bluuebunny/crossref_metadata_2025 huggingface dataset:
Vector competence of selected South African Culicoides species for the Bryanston serotype of equine encephalosis virus
Authors: Venter G. J. , Groenewald D. M. , Paweska J. T. , Venter E. H. , Howell P. G.
Published: March 2003

Equine encephalosis virus (EEV) was recognized and described in the Republic of South Africa in 1967 and subsequent serological studies have shown this orbivirus to be both widespread and prevalent in southern Africa. In the present study it was shown that wild‐caught Culicoides (Avaritia) imicola Kieffer (Diptera: Ceratopogonidae) can become infected with and permit the replication of the Bryanston serotype of EEV following membrane‐feeding on infective blood containing 5.0 log10 plaque‐forming‐units (PFU)/ml. The mean prevalence of Bryanston virus infection in C. imicola after 10 days extrinsic incubation at 23.5°C was 22.3% (23/103). The mean infectivity of Bryanston virus in the infected C. imicola increased from 1.3 log10 PFU/midge, in insects assayed immediately after feeding on the blood‐virus mixture, to 2.6 log10 PFU/midge in insects assayed after incubation. The virus concentration in individual C. imicola infected with the Bryanston serotype of EEV ranged from 0.7 to 3.6 log10 PFU/midge. Bryanston virus titres higher than 2.5 log10 TCID50, found in individual C. imicola, suggest that this species may be able to transmit this virus to susceptible hosts. Prevalence of virus infection in C. imicola was determined by PFU and microtitration assays on both BHK and Vero cells and confirmation of the Bryanston serotype of EEV was determined by plaque inhibition. No virus replication could be demonstrated in 102 C. nivosus tested after the incubation period, suggesting that not all Culicoides species are equally susceptible to Bryanston virus infection. Other Culicoides species that survived the incubation period and that were negative for the presence of Bryanston virus were C. pycnostictus (42), C. leucostictus (7), C. magnus (2), C. bolitinos (1) and C. bedfordi (1).
Intraspecific variability in natural populations of Glossina palpalis gambiensis from West Africa, revealed by genetic and morphometric analyses
Authors: Solano P. , De La Rocque S. , Cuisance D. , Geoffroy B. , De Meeus T. , Cuny G. , Duvallet G.
Published: March 2003

Glossina palpalis gambiensis Vanderplank (Diptera: Glossinidae) from West Africa (Senegal and Burkina Faso) were analysed for microsatellite DNA polymorphisms and size of the wings. In the overall sample a strong heterozygote deficiency was found at two polymorphic microsatellite loci. It led to a highly significant value of Fis (within‐sample heterozygote deficit) in the western zone of Sideradougou area in Burkina Faso. Genetic differentiation was significant on a macrogeographic scale, i.e. between tsetse coming from Senegal and Burkina Faso. Wing measures also differed between these two countries; flies from Senegal appeared to be smaller. Microsatellite loci further allowed differentiation of populations of G. palpalis gambiensis trapped on the same hydrographic network a few kilometres apart. The results are interpreted as indicating that further investigations will allow the study of genetic variability of tsetse flies in relation to the dynamics of transmission of human and animal trypanosomoses.
Annual and spatial activity of dung flies and carrion in a Mediterranean holm‐oak pasture ecosystem
Authors: Martínez‐Sánchez A. , Rojo S. , Marcos‐García M. A.
Published: March 2003

The annual activity and spatial distribution of Muscidae and Calliphoridae were investigated in a holm‐oak (‘dehesa’) ecosystem in western Spain over two years in pasture and woodland habitats, using wind‐orientated traps baited with a mixture of fresh cattle faeces, liver and sodium sulphide solution. Lucilia sericata (Meigen) was always the dominant species and, with Chrysomya albiceps (Weidemann), Hydrotaea ignava (Harris), Muscina levida (Harris) and Muscina prolapsa (Harris), was more abundant during the second than the first year. By contrast, Calliphora vicina Robineau‐Desvoidy, Calliphora vomitoria (L.), Hydrotaea armipes (Fallén), Hydrotaea penicillata (Rondani) and Hydrotaea dentipes (Fabricius) were more numerous during the first than the second year of the study. In summer, the Diptera sampled were significantly more abundant in a wooded than a pasture area. However, in autumn, while H. penicillata remained significantly more abundant in woodland, L. sericata became more abundant in the pasture, whereas C. vicina was captured in open and wooded areas in similar proportions. During winter and spring the populations sampled were relatively small. The changing patterns of abundance are discussed in relation to differences in climate within and between years.
Life‐cycle stage morphology of Psoroptes mange mites
Authors: Sanders A. , Froggatt P. , Wall R. , Smith K. E.
Published: March 2003

Detailed life‐cycle stage descriptions for the ectoparasitic mite Psoroptes ovis (Hering) (Acari: Psoroptidae) from rabbit hosts (syn. Psoroptes cuniculi) are presented. The results resolve a number of contradictions in the literature relating to the recognition of the life cycle stages of these mites. This study supports the view that there are two distinct male nymphal stages, both lacking dorsoposterior tubercles. The male tritonymph is significantly larger than the protonymph and has five pairs of metapodosomal setae rather than three. In addition, male tritonymphs have two pairs of cuticular pits on the central metapodosoma rather than the single pair of the protonymph. The results also show that the female protonymph can be distinguished from the male nymphal stages and the female tritonymph. Both female nymphal stages possess dorsoposterior tubercles, but the protonymph is significantly smaller than the tritonymph. In addition, the protonymph possesses three pairs of metapodosomal setae rather than five, one pair of cuticular pits rather than two, and a pulvillus on leg IV which is absent in the female tritonymph. The presence of dorsoposterior tubercles enables the female nymphs to be distinguished easily from the males. By contrast, distinguishing between the nymphal stages of the same sex relies on the identification of both the number of metapodosomal setae and cuticular pits. These descriptions are used to produce a key, which allows the various stages of both sexes to be distinguished.
Insecticide‐treated cattle for tsetse control: the power and the problems
Authors: Hargrove J. W. , Omolo S. , Msalilwa J. S. I. , Fox B.
Published: March 2003

Trypanosomiasis control increasingly involves financial input from livestock owners and their active participation. If control is carried out on smaller scales than in the past, methods such as aerial and ground spraying and sterile insect techniques will have reduced application. There will be increased reliance on trypanocidal drugs, and bait methods of tsetse control – where flies are attracted to point sources and killed. If drug resistance develops, cheap and simple bait methods offer the only means of disease control that might be applied, and paid for, by stockowners themselves. The methods have been effective in some circumstances, but not in others, and it is important to understand the reasons for the successes and the failures. Analysis is presented of the results of two Tanzanian tsetse control campaigns involving the use of insecticide‐treated cattle. Between 1991, &, 1996, following the introduction of widespread dipping in the Kagera Region, trypanosomiasis declined from > 19 000 cases to < 2400 and deaths from > 1000 to 29. On four ranches in the region, tsetse have been almost eliminated and trypanosomiasis prophylaxis is no longer used. Similarly aggressive use of pyrethroids on Mkwaja Ranch in Tanga Region has not had such dramatic effects. Tsetse and trypanosomiasis are still common, despite high levels of prophylaxis and the deployment of ≈ 200 odour‐baited targets. The difference in the results is attributed to a combination of the much smaller area covered by treated animals at Mkwaja, a greater susceptibility to re‐invasion and a more suitable habitat for the flies. A better understanding of the dynamics of the use of insecticide‐treated cattle is needed before we can predict confidently the outcome of particular control operations.
Invasion of West African cattle by the tick Amblyomma variegatum
Authors: Stachurski F.
Published: March 2003

Studies in Cameroon and Burkina Faso examined the invasion process of cattle by adult Amblyomma variegatum Fabricius (Acari: Ixodidae) ticks. Nearly all the ticks picked up in the pasture during grazing were found on the limb ends, near the hooves, where they temporarily attached. Then when the cattle lay down, the ticks moved from the feet towards the predilection sites, where they attached definitively. Many ticks disappeared during this displacement. All the female ticks and approximately 70% of the males were thus unable to attach to the predilection sites as long as the pioneer males had not attached and started to produce attraction‐aggregation‐attachment pheromones. Nevertheless, A. variegatum females and males attached to the feet in similar numbers during grazing, whether the cattle were already infested or not, indicating that stimuli originating from the hosts are powerful enough to attract both sexes. After attachment of the pioneer males, the number of ticks that successfully reached the predilection sites increased. However, even on infested animals, 40–50% of A. variegatum ticks found near the hooves after the grazing periods disappeared during the night following their capture. When moving from the temporary attachment sites towards the final ones, one‐third of the ticks changed the individual host. Considering this two‐stage infestation process, it is suggested that a targeted tick control, using a foot‐bath, might greatly reduce cattle infestation. In particular, it could be effective in traditional herds, with animals grazing permanently during the day, lying down only once back in the night pen.
Effect of carbon dioxide on the Oriental cockroach Blatta orientalis
Authors: Gannon B. , Le Patourel G. , Young R.
Published: March 2003

Exposure to high concentrations of carbon dioxide (CO2) killed adult and nymphal stages of the oriental cockroach Blatta orientalis L. (Dictyoptera: Blattidae) with LT50 values of 11.5–16.2 h for 60% CO2 in air and 5.7–7.1 h for 100% CO2 at 20°C; corresponding LT50s at 28°C were 2.8–4.6 h for 60% CO2 in air and 2.3–3.6 h for 100% CO2. Complete kill of mobile stages was obtained within 24 h using 60% CO2 at 20°C. Survivors of treatments with 100% CO2 at 28°C remained completely paralysed for up to 3 days post‐treatment and took up to 5 days to regain normal movement, but adult females then resumed production of oothecae with no significant loss in fecundity. Oothecae 5 or 30 days after deposition required 60–84 h exposure to 60% CO2 at 20°C to prevent emergence of nymphs but less time using 100% CO2 at 28°C. At 28°C, when adult females were treated with 100% CO2 and 52% r.h. for 6 h (giving 100% mortality) loss of weight was significantly greater than that following treatment with air at 52% r.h. for 6 h (giving no mortality). However, significantly greater weight loss also occurred when they were treated with dried air (< 10% r.h.) for 6 h, also with no mortality. The toxicity of CO2 to mobile stages of the oriental cockroach appeared to result from irreversible effects on the nervous system, rather than from water loss during exposure.
Background odour induces adaptation and sensitization of olfactory receptors in the antennae of houseflies
Authors: Kelling F. J. , Ialenti F. , Den Otter C. J.
Published: March 2003

Abstract The presence of background odour was found to have a small but significant effect on the sensitivity of the antennal olfactory system of houseflies, Musca domestica Linnaeus (Diptera: Muscidae), to new pulses of odour. We show that cross‐adaptation and cross‐sensitization between a background odour of (±)‐1‐octen‐3‐ol and pulses of (±)‐1‐octen‐3‐ol, 2‐pentanone and R‐(+)‐limonene can occur, confirming that olfactory receptor cells are sensitive to different odours. Background odour can increase the responses to low concentration odour pulses and decrease the responses to higher concentration odour pulses. It is suggested that background odour has a larger effect on olfactory receptor cells that respond with a tonic increase of spike frequency, giving information about the level of odour concentration, i.e. the ‘static’ environment. Cells that respond in a phasic way only provide information on the dynamics of the olfactory environment.
Seasonal variations in the distribution and abundance of the tsetse fly, Glossina morsitans morsitans in eastern Zambia
Authors: Van Den Bossche P. , De Deken R.
Published: March 2003

Abstract The seasonal changes in the distribution of Glossina morsitans morsitans Westwood (Diptera: Glossinidae) and its main host, cattle, were examined in a cultivated area of the plateau of eastern Zambia. During four consecutive years, the tsetse and cattle populations were monitored along a fly‐round transect traversing the two main vegetation types in the study area. These were miombo, a one‐storied open woodland with the genera Brachystegia and Julbernardia dominant, and munga, a one‐ or two‐storied woodland where the principal tree genera were Acacia, Combretum and Terminalia. Concurrently, a capture/mark/release/recapture (CMRR) exercise was conducted along two other transects also traversing both vegetation types. The index of apparent abundance of tsetse (IAA) in miombo increased at the beginning of the rainy season (November), reached its peak at the end of the rainy season (April) and was low during the cold season (May to late August), but especially the hot dry season (September to late October). The IAA of tsetse in munga showed a pattern that was the reverse of that in miombo. The seasonal changes in the IAA of tsetse in both vegetation types were in accordance with changes in the movement patterns of tsetse between the two vegetation type as observed using CMRR. The distribution and abundance of cattle along the transect also showed a seasonal trend. This was especially so in munga, during the first three years of observations, where cattle abundance increased gradually from June onwards, reached a maximum at the end of the hot dry season (October–November) and declined steeply at the start of the rainy season (November–December). In both vegetation types, the monthly mean IAA of tsetse was positively correlated with the abundance of cattle in the previous month. It is concluded that the distribution of tsetse in cultivated area of the eastern plateau of Zambia undergoes substantial seasonal changes, which can partly be attributed to changes in the distribution of cattle. The implications of these observations for the control of tsetse are discussed.
Evidence for p‐glycoprotein modification of insecticide toxicity in mosquitoes of the Culex pipiens complex
Authors: Buss D. S. , Mccaffery A. R. , Callaghan A.
Published: March 2003

Abstract Pesticide resistance has parallels with multi‐drug resistance syndrome of tumours in clinical medicine, which has been linked to an ATP‐dependent pump, p‐glycoprotein (P‐gp). P‐gps pump drugs out of the cell, thereby reducing cellular concentrations of the chemical. P‐gps have been found in several invertebrate species and have been shown to provide a defence against environmental xenobiotics, including pesticides.

This study used a model cell culture system to investigate the interaction of pesticides with P‐gp. Ivermectin and endosulfan were shown to be strong inhibitors of dye transport out of cells, which is a standard measure of P‐gp modulation. We then investigated the action of a P‐gp inhibitor, verapamil (calcium channel blocker), on insecticide toxicity to fourth‐instar mosquito larvae of the Culex pipiens L. complex (Diptera: Culicidae). Verapamil increased toxicity to examples of three insecticide classes (cypermethrin, endosulfan, ivermectin), but not to chlorpyrifos (organophosphate).

The discovery of a novel protective mechanism in mosquitoes, with a wide substrate range, has implications for the control of important pest and vector species.
Isoenzyme differentiation of Aedes aegypti populations in French Guiana
Authors: Failloux A.‐B. , Fouque F. , Vazeille M. , Rodhain F.
Published: March 2003

Abstract Population genetics of peri‐domestic Aedes aegypti (Diptera: Culicidae), vector of dengue and yellow fever, were investigated by gel electrophoresis of 10 enzyme loci in 14 samples of mosquito larvae collected in 1997–1998 from localities separated by distances of 3–275 km in French Guiana. Genetic differentiation between geographical populations was generally high (mean FST = + 0.111, P < 10−5) even among seven sites <30 km apart (FST = + 0.137, P < 0.05), but not positively correlated with distance. Thus, Ae. aegypti comprises a mosaic of genetically differentiated populations in French Guiana. This may be attributed to reinvasion from diverse origins through repeated founder events after this vector species was eliminated during the 1940s to 1960s.
Motivation for medical school: the relationship to gender and specialty preferences in a nationwide sample
Authors: Vaglum  , Wiers‐Jenssen  , Ekeberg
Published: March 2003

Objectives

Motivation for going to medical school and career plans of a 1 year cohort of students entering medical school in Norway (n = 420 response rate: 90%, 54% women, mean age: 22 years) were surveyed by a postal questionnaire the first month after they had started.

Design

Motives for choosing medicine were categorized into three indexes: `people orientated', `status/security orientated' and `natural science orientated' motives.

Setting

University of Oslo.

Subjects

Medical students.

Results

Students picked out which they preferred among 53 specialties. The highest motivational scores were on the `person orientated' index, female students scoring higher than men. Female students were, however, nearly as highly motivated by status/security and interests in natural science as were men. `Person orientated' and `natural science orientated' motives exerted the strongest influence on specialty preferences. Those who preferred family medicine were more person orientated and less natural science orientated, while those who preferred internal medicine were more natural science orientated. Father being a physician did not influence the motivational pattern, but increased the preference for laboratory and internal medicine. Frequently repeated upper secondary school exams for acceptance into medical school were negatively related to natural science motivation, and to increased preference for becoming a surgeon.

Conclusions

In this first month of the curriculum students regarded person oriented motives as the most important for becoming a doctor.
Mitochondrial DNA variation in natural populations of the mushroom Agaricus bisporus
Authors: XU JIANPING , KERRIGAN RICHARD W. , SONNENBERG ANTON S. , CALLAC PHILIPPE , HORGEN PAUL A. , ANDERSON JAMES B.
Published: March 2003

We investigated the patterns of mitochondrial DNA variation in the global population of the commercial mushroom Agaricus bisporus. Through the analysis of RFLP's among 441 isolates from nine countries in North America and Eurasia, we found a total of 140 mtDNA haplotypes. Based on population genetic analysis, there are four genetically distinct natural populations in this species, found in coastal California, desert California, France and Alberta (Canada). While 134 of the 140 mtDNA haplotypes were unique to single geographical regions, two mtDNA haplotypes, mt001 and mt002, were found in almost every population surveyed. These two mtDNA haplotypes also predominate among cultivars used throughout the world for at least the last two decades. These two mtDNA haplotypes are more similar to the cosmopolitan groups of mtDNA haplotypes than to the indigeneous clusters of mtDNA haplotypes from the two Californian regions.
Comparative phylogeography and the identification of genetically divergent areas for conservation
Authors: MORITZ CRAIG , FAITH DANIEL P.
Published: March 2003

Genetic diversity is recognized as a fundamental component of biodiversity and its protection is incorporated in several conventions and policies. However, neither the concepts nor the methods for assessing conservation value of the spatial distribution of genetic diversity have been resolved. Comparative phylogeography can identify suites of species that have a common history of vicariance. In this study we explore the strengths and limitations of Faith’s measure of ‘Phylogenetic Diversity’ (PD) as a method for predicting from multiple intraspecific phylogeographies the underlying feature diversity represented by combinations of areas. An advantage of the PD approach is that information on the spatial distribution of genetic diversity can be combined across species and expressed in a form that allows direct comparison with patterns of species distributions. It also seeks to estimate the same parameter, feature diversity, regardless of the level of biological organization. We extend the PD approach by using Venn diagrams to identify the components of PD, including those unique to or shared among areas and those which represent homoplasy on an area tree or which are shared across all areas. PD estimation should be complemented by analysis of these components and inspection of the contributing phylogeographies. We illustrate the application of the approach using mtDNA phylogeographies from vertebrates resident in the wet tropical rainforests of north‐east Queensland and compare the results to biodiversity assessments based on the distribution of endemic vertebrate species. The genetic vs. species approaches produce different assessments of conservation value, perhaps reflecting differences in the temporal and spatial scale of the determining processes. The two approaches should be seen as complementary and, in this case, conservation planning should incorporate information on both dimensions of biodiversity.
Extrapair paternity, inclusive fitness, and within‐group benefits of helping in western bluebirds
Authors: DICKINSON J. L. , AKRE J. J.
Published: March 2003

In central coastal California, USA, 3–16% of western bluebird (Sialia mexicana) pairs have adult male helpers at the nest. Demographic data on a colour‐ringed population over a 13‐year period indicate that helpers gain a small indirect fitness benefit through increases in the number of young fledged from nests of close kin. A small proportion of adult helpers (16%) that were able to breed and help simultaneously had higher annual inclusive fitness than males that only bred. These males comprised such a minor proportion of helpers that the mean fitness of helpers was still lower than the mean fitness of independent breeders. We used DNA fingerprinting to determine whether extrapair fertilizations alter within‐group benefits enough to tip the balance in favour of helping behaviour. Overall, 19% of 207 offspring were sired by males other than their social father and extrapair fertilizations occurred in 45% of 51 nests. Intraspecific brood parasitism was rare so that mean mother‐nestling relatedness approximated the expected value of 0.5. Extrapair paternity reduced putative father‐offspring relatedness to 0.38. Mean helper‐nestling relatedness was 0.41 for helpers assisting one or both parents and 0.28 for helpers aiding their brothers. Helpers rarely sired offspring in the nests at which they helped. Helping was not conditional on paternity and helpers were not significantly more closely related to offspring in their parents’ nests than to offspring in their own nests. Although helpers may derive extracurricular benefits if helping increases their own or their father's opportunities for extrapair fertilizations, within‐nest inclusive fitness benefits of helping do not compensate males for failing to breed. Breeding failure and constraints on breeding are the most likely explanations for why most helpers help.
Microsatellite and mitochondrial DNA assessment of population structure and stocking effects in Arctic charr Salvelinus alpinus (Teleostei: Salmonidae) from central Alpine lakes
Authors: BRUNNER P. C. , DOUGLAS M. R. , BERNATCHEZ L.
Published: March 2003

Despite geographical isolation and widespread phenotypic polymorphism, previous population genetic studies of Arctic charr, Salvelinus alpinus, have detected low levels of intra‐ and interpopulation variation. In this study, two approaches were used to test the generality of low genetic diversity among 15 Arctic charr populations from three major drainages of the central Alpine region of Europe. First, a representative subsample of each drainage was screened by PCR–RFLP analysis of mtDNA using 31 restriction enzymes. All individuals but one shared an identical haplotype. In contrast, microsatellite DNA variation revealed high levels of genetic diversity within and among populations. The number of alleles per locus ranged from six to 49, resulting in an overall expected heterozygosity from 0.72 ± 0.09 to 0.87 ± 0.04 depending on the locus. Despite evidence for fish transfers among Alpine charr populations over centuries, genetic diversity was substantially structured, as revealed by hierarchical Φ statistics. Eighteen per cent of total genetic variance was apportioned to substructuring among Rhône, Rhine, and Danube river systems, whereas 19% was due to partitioning among populations within each drainage. Cluster analyses corroborated these results by drainage‐specific grouping of nonstocked populations, but also revealed damaging effects of stocking practices in others. However, these results suggest that long‐term stocking practices did not generally alter natural genetic partitioning, and stress the importance of considering genetic diversity of Arctic charr in the Alpine region for sound management. The results also refute the general view of Arctic charr being a genetically depauperate species and show the potential usefulness of microsatellite DNAs in addressing evolutionary and conservation issues in this species.
Recent divergence between two morphologically differentiated subspecies of bluethroat (Aves: Muscicapidae: Luscinia svecica) inferred from mitochondrial DNA sequence variation
Authors: QUESTIAU S. , EYBERT M.‐C. , GAGINSKAYA A. R. , GIELLY L. , TABERLET P.
Published: March 2003

We assessed the mitochondrial DNA sequence divergence of a 718 bp fragment of the control region and 1007 bp of the cytochrome b gene between two allopatric morphologically different subspecies of bluethroat (Luscinia svecica). None of the 17 total haplotypes was shared between L. s. namnetum and L. s. svecica. However, the mean distances between subspecies were very low for both fragments (0.00168 ± 0.00001 (mean ± SE) for the control region; 0.00306 ± 0.00016 for the cytochrome b gene). Only one substitution made the two subspecies genetically differentiated, highlighting their recent divergence. Interestingly, the control region was not more variable than the cytochrome b gene.
Population structure of nuclear and mitochondrial DNA variation among humpback whales in the North Pacific
Authors: BAKER C. S. , MEDRANO‐GONZALEZ L. , CALAMBOKIDIS J. , PERRY A. , PICHLER F. , ROSENBAUM H. , STRALEY J. M. , URBAN‐RAMIREZ J. , YAMAGUCHI M. , VON ZIEGESAR O.
Published: March 2003

The population structure of variation in a nuclear actin intron and the control region of mitochondrial DNA is described for humpback whales from eight regions in the North Pacific Ocean: central California, Baja Peninsula, nearshore Mexico (Bahia Banderas), offshore Mexico (Socorro Island), southeastern Alaska, central Alaska (Prince Williams Sound), Hawaii and Japan (Ogasawara Islands). Primary mtDNA haplotypes and intron alleles were identified using selected restriction fragment length polymorphisms of target sequences amplified by the polymerase chain reaction (PCR–RFLP). There was little evidence of heterogeneity in the frequencies of mtDNA haplotypes or actin intron alleles due to the year or sex composition of the sample. However, frequencies of four mtDNA haplotypes showed marked regional differences in their distributions (ΦST= 0.277;P< 0.001;n= 205 individuals) while the two alleles showed significant, but less marked, regional differences (ΦST= 0.033;P< 0.013;n= 400 chromosomes). An hierarchical analysis of variance in frequencies of haplotypes and alleles supported the grouping of six regions into a central and eastern stock with further partitioning of variance among regions within stocks for haplotypes but not for alleles. Based on available genetic and demographic evidence, the southeastern Alaska and central California feeding grounds were selected for additional analyses of nuclear differentiation using allelic variation at four microsatellite loci. All four loci showed significant differences in allele frequencies (overallFST= 0.043;P< 0.001; averagen= 139 chromosomes per locus), indicating at least partial reproductive isolation between the two regions as well as the segregation of mtDNA lineages. Although the two feeding grounds were not panmictic for nuclear or mitochondrial loci, estimates of long‐term migration rates suggested that male‐mediated gene flow was several‐fold greater than female gene flow. These results include and extend the range and sample size of previously published work, providing additional evidence for the significance of genetic management units within oceanic populations of humpback whales.
Founder events and variation at microsatellite loci in an insular passerine bird, the Laysan finch (Telespiza cantans)
Authors: TARR C. L. , CONANT S. , FLEISCHER R. C.
Published: March 2003

Historically documented founder events provide opportunities to assess the effects of population size reductions on genetic variation, but the actual magnitude of genetic change can be measured only when direct comparisons can be made to the source or ancestral population. We assayed variation at nine microsatellite loci in the translocated population of the Laysan finch (Telespiza cantans) at Pearl and Hermes reef (PHR), and compared the level of variation to that in the source population on Laysan Island. Heterogeneity in allele frequencies was highly significant at eight of the nine loci, primarily as a result of fluctuations in allele frequencies in the three PHR populations. Intra‐ and interpopulational measures of genetic diversity generally matched predictions based on the well‐documented history of three islet populations at PHR: significantly lower numbers of alleles and polymorphic loci, as well as higher pairwise FST values and genetic distance, were observed for the two populations that underwent severe size reductions. Changes in heterozygosity at single loci were unpredictable, as both significant increases and decreases were observed in founder populations. A significant excess of heterozygotes was found in two populations and was highly significant over all four finch populations (P < 0.003). Estimates of effective population size from temporal changes in heterozygosity and allele frequencies were very small (Ne≤ 30) as a result of the founding events and the constraints of islet area on population numbers. We concluded that the PHR population is not adequate as a secondary genetic reserve for T. cantans, and an alternative refuge needs to be established.
Density and variability of dinucleotide microsatellites in the parthenogenetic polyploid snail Melanoides tuberculata
Authors: SAMADI S. , ARTIGUEBIELLE E. , ESTOUP A. , POINTIER J.‐P. , SILVAIN J.‐F. , HELLER J. , CARIOU M.‐L. , JARNE P.
Published: March 2003

Characterization of microsatellites in the parthenogenetic polyploid snail Melanoides tuberculata revealed an unusual high density of dinucleotide repeats. Multiple banding patterns were obtained at these loci, and interpreted as a consequence of polyploidy. Microsatellite variability was low within, but high between, shell morphotypes. Genotypes were wholly transmitted from mothers to offspring. These results suggest that reproduction is strictly apomictic, and that shell morphotypes are genetic clones.
Mitochondrial and nuclear DNA sequence variability among populations of rainbow trout (Oncorhynchus mykiss)
Authors: BAGLEY M. J. , GALL G. A. E.
Published: March 2003

Mitochondrial and nuclear DNA variability was examined to assess population genetic structure and phylogeographic relationships in rainbow trout. Single‐strand conformation polymorphisms and restriction site differences within 1055 bp of the mitochondrial D‐loop region and 1566 bp of nuclear DNA in six single‐copy nuclear DNA regions identified 31 mitochondrial genotypes and 50 nuclear alleles. Gene trees were constructed by sequencing each variant allele or mitochondrial genotype identified. Examination of 30 populations in 10 native rainbow trout groups using an analysis of molecular variance (AMOVA) indicated that 65% of mitochondrial variability and 35% of nuclear variability was explained by differences among the 10 groups. Phylogenetic patterns evident in mitochondrial and nuclear DNA were not always concordant. Differences in the evolutionary patterns detected by mitochondrial and nuclear DNA may reflect the differential impact of past introgression events on variability in the two genomes.
‘Floral’ scent production by Puccinia rust fungi that mimic flowers
Authors: RAGUSO ROBERT A. , ROY BARBARA A.
Published: March 2003

Crucifers (Brassicaceae) in 11 genera are often infected by rust fungi in the Puccinia monoica complex. Infection causes a ‘pseudoflower’ to form that is important for attracting insect visitors that sexually outcross the fungus. ‘Pollinator’ attraction is accomplished through visual floral mimicry, the presence of a nectar reward and floral fragrances. Here we used gas chromatography and mass spectrometry to identify and quantify fragrance production by these rust fungi on several Arabis hosts, and by co‐occurring true flowers that share insect visitors. Fungal pseudoflowers produced distinctive floral fragrances composed primarily of aromatic alcohols, aldehydes and esters. Pseudoflower fragrances were chemically similar to noctuid‐moth‐pollinated flowers, such as Cestrum nocturnum and Abelia grandiflora, but were very different from host flowers, host vegetation and the flowers of coblooming, nonhost angiosperms. There was variation in the quantity and composition of fragrance profiles from different fungal species as well as within and among hosts. The evolution of scent chemistry is relatively conservative in these fungi and can be most parsimoniously explained in three steps by combining chemical data with a previously determined rDNA ITS sequence‐based phylogeny. Pseudoflower scent does not appear to represent a simple modification of host floral or vegetative emissions, nor does it mimic the scent of coblooming flowers. Instead, we suspect that the unique fragrances, beyond their function as pollinator attractants, may be important in reducing gamete loss by reinforcing constancy among foraging insects.
Considerations for measuring genetic variation and population structure with multilocus fingerprinting
Authors: CALL DOUGLAS R. , HALLETT JAMES G. , MECH STEPHEN G. , EVANS MARC
Published: March 2003

Multilocus DNA fingerprinting provides a cost‐effective means to rapidly assay genetic variation at many loci. While this makes the technique particularly attractive for studies of evolution and conservation biology, fingerprint data can be difficult to interpret. Measurement errors inherent with the technique force investigators to group similar‐sized alleles (bands) into discrete bins before estimating genetic parameters. If too little error is accounted for in this process homologous alleles will not be grouped in a common bin, whereas overestimated error can produce bins with homoplasic alleles. We used simulations and empirical data for two frog species (Rana luteiventris and Hyla regilla) to demonstrate that mean band‐sharing (S¯xy) and heterozygosity (H¯E) are a function of both bin width and band profile complexity (i.e. number and distribution of bands). These estimators are also sensitive to the number of lanes included in the analysis when bin width is wide and a floating bin algorithm is employed. Multilocus estimates of H¯E were highly correlated with S¯xy and thus provide no additional information about genetic variation. Estimates of population subdivision (F^ and Φ^ST) appeared robust to changes in bin size. We also examined the issue of statistical independence for band‐sharing data when comparisons are made among all samples. This analysis indicated that the covariance between band‐sharing statistics was very small and not statistically different from zero. We recommend that sensitivity analyses for bin size be used to improve confidence in the biological interpretation of multilocus fingerprints, and that the covariance structure for band‐sharing statistics be examined.
Random amplified polymorphic DNA (RAPD) variation among native little bluestem [Schizachyrium scoparium (Michx.) Nash] populations from sites of high and low fertility in forest and grassland biomes
Authors: HUFF D. R. , QUINN J. A. , HIGGINS B. , PALAZZO A. J.
Published: March 2003

Random amplified polymorphic DNA (RAPD) markers were used to provide estimates of the comparative genetic variation within and among four native populations of Schizachyrium scoparium. Genotypes were collected from high‐ and low‐fertility sites in both New Jersey (forest biome) and in Oklahoma (grassland biome), USA, and propagated in the greenhouse. Four oligonucleotide primers, 10 bp in length, produced a total of 60 RAPD markers, with the minimum marker difference between any two individuals being 14 markers. Euclidean metric distances were calculated among all individuals, and the analysis of molecular variance (AMOVA) technique was used to apportion the total genetic variation among individuals within populations, populations within fertility levels, populations within biomes, fertility levels, and biomes. Even though most genetic variation resided within populations, statistically significant differences were detected between populations within each biome. Furthermore, genetic distances between high and low fertility levels within biomes were equal to or greater than biome distances. Therefore, in this wide‐ranging and highly variable species, RAPD analysis suggests that local site differences in fertility and ecological history can promote genetic differentiation equal to or greater than geographical differentiation.
Consensus multiplex PCR–restriction fragment length polymorphism (RFLP) for rapid detection of plant mitochondrial DNA polymorphism
Authors: CHEN H. , SUN M.
Published: March 2003

A fast, simple, and efficient approach, termed consensus multiplex PCR–RFLP, was developed and employed to detect mitochondrial (mt)DNA variation in three orchid species, Spiranthes hongkongensis, S. sinensis, and S. spiralis. Using multiplex PCR, three pairs of consensus mitchondrial primers were added simultaneously into each reaction tube to amplify three nonoverlapping introns located in the NADH dehydrogenase genes. Fragment length differences in the multiplex PCR amplicons were directly detectable between S. spiralis and the other two species. Further restriction analysis of the multiplex PCR amplicons revealed sufficient mtDNA polymorphism, suitable for phylogenetic studies at the interspecific level. This approach is well suited for large‐scale population surveys of mitochondrial genome diversity in plants. Additionally, the maternal mode of inheritance of organelle genomes renders this approach valuable for rapid identification of the origin and specific parentage of hybrid or allopolyploid species.
Analysis of clonal diversity of the peach–potato aphid, Myzus persicae (Sulzer), in Scotland, UK and evidence for the existence of a predominant clone
Authors: FENTON B. , WOODFORD J. A. T. , MALLOCH G.
Published: March 2003

Clones of the peach–potato aphid, Myzus persicae (Sulzer), mostly from Scotland, UK were examined using an rDNA fingerprinting technique. Eighty patterns (genotypes) were found amongst the 276 clones. A large number of clones (30%) from all sample areas in Scotland exhibited the same simple pattern, suggesting the presence of a single M. persicae clone. There was no difference in genotype distributions between M. persicae collected from brassica or potato crops, suggesting that host‐adapted genotypes have no advantage in the field. Different fingerprints were randomly distributed in the environment, although clones taken from the same leaf were more often the same fingerprint. Highly distinctive fingerprints, which were more widely distributed, suggest that this technique could be used to follow individual clones. In addition to the common clonal type, multiple fingerprint bands were found over successive years, implying that, in Scotland, local overwintering asexual populations are the most common source of M. persicae in the following year.
Molecular phylogeny and ecological diversification in a clade of New World songbirds (genus Vireo)
Authors: CICERO C. , JOHNSON N. K.
Published: March 2003

We constructed a molecular phylogeny for a clade of eye‐ringed vireos (Vireo flavifrons and the V. solitarius complex) to examine existing hypotheses of speciation and ecological diversification. Complete sequences of the mtDNA cytochrome b gene were obtained from 47 individuals of this group plus four vireonid outgroups. Mean levels of sequence divergence in the clade varied from 0.29% to 5.7%. Differences were greatest between V. flavifrons and four taxa of ‘V. solitarius’. The latter separated into three taxonomic, geographical and ecological groups: V. plumbeus plumbeus, V. cassinii cassinii, and V. solitarius solitarius plus V. solitarius alticola. These differed by an average of 2.6–3.2%. Populations within each group revealed low levels of sequence variation (x‐ = 0.20%) and little geographical structuring. The mtDNA data generally corroborate results from allozymes. V. plumbeus shows a loss of yellow‐green carotenoid pigmentation from the ancestral condition. The occupancy of relatively dry habitats by this species and V.cassinii represents a derived ecological shift from more‐humid environments occupied by other species of vireonids. Ecological divergence in this clade occurred in allopatry and is associated with generic‐level stability in morphometrics and foraging styles. Migratory behaviour and seasonal habitat shifts apparently evolved multiple times in vireos breeding in temperate environments. Present geographical and ecological distributions, and low levels of intrataxon genetic divergence, are hypothesized to be the result of postglacial regionalization of climate–plant associations and rapid northward expansion of breeding ranges.
An evaluation of RAPD fragment reproducibility and nature
Authors: PÉREZ T. , ALBORNOZ J. , DOMÍNGUEZ A.
Published: March 2003

Random amplified polymorphic DNA (RAPD) fragment reproducibility was assayed in three animal species: red deer (Cervus elaphus), wild boar (Sus scrofa) and fruit fly (Drosophila melanogaster). Ten 10‐mer primers (Operon) were tested in two replicate reactions per individual under different stringency conditions (annealing temperatures of 35 °C or 45 °C). Two estimates were generated from the data: autosimilarity, which tests the reproducibility of overall banding patterns, and band repeatability, which tests the reproducibility of specific bands. Autosimilarity (the similarity of individuals with themselves) was lower than 1 for all three species ranging between values of 0.66 forDrosophilaat 45 °C and 0.88 for wild boar at 35 °C. Band repeatability was estimated as the proportion of individuals showing homologous bands in both replicates. The fraction of repeatable bands was 23% for deer, 36% for boar and 26% for fruit fly, all at an annealing temperature of 35 °C. Raising the annealing temperature did not improve repeatability. Phage lambda DNA was subjected to amplification and the pattern of bands compared with theoretical expectations based on nucleotide sequence. Observed fragments could not be related to expected ones, even if a 2bp mismatch is allowed. Therefore, the nature of genetic variation uncovered by the RAPD method is unclear. These data demonstrate that prudence should guide inferences about population structure and nucleotide divergence based on RAPD markers.
Mitochondrial DNA variable number tandem repeats (VNTRs): utility and problems in molecular ecology
Authors: LUNT DAVID H. , WHIPPLE LAWRENCE E. , HYMAN BRADLEY C.
Published: March 2003

Analysis of mitochondrial (mt)DNA size polymorphism in the form of variable number tandem repeats (mtVNTRs) has become an increasingly popular methodology for addressing questions in molecular ecology. When detected by PCR, mtVNTR analysis can provide a sensitive, rapid, and cost‐effective measure of genetic variability that may be exploited in studies of population differentiation and biogeography. Despite the emergence of this approach, there has been little critical evaluation of its success or utility as a practical tool. In this review, we identify problematic methodological, theoretical and interpretive factors that can influence the utility of mtVNTR analysis. The reliability of the procedure is considered in terms of both detection of alleles and scoring of intra‐individual allele frequencies. While many of the potential technical problems of the technique do not raise serious practical concerns, this rapid and sensitive methodology is seriously compromised by the difficulty of reliably assessing allele frequencies, of assaying only germline tissue, and in our ignorance of the mechanisms generating mtVNTR diversity. Thus, although there is a considerable potential for mtVNTR pilot studies to assess genetic diversity, the utility of the technique to resolve broader questions in molecular ecology should be treated cautiously until such a time as the system is better understood.
Mutability of microsatellites developed for the antCamponotus consobrinus
Authors: CROZIER R. H. , KAUFMANN B. , CAREW M. E. , CROZIER Y. C.
Published: March 2003

Five highly polymorphic (GA)nmicrosatellite loci are reported for the formicine antCamponotus consobrinus. The occurrence of many nests with a simple family structure enabled a search for new mutations, 11 of which were found from 3055 informative typings. These mutations were not randomly distributed across loci, 10 of them occurring at the locus Ccon70. The spectrum of mutations across alleles at Ccon70 was also nonrandom, with all of them occurring in alleles in the upper half of the allele size distribution. Six of the Ccon70 mutations decreased allele size. The mutations observed fit the stepwise mutation model well, i.e. mutations could always be assigned to an allele which differed in size from them by one repeat unit. The parental origins of the Ccon70 mutations were established and appear more female biased than vertebrate mutations, significantly so compared with human haemophilia A and primate intron mutations. This result may indicate that the lack of meiosis in males (which are haploid in ants) reduces the mutation rate in that sex relative to species in which both sexes are diploid.
Microsatellite variation and assessment of genetic structure in tea tree (Melaleuca alternifolia– Myrtaceae)
Authors: Rossetto M. , Slade R. W. , Baverstock P. R. , Henry R. J. , Lee L. S.
Published: March 2003

Analysis of five microsatellite loci in 500Melaleuca alternifoliaindividuals produced 98 alleles that were useful for population genetic studies. Considerable levels of observed heterozygosity were recorded (HO= 0.724), with ≈ 90% of the variability being detected within populations. A low level of selfing (14%) was suggested to be the principal cause of excess homozygosity in a number of populations (overallFIS= 0.073). This study showed low levels of inbreeding in certain populations as well as a significant isolation‐by‐distance model. Only two groups of populations (Queensland and New South Wales) constituted different genetic provenances as a result of geographical isolation. TheM. alternifoliadata suggest that microsatellite loci did not always arise by a stepwise mutation process but that larger jumps in allele size may be involved in their evolution.