bluuebunny/crossref_metadata_2025 huggingface dataset:
Cattle breed‐variation in infestation by the horn fly Haematobia irritans
Authors: Guglielmone A. A. , Curto E. , Anziani O. S. , Mangold A. J.
Published: March 2003

A study was carried out to assess the resistance of pure and cross‐bred groups of cattle to the horn fly Haematobia irritans (Linnaeus) (Diptera: Muscidae) in northern Argentina. Pure‐bred cattle were Criolla, Iberian Bos taurus Linnaeus (Artiodactyla: Bovidae) and Nellore, Bos indicus Linnaeus (Artiodactyla: Bovidae). Cross‐bred cattle were Hereford, British B. taurus (34%) × Nellore (66%) and Hereford (66%) × Nellore (34%). All were heifers and animals were maintained in two groups, each containing a mixture of pure and cross‐breeds. The lowest fly numbers were found on Criolla heifers and the highest on Hereford × Nellore cross‐breeds. However, it could not be determined from this study whether this was a consequence of breed and/or size, as Criolla heifers were lighter than the corresponding Hereford × Nellore heifers. Fly numbers on the heifers followed an approximately negative binomial distribution. However, the ranking of individual animals in their level of infestation within subgroups was not consistent. Hence, culling the most infested heifers on any given date would at best give only a small improvement in H. irritans control.
Feeding and survival of Culicoides sonorensis on cattle treated with permethrin or pirimiphos‐methyl
Authors: Mullens B. A. , Velten R. K. , Gerry A. C. , Braverman Y. , Endris R. G.
Published: March 2003

The persistence of permethrin (5% a.i.) and pirimiphos‐methyl (27% a.i.), applied to the dorsum of calves in the field against Culicoides sonorensis Wirth and Jones (Diptera: Ceratopogonidae), was estimated using a hair‐blood‐feeding bioassay in the laboratory. Hair clippings were taken before treatment and 3, 7, 14, 21, 28, 42 and 56 days after treatment from the dorsum, side and belly of treated and control calves. Laboratory‐reared insects were allowed to feed through thin hair layers and a parafilm membrane on sheep blood warmed using a water‐jacketed feeder. Some intoxication after exposure to hair was noted up to 28 days after treatment with permethrin and up to 14 days after treatment with pirimiphos‐methyl. Hair from the dorsum caused more intoxication for a longer period than hair from other body regions. Permethrin and pirimiphos‐methyl applied to the back did not significantly reduce overall engorgement (body regions pooled) after treatment. Permethrin residues on hair remained far higher on the back than other body regions and were related to insect intoxication and reduction in engorgement in the laboratory. Residues on belly hair never exceeded 12 p.p.m. and did not result in significantly reduced feeding at any time. Engorged insects that exhibited sublethal intoxication from feeding through permethrin‐treated hair did recover and matured numbers of eggs comparable to controls. Field trials using treated and control calves and enclosure nets showed that dorsal applications of 5% permethrin were not effective in reducing engorgement, despite some intoxication. Vacuum samples from a calf showed that C. sonorensis fed primarily on the belly. A 0.2% permethrin application on the belly (250 ml) did result in > 80% reduction of C. sonorensis in the enclosure nets at 3 and 7 days after treatment, but activity had subsided by 10 days after treatment. The utility of insecticidal treatments for suppression of this vector is discussed.
Use of deltamethrin ‘pour‐on’ insecticide for the control of cattle trypanosomosis in the presence of high tsetse invasion
Authors: Rowlands G. J. , Leak S. G. A. , Mulatu Woudyalew , Nagda S. M. , Wilson A. , D'Ieteren G. D. M.
Published: March 2003

A deltamethrin ‘pour‐on’ insecticide was applied monthly to over 2000 cattle exposed to a high challenge of drug‐resistant trypanosomes and high tsetse re‐invasion pressure in the Ghibe valley, south‐west Ethiopia. Blood samples were taken monthly from an average of 760 cattle for determination of PCV and presence of trypanosomes. The area of the valley is approximately 350 km2 and the cattle grazed in roughly four locations covering about a quarter to half of the area. Two years before the trial commenced, Glossina morsitans submorsitans Newstead (Diptera: Glossinidae) began to invade the valley. Despite the use of the pour‐on the mean apparent density of G. m. submorsitans continued to rise, and, during the 4 years of tsetse control, was more than three‐fold higher than that recorded during the previous 18 months. Over the same period there was little change in the apparent density of Glossina pallidipes Austen (Diptera: Glossinidae). By contrast, the mean monthly prevalence of trypanosome infections in cattle over 36 months of age decreased from 38.3 to 29.0%, the incidence of new infections decreased from 26.6 to 16.0% (a reduction of 40%), and packed cell volume in cattle increased from 21.7 to 24.1%. Evidence of a change in apparent parasite transmission rate was demonstrated by regression of infection incidence in cattle on the logarithm of apparent density of G. m. submorsitans. Before the trial started the regression coefficient was 45.8 ± 6.3 and this reduced to 9.2 ± 2.5% incidence per loge (flies/trap/day) during the period of tsetse control. It was concluded that this indicated reductions in tsetse numbers in the immediate vicinities of cattle in a way that was not reflected in overall tsetse catches. Nevertheless, the comparatively high levels of trypanosome prevalence that persisted in the cattle demonstrates that, where invasion prevalence is high, treatment of small pockets of cattle will not eradicate tsetse. To achieve more significant reduction in trypanosome prevalence in cattle, integrated methods of control utilizing target barriers in the major routes of invasion will be needed.
Biting behaviour and potential vector status of anthropophilic blackflies in a new focus of human onchocerciasis at Minaçu, central Brazil
Authors: Shelley A. J. , Maia‐Herzog M. , Dias A. P. A. Luna , Camargo M. , Costa E. G. , Garritano P. , Lowry C. A.
Published: March 2003

Monthly collections were made of man‐biting female blackflies: Simulium auripellitum Enderlein, S. guianense Wise, S. minusculum Lutz and S. nigrimanum Macquart (Diptera: Simuliidae) from four catching stations in the newly discovered focus of human onchocerciasis at Minaçu (13°35′ S 48°18′ W), 300 km north of Brasília in Goiás State. These provided baseline data on biting habits, population density and seasonal prevalence during the year before completion of the Serra da Mesa hydroelectric dam on the Rio Tocantins near Minaçu, in a project investigating the effect of dam construction on onchocerciasis transmission in the area. All four simuliid species were most abundant during the dry season, and only bit in low numbers (S. auripellitum S.minusculum, S. nigrimanum) or were absent (S. guianense) in the wet season. Simulium minusculum was the predominant species at all catching stations, being particularly abundant by the large River Tocantins. The other three species were mainly associated with smaller rivers. In the dry season, biting rhythms of S. minusculum varied with catching site, while S. nigrimanum showed peaks of activity in early morning and during the afternoon. Experimental infection with Onchocerca volvulus (Leuckart) (Nematoda: Onchocercidae), from a human volunteer, showed that this parasite could develop fully in the four simuliid species, which are all considered to be potential vectors in the area.
Landing responses of Anopheles gambiae elicited by oxocarboxylic acids
Authors: Healy T. P. , Copland M. J. W. , Cork A. , Przyborowska A. , Halket J. M.
Published: March 2003

Abstract A wind tunnel bioassay and video system were used to observe Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) landing on glass cylinders, heated to human skin temperature (34°C) and treated with aqueous solutions of oxocarboxylic acids. Six of nine compounds tested: 2‐oxobutanoic, 2‐oxo‐3‐methylbutanoic, 2‐oxopentanoic, 2‐oxo‐3‐methylpentanoic, 2‐oxo‐4‐methylpentanoic and 2‐oxohexanoic elicited significant landing responses in comparison to a water control. Landing responses appeared to be restricted to C4–C6, 2‐oxocarboxylic acids. A solution of 1 µg/µL of 2‐oxopentanoic acid elicited the highest level of response that was temperature dependent: significant numbers of landings occurred only within ± 2°C of human skin temperature. Chemical analysis by linked gas‐liquid chromatography/mass spectrometry of methyl‐oxime, trimethylsilyl derivatized samples of human sweat extracts revealed the presence of 2‐oxopropanoic (pyruvic) acid and three behaviourally active, branched chain acids: 2‐oxo‐3‐methylbutanoic, 2‐oxo‐3‐methylpentanoic and 2‐oxo‐4‐methylpentanoic.
Molecular and morphological studies on the Anopheles minimus group of mosquitoes in southern China: taxonomic review, distribution and malaria vector status
Authors: CHEN B. , HARBACH R. E. , BUTLIN R. K.
Published: March 2003

Abstract. Mosquitoes of the Anopheles minimus group (Diptera: Culicidae) from nine Provinces of southern China were identified morphologically and by molecular characterization, using single‐strand conformation polymorphisms (SSCPs) and sequence data for the D3 region of the 28S ribosomal DNA and the mitochondrial COII locus. Species A and C (sensu Green et al., 1990) of the An. minimus complex were found to be sympatric in Yunnan Province. Species A occurs eastward from Yunnan through southern Guangxi, Hainan, Guangdong and Taiwan Provinces, whereas species C occurs northward to northern Guangxi, Guizhou and Sichuan Provinces. Morphological and molecular evidence (based on specimens from the field and four isofemale lines) shows that An. minimus forms A and B (sensu Yu & Li, 1984) are morphological variants of species A, which is accepted as An. minimus Theobald sensu stricto (type‐locality: Pokfulam, Hong Kong). The so‐called subspecies x of An. minimus (sensu Baba, 1950) is reinterpreted as An. aconitus Dönitz. The distribution and vector status of members of the An. minimus group are discussed in relation to the historical and current transmission of malaria and filariasis in China. Both An. minimus A and C have been implicated as widespread vectors of malaria, whereas only species A has been found in Hainan, where An. minimus s.l. was a vector of Bancroftian filariasis. The presence of An. aconitus in Hainan and Yunnan Provinces is confirmed, but the occurrence of An. varuna Iyengar and An. fluviatilis James, which were previously recorded in China, could not be verified.
Video recording feedback: a feasible and effective approach to teaching history‐taking and physical examination skills in undergraduate paediatric medicine
Authors: Paul S , Dawson K P , Lanphear J H , Cheema M Y
Published: March 2003

Medical educators have always recognized the need to teach and train medical graduates and undergraduates the skills of conducting a consultation. Several authors have established the efficacy of using constructive feedback on videotape of each student's interaction with a patient to teach and enhance such skills. This study reports `students' perceptions' of the feedback process used in the Junior Paediatric Clerkship at the Faculty of Medicine of the United Arab Emirates University. An unexpected 73% of the respondents believed that self‐observation influenced development of their clinical skills. More than 80% said that the feedback from instructors and peers helped them to improve their clinical skills, but they would have liked to have more than one of their consultations recorded and reviewed. It was found that 75% of the students felt that self‐critique of their performance made them aware of their strengths and weaknesses and their skills in analysing and evaluating consultations had been enhanced. It was found from Kruskal Wallis one‐way ANOVA that the students' professional attitude, empathy, and warmth towards the patients differed highly significantly (P = 0·0062, 0·0089, 0·0007, respectively) from self‐assurance, self‐confidence and competence. They were also deficient in certain areas of history‐taking, interviewing skills, and physical examination techniques and perceived they needed more training in order to be proficient.
Undergraduate teaching in a day surgery unit: a 2‐year evaluation
Authors: Seabrook M A , Lawson M , Woodfield S , Baskerville P A
Published: March 2003

Medical schools are having to adapt their teaching in response to the reduction in inpatient availability and the increase in outpatient and community care. A surgical course for first clinical‐year undergraduate medical students was established in the day surgery unit at King's College School of Medicine and Dentistry in 1995. It was considered desirable because of the shift to day‐case surgery, and proved feasible to run (Seabrook et al. 1997a). The course is taken by one‐third of the annual intake of 120 students. A formal evaluation was undertaken comprising comparison of student performance in end‐of‐year clinical and multiple choice examinations and of acceptability to students, teachers and managers. The results showed no significant differences in performance between students who had taken the day‐surgery course and those on other surgical attachments. Students' satisfaction with the course was significantly higher on nine individual criteria and lower on four criteria. The teaching was positively viewed by teachers and managers, despite having costs as well as benefits. We conclude that day‐surgery centres can be used successfully to teach medical undergraduates. Experience in both inpatient and day‐case environments should benefit students by reflecting more closely the reality of current surgical care.
Extensive clonality in the endangered shrub Haloragodendron lucasii (Haloragaceae) revealed by allozymes and RAPDs
Authors: SYDES MARITA A. , PEAKALL ROD
Published: March 2003

The occurrence of clonality in threatened plants can have important implications for their conservation. In this study, allozymes and RAPDs were used to determine the extent of clonality in the endangered shrub Haloragodendron lucasii (Haloragaceae), which is known from only four sites within an 8 km range. Allozyme markers identified only six multilocus genotypes among the 53 ramets sampled across the four sites, although a total of 54 different genotypes were possible with the three polymorphic allozyme loci detected. The polymorphic bands detected in the RAPD analysis were capable of producing 246 genotypes, but again only six multilocus genotypes were delineated. The allozyme and RAPD data were congruent at three of the four sites. At the fourth site two genotypes were detected by each marker; however, once combined, three multilocus genotypes were observed. The probabilities that the observed number of replicates of each combined allozyme and RAPD genotype could be generated by sexual reproduction were less than 10–18, leaving little doubt that clonality is the explanation for the observed patterns of genotypes. The genetic conclusions are supported by root excavations which show potential for vegetative reproduction and the observation of no sexual reproduction in the species. The recognition of extensive clonality in H. lucasii has had immediate implications for the conservation management of the species and resulted in changes to the management priorities for the species. Thus it is clear that appropriate genetic studies can play an important role in the management of threatened species.
Influence of diet on the structure and function of the bacterial hindgut community of crickets
Authors: SANTO DOMINGO J. W. , KAUFMAN M. G. , KLUG M. J. , HOLBEN W. E. , HARRIS D. , TIEDJE J. M.
Published: March 2003

The effect of diets varying in carbohydrate and protein content on the structure and function of the hindgut microbiota of crickets was evaluated by determining bacterial densities, fermentation activity, and guanine plus cytosine (G + C) profiles of the DNA extracted from the microbial hindgut community. DNA isolated from the gut community was fractionated and quantified according to G + C content as a comprehensive, coarse‐level measure of the composition and structure of the community. The bacterial densities measured by direct counts were not significantly different among the four diets. The crickets were initially reared in the laboratory on cricket chow, which resulted in a hindgut community dominated by bacteria with a G + C content between 32% and 57%. Crickets shifted to an alfalfa diet showed a similar hindgut community G + C profile, although microbial populations with DNA between 35% and 45% G + C were more abundant in alfalfa‐ than chow‐fed crickets. The apparent complexity of the gut community was reduced in crickets fed beet‐pulp and protein‐based diets compared to those fed chow and alfalfa, and was dominated by populations with a low percentage G + C content. Hindgut communities in crickets fed pulp and protein diets also showed a decrease in hydrogen and carbon dioxide production, suggesting that these diets affected the biochemical activity of the hindgut community. The protein‐based diet resulted in a decrease in the rate of evolution of volatile fatty acids, while the ratio of butyrate production to acetate and propionate production was significantly higher in these crickets. Our results show the emergence of a new microbial community structure concomitant with changes in microbial biochemical activity due to shifts in the cricket’s dietary regime.
Mating frequency of ant queens with alternative dispersal strategies, as revealed by microsatellite analysis of sperm
Authors: CHAPUISAT
Published: March 2003

In social Hymenoptera (ants, bees, and wasps), the number of males that mate with the same queen affects social and genetic organization of the colony. However, the selective forces leading to single mating in certain conditions and multiple mating in others remain enigmatic. In this study, I investigated whether queens of the wood ant Formica paralugubris adopting different dispersal strategies varied in their mating frequency (the number of males with whom they mated). The frequency of multiple mating was determined by using microsatellite markers to genotype the sperm stored in the spermatheca of queens, and the validity of this method was confirmed by analysing mother–offspring combinations obtained from experimental single‐queen colonies. Dispersing queens, which may found new colonies, did not mate with more males than queens that stayed within polygynous colonies, where the presence of numerous reproductive individuals ensured a high level of genetic diversity. Hence, this study provides no support to the hypotheses that multiple mating is beneficial because it increases genetic variability within colonies. Most of the F. paralugubris queens mated with a single male, whatever their dispersal strategy and life history. Moreover, multiple mating had little effect on colony genetic structure: the effective mating frequency was 1.11 when calculated from within‐brood relatedness, and 1.13 when calculated from the number of mates detected in the sperm. Hence, occasional multiple mating by F. paralugubris queens may have no adaptive significance.
Genetic variation and bill size dimorphism in a passerine bird, the reed bunting Emberiza schoeniclus
Authors: GRAPPUTO A. , PILASTRO A. , MARIN G.
Published: March 2003

In passerine birds morphological differentiation in bill size within species is not commonly observed. Bill size is usually associated with a trophic niche, and strong differences in it may reflect the process of genetic differentiation and, possibly, speciation. We used both mitochondrial DNA (mtDNA) and nuclear microsatellites to study genetic variation between two subspecies of reed bunting, Emberiza schoeniclus schoeniclus and E.s. intermedia, along their distributional boundary in western Europe. These two subspecies are characterized by a high dimorphism in bill size and, although breeding populations of the two subspecies are found very close to each other in northern Italy, apparently no interbreeding occurs. The observed morphological pattern between the two subspecies may be maintained by geographically varying selective forces or, alternatively, may be the result of a long geographical separation followed by a secondary contact. MtDNA sequences of cytochrome b and ND5 (515 bp) showed little variation and did not discriminate between the two subspecies, indicating a divergence time of less than 500 000 years. The analysis of four microsatellite loci suggested a clear, although weak, degree of genetic differentiation in the large‐ and small‐billed populations, as indicated by FST and RST values and genetic distances. The correlation between bill size and genetic distance between populations remained significant after accounting for the geographical distances between sampling localities. Altogether, these results indicate a very recent genetic differentiation between the two bill morphs and suggest that a strong selection for large bills in the southern part of the breeding range is probably involved in maintaining the geographical differentiation of this species.
Molecular analysis of the efficiency of sloughed skin sampling in whale population genetics
Authors: VALSECCHI ELENA , GLOCKNER‐FERRARI DEBBIE , FERRARI MARK , AMOS WILLIAM
Published: March 2003

Sloughed whale skin contains enough DNA for genetic analysis, and offers a nonintrusive method for collecting tissue. Here, we examine the efficiency of sloughed skin sampling using 1460 samples collected from free‐ranging humpback whales. Samples were sexed and screened for up to 10 microsatellite markers. The vast majority of samples appear genetically compatible with field observations. About 1% of groups revealed more genotypes than whales, but we argue that this is more likely to be due to unobserved whales than to contamination. Sloughed skin sampling is particularly effective when applied to active groups and offers a viable alternative to biopsy darting in regions where darting is either not permitted or otherwise undesirable.
Fertilization and defoliation frequency affect genetic diversity of Festuca pratensis Huds. in permanent grasslands
Authors: KÖLLIKER R. , STADELMANN F. J. , REIDY B. , NÖSBERGER J.
Published: March 2003

Permanent pastures and meadows are species‐rich vegetation systems that play an important role in the ecology and agriculture of temperate climates. Intensive management reduces species diversity and may also influence the genetic diversity within individual species and populations. The objective of this study was to assess genetic variability of meadow fescue, an important component of species‐rich grasslands, and to determine whether fertilization and defoliation frequency influence genetic variability within natural populations. Genetic diversity of six natural populations and three cultivars of Festuca pratensis was investigated using randomly amplified polymorphic DNA (RAPD) markers and agronomic traits. Samples of natural populations were taken from two unrelated long‐term experiments, where treatments had been applied for 11–38 years. RAPD analysis detected a clear genetic distinction of the cultivars from the natural populations. Genetic variability within cultivars was lower than within natural populations. Analysis of molecular variance (AMOVA) showed a significant effect of management on genetic variability. Fertilization and frequent defoliation led to a reduction in genetic variability within natural populations. Analysis of agronomic traits was only partially congruent with the results of RAPD analysis. This study shows that significant genetic variability exists within cultivars and natural populations of Festuca pratensis and can be reduced by intensive management.
A nuclear DNA basis for shelf‐ and bank‐scale population structure in northwest Atlantic cod (Gadus morhua): Labrador to Georges Bank
Authors: RUZZANTE D. E. , TAGGART C. T. , COOK D.
Published: March 2003

Variation at five microsatellite DNA loci scored in ≈ 1300 individuals provided evidence of genetic structure among 14 cod (Gadus morhua) populations spanning the range of the species in the northwest (NW) Atlantic. Using DA and DSW measures of genetic distance, as well as FST and RST measures of population structure, differences are revealed among populations at continental shelf scales (NE Newfoundland Shelf, Grand Banks, Flemish Cap, Scotian Shelf, Georges Bank) where regions are separated by submarine saddles, channels and trenches. However, we also provide evidence of genetic structure at spawning‐bank scales consistent with variation in oceanographic features and in the spatiotemporal distribution of spawning, each of which may represent barriers to gene flow among geographically contiguous populations inhabiting a highly advective environment. The differences described are consistent with postdispersal spawning fidelity to natal areas, a behaviour that may be facilitated by topographically induced gyre‐like circulations that can act as retention mechanisms. Significant degrees of substructure among neighbouring and contiguous cod populations may be most easily explained by the associated oceanographic features and processes that conceivably form the template for the evolution of the structure. We suggest that bathymetric and hydrodynamic structure represents a rational starting point for developing hypotheses to examine the processes that lead to the genetic structuring of marine fish species.
Genetic variation in the Afromontane tree Prunus africana, an endangered medicinal species
Authors: Dawson I. K. , Powell W.
Published: March 2003

An understanding of the patterns of variation within and among populations of tropical trees is essential for devising optimum genetic management strategies for their conservation and sustainable utilization. Here, random amplified polymorphic DNA (RAPD) analysis was used to partition variation within and among 10 populations of the endangered Afromontane medicinal tree, Prunus africana, sampled from five countries across the geographical range of the species (Cameroon, Ethiopia, Kenya, Madagascar and Uganda). Analysis of molecular variance (
AMOVA) employed 48 RAPD markers and revealed most variation among countries (66%, P < 0.001). However, variation among individuals within populations and among populations within Cameroon and Madagascar was also highly significant. Analysis of population product frequency data indicated Ugandan material to be more similar to populations from Cameroon than populations from Kenya and Ethiopia, while Malagash populations were most distinct. The implications of these findings for determining appropriate approaches for conservation of the species, particularly in Cameroon and Madagascar, are discussed.
Population subdivision among desert bighorn sheep (Oviscanadensis) ewes revealed by mitochondrial DNA analysis
Authors: Boyce W. M. , Ramey R. R. , Rodwell T. C. , Rubin E. S. , Singer R. S.
Published: March 2003

We used behavioural observations and mitochondrial DNA (mtDNA) sequence analysis to examine demographic and genetic structure within and among home‐range groups of desert bighorn sheep (Oviscanadensis) ewes in the Peninsular Ranges of southern California, USA. We identified substantial genetic variation in the first 515 bp of the mtDNA control region and determined that seven haplotypes were distributed in a nonrandom fashion among these ewe subpopulations. Although a significant (P < 0.01) amount of mtDNA variation (33%) was partitioned among home‐range groups, we did not find strong evidence for matrilineal substructuring within these groups. Based on analyses of molecular variance, and comparisons of behavioural associations and distances between centres of activity, we concluded that within a given home‐range group, bighorn sheep ewes generally associate with other ewes based on their availability rather than their matrilineal relationships. Our results also supported the conclusion that multiple ewe subpopulations exist within the Peninsular Ranges, and that these subpopulations are the most basic demographic and genetic units.
Genetic variation of Calycophyllum spruceanum in the Peruvian Amazon Basin, revealed by amplified fragment length polymorphism (AFLP) analysis
Authors: RUSSELL J. R. , WEBER J. C. , BOOTH A. , POWELL W. , DAWSON C. SOTELO‐MONTES† and I. K.
Published: March 2003

An understanding of the level, structure and origin of genetic variation within and among populations of tropical trees is essential for devising optimum management strategies for their sustainable utilization and conservation. Here, amplified fragment length polymorphism (AFLP) analysis was used to partition genetic variation within and among nine populations of the predominantly riverine tree, Calycophyllum spruceanum, sampled across a wide geographical range along river tributaries of the Peruvian Amazon Basin. Analysis of molecular variance (AMOVA) employed 65 AFLP markers and revealed most variation among individuals within populations (91%), although variation among populations was highly significant (P < 0.001). Calculation of genetic distances and nested AMOVA indicated a degree of structuring among populations based on geographical proximity, although clustering did not depend on geographical distance alone. No firm evidence was obtained for unidirectional seed dispersal by water playing an important role in determining genetic structure over the geographical range sampled. Implications of data for optimising genetic management of the species are discussed and areas for further study identified.
Population genetics of Fomitopsis rosea– a wood‐decay fungus of the old‐growth European taiga
Authors: Högberg Nils , Stenlid Jan
Published: March 2003

The genetic structure of the wood‐decay fungus Fomitopsis rosea (Alb. et Schw. Fr.) Karst is presented for populations sampled in Russia, Sweden and Finland. A total of 11 variable arbitrary primed (AP)–PCR markers were found to be segregated in a 1:1 ratio. The genotype for each fruiting body was inferred from the genotypes of the haploid single‐spore isolates. Observed heterozygosity was lowest in southern Fennoscandia, the area with the longest history of forestry management. Overall, there was a deficit of heterozygotes compared with frequencies of heterozygotes predicted from Hardy–Weinberg expectations. When we partitioned the deficit of heterozygotes into the hierarchical genetic structure by means of F‐statistics we found that the possible causes for it were both limited gene flow between regions and local nonrandom mating within all populations. Future management for the conservation of F. rosea populations and how the results relate to the life cycle of basidomycete fungi are discussed.
Estimating population structure in diploids with multilocus dominant DNA markers
Authors: Zhivotovsky Lev A.
Published: March 2003

Multilocus DNA markers [random amplified polymorphic DNA (RAPDs), amplified fragment length polymorphism (AFLPs)] are important for population studies because they reveal many polymorphic loci distributed over the genome. The markers are dominant, that is two phenotypes are distinguished at each locus, with a band and with no band. The latter one represents null‐homozygotes with unamplified, recessive null‐alleles. The frequency of a null‐allele can be estimated by taking the square root of the fraction of individuals with no band. Lynch and Milligan (1994) have suggested a modified procedure that reduces bias introduced by the square‐root transform. However, the procedure recommends to ignore those samples in which fewer than four null‐homozygotes are observed. This may lead to significant bias in estimates of genetic diversity. In this study, I introduce a Bayesian approach to estimation of null‐allele frequencies for dominant DNA markers. It follows from computer simulations and data on two conifer species that the Bayesian method gives nearly unbiased estimates of heterozygosity, genetic distances andF‐statistics. The influence of a prior distribution and departure from Hardy–Weinberg proportions on the estimates is also considered.
Ribosomal small subunit sequence variation within spores of an arbuscular mycorrhizal fungus, Scutellospora sp.
Authors: Clapp J. P. , Fitter A. H. , Young J. P. W.
Published: March 2003

Roots of bluebell (Hyacinthoides nonscripta) were sampled from a woodland in Yorkshire, UK and spores of an arbuscular mycorrhizal fungus Scutellospora sp., were obtained from the surrounding soil. Partial small subunit (SSU) ribosomal RNA sequences were amplified from both roots and spores using either the universal forward primer SS38 or the Glomales‐specific primer VANS1, with the reverse Gigasporaceae‐specific primer VAGIGA. Amplified products were cloned and sequenced. Both spores and roots yielded sequences related to those known from fungi within the Glomales, with up to four distinct SSU sequences obtained from individual spores. The VANS1 primer‐binding site varied considerably in sequence and only a subset of Scutellospora sequences were amplified when the VANS1 primer was used. In addition to glomalean sequences, a number of different sequences, apparently from ascomycetes, were obtained from both root and spore samples.
Extent and degree of hybridization between exotic (Spartina alterniflora) and native (S. foliosa) cordgrass (Poaceae) in California, USA determined by random amplified polymorphic DNA (RAPDs)
Authors: Ayres Debra R. , Garcia‐Rossi Dino , Davis Heather G. , Strong Donald R.
Published: March 2003

Spartina alterniflora, smooth cordgrass, native to the eastern USA, was introduced into south San Francisco Bay ≈ 25 years ago. It has spread by purposeful introduction of rooted plants and dispersal of seeds on the tides. Previous work suggested that S. alterniflora was competitively superior to the native California cordgrass, S. foliosa, and that the two species hybridized. The present study determined the spread of S. alterniflora and S. foliosa × alterniflora hybrids in California and examined the degree of hybridization. We used nuclear DNA markers diagnostic for each species to detect the parental species and nine categories of hybrids. The California coast outside San Francisco Bay contained only the native species. All hybrid categories exist in the Bay, implying that several generations of crossing have occurred and that hybridization is bidirectional. Hybrids were found principally near sites of deliberate introduction of the exotic species. Where S. alterniflora was deliberately planted, we found approximately equal numbers of S. alterniflora and hybrid individuals; S. foliosa was virtually absent. Marshes colonized by water‐dispersed seed contained the full gamut of phenotypes with intermediate‐type hybrids predominating. The proliferation of hybrids could result in local extinction of S. foliosa. What is more, S. alterniflora has the ability to greatly modify the estuary ecosystem to the detriment of other native species and human uses of the Bay. To the extent that they share these engineering abilities, the proliferation of cordgrass hybrids could grossly alter the character of the San Francisco Bay.
Genetic structure and gene flow among Komodo dragon populations inferredby microsatellite loci analysis
Authors: Ciofi Claudio , Bruford Mike W.
Published: March 2003

A general concern for the conservation of endangered species is the maintenance of genetic variation within populations, particularly when they become isolated and reduced in size. Estimates of gene flow and effective population size are therefore important for any conservation initiative directed to the long‐term persistence of a species in its natural habitat. In the present study, 10 microsatellite loci were used to assess the level of genetic variability among populations of the Komodo dragonVaranus komodoensis. Effective population size was calculated and gene flow estimates were compared with palaeogeographic data in order to assess the degree of vulnerability of four island populations. Rinca and Flores, currently separated by an isthmus of about 200 m, retained a high level of genetic diversity and showed a high degree of genetic similarity, with gene flow values close to one migrant per generation. The island of Komodo showed by far the highest levels of genetic divergence, and its allelic distinctiveness was considered of great importance in the maintenance of genetic variability within the species. A lack of distinct alleles and low levels of gene flow and genetic variability were found for the small population of Gili Motang island, which was identified as vulnerable to stochastic threats. Our results are potentially important for both the short‐ and long‐term management of the Komodo dragon, and are critical in view of future re‐introduction or augmentation in areas where the species is now extinct or depleted.
Armadillos exhibit less genetic polymorphism in North America than in South America: nuclear and mitochondrial data confirm a founder effect in Dasypus novemcinctus (Xenarthra)
Authors: Huchon Dorothée , Delsuc Frédéric , Catzeflis François M. , Douzery Emmanuel J. P.
Published: March 2003

Heterozygosity at eight nuclear enzymatic loci and mitochondrial DNA control region (D‐loop) sequence polymorphism was compared between North and South American nine‐banded armadillos (Dasypus novemcinctus: Xenarthra, Dasypodidae). All markers revealed a striking genetic homogeneity amongst Texas, Louisiana, and Mississippi individuals, vs. the usual level of polymorphism for the French Guiana population. This may reflect a founder effect during colonization of North America. Occurrence of polymorphism in the D‐loop microsatellite motif of North American armadillos suggests a recent recovery of mitochondrial variability. Phylogeographic analyses using Dasypus kappleri as outgroup provides evidence for a clear separation between North and South American control region haplotypes.
Mating frequency and genetic structure of the Argentine antLinepithema humile
Authors: Krieger Michael J. B. , Keller Laurent
Published: March 2003

The nest and population genetic structures of the Argentine ant,Linepithema humilewere investigated using eight microsatellite loci. Genotypes of the sperm from spermathecae of 87 queens were consistent with all queens being singly inseminated. The probability of a double mating remaining undetected was low (0.012) suggesting that no queens or only a very low proportion mate multiply. The relatedness between the queens and their mates was negative (R = −0.164 ± 0.044) and significantly different to zero (P = 0.020). However, the high negative relatedness value was caused by a significant allele frequency difference between the sexes at a single locus (Lhum‐28). When this locus was removed from the analyses, the relatedness was not significantly different from zero (R = 0.013 ± 0.050,P = 0.812). Analysis of 10 nests revealed that the genetic differentiation among nests was weak (FST = 0.003) and not distinguishable from zero (P = 0.468). Similarly, the overall relatedness among nestmate females was not significantly different from zero (R = 0.007 ± 0.018,P = 0.706). These results are consistent with the lack of distinct nest boundaries and the large number of queens per nest in the population studied. Although mating takes place inside the nest, the inbreeding coefficient was close to zero (F = 0.007 ± 0.025,P = 0.786). Overall, these data indicate substantial local gene flow mediated by movement of reproductives among colonies.
Conservation genetics of bush mango from central/west Africa: implications from random amplified polymorphic DNA analysis
Authors: Lowe A. J. , Gillies A. C. M. , Wilson J. , Dawson I. K.
Published: March 2003

Genetic variation was assessed in the two bush mango species, Irvingia gabonensis and I. wombolu, valuable multipurpose fruit trees from central and west Africa that are currently undergoing domestication. A total of 130 individuals sampled from Cameroon, Nigeria and Gabon were analysed using 74 random amplified polymorphic DNAs (RAPDs). Significant genetic integrity was found in the two morphologically similar species (among‐species analysis of molecular variance [amova] variance component 25.8%, P < 0.001), with no evidence of hybridization, even between individuals from areas of sympatry where hybridization was considered probable. Results suggest that large‐scale transplantation of either species into new habitats will probably not lead to genetic introgression from or into the other species. Therefore, subsequent cultivation of the two species should not be hindered by this consideration, although further studies on the potential for hybridization/introgression between these species would be prudent. Significant genetic differentiation of both species (among‐countries within species, nested amova variance component 9.8%, P < 0.001) was observed over the sampled regions, and genetic similarity of samples decreased significantly with increasing geographical distance, according to number of alleles in common (NAC) analysis. ‘Hot spots’ of genetic diversity were found clustered in southern Nigeria and southern Cameroon for I. wombolu, and in southern Nigeria, southern Cameroon and central Gabon for I. gabonensis. The possible reasons for this distribution of genetic variation are discussed, but it may reflect evolutionary history, as these populations occur in areas of postulated Pleistocene refugia. The application of these results to domestication programmes and, in the light of extensive deforestation in the region, conservation approaches, is discussed.
Effect of crop rotation and soil cover on alteration of the soil microflora generated by the culture of transgenic plants producing opines
Authors: Oger P. , Mansouri H. , Dessaux Y.
Published: March 2003

The culture of transgenic Lotus corniculatus plants producing opines, which are bacterial growth substrates, leads to the selection of rhizospheric bacteria able to utilize these substrates. We have investigated the fate of the opine‐utilizing community over time under different experimental conditions following elimination of selective pressure exerted by the transgenic plants. These plants were removed from the soil, which was either left unplanted or replanted with wild‐type L. corniculatus or wheat plants. The density of opine‐utilizing bacteria in the fallow soils remained essentially unchanged throughout the experiment, regardless of the soil of origin (soil planted with wild‐type or transgenic plants). When wild‐type Lotus plants were used to replace their transgenic counterparts, only the bacterial populations able to utilize the opines were affected. Long‐term changes affecting the opine‐utilizing bacterial community on Lotus roots was dependent upon the opine studied. The concentration of nopaline utilizers decreased, upon replacement of the transgenic plants, to a level similar to that of normal plants, while the concentration of mannopine utilizers decreased to levels intermediate between transgenic and normal plants. These data indicate that: (i) the opine‐utilizing bacterial populations can be controlled in the rhizosphere via plant‐exudate engineering; (ii) the interaction between the engineered plants and their root‐associated micro‐organisms is transgene specific; and (iii) alterations induced by the cultivation of transgenic plants may sometimes be persistent. Furthermore, opine‐utilizing bacterial populations can be controlled by crop rotation. Therefore, favouring the growth of a rhizobacterium of agronomic interest via an opine‐based strategy appears feasible.
Mitochondrial haplotype variation and phylogeography of Iberian brown trout populations
Authors: Machordom A. , Suárez J. , Almodóvar A. , Bautista J. M.
Published: March 2003

The biogeographical distribution of brown trout mitochondrial DNA haplotypes throughout the Iberian Peninsula was established by polymerase chain reaction‐restriction fragment polymorphism analysis. The study of 507 specimens from 58 localities representing eight widely separated Atlantic‐slope (north and west Iberian coasts) and six Mediterranean drainage systems served to identify five main groups of mitochondrial haplotypes: (i) haplotypes corresponding to non‐native, hatchery‐reared brown trout that were widely distributed but also found in wild populations of northern Spain (Cantabrian slope); (ii) a widespread Atlantic haplotype group; (iii) a haplotype restricted to the Duero Basin; (iv) a haplotype shown by southern Iberian populations; and (v) a Mediterranean haplotype. The Iberian distribution of these haplotypes reflects both the current fishery management policy of introducing non‐native brown trout, and Messinian palaeobiogeography. Our findings complement and extend previous allozyme studies on Iberian brown trout and improve present knowledge of glacial refugia and postglacial movement of brown trout lineages.
Reconciling patterns of genetic variation with stream structure, earth history and biology in the Australian freshwater fish Craterocephalus stercusmuscarum (Atherinidae)
Authors: Mcglashan D. J. , Hughes J. M.
Published: March 2003

We examined the consequences of barriers, stream architecture and putative dispersal capability on levels of genetic differentiation among populations of the freshwater fish Craterocephalus stercusmuscarum. Seven polymorphic allozyme loci and sequences of a 498‐bp fragment of the ATPase 6 mitochondrial DNA (mtDNA) gene were used to assess patterns of genetic variation among 16 populations from upland and lowland streams of five drainages in northern Queensland, Australia. Concordant patterns at both genetic markers revealed that there were significant levels of genetic subdivision among all populations, while an analysis of molecular variation showed that the distribution of genetic diversity was not consistent with contemporary drainage structure. There were reciprocally monophyletic mtDNA clades and fixed or large frequency differences at allozyme loci either side of instream barriers such as waterfalls. This implied barriers were effective in restricting gene flow between upland and lowland populations separated by waterfalls. However, there were two genetically distinct groups in upland areas, even within the same subcatchment, as well as high levels of genetic subdivision among lowland populations, suggesting barriers alone do not explain the patterns of genetic diversity. The data revealed a complex phylogeographic pattern, which we interpreted to be the result of one or more invasion events of independent lineages to different sections of each drainage, possibly mediated by well documented geomorphological changes. Our results highlight the importance of earth structure and history in shaping population genetic structure in stream organisms where dispersal capability may be limited, and reveal that the contemporary structure of drainages is not necessarily a good indicator of genetic relationships among populations.