disease), which are known to have had major impact on other carnivore populations, are unlikely to have impacted strongly on the population dynamics of Tanzanian leopards. The explanation may be found in their solitary life‐style, their often nonconfrontational behaviour toward interspecific competitors, or that any bottlenecks have been of limited size, localized, or too short to have affected genetic variation to any measurable degree. Since the genetic structuring is weak, gene flow is not restricted to within protected areas. Local loss of genetic variation is therefore not of immediate concern.
Molecular analysis of orchid pollinaria and pollinaria‐remains found on insects
Authors: Widmer A. , Cozzolino S. , Pellegrino G. , Soliva M. , Dafni A.
Published: March 2003

Direct observations of pollinator visits to orchids are often difficult and time consuming, especially in orchids with a deceptive pollination system where seed set is typically pollinator‐limited. This lack of direct observations greatly inhibits our understanding of orchid–pollinator relationships and especially the degree of pollinator‐specificity. Here we describe a molecular approach to the study of orchid–pollinator relationships based on the analysis of DNA recovered from pollinaria found on insects. The insects were collected from nectar‐rich plants flowering near natural orchid populations, or taken from museum collections. Sequence analysis of the nuclear ribosomal ITS region allowed the identification of the orchid species or species‐group from which the pollinaria originated. Four out of eight orchid–pollinator relationships established with this approach have not been reported previously, which highlights the value of molecular tools for the study of orchid pollination biology.
Patterns and levels of gene flow in Rhododendron metternichii var. hondoense revealed by microsatellite analysis
Authors: Kameyama Yoshiaki , Isagi Yuji , Nakagoshi Nobukazu
Published: March 2003

Parentage analysis was conducted to elucidate the patterns and levels of gene flow in Rhododendron metternichii Sieb. et Zucc. var. hondoense Nakai in a 150 × 70 m quadrat in Hiroshima Prefecture, western Japan. The population of R. metternichii occurred as three subpopulations at the study site. Seventy seedlings were randomly collected from each of three 10 × 10 m plots (S1, S2, and S3) on the forest floor of each subpopulation (A1, A2, and A3). Almost all parents (93.8%) of the 70 seedlings were unambiguously identified by using 12 pairs of microsatellite markers. Within the quadrat, adult trees less than 5 m from the centre of the seedling bank (plots S1, S2, and S3) produced large numbers of seedlings. The effects of tree height and distance from the seedling bank on the relative fertilities of adult trees were highly variable among subpopulations because of the differences in population structure near the seedling bank: neither distance nor tree height had any significant effect in subpopulation A1; distance from the seedling bank had a significant effect in subpopulation A2; and tree height had a significant effect in subpopulation A3. Although gene flow within each subpopulation was highly restricted to less than 25 m and gene flow among the three subpopulations was extremely small (0–2%), long‐distance gene flow from outside the quadrat reached 50%. This long‐distance gene flow may be caused by a combination of topographical and vegetational heterogeneity, differences in flowering phenology, and genetic substructuring within subpopulations.